all messages for Guix-related lists mirrored at yhetil.org
 help / color / mirror / code / Atom feed
blob 04de7808baa111c49b034a95f9d35b75a19b62ce 458491 bytes (raw)
name: doc/guix.texi 	 # note: path name is non-authoritative(*)

    1
    2
    3
    4
    5
    6
    7
    8
    9
   10
   11
   12
   13
   14
   15
   16
   17
   18
   19
   20
   21
   22
   23
   24
   25
   26
   27
   28
   29
   30
   31
   32
   33
   34
   35
   36
   37
   38
   39
   40
   41
   42
   43
   44
   45
   46
   47
   48
   49
   50
   51
   52
   53
   54
   55
   56
   57
   58
   59
   60
   61
   62
   63
   64
   65
   66
   67
   68
   69
   70
   71
   72
   73
   74
   75
   76
   77
   78
   79
   80
   81
   82
   83
   84
   85
   86
   87
   88
   89
   90
   91
   92
   93
   94
   95
   96
   97
   98
   99
  100
  101
  102
  103
  104
  105
  106
  107
  108
  109
  110
  111
  112
  113
  114
  115
  116
  117
  118
  119
  120
  121
  122
  123
  124
  125
  126
  127
  128
  129
  130
  131
  132
  133
  134
  135
  136
  137
  138
  139
  140
  141
  142
  143
  144
  145
  146
  147
  148
  149
  150
  151
  152
  153
  154
  155
  156
  157
  158
  159
  160
  161
  162
  163
  164
  165
  166
  167
  168
  169
  170
  171
  172
  173
  174
  175
  176
  177
  178
  179
  180
  181
  182
  183
  184
  185
  186
  187
  188
  189
  190
  191
  192
  193
  194
  195
  196
  197
  198
  199
  200
  201
  202
  203
  204
  205
  206
  207
  208
  209
  210
  211
  212
  213
  214
  215
  216
  217
  218
  219
  220
  221
  222
  223
  224
  225
  226
  227
  228
  229
  230
  231
  232
  233
  234
  235
  236
  237
  238
  239
  240
  241
  242
  243
  244
  245
  246
  247
  248
  249
  250
  251
  252
  253
  254
  255
  256
  257
  258
  259
  260
  261
  262
  263
  264
  265
  266
  267
  268
  269
  270
  271
  272
  273
  274
  275
  276
  277
  278
  279
  280
  281
  282
  283
  284
  285
  286
  287
  288
  289
  290
  291
  292
  293
  294
  295
  296
  297
  298
  299
  300
  301
  302
  303
  304
  305
  306
  307
  308
  309
  310
  311
  312
  313
  314
  315
  316
  317
  318
  319
  320
  321
  322
  323
  324
  325
  326
  327
  328
  329
  330
  331
  332
  333
  334
  335
  336
  337
  338
  339
  340
  341
  342
  343
  344
  345
  346
  347
  348
  349
  350
  351
  352
  353
  354
  355
  356
  357
  358
  359
  360
  361
  362
  363
  364
  365
  366
  367
  368
  369
  370
  371
  372
  373
  374
  375
  376
  377
  378
  379
  380
  381
  382
  383
  384
  385
  386
  387
  388
  389
  390
  391
  392
  393
  394
  395
  396
  397
  398
  399
  400
  401
  402
  403
  404
  405
  406
  407
  408
  409
  410
  411
  412
  413
  414
  415
  416
  417
  418
  419
  420
  421
  422
  423
  424
  425
  426
  427
  428
  429
  430
  431
  432
  433
  434
  435
  436
  437
  438
  439
  440
  441
  442
  443
  444
  445
  446
  447
  448
  449
  450
  451
  452
  453
  454
  455
  456
  457
  458
  459
  460
  461
  462
  463
  464
  465
  466
  467
  468
  469
  470
  471
  472
  473
  474
  475
  476
  477
  478
  479
  480
  481
  482
  483
  484
  485
  486
  487
  488
  489
  490
  491
  492
  493
  494
  495
  496
  497
  498
  499
  500
  501
  502
  503
  504
  505
  506
  507
  508
  509
  510
  511
  512
  513
  514
  515
  516
  517
  518
  519
  520
  521
  522
  523
  524
  525
  526
  527
  528
  529
  530
  531
  532
  533
  534
  535
  536
  537
  538
  539
  540
  541
  542
  543
  544
  545
  546
  547
  548
  549
  550
  551
  552
  553
  554
  555
  556
  557
  558
  559
  560
  561
  562
  563
  564
  565
  566
  567
  568
  569
  570
  571
  572
  573
  574
  575
  576
  577
  578
  579
  580
  581
  582
  583
  584
  585
  586
  587
  588
  589
  590
  591
  592
  593
  594
  595
  596
  597
  598
  599
  600
  601
  602
  603
  604
  605
  606
  607
  608
  609
  610
  611
  612
  613
  614
  615
  616
  617
  618
  619
  620
  621
  622
  623
  624
  625
  626
  627
  628
  629
  630
  631
  632
  633
  634
  635
  636
  637
  638
  639
  640
  641
  642
  643
  644
  645
  646
  647
  648
  649
  650
  651
  652
  653
  654
  655
  656
  657
  658
  659
  660
  661
  662
  663
  664
  665
  666
  667
  668
  669
  670
  671
  672
  673
  674
  675
  676
  677
  678
  679
  680
  681
  682
  683
  684
  685
  686
  687
  688
  689
  690
  691
  692
  693
  694
  695
  696
  697
  698
  699
  700
  701
  702
  703
  704
  705
  706
  707
  708
  709
  710
  711
  712
  713
  714
  715
  716
  717
  718
  719
  720
  721
  722
  723
  724
  725
  726
  727
  728
  729
  730
  731
  732
  733
  734
  735
  736
  737
  738
  739
  740
  741
  742
  743
  744
  745
  746
  747
  748
  749
  750
  751
  752
  753
  754
  755
  756
  757
  758
  759
  760
  761
  762
  763
  764
  765
  766
  767
  768
  769
  770
  771
  772
  773
  774
  775
  776
  777
  778
  779
  780
  781
  782
  783
  784
  785
  786
  787
  788
  789
  790
  791
  792
  793
  794
  795
  796
  797
  798
  799
  800
  801
  802
  803
  804
  805
  806
  807
  808
  809
  810
  811
  812
  813
  814
  815
  816
  817
  818
  819
  820
  821
  822
  823
  824
  825
  826
  827
  828
  829
  830
  831
  832
  833
  834
  835
  836
  837
  838
  839
  840
  841
  842
  843
  844
  845
  846
  847
  848
  849
  850
  851
  852
  853
  854
  855
  856
  857
  858
  859
  860
  861
  862
  863
  864
  865
  866
  867
  868
  869
  870
  871
  872
  873
  874
  875
  876
  877
  878
  879
  880
  881
  882
  883
  884
  885
  886
  887
  888
  889
  890
  891
  892
  893
  894
  895
  896
  897
  898
  899
  900
  901
  902
  903
  904
  905
  906
  907
  908
  909
  910
  911
  912
  913
  914
  915
  916
  917
  918
  919
  920
  921
  922
  923
  924
  925
  926
  927
  928
  929
  930
  931
  932
  933
  934
  935
  936
  937
  938
  939
  940
  941
  942
  943
  944
  945
  946
  947
  948
  949
  950
  951
  952
  953
  954
  955
  956
  957
  958
  959
  960
  961
  962
  963
  964
  965
  966
  967
  968
  969
  970
  971
  972
  973
  974
  975
  976
  977
  978
  979
  980
  981
  982
  983
  984
  985
  986
  987
  988
  989
  990
  991
  992
  993
  994
  995
  996
  997
  998
  999
 1000
 1001
 1002
 1003
 1004
 1005
 1006
 1007
 1008
 1009
 1010
 1011
 1012
 1013
 1014
 1015
 1016
 1017
 1018
 1019
 1020
 1021
 1022
 1023
 1024
 1025
 1026
 1027
 1028
 1029
 1030
 1031
 1032
 1033
 1034
 1035
 1036
 1037
 1038
 1039
 1040
 1041
 1042
 1043
 1044
 1045
 1046
 1047
 1048
 1049
 1050
 1051
 1052
 1053
 1054
 1055
 1056
 1057
 1058
 1059
 1060
 1061
 1062
 1063
 1064
 1065
 1066
 1067
 1068
 1069
 1070
 1071
 1072
 1073
 1074
 1075
 1076
 1077
 1078
 1079
 1080
 1081
 1082
 1083
 1084
 1085
 1086
 1087
 1088
 1089
 1090
 1091
 1092
 1093
 1094
 1095
 1096
 1097
 1098
 1099
 1100
 1101
 1102
 1103
 1104
 1105
 1106
 1107
 1108
 1109
 1110
 1111
 1112
 1113
 1114
 1115
 1116
 1117
 1118
 1119
 1120
 1121
 1122
 1123
 1124
 1125
 1126
 1127
 1128
 1129
 1130
 1131
 1132
 1133
 1134
 1135
 1136
 1137
 1138
 1139
 1140
 1141
 1142
 1143
 1144
 1145
 1146
 1147
 1148
 1149
 1150
 1151
 1152
 1153
 1154
 1155
 1156
 1157
 1158
 1159
 1160
 1161
 1162
 1163
 1164
 1165
 1166
 1167
 1168
 1169
 1170
 1171
 1172
 1173
 1174
 1175
 1176
 1177
 1178
 1179
 1180
 1181
 1182
 1183
 1184
 1185
 1186
 1187
 1188
 1189
 1190
 1191
 1192
 1193
 1194
 1195
 1196
 1197
 1198
 1199
 1200
 1201
 1202
 1203
 1204
 1205
 1206
 1207
 1208
 1209
 1210
 1211
 1212
 1213
 1214
 1215
 1216
 1217
 1218
 1219
 1220
 1221
 1222
 1223
 1224
 1225
 1226
 1227
 1228
 1229
 1230
 1231
 1232
 1233
 1234
 1235
 1236
 1237
 1238
 1239
 1240
 1241
 1242
 1243
 1244
 1245
 1246
 1247
 1248
 1249
 1250
 1251
 1252
 1253
 1254
 1255
 1256
 1257
 1258
 1259
 1260
 1261
 1262
 1263
 1264
 1265
 1266
 1267
 1268
 1269
 1270
 1271
 1272
 1273
 1274
 1275
 1276
 1277
 1278
 1279
 1280
 1281
 1282
 1283
 1284
 1285
 1286
 1287
 1288
 1289
 1290
 1291
 1292
 1293
 1294
 1295
 1296
 1297
 1298
 1299
 1300
 1301
 1302
 1303
 1304
 1305
 1306
 1307
 1308
 1309
 1310
 1311
 1312
 1313
 1314
 1315
 1316
 1317
 1318
 1319
 1320
 1321
 1322
 1323
 1324
 1325
 1326
 1327
 1328
 1329
 1330
 1331
 1332
 1333
 1334
 1335
 1336
 1337
 1338
 1339
 1340
 1341
 1342
 1343
 1344
 1345
 1346
 1347
 1348
 1349
 1350
 1351
 1352
 1353
 1354
 1355
 1356
 1357
 1358
 1359
 1360
 1361
 1362
 1363
 1364
 1365
 1366
 1367
 1368
 1369
 1370
 1371
 1372
 1373
 1374
 1375
 1376
 1377
 1378
 1379
 1380
 1381
 1382
 1383
 1384
 1385
 1386
 1387
 1388
 1389
 1390
 1391
 1392
 1393
 1394
 1395
 1396
 1397
 1398
 1399
 1400
 1401
 1402
 1403
 1404
 1405
 1406
 1407
 1408
 1409
 1410
 1411
 1412
 1413
 1414
 1415
 1416
 1417
 1418
 1419
 1420
 1421
 1422
 1423
 1424
 1425
 1426
 1427
 1428
 1429
 1430
 1431
 1432
 1433
 1434
 1435
 1436
 1437
 1438
 1439
 1440
 1441
 1442
 1443
 1444
 1445
 1446
 1447
 1448
 1449
 1450
 1451
 1452
 1453
 1454
 1455
 1456
 1457
 1458
 1459
 1460
 1461
 1462
 1463
 1464
 1465
 1466
 1467
 1468
 1469
 1470
 1471
 1472
 1473
 1474
 1475
 1476
 1477
 1478
 1479
 1480
 1481
 1482
 1483
 1484
 1485
 1486
 1487
 1488
 1489
 1490
 1491
 1492
 1493
 1494
 1495
 1496
 1497
 1498
 1499
 1500
 1501
 1502
 1503
 1504
 1505
 1506
 1507
 1508
 1509
 1510
 1511
 1512
 1513
 1514
 1515
 1516
 1517
 1518
 1519
 1520
 1521
 1522
 1523
 1524
 1525
 1526
 1527
 1528
 1529
 1530
 1531
 1532
 1533
 1534
 1535
 1536
 1537
 1538
 1539
 1540
 1541
 1542
 1543
 1544
 1545
 1546
 1547
 1548
 1549
 1550
 1551
 1552
 1553
 1554
 1555
 1556
 1557
 1558
 1559
 1560
 1561
 1562
 1563
 1564
 1565
 1566
 1567
 1568
 1569
 1570
 1571
 1572
 1573
 1574
 1575
 1576
 1577
 1578
 1579
 1580
 1581
 1582
 1583
 1584
 1585
 1586
 1587
 1588
 1589
 1590
 1591
 1592
 1593
 1594
 1595
 1596
 1597
 1598
 1599
 1600
 1601
 1602
 1603
 1604
 1605
 1606
 1607
 1608
 1609
 1610
 1611
 1612
 1613
 1614
 1615
 1616
 1617
 1618
 1619
 1620
 1621
 1622
 1623
 1624
 1625
 1626
 1627
 1628
 1629
 1630
 1631
 1632
 1633
 1634
 1635
 1636
 1637
 1638
 1639
 1640
 1641
 1642
 1643
 1644
 1645
 1646
 1647
 1648
 1649
 1650
 1651
 1652
 1653
 1654
 1655
 1656
 1657
 1658
 1659
 1660
 1661
 1662
 1663
 1664
 1665
 1666
 1667
 1668
 1669
 1670
 1671
 1672
 1673
 1674
 1675
 1676
 1677
 1678
 1679
 1680
 1681
 1682
 1683
 1684
 1685
 1686
 1687
 1688
 1689
 1690
 1691
 1692
 1693
 1694
 1695
 1696
 1697
 1698
 1699
 1700
 1701
 1702
 1703
 1704
 1705
 1706
 1707
 1708
 1709
 1710
 1711
 1712
 1713
 1714
 1715
 1716
 1717
 1718
 1719
 1720
 1721
 1722
 1723
 1724
 1725
 1726
 1727
 1728
 1729
 1730
 1731
 1732
 1733
 1734
 1735
 1736
 1737
 1738
 1739
 1740
 1741
 1742
 1743
 1744
 1745
 1746
 1747
 1748
 1749
 1750
 1751
 1752
 1753
 1754
 1755
 1756
 1757
 1758
 1759
 1760
 1761
 1762
 1763
 1764
 1765
 1766
 1767
 1768
 1769
 1770
 1771
 1772
 1773
 1774
 1775
 1776
 1777
 1778
 1779
 1780
 1781
 1782
 1783
 1784
 1785
 1786
 1787
 1788
 1789
 1790
 1791
 1792
 1793
 1794
 1795
 1796
 1797
 1798
 1799
 1800
 1801
 1802
 1803
 1804
 1805
 1806
 1807
 1808
 1809
 1810
 1811
 1812
 1813
 1814
 1815
 1816
 1817
 1818
 1819
 1820
 1821
 1822
 1823
 1824
 1825
 1826
 1827
 1828
 1829
 1830
 1831
 1832
 1833
 1834
 1835
 1836
 1837
 1838
 1839
 1840
 1841
 1842
 1843
 1844
 1845
 1846
 1847
 1848
 1849
 1850
 1851
 1852
 1853
 1854
 1855
 1856
 1857
 1858
 1859
 1860
 1861
 1862
 1863
 1864
 1865
 1866
 1867
 1868
 1869
 1870
 1871
 1872
 1873
 1874
 1875
 1876
 1877
 1878
 1879
 1880
 1881
 1882
 1883
 1884
 1885
 1886
 1887
 1888
 1889
 1890
 1891
 1892
 1893
 1894
 1895
 1896
 1897
 1898
 1899
 1900
 1901
 1902
 1903
 1904
 1905
 1906
 1907
 1908
 1909
 1910
 1911
 1912
 1913
 1914
 1915
 1916
 1917
 1918
 1919
 1920
 1921
 1922
 1923
 1924
 1925
 1926
 1927
 1928
 1929
 1930
 1931
 1932
 1933
 1934
 1935
 1936
 1937
 1938
 1939
 1940
 1941
 1942
 1943
 1944
 1945
 1946
 1947
 1948
 1949
 1950
 1951
 1952
 1953
 1954
 1955
 1956
 1957
 1958
 1959
 1960
 1961
 1962
 1963
 1964
 1965
 1966
 1967
 1968
 1969
 1970
 1971
 1972
 1973
 1974
 1975
 1976
 1977
 1978
 1979
 1980
 1981
 1982
 1983
 1984
 1985
 1986
 1987
 1988
 1989
 1990
 1991
 1992
 1993
 1994
 1995
 1996
 1997
 1998
 1999
 2000
 2001
 2002
 2003
 2004
 2005
 2006
 2007
 2008
 2009
 2010
 2011
 2012
 2013
 2014
 2015
 2016
 2017
 2018
 2019
 2020
 2021
 2022
 2023
 2024
 2025
 2026
 2027
 2028
 2029
 2030
 2031
 2032
 2033
 2034
 2035
 2036
 2037
 2038
 2039
 2040
 2041
 2042
 2043
 2044
 2045
 2046
 2047
 2048
 2049
 2050
 2051
 2052
 2053
 2054
 2055
 2056
 2057
 2058
 2059
 2060
 2061
 2062
 2063
 2064
 2065
 2066
 2067
 2068
 2069
 2070
 2071
 2072
 2073
 2074
 2075
 2076
 2077
 2078
 2079
 2080
 2081
 2082
 2083
 2084
 2085
 2086
 2087
 2088
 2089
 2090
 2091
 2092
 2093
 2094
 2095
 2096
 2097
 2098
 2099
 2100
 2101
 2102
 2103
 2104
 2105
 2106
 2107
 2108
 2109
 2110
 2111
 2112
 2113
 2114
 2115
 2116
 2117
 2118
 2119
 2120
 2121
 2122
 2123
 2124
 2125
 2126
 2127
 2128
 2129
 2130
 2131
 2132
 2133
 2134
 2135
 2136
 2137
 2138
 2139
 2140
 2141
 2142
 2143
 2144
 2145
 2146
 2147
 2148
 2149
 2150
 2151
 2152
 2153
 2154
 2155
 2156
 2157
 2158
 2159
 2160
 2161
 2162
 2163
 2164
 2165
 2166
 2167
 2168
 2169
 2170
 2171
 2172
 2173
 2174
 2175
 2176
 2177
 2178
 2179
 2180
 2181
 2182
 2183
 2184
 2185
 2186
 2187
 2188
 2189
 2190
 2191
 2192
 2193
 2194
 2195
 2196
 2197
 2198
 2199
 2200
 2201
 2202
 2203
 2204
 2205
 2206
 2207
 2208
 2209
 2210
 2211
 2212
 2213
 2214
 2215
 2216
 2217
 2218
 2219
 2220
 2221
 2222
 2223
 2224
 2225
 2226
 2227
 2228
 2229
 2230
 2231
 2232
 2233
 2234
 2235
 2236
 2237
 2238
 2239
 2240
 2241
 2242
 2243
 2244
 2245
 2246
 2247
 2248
 2249
 2250
 2251
 2252
 2253
 2254
 2255
 2256
 2257
 2258
 2259
 2260
 2261
 2262
 2263
 2264
 2265
 2266
 2267
 2268
 2269
 2270
 2271
 2272
 2273
 2274
 2275
 2276
 2277
 2278
 2279
 2280
 2281
 2282
 2283
 2284
 2285
 2286
 2287
 2288
 2289
 2290
 2291
 2292
 2293
 2294
 2295
 2296
 2297
 2298
 2299
 2300
 2301
 2302
 2303
 2304
 2305
 2306
 2307
 2308
 2309
 2310
 2311
 2312
 2313
 2314
 2315
 2316
 2317
 2318
 2319
 2320
 2321
 2322
 2323
 2324
 2325
 2326
 2327
 2328
 2329
 2330
 2331
 2332
 2333
 2334
 2335
 2336
 2337
 2338
 2339
 2340
 2341
 2342
 2343
 2344
 2345
 2346
 2347
 2348
 2349
 2350
 2351
 2352
 2353
 2354
 2355
 2356
 2357
 2358
 2359
 2360
 2361
 2362
 2363
 2364
 2365
 2366
 2367
 2368
 2369
 2370
 2371
 2372
 2373
 2374
 2375
 2376
 2377
 2378
 2379
 2380
 2381
 2382
 2383
 2384
 2385
 2386
 2387
 2388
 2389
 2390
 2391
 2392
 2393
 2394
 2395
 2396
 2397
 2398
 2399
 2400
 2401
 2402
 2403
 2404
 2405
 2406
 2407
 2408
 2409
 2410
 2411
 2412
 2413
 2414
 2415
 2416
 2417
 2418
 2419
 2420
 2421
 2422
 2423
 2424
 2425
 2426
 2427
 2428
 2429
 2430
 2431
 2432
 2433
 2434
 2435
 2436
 2437
 2438
 2439
 2440
 2441
 2442
 2443
 2444
 2445
 2446
 2447
 2448
 2449
 2450
 2451
 2452
 2453
 2454
 2455
 2456
 2457
 2458
 2459
 2460
 2461
 2462
 2463
 2464
 2465
 2466
 2467
 2468
 2469
 2470
 2471
 2472
 2473
 2474
 2475
 2476
 2477
 2478
 2479
 2480
 2481
 2482
 2483
 2484
 2485
 2486
 2487
 2488
 2489
 2490
 2491
 2492
 2493
 2494
 2495
 2496
 2497
 2498
 2499
 2500
 2501
 2502
 2503
 2504
 2505
 2506
 2507
 2508
 2509
 2510
 2511
 2512
 2513
 2514
 2515
 2516
 2517
 2518
 2519
 2520
 2521
 2522
 2523
 2524
 2525
 2526
 2527
 2528
 2529
 2530
 2531
 2532
 2533
 2534
 2535
 2536
 2537
 2538
 2539
 2540
 2541
 2542
 2543
 2544
 2545
 2546
 2547
 2548
 2549
 2550
 2551
 2552
 2553
 2554
 2555
 2556
 2557
 2558
 2559
 2560
 2561
 2562
 2563
 2564
 2565
 2566
 2567
 2568
 2569
 2570
 2571
 2572
 2573
 2574
 2575
 2576
 2577
 2578
 2579
 2580
 2581
 2582
 2583
 2584
 2585
 2586
 2587
 2588
 2589
 2590
 2591
 2592
 2593
 2594
 2595
 2596
 2597
 2598
 2599
 2600
 2601
 2602
 2603
 2604
 2605
 2606
 2607
 2608
 2609
 2610
 2611
 2612
 2613
 2614
 2615
 2616
 2617
 2618
 2619
 2620
 2621
 2622
 2623
 2624
 2625
 2626
 2627
 2628
 2629
 2630
 2631
 2632
 2633
 2634
 2635
 2636
 2637
 2638
 2639
 2640
 2641
 2642
 2643
 2644
 2645
 2646
 2647
 2648
 2649
 2650
 2651
 2652
 2653
 2654
 2655
 2656
 2657
 2658
 2659
 2660
 2661
 2662
 2663
 2664
 2665
 2666
 2667
 2668
 2669
 2670
 2671
 2672
 2673
 2674
 2675
 2676
 2677
 2678
 2679
 2680
 2681
 2682
 2683
 2684
 2685
 2686
 2687
 2688
 2689
 2690
 2691
 2692
 2693
 2694
 2695
 2696
 2697
 2698
 2699
 2700
 2701
 2702
 2703
 2704
 2705
 2706
 2707
 2708
 2709
 2710
 2711
 2712
 2713
 2714
 2715
 2716
 2717
 2718
 2719
 2720
 2721
 2722
 2723
 2724
 2725
 2726
 2727
 2728
 2729
 2730
 2731
 2732
 2733
 2734
 2735
 2736
 2737
 2738
 2739
 2740
 2741
 2742
 2743
 2744
 2745
 2746
 2747
 2748
 2749
 2750
 2751
 2752
 2753
 2754
 2755
 2756
 2757
 2758
 2759
 2760
 2761
 2762
 2763
 2764
 2765
 2766
 2767
 2768
 2769
 2770
 2771
 2772
 2773
 2774
 2775
 2776
 2777
 2778
 2779
 2780
 2781
 2782
 2783
 2784
 2785
 2786
 2787
 2788
 2789
 2790
 2791
 2792
 2793
 2794
 2795
 2796
 2797
 2798
 2799
 2800
 2801
 2802
 2803
 2804
 2805
 2806
 2807
 2808
 2809
 2810
 2811
 2812
 2813
 2814
 2815
 2816
 2817
 2818
 2819
 2820
 2821
 2822
 2823
 2824
 2825
 2826
 2827
 2828
 2829
 2830
 2831
 2832
 2833
 2834
 2835
 2836
 2837
 2838
 2839
 2840
 2841
 2842
 2843
 2844
 2845
 2846
 2847
 2848
 2849
 2850
 2851
 2852
 2853
 2854
 2855
 2856
 2857
 2858
 2859
 2860
 2861
 2862
 2863
 2864
 2865
 2866
 2867
 2868
 2869
 2870
 2871
 2872
 2873
 2874
 2875
 2876
 2877
 2878
 2879
 2880
 2881
 2882
 2883
 2884
 2885
 2886
 2887
 2888
 2889
 2890
 2891
 2892
 2893
 2894
 2895
 2896
 2897
 2898
 2899
 2900
 2901
 2902
 2903
 2904
 2905
 2906
 2907
 2908
 2909
 2910
 2911
 2912
 2913
 2914
 2915
 2916
 2917
 2918
 2919
 2920
 2921
 2922
 2923
 2924
 2925
 2926
 2927
 2928
 2929
 2930
 2931
 2932
 2933
 2934
 2935
 2936
 2937
 2938
 2939
 2940
 2941
 2942
 2943
 2944
 2945
 2946
 2947
 2948
 2949
 2950
 2951
 2952
 2953
 2954
 2955
 2956
 2957
 2958
 2959
 2960
 2961
 2962
 2963
 2964
 2965
 2966
 2967
 2968
 2969
 2970
 2971
 2972
 2973
 2974
 2975
 2976
 2977
 2978
 2979
 2980
 2981
 2982
 2983
 2984
 2985
 2986
 2987
 2988
 2989
 2990
 2991
 2992
 2993
 2994
 2995
 2996
 2997
 2998
 2999
 3000
 3001
 3002
 3003
 3004
 3005
 3006
 3007
 3008
 3009
 3010
 3011
 3012
 3013
 3014
 3015
 3016
 3017
 3018
 3019
 3020
 3021
 3022
 3023
 3024
 3025
 3026
 3027
 3028
 3029
 3030
 3031
 3032
 3033
 3034
 3035
 3036
 3037
 3038
 3039
 3040
 3041
 3042
 3043
 3044
 3045
 3046
 3047
 3048
 3049
 3050
 3051
 3052
 3053
 3054
 3055
 3056
 3057
 3058
 3059
 3060
 3061
 3062
 3063
 3064
 3065
 3066
 3067
 3068
 3069
 3070
 3071
 3072
 3073
 3074
 3075
 3076
 3077
 3078
 3079
 3080
 3081
 3082
 3083
 3084
 3085
 3086
 3087
 3088
 3089
 3090
 3091
 3092
 3093
 3094
 3095
 3096
 3097
 3098
 3099
 3100
 3101
 3102
 3103
 3104
 3105
 3106
 3107
 3108
 3109
 3110
 3111
 3112
 3113
 3114
 3115
 3116
 3117
 3118
 3119
 3120
 3121
 3122
 3123
 3124
 3125
 3126
 3127
 3128
 3129
 3130
 3131
 3132
 3133
 3134
 3135
 3136
 3137
 3138
 3139
 3140
 3141
 3142
 3143
 3144
 3145
 3146
 3147
 3148
 3149
 3150
 3151
 3152
 3153
 3154
 3155
 3156
 3157
 3158
 3159
 3160
 3161
 3162
 3163
 3164
 3165
 3166
 3167
 3168
 3169
 3170
 3171
 3172
 3173
 3174
 3175
 3176
 3177
 3178
 3179
 3180
 3181
 3182
 3183
 3184
 3185
 3186
 3187
 3188
 3189
 3190
 3191
 3192
 3193
 3194
 3195
 3196
 3197
 3198
 3199
 3200
 3201
 3202
 3203
 3204
 3205
 3206
 3207
 3208
 3209
 3210
 3211
 3212
 3213
 3214
 3215
 3216
 3217
 3218
 3219
 3220
 3221
 3222
 3223
 3224
 3225
 3226
 3227
 3228
 3229
 3230
 3231
 3232
 3233
 3234
 3235
 3236
 3237
 3238
 3239
 3240
 3241
 3242
 3243
 3244
 3245
 3246
 3247
 3248
 3249
 3250
 3251
 3252
 3253
 3254
 3255
 3256
 3257
 3258
 3259
 3260
 3261
 3262
 3263
 3264
 3265
 3266
 3267
 3268
 3269
 3270
 3271
 3272
 3273
 3274
 3275
 3276
 3277
 3278
 3279
 3280
 3281
 3282
 3283
 3284
 3285
 3286
 3287
 3288
 3289
 3290
 3291
 3292
 3293
 3294
 3295
 3296
 3297
 3298
 3299
 3300
 3301
 3302
 3303
 3304
 3305
 3306
 3307
 3308
 3309
 3310
 3311
 3312
 3313
 3314
 3315
 3316
 3317
 3318
 3319
 3320
 3321
 3322
 3323
 3324
 3325
 3326
 3327
 3328
 3329
 3330
 3331
 3332
 3333
 3334
 3335
 3336
 3337
 3338
 3339
 3340
 3341
 3342
 3343
 3344
 3345
 3346
 3347
 3348
 3349
 3350
 3351
 3352
 3353
 3354
 3355
 3356
 3357
 3358
 3359
 3360
 3361
 3362
 3363
 3364
 3365
 3366
 3367
 3368
 3369
 3370
 3371
 3372
 3373
 3374
 3375
 3376
 3377
 3378
 3379
 3380
 3381
 3382
 3383
 3384
 3385
 3386
 3387
 3388
 3389
 3390
 3391
 3392
 3393
 3394
 3395
 3396
 3397
 3398
 3399
 3400
 3401
 3402
 3403
 3404
 3405
 3406
 3407
 3408
 3409
 3410
 3411
 3412
 3413
 3414
 3415
 3416
 3417
 3418
 3419
 3420
 3421
 3422
 3423
 3424
 3425
 3426
 3427
 3428
 3429
 3430
 3431
 3432
 3433
 3434
 3435
 3436
 3437
 3438
 3439
 3440
 3441
 3442
 3443
 3444
 3445
 3446
 3447
 3448
 3449
 3450
 3451
 3452
 3453
 3454
 3455
 3456
 3457
 3458
 3459
 3460
 3461
 3462
 3463
 3464
 3465
 3466
 3467
 3468
 3469
 3470
 3471
 3472
 3473
 3474
 3475
 3476
 3477
 3478
 3479
 3480
 3481
 3482
 3483
 3484
 3485
 3486
 3487
 3488
 3489
 3490
 3491
 3492
 3493
 3494
 3495
 3496
 3497
 3498
 3499
 3500
 3501
 3502
 3503
 3504
 3505
 3506
 3507
 3508
 3509
 3510
 3511
 3512
 3513
 3514
 3515
 3516
 3517
 3518
 3519
 3520
 3521
 3522
 3523
 3524
 3525
 3526
 3527
 3528
 3529
 3530
 3531
 3532
 3533
 3534
 3535
 3536
 3537
 3538
 3539
 3540
 3541
 3542
 3543
 3544
 3545
 3546
 3547
 3548
 3549
 3550
 3551
 3552
 3553
 3554
 3555
 3556
 3557
 3558
 3559
 3560
 3561
 3562
 3563
 3564
 3565
 3566
 3567
 3568
 3569
 3570
 3571
 3572
 3573
 3574
 3575
 3576
 3577
 3578
 3579
 3580
 3581
 3582
 3583
 3584
 3585
 3586
 3587
 3588
 3589
 3590
 3591
 3592
 3593
 3594
 3595
 3596
 3597
 3598
 3599
 3600
 3601
 3602
 3603
 3604
 3605
 3606
 3607
 3608
 3609
 3610
 3611
 3612
 3613
 3614
 3615
 3616
 3617
 3618
 3619
 3620
 3621
 3622
 3623
 3624
 3625
 3626
 3627
 3628
 3629
 3630
 3631
 3632
 3633
 3634
 3635
 3636
 3637
 3638
 3639
 3640
 3641
 3642
 3643
 3644
 3645
 3646
 3647
 3648
 3649
 3650
 3651
 3652
 3653
 3654
 3655
 3656
 3657
 3658
 3659
 3660
 3661
 3662
 3663
 3664
 3665
 3666
 3667
 3668
 3669
 3670
 3671
 3672
 3673
 3674
 3675
 3676
 3677
 3678
 3679
 3680
 3681
 3682
 3683
 3684
 3685
 3686
 3687
 3688
 3689
 3690
 3691
 3692
 3693
 3694
 3695
 3696
 3697
 3698
 3699
 3700
 3701
 3702
 3703
 3704
 3705
 3706
 3707
 3708
 3709
 3710
 3711
 3712
 3713
 3714
 3715
 3716
 3717
 3718
 3719
 3720
 3721
 3722
 3723
 3724
 3725
 3726
 3727
 3728
 3729
 3730
 3731
 3732
 3733
 3734
 3735
 3736
 3737
 3738
 3739
 3740
 3741
 3742
 3743
 3744
 3745
 3746
 3747
 3748
 3749
 3750
 3751
 3752
 3753
 3754
 3755
 3756
 3757
 3758
 3759
 3760
 3761
 3762
 3763
 3764
 3765
 3766
 3767
 3768
 3769
 3770
 3771
 3772
 3773
 3774
 3775
 3776
 3777
 3778
 3779
 3780
 3781
 3782
 3783
 3784
 3785
 3786
 3787
 3788
 3789
 3790
 3791
 3792
 3793
 3794
 3795
 3796
 3797
 3798
 3799
 3800
 3801
 3802
 3803
 3804
 3805
 3806
 3807
 3808
 3809
 3810
 3811
 3812
 3813
 3814
 3815
 3816
 3817
 3818
 3819
 3820
 3821
 3822
 3823
 3824
 3825
 3826
 3827
 3828
 3829
 3830
 3831
 3832
 3833
 3834
 3835
 3836
 3837
 3838
 3839
 3840
 3841
 3842
 3843
 3844
 3845
 3846
 3847
 3848
 3849
 3850
 3851
 3852
 3853
 3854
 3855
 3856
 3857
 3858
 3859
 3860
 3861
 3862
 3863
 3864
 3865
 3866
 3867
 3868
 3869
 3870
 3871
 3872
 3873
 3874
 3875
 3876
 3877
 3878
 3879
 3880
 3881
 3882
 3883
 3884
 3885
 3886
 3887
 3888
 3889
 3890
 3891
 3892
 3893
 3894
 3895
 3896
 3897
 3898
 3899
 3900
 3901
 3902
 3903
 3904
 3905
 3906
 3907
 3908
 3909
 3910
 3911
 3912
 3913
 3914
 3915
 3916
 3917
 3918
 3919
 3920
 3921
 3922
 3923
 3924
 3925
 3926
 3927
 3928
 3929
 3930
 3931
 3932
 3933
 3934
 3935
 3936
 3937
 3938
 3939
 3940
 3941
 3942
 3943
 3944
 3945
 3946
 3947
 3948
 3949
 3950
 3951
 3952
 3953
 3954
 3955
 3956
 3957
 3958
 3959
 3960
 3961
 3962
 3963
 3964
 3965
 3966
 3967
 3968
 3969
 3970
 3971
 3972
 3973
 3974
 3975
 3976
 3977
 3978
 3979
 3980
 3981
 3982
 3983
 3984
 3985
 3986
 3987
 3988
 3989
 3990
 3991
 3992
 3993
 3994
 3995
 3996
 3997
 3998
 3999
 4000
 4001
 4002
 4003
 4004
 4005
 4006
 4007
 4008
 4009
 4010
 4011
 4012
 4013
 4014
 4015
 4016
 4017
 4018
 4019
 4020
 4021
 4022
 4023
 4024
 4025
 4026
 4027
 4028
 4029
 4030
 4031
 4032
 4033
 4034
 4035
 4036
 4037
 4038
 4039
 4040
 4041
 4042
 4043
 4044
 4045
 4046
 4047
 4048
 4049
 4050
 4051
 4052
 4053
 4054
 4055
 4056
 4057
 4058
 4059
 4060
 4061
 4062
 4063
 4064
 4065
 4066
 4067
 4068
 4069
 4070
 4071
 4072
 4073
 4074
 4075
 4076
 4077
 4078
 4079
 4080
 4081
 4082
 4083
 4084
 4085
 4086
 4087
 4088
 4089
 4090
 4091
 4092
 4093
 4094
 4095
 4096
 4097
 4098
 4099
 4100
 4101
 4102
 4103
 4104
 4105
 4106
 4107
 4108
 4109
 4110
 4111
 4112
 4113
 4114
 4115
 4116
 4117
 4118
 4119
 4120
 4121
 4122
 4123
 4124
 4125
 4126
 4127
 4128
 4129
 4130
 4131
 4132
 4133
 4134
 4135
 4136
 4137
 4138
 4139
 4140
 4141
 4142
 4143
 4144
 4145
 4146
 4147
 4148
 4149
 4150
 4151
 4152
 4153
 4154
 4155
 4156
 4157
 4158
 4159
 4160
 4161
 4162
 4163
 4164
 4165
 4166
 4167
 4168
 4169
 4170
 4171
 4172
 4173
 4174
 4175
 4176
 4177
 4178
 4179
 4180
 4181
 4182
 4183
 4184
 4185
 4186
 4187
 4188
 4189
 4190
 4191
 4192
 4193
 4194
 4195
 4196
 4197
 4198
 4199
 4200
 4201
 4202
 4203
 4204
 4205
 4206
 4207
 4208
 4209
 4210
 4211
 4212
 4213
 4214
 4215
 4216
 4217
 4218
 4219
 4220
 4221
 4222
 4223
 4224
 4225
 4226
 4227
 4228
 4229
 4230
 4231
 4232
 4233
 4234
 4235
 4236
 4237
 4238
 4239
 4240
 4241
 4242
 4243
 4244
 4245
 4246
 4247
 4248
 4249
 4250
 4251
 4252
 4253
 4254
 4255
 4256
 4257
 4258
 4259
 4260
 4261
 4262
 4263
 4264
 4265
 4266
 4267
 4268
 4269
 4270
 4271
 4272
 4273
 4274
 4275
 4276
 4277
 4278
 4279
 4280
 4281
 4282
 4283
 4284
 4285
 4286
 4287
 4288
 4289
 4290
 4291
 4292
 4293
 4294
 4295
 4296
 4297
 4298
 4299
 4300
 4301
 4302
 4303
 4304
 4305
 4306
 4307
 4308
 4309
 4310
 4311
 4312
 4313
 4314
 4315
 4316
 4317
 4318
 4319
 4320
 4321
 4322
 4323
 4324
 4325
 4326
 4327
 4328
 4329
 4330
 4331
 4332
 4333
 4334
 4335
 4336
 4337
 4338
 4339
 4340
 4341
 4342
 4343
 4344
 4345
 4346
 4347
 4348
 4349
 4350
 4351
 4352
 4353
 4354
 4355
 4356
 4357
 4358
 4359
 4360
 4361
 4362
 4363
 4364
 4365
 4366
 4367
 4368
 4369
 4370
 4371
 4372
 4373
 4374
 4375
 4376
 4377
 4378
 4379
 4380
 4381
 4382
 4383
 4384
 4385
 4386
 4387
 4388
 4389
 4390
 4391
 4392
 4393
 4394
 4395
 4396
 4397
 4398
 4399
 4400
 4401
 4402
 4403
 4404
 4405
 4406
 4407
 4408
 4409
 4410
 4411
 4412
 4413
 4414
 4415
 4416
 4417
 4418
 4419
 4420
 4421
 4422
 4423
 4424
 4425
 4426
 4427
 4428
 4429
 4430
 4431
 4432
 4433
 4434
 4435
 4436
 4437
 4438
 4439
 4440
 4441
 4442
 4443
 4444
 4445
 4446
 4447
 4448
 4449
 4450
 4451
 4452
 4453
 4454
 4455
 4456
 4457
 4458
 4459
 4460
 4461
 4462
 4463
 4464
 4465
 4466
 4467
 4468
 4469
 4470
 4471
 4472
 4473
 4474
 4475
 4476
 4477
 4478
 4479
 4480
 4481
 4482
 4483
 4484
 4485
 4486
 4487
 4488
 4489
 4490
 4491
 4492
 4493
 4494
 4495
 4496
 4497
 4498
 4499
 4500
 4501
 4502
 4503
 4504
 4505
 4506
 4507
 4508
 4509
 4510
 4511
 4512
 4513
 4514
 4515
 4516
 4517
 4518
 4519
 4520
 4521
 4522
 4523
 4524
 4525
 4526
 4527
 4528
 4529
 4530
 4531
 4532
 4533
 4534
 4535
 4536
 4537
 4538
 4539
 4540
 4541
 4542
 4543
 4544
 4545
 4546
 4547
 4548
 4549
 4550
 4551
 4552
 4553
 4554
 4555
 4556
 4557
 4558
 4559
 4560
 4561
 4562
 4563
 4564
 4565
 4566
 4567
 4568
 4569
 4570
 4571
 4572
 4573
 4574
 4575
 4576
 4577
 4578
 4579
 4580
 4581
 4582
 4583
 4584
 4585
 4586
 4587
 4588
 4589
 4590
 4591
 4592
 4593
 4594
 4595
 4596
 4597
 4598
 4599
 4600
 4601
 4602
 4603
 4604
 4605
 4606
 4607
 4608
 4609
 4610
 4611
 4612
 4613
 4614
 4615
 4616
 4617
 4618
 4619
 4620
 4621
 4622
 4623
 4624
 4625
 4626
 4627
 4628
 4629
 4630
 4631
 4632
 4633
 4634
 4635
 4636
 4637
 4638
 4639
 4640
 4641
 4642
 4643
 4644
 4645
 4646
 4647
 4648
 4649
 4650
 4651
 4652
 4653
 4654
 4655
 4656
 4657
 4658
 4659
 4660
 4661
 4662
 4663
 4664
 4665
 4666
 4667
 4668
 4669
 4670
 4671
 4672
 4673
 4674
 4675
 4676
 4677
 4678
 4679
 4680
 4681
 4682
 4683
 4684
 4685
 4686
 4687
 4688
 4689
 4690
 4691
 4692
 4693
 4694
 4695
 4696
 4697
 4698
 4699
 4700
 4701
 4702
 4703
 4704
 4705
 4706
 4707
 4708
 4709
 4710
 4711
 4712
 4713
 4714
 4715
 4716
 4717
 4718
 4719
 4720
 4721
 4722
 4723
 4724
 4725
 4726
 4727
 4728
 4729
 4730
 4731
 4732
 4733
 4734
 4735
 4736
 4737
 4738
 4739
 4740
 4741
 4742
 4743
 4744
 4745
 4746
 4747
 4748
 4749
 4750
 4751
 4752
 4753
 4754
 4755
 4756
 4757
 4758
 4759
 4760
 4761
 4762
 4763
 4764
 4765
 4766
 4767
 4768
 4769
 4770
 4771
 4772
 4773
 4774
 4775
 4776
 4777
 4778
 4779
 4780
 4781
 4782
 4783
 4784
 4785
 4786
 4787
 4788
 4789
 4790
 4791
 4792
 4793
 4794
 4795
 4796
 4797
 4798
 4799
 4800
 4801
 4802
 4803
 4804
 4805
 4806
 4807
 4808
 4809
 4810
 4811
 4812
 4813
 4814
 4815
 4816
 4817
 4818
 4819
 4820
 4821
 4822
 4823
 4824
 4825
 4826
 4827
 4828
 4829
 4830
 4831
 4832
 4833
 4834
 4835
 4836
 4837
 4838
 4839
 4840
 4841
 4842
 4843
 4844
 4845
 4846
 4847
 4848
 4849
 4850
 4851
 4852
 4853
 4854
 4855
 4856
 4857
 4858
 4859
 4860
 4861
 4862
 4863
 4864
 4865
 4866
 4867
 4868
 4869
 4870
 4871
 4872
 4873
 4874
 4875
 4876
 4877
 4878
 4879
 4880
 4881
 4882
 4883
 4884
 4885
 4886
 4887
 4888
 4889
 4890
 4891
 4892
 4893
 4894
 4895
 4896
 4897
 4898
 4899
 4900
 4901
 4902
 4903
 4904
 4905
 4906
 4907
 4908
 4909
 4910
 4911
 4912
 4913
 4914
 4915
 4916
 4917
 4918
 4919
 4920
 4921
 4922
 4923
 4924
 4925
 4926
 4927
 4928
 4929
 4930
 4931
 4932
 4933
 4934
 4935
 4936
 4937
 4938
 4939
 4940
 4941
 4942
 4943
 4944
 4945
 4946
 4947
 4948
 4949
 4950
 4951
 4952
 4953
 4954
 4955
 4956
 4957
 4958
 4959
 4960
 4961
 4962
 4963
 4964
 4965
 4966
 4967
 4968
 4969
 4970
 4971
 4972
 4973
 4974
 4975
 4976
 4977
 4978
 4979
 4980
 4981
 4982
 4983
 4984
 4985
 4986
 4987
 4988
 4989
 4990
 4991
 4992
 4993
 4994
 4995
 4996
 4997
 4998
 4999
 5000
 5001
 5002
 5003
 5004
 5005
 5006
 5007
 5008
 5009
 5010
 5011
 5012
 5013
 5014
 5015
 5016
 5017
 5018
 5019
 5020
 5021
 5022
 5023
 5024
 5025
 5026
 5027
 5028
 5029
 5030
 5031
 5032
 5033
 5034
 5035
 5036
 5037
 5038
 5039
 5040
 5041
 5042
 5043
 5044
 5045
 5046
 5047
 5048
 5049
 5050
 5051
 5052
 5053
 5054
 5055
 5056
 5057
 5058
 5059
 5060
 5061
 5062
 5063
 5064
 5065
 5066
 5067
 5068
 5069
 5070
 5071
 5072
 5073
 5074
 5075
 5076
 5077
 5078
 5079
 5080
 5081
 5082
 5083
 5084
 5085
 5086
 5087
 5088
 5089
 5090
 5091
 5092
 5093
 5094
 5095
 5096
 5097
 5098
 5099
 5100
 5101
 5102
 5103
 5104
 5105
 5106
 5107
 5108
 5109
 5110
 5111
 5112
 5113
 5114
 5115
 5116
 5117
 5118
 5119
 5120
 5121
 5122
 5123
 5124
 5125
 5126
 5127
 5128
 5129
 5130
 5131
 5132
 5133
 5134
 5135
 5136
 5137
 5138
 5139
 5140
 5141
 5142
 5143
 5144
 5145
 5146
 5147
 5148
 5149
 5150
 5151
 5152
 5153
 5154
 5155
 5156
 5157
 5158
 5159
 5160
 5161
 5162
 5163
 5164
 5165
 5166
 5167
 5168
 5169
 5170
 5171
 5172
 5173
 5174
 5175
 5176
 5177
 5178
 5179
 5180
 5181
 5182
 5183
 5184
 5185
 5186
 5187
 5188
 5189
 5190
 5191
 5192
 5193
 5194
 5195
 5196
 5197
 5198
 5199
 5200
 5201
 5202
 5203
 5204
 5205
 5206
 5207
 5208
 5209
 5210
 5211
 5212
 5213
 5214
 5215
 5216
 5217
 5218
 5219
 5220
 5221
 5222
 5223
 5224
 5225
 5226
 5227
 5228
 5229
 5230
 5231
 5232
 5233
 5234
 5235
 5236
 5237
 5238
 5239
 5240
 5241
 5242
 5243
 5244
 5245
 5246
 5247
 5248
 5249
 5250
 5251
 5252
 5253
 5254
 5255
 5256
 5257
 5258
 5259
 5260
 5261
 5262
 5263
 5264
 5265
 5266
 5267
 5268
 5269
 5270
 5271
 5272
 5273
 5274
 5275
 5276
 5277
 5278
 5279
 5280
 5281
 5282
 5283
 5284
 5285
 5286
 5287
 5288
 5289
 5290
 5291
 5292
 5293
 5294
 5295
 5296
 5297
 5298
 5299
 5300
 5301
 5302
 5303
 5304
 5305
 5306
 5307
 5308
 5309
 5310
 5311
 5312
 5313
 5314
 5315
 5316
 5317
 5318
 5319
 5320
 5321
 5322
 5323
 5324
 5325
 5326
 5327
 5328
 5329
 5330
 5331
 5332
 5333
 5334
 5335
 5336
 5337
 5338
 5339
 5340
 5341
 5342
 5343
 5344
 5345
 5346
 5347
 5348
 5349
 5350
 5351
 5352
 5353
 5354
 5355
 5356
 5357
 5358
 5359
 5360
 5361
 5362
 5363
 5364
 5365
 5366
 5367
 5368
 5369
 5370
 5371
 5372
 5373
 5374
 5375
 5376
 5377
 5378
 5379
 5380
 5381
 5382
 5383
 5384
 5385
 5386
 5387
 5388
 5389
 5390
 5391
 5392
 5393
 5394
 5395
 5396
 5397
 5398
 5399
 5400
 5401
 5402
 5403
 5404
 5405
 5406
 5407
 5408
 5409
 5410
 5411
 5412
 5413
 5414
 5415
 5416
 5417
 5418
 5419
 5420
 5421
 5422
 5423
 5424
 5425
 5426
 5427
 5428
 5429
 5430
 5431
 5432
 5433
 5434
 5435
 5436
 5437
 5438
 5439
 5440
 5441
 5442
 5443
 5444
 5445
 5446
 5447
 5448
 5449
 5450
 5451
 5452
 5453
 5454
 5455
 5456
 5457
 5458
 5459
 5460
 5461
 5462
 5463
 5464
 5465
 5466
 5467
 5468
 5469
 5470
 5471
 5472
 5473
 5474
 5475
 5476
 5477
 5478
 5479
 5480
 5481
 5482
 5483
 5484
 5485
 5486
 5487
 5488
 5489
 5490
 5491
 5492
 5493
 5494
 5495
 5496
 5497
 5498
 5499
 5500
 5501
 5502
 5503
 5504
 5505
 5506
 5507
 5508
 5509
 5510
 5511
 5512
 5513
 5514
 5515
 5516
 5517
 5518
 5519
 5520
 5521
 5522
 5523
 5524
 5525
 5526
 5527
 5528
 5529
 5530
 5531
 5532
 5533
 5534
 5535
 5536
 5537
 5538
 5539
 5540
 5541
 5542
 5543
 5544
 5545
 5546
 5547
 5548
 5549
 5550
 5551
 5552
 5553
 5554
 5555
 5556
 5557
 5558
 5559
 5560
 5561
 5562
 5563
 5564
 5565
 5566
 5567
 5568
 5569
 5570
 5571
 5572
 5573
 5574
 5575
 5576
 5577
 5578
 5579
 5580
 5581
 5582
 5583
 5584
 5585
 5586
 5587
 5588
 5589
 5590
 5591
 5592
 5593
 5594
 5595
 5596
 5597
 5598
 5599
 5600
 5601
 5602
 5603
 5604
 5605
 5606
 5607
 5608
 5609
 5610
 5611
 5612
 5613
 5614
 5615
 5616
 5617
 5618
 5619
 5620
 5621
 5622
 5623
 5624
 5625
 5626
 5627
 5628
 5629
 5630
 5631
 5632
 5633
 5634
 5635
 5636
 5637
 5638
 5639
 5640
 5641
 5642
 5643
 5644
 5645
 5646
 5647
 5648
 5649
 5650
 5651
 5652
 5653
 5654
 5655
 5656
 5657
 5658
 5659
 5660
 5661
 5662
 5663
 5664
 5665
 5666
 5667
 5668
 5669
 5670
 5671
 5672
 5673
 5674
 5675
 5676
 5677
 5678
 5679
 5680
 5681
 5682
 5683
 5684
 5685
 5686
 5687
 5688
 5689
 5690
 5691
 5692
 5693
 5694
 5695
 5696
 5697
 5698
 5699
 5700
 5701
 5702
 5703
 5704
 5705
 5706
 5707
 5708
 5709
 5710
 5711
 5712
 5713
 5714
 5715
 5716
 5717
 5718
 5719
 5720
 5721
 5722
 5723
 5724
 5725
 5726
 5727
 5728
 5729
 5730
 5731
 5732
 5733
 5734
 5735
 5736
 5737
 5738
 5739
 5740
 5741
 5742
 5743
 5744
 5745
 5746
 5747
 5748
 5749
 5750
 5751
 5752
 5753
 5754
 5755
 5756
 5757
 5758
 5759
 5760
 5761
 5762
 5763
 5764
 5765
 5766
 5767
 5768
 5769
 5770
 5771
 5772
 5773
 5774
 5775
 5776
 5777
 5778
 5779
 5780
 5781
 5782
 5783
 5784
 5785
 5786
 5787
 5788
 5789
 5790
 5791
 5792
 5793
 5794
 5795
 5796
 5797
 5798
 5799
 5800
 5801
 5802
 5803
 5804
 5805
 5806
 5807
 5808
 5809
 5810
 5811
 5812
 5813
 5814
 5815
 5816
 5817
 5818
 5819
 5820
 5821
 5822
 5823
 5824
 5825
 5826
 5827
 5828
 5829
 5830
 5831
 5832
 5833
 5834
 5835
 5836
 5837
 5838
 5839
 5840
 5841
 5842
 5843
 5844
 5845
 5846
 5847
 5848
 5849
 5850
 5851
 5852
 5853
 5854
 5855
 5856
 5857
 5858
 5859
 5860
 5861
 5862
 5863
 5864
 5865
 5866
 5867
 5868
 5869
 5870
 5871
 5872
 5873
 5874
 5875
 5876
 5877
 5878
 5879
 5880
 5881
 5882
 5883
 5884
 5885
 5886
 5887
 5888
 5889
 5890
 5891
 5892
 5893
 5894
 5895
 5896
 5897
 5898
 5899
 5900
 5901
 5902
 5903
 5904
 5905
 5906
 5907
 5908
 5909
 5910
 5911
 5912
 5913
 5914
 5915
 5916
 5917
 5918
 5919
 5920
 5921
 5922
 5923
 5924
 5925
 5926
 5927
 5928
 5929
 5930
 5931
 5932
 5933
 5934
 5935
 5936
 5937
 5938
 5939
 5940
 5941
 5942
 5943
 5944
 5945
 5946
 5947
 5948
 5949
 5950
 5951
 5952
 5953
 5954
 5955
 5956
 5957
 5958
 5959
 5960
 5961
 5962
 5963
 5964
 5965
 5966
 5967
 5968
 5969
 5970
 5971
 5972
 5973
 5974
 5975
 5976
 5977
 5978
 5979
 5980
 5981
 5982
 5983
 5984
 5985
 5986
 5987
 5988
 5989
 5990
 5991
 5992
 5993
 5994
 5995
 5996
 5997
 5998
 5999
 6000
 6001
 6002
 6003
 6004
 6005
 6006
 6007
 6008
 6009
 6010
 6011
 6012
 6013
 6014
 6015
 6016
 6017
 6018
 6019
 6020
 6021
 6022
 6023
 6024
 6025
 6026
 6027
 6028
 6029
 6030
 6031
 6032
 6033
 6034
 6035
 6036
 6037
 6038
 6039
 6040
 6041
 6042
 6043
 6044
 6045
 6046
 6047
 6048
 6049
 6050
 6051
 6052
 6053
 6054
 6055
 6056
 6057
 6058
 6059
 6060
 6061
 6062
 6063
 6064
 6065
 6066
 6067
 6068
 6069
 6070
 6071
 6072
 6073
 6074
 6075
 6076
 6077
 6078
 6079
 6080
 6081
 6082
 6083
 6084
 6085
 6086
 6087
 6088
 6089
 6090
 6091
 6092
 6093
 6094
 6095
 6096
 6097
 6098
 6099
 6100
 6101
 6102
 6103
 6104
 6105
 6106
 6107
 6108
 6109
 6110
 6111
 6112
 6113
 6114
 6115
 6116
 6117
 6118
 6119
 6120
 6121
 6122
 6123
 6124
 6125
 6126
 6127
 6128
 6129
 6130
 6131
 6132
 6133
 6134
 6135
 6136
 6137
 6138
 6139
 6140
 6141
 6142
 6143
 6144
 6145
 6146
 6147
 6148
 6149
 6150
 6151
 6152
 6153
 6154
 6155
 6156
 6157
 6158
 6159
 6160
 6161
 6162
 6163
 6164
 6165
 6166
 6167
 6168
 6169
 6170
 6171
 6172
 6173
 6174
 6175
 6176
 6177
 6178
 6179
 6180
 6181
 6182
 6183
 6184
 6185
 6186
 6187
 6188
 6189
 6190
 6191
 6192
 6193
 6194
 6195
 6196
 6197
 6198
 6199
 6200
 6201
 6202
 6203
 6204
 6205
 6206
 6207
 6208
 6209
 6210
 6211
 6212
 6213
 6214
 6215
 6216
 6217
 6218
 6219
 6220
 6221
 6222
 6223
 6224
 6225
 6226
 6227
 6228
 6229
 6230
 6231
 6232
 6233
 6234
 6235
 6236
 6237
 6238
 6239
 6240
 6241
 6242
 6243
 6244
 6245
 6246
 6247
 6248
 6249
 6250
 6251
 6252
 6253
 6254
 6255
 6256
 6257
 6258
 6259
 6260
 6261
 6262
 6263
 6264
 6265
 6266
 6267
 6268
 6269
 6270
 6271
 6272
 6273
 6274
 6275
 6276
 6277
 6278
 6279
 6280
 6281
 6282
 6283
 6284
 6285
 6286
 6287
 6288
 6289
 6290
 6291
 6292
 6293
 6294
 6295
 6296
 6297
 6298
 6299
 6300
 6301
 6302
 6303
 6304
 6305
 6306
 6307
 6308
 6309
 6310
 6311
 6312
 6313
 6314
 6315
 6316
 6317
 6318
 6319
 6320
 6321
 6322
 6323
 6324
 6325
 6326
 6327
 6328
 6329
 6330
 6331
 6332
 6333
 6334
 6335
 6336
 6337
 6338
 6339
 6340
 6341
 6342
 6343
 6344
 6345
 6346
 6347
 6348
 6349
 6350
 6351
 6352
 6353
 6354
 6355
 6356
 6357
 6358
 6359
 6360
 6361
 6362
 6363
 6364
 6365
 6366
 6367
 6368
 6369
 6370
 6371
 6372
 6373
 6374
 6375
 6376
 6377
 6378
 6379
 6380
 6381
 6382
 6383
 6384
 6385
 6386
 6387
 6388
 6389
 6390
 6391
 6392
 6393
 6394
 6395
 6396
 6397
 6398
 6399
 6400
 6401
 6402
 6403
 6404
 6405
 6406
 6407
 6408
 6409
 6410
 6411
 6412
 6413
 6414
 6415
 6416
 6417
 6418
 6419
 6420
 6421
 6422
 6423
 6424
 6425
 6426
 6427
 6428
 6429
 6430
 6431
 6432
 6433
 6434
 6435
 6436
 6437
 6438
 6439
 6440
 6441
 6442
 6443
 6444
 6445
 6446
 6447
 6448
 6449
 6450
 6451
 6452
 6453
 6454
 6455
 6456
 6457
 6458
 6459
 6460
 6461
 6462
 6463
 6464
 6465
 6466
 6467
 6468
 6469
 6470
 6471
 6472
 6473
 6474
 6475
 6476
 6477
 6478
 6479
 6480
 6481
 6482
 6483
 6484
 6485
 6486
 6487
 6488
 6489
 6490
 6491
 6492
 6493
 6494
 6495
 6496
 6497
 6498
 6499
 6500
 6501
 6502
 6503
 6504
 6505
 6506
 6507
 6508
 6509
 6510
 6511
 6512
 6513
 6514
 6515
 6516
 6517
 6518
 6519
 6520
 6521
 6522
 6523
 6524
 6525
 6526
 6527
 6528
 6529
 6530
 6531
 6532
 6533
 6534
 6535
 6536
 6537
 6538
 6539
 6540
 6541
 6542
 6543
 6544
 6545
 6546
 6547
 6548
 6549
 6550
 6551
 6552
 6553
 6554
 6555
 6556
 6557
 6558
 6559
 6560
 6561
 6562
 6563
 6564
 6565
 6566
 6567
 6568
 6569
 6570
 6571
 6572
 6573
 6574
 6575
 6576
 6577
 6578
 6579
 6580
 6581
 6582
 6583
 6584
 6585
 6586
 6587
 6588
 6589
 6590
 6591
 6592
 6593
 6594
 6595
 6596
 6597
 6598
 6599
 6600
 6601
 6602
 6603
 6604
 6605
 6606
 6607
 6608
 6609
 6610
 6611
 6612
 6613
 6614
 6615
 6616
 6617
 6618
 6619
 6620
 6621
 6622
 6623
 6624
 6625
 6626
 6627
 6628
 6629
 6630
 6631
 6632
 6633
 6634
 6635
 6636
 6637
 6638
 6639
 6640
 6641
 6642
 6643
 6644
 6645
 6646
 6647
 6648
 6649
 6650
 6651
 6652
 6653
 6654
 6655
 6656
 6657
 6658
 6659
 6660
 6661
 6662
 6663
 6664
 6665
 6666
 6667
 6668
 6669
 6670
 6671
 6672
 6673
 6674
 6675
 6676
 6677
 6678
 6679
 6680
 6681
 6682
 6683
 6684
 6685
 6686
 6687
 6688
 6689
 6690
 6691
 6692
 6693
 6694
 6695
 6696
 6697
 6698
 6699
 6700
 6701
 6702
 6703
 6704
 6705
 6706
 6707
 6708
 6709
 6710
 6711
 6712
 6713
 6714
 6715
 6716
 6717
 6718
 6719
 6720
 6721
 6722
 6723
 6724
 6725
 6726
 6727
 6728
 6729
 6730
 6731
 6732
 6733
 6734
 6735
 6736
 6737
 6738
 6739
 6740
 6741
 6742
 6743
 6744
 6745
 6746
 6747
 6748
 6749
 6750
 6751
 6752
 6753
 6754
 6755
 6756
 6757
 6758
 6759
 6760
 6761
 6762
 6763
 6764
 6765
 6766
 6767
 6768
 6769
 6770
 6771
 6772
 6773
 6774
 6775
 6776
 6777
 6778
 6779
 6780
 6781
 6782
 6783
 6784
 6785
 6786
 6787
 6788
 6789
 6790
 6791
 6792
 6793
 6794
 6795
 6796
 6797
 6798
 6799
 6800
 6801
 6802
 6803
 6804
 6805
 6806
 6807
 6808
 6809
 6810
 6811
 6812
 6813
 6814
 6815
 6816
 6817
 6818
 6819
 6820
 6821
 6822
 6823
 6824
 6825
 6826
 6827
 6828
 6829
 6830
 6831
 6832
 6833
 6834
 6835
 6836
 6837
 6838
 6839
 6840
 6841
 6842
 6843
 6844
 6845
 6846
 6847
 6848
 6849
 6850
 6851
 6852
 6853
 6854
 6855
 6856
 6857
 6858
 6859
 6860
 6861
 6862
 6863
 6864
 6865
 6866
 6867
 6868
 6869
 6870
 6871
 6872
 6873
 6874
 6875
 6876
 6877
 6878
 6879
 6880
 6881
 6882
 6883
 6884
 6885
 6886
 6887
 6888
 6889
 6890
 6891
 6892
 6893
 6894
 6895
 6896
 6897
 6898
 6899
 6900
 6901
 6902
 6903
 6904
 6905
 6906
 6907
 6908
 6909
 6910
 6911
 6912
 6913
 6914
 6915
 6916
 6917
 6918
 6919
 6920
 6921
 6922
 6923
 6924
 6925
 6926
 6927
 6928
 6929
 6930
 6931
 6932
 6933
 6934
 6935
 6936
 6937
 6938
 6939
 6940
 6941
 6942
 6943
 6944
 6945
 6946
 6947
 6948
 6949
 6950
 6951
 6952
 6953
 6954
 6955
 6956
 6957
 6958
 6959
 6960
 6961
 6962
 6963
 6964
 6965
 6966
 6967
 6968
 6969
 6970
 6971
 6972
 6973
 6974
 6975
 6976
 6977
 6978
 6979
 6980
 6981
 6982
 6983
 6984
 6985
 6986
 6987
 6988
 6989
 6990
 6991
 6992
 6993
 6994
 6995
 6996
 6997
 6998
 6999
 7000
 7001
 7002
 7003
 7004
 7005
 7006
 7007
 7008
 7009
 7010
 7011
 7012
 7013
 7014
 7015
 7016
 7017
 7018
 7019
 7020
 7021
 7022
 7023
 7024
 7025
 7026
 7027
 7028
 7029
 7030
 7031
 7032
 7033
 7034
 7035
 7036
 7037
 7038
 7039
 7040
 7041
 7042
 7043
 7044
 7045
 7046
 7047
 7048
 7049
 7050
 7051
 7052
 7053
 7054
 7055
 7056
 7057
 7058
 7059
 7060
 7061
 7062
 7063
 7064
 7065
 7066
 7067
 7068
 7069
 7070
 7071
 7072
 7073
 7074
 7075
 7076
 7077
 7078
 7079
 7080
 7081
 7082
 7083
 7084
 7085
 7086
 7087
 7088
 7089
 7090
 7091
 7092
 7093
 7094
 7095
 7096
 7097
 7098
 7099
 7100
 7101
 7102
 7103
 7104
 7105
 7106
 7107
 7108
 7109
 7110
 7111
 7112
 7113
 7114
 7115
 7116
 7117
 7118
 7119
 7120
 7121
 7122
 7123
 7124
 7125
 7126
 7127
 7128
 7129
 7130
 7131
 7132
 7133
 7134
 7135
 7136
 7137
 7138
 7139
 7140
 7141
 7142
 7143
 7144
 7145
 7146
 7147
 7148
 7149
 7150
 7151
 7152
 7153
 7154
 7155
 7156
 7157
 7158
 7159
 7160
 7161
 7162
 7163
 7164
 7165
 7166
 7167
 7168
 7169
 7170
 7171
 7172
 7173
 7174
 7175
 7176
 7177
 7178
 7179
 7180
 7181
 7182
 7183
 7184
 7185
 7186
 7187
 7188
 7189
 7190
 7191
 7192
 7193
 7194
 7195
 7196
 7197
 7198
 7199
 7200
 7201
 7202
 7203
 7204
 7205
 7206
 7207
 7208
 7209
 7210
 7211
 7212
 7213
 7214
 7215
 7216
 7217
 7218
 7219
 7220
 7221
 7222
 7223
 7224
 7225
 7226
 7227
 7228
 7229
 7230
 7231
 7232
 7233
 7234
 7235
 7236
 7237
 7238
 7239
 7240
 7241
 7242
 7243
 7244
 7245
 7246
 7247
 7248
 7249
 7250
 7251
 7252
 7253
 7254
 7255
 7256
 7257
 7258
 7259
 7260
 7261
 7262
 7263
 7264
 7265
 7266
 7267
 7268
 7269
 7270
 7271
 7272
 7273
 7274
 7275
 7276
 7277
 7278
 7279
 7280
 7281
 7282
 7283
 7284
 7285
 7286
 7287
 7288
 7289
 7290
 7291
 7292
 7293
 7294
 7295
 7296
 7297
 7298
 7299
 7300
 7301
 7302
 7303
 7304
 7305
 7306
 7307
 7308
 7309
 7310
 7311
 7312
 7313
 7314
 7315
 7316
 7317
 7318
 7319
 7320
 7321
 7322
 7323
 7324
 7325
 7326
 7327
 7328
 7329
 7330
 7331
 7332
 7333
 7334
 7335
 7336
 7337
 7338
 7339
 7340
 7341
 7342
 7343
 7344
 7345
 7346
 7347
 7348
 7349
 7350
 7351
 7352
 7353
 7354
 7355
 7356
 7357
 7358
 7359
 7360
 7361
 7362
 7363
 7364
 7365
 7366
 7367
 7368
 7369
 7370
 7371
 7372
 7373
 7374
 7375
 7376
 7377
 7378
 7379
 7380
 7381
 7382
 7383
 7384
 7385
 7386
 7387
 7388
 7389
 7390
 7391
 7392
 7393
 7394
 7395
 7396
 7397
 7398
 7399
 7400
 7401
 7402
 7403
 7404
 7405
 7406
 7407
 7408
 7409
 7410
 7411
 7412
 7413
 7414
 7415
 7416
 7417
 7418
 7419
 7420
 7421
 7422
 7423
 7424
 7425
 7426
 7427
 7428
 7429
 7430
 7431
 7432
 7433
 7434
 7435
 7436
 7437
 7438
 7439
 7440
 7441
 7442
 7443
 7444
 7445
 7446
 7447
 7448
 7449
 7450
 7451
 7452
 7453
 7454
 7455
 7456
 7457
 7458
 7459
 7460
 7461
 7462
 7463
 7464
 7465
 7466
 7467
 7468
 7469
 7470
 7471
 7472
 7473
 7474
 7475
 7476
 7477
 7478
 7479
 7480
 7481
 7482
 7483
 7484
 7485
 7486
 7487
 7488
 7489
 7490
 7491
 7492
 7493
 7494
 7495
 7496
 7497
 7498
 7499
 7500
 7501
 7502
 7503
 7504
 7505
 7506
 7507
 7508
 7509
 7510
 7511
 7512
 7513
 7514
 7515
 7516
 7517
 7518
 7519
 7520
 7521
 7522
 7523
 7524
 7525
 7526
 7527
 7528
 7529
 7530
 7531
 7532
 7533
 7534
 7535
 7536
 7537
 7538
 7539
 7540
 7541
 7542
 7543
 7544
 7545
 7546
 7547
 7548
 7549
 7550
 7551
 7552
 7553
 7554
 7555
 7556
 7557
 7558
 7559
 7560
 7561
 7562
 7563
 7564
 7565
 7566
 7567
 7568
 7569
 7570
 7571
 7572
 7573
 7574
 7575
 7576
 7577
 7578
 7579
 7580
 7581
 7582
 7583
 7584
 7585
 7586
 7587
 7588
 7589
 7590
 7591
 7592
 7593
 7594
 7595
 7596
 7597
 7598
 7599
 7600
 7601
 7602
 7603
 7604
 7605
 7606
 7607
 7608
 7609
 7610
 7611
 7612
 7613
 7614
 7615
 7616
 7617
 7618
 7619
 7620
 7621
 7622
 7623
 7624
 7625
 7626
 7627
 7628
 7629
 7630
 7631
 7632
 7633
 7634
 7635
 7636
 7637
 7638
 7639
 7640
 7641
 7642
 7643
 7644
 7645
 7646
 7647
 7648
 7649
 7650
 7651
 7652
 7653
 7654
 7655
 7656
 7657
 7658
 7659
 7660
 7661
 7662
 7663
 7664
 7665
 7666
 7667
 7668
 7669
 7670
 7671
 7672
 7673
 7674
 7675
 7676
 7677
 7678
 7679
 7680
 7681
 7682
 7683
 7684
 7685
 7686
 7687
 7688
 7689
 7690
 7691
 7692
 7693
 7694
 7695
 7696
 7697
 7698
 7699
 7700
 7701
 7702
 7703
 7704
 7705
 7706
 7707
 7708
 7709
 7710
 7711
 7712
 7713
 7714
 7715
 7716
 7717
 7718
 7719
 7720
 7721
 7722
 7723
 7724
 7725
 7726
 7727
 7728
 7729
 7730
 7731
 7732
 7733
 7734
 7735
 7736
 7737
 7738
 7739
 7740
 7741
 7742
 7743
 7744
 7745
 7746
 7747
 7748
 7749
 7750
 7751
 7752
 7753
 7754
 7755
 7756
 7757
 7758
 7759
 7760
 7761
 7762
 7763
 7764
 7765
 7766
 7767
 7768
 7769
 7770
 7771
 7772
 7773
 7774
 7775
 7776
 7777
 7778
 7779
 7780
 7781
 7782
 7783
 7784
 7785
 7786
 7787
 7788
 7789
 7790
 7791
 7792
 7793
 7794
 7795
 7796
 7797
 7798
 7799
 7800
 7801
 7802
 7803
 7804
 7805
 7806
 7807
 7808
 7809
 7810
 7811
 7812
 7813
 7814
 7815
 7816
 7817
 7818
 7819
 7820
 7821
 7822
 7823
 7824
 7825
 7826
 7827
 7828
 7829
 7830
 7831
 7832
 7833
 7834
 7835
 7836
 7837
 7838
 7839
 7840
 7841
 7842
 7843
 7844
 7845
 7846
 7847
 7848
 7849
 7850
 7851
 7852
 7853
 7854
 7855
 7856
 7857
 7858
 7859
 7860
 7861
 7862
 7863
 7864
 7865
 7866
 7867
 7868
 7869
 7870
 7871
 7872
 7873
 7874
 7875
 7876
 7877
 7878
 7879
 7880
 7881
 7882
 7883
 7884
 7885
 7886
 7887
 7888
 7889
 7890
 7891
 7892
 7893
 7894
 7895
 7896
 7897
 7898
 7899
 7900
 7901
 7902
 7903
 7904
 7905
 7906
 7907
 7908
 7909
 7910
 7911
 7912
 7913
 7914
 7915
 7916
 7917
 7918
 7919
 7920
 7921
 7922
 7923
 7924
 7925
 7926
 7927
 7928
 7929
 7930
 7931
 7932
 7933
 7934
 7935
 7936
 7937
 7938
 7939
 7940
 7941
 7942
 7943
 7944
 7945
 7946
 7947
 7948
 7949
 7950
 7951
 7952
 7953
 7954
 7955
 7956
 7957
 7958
 7959
 7960
 7961
 7962
 7963
 7964
 7965
 7966
 7967
 7968
 7969
 7970
 7971
 7972
 7973
 7974
 7975
 7976
 7977
 7978
 7979
 7980
 7981
 7982
 7983
 7984
 7985
 7986
 7987
 7988
 7989
 7990
 7991
 7992
 7993
 7994
 7995
 7996
 7997
 7998
 7999
 8000
 8001
 8002
 8003
 8004
 8005
 8006
 8007
 8008
 8009
 8010
 8011
 8012
 8013
 8014
 8015
 8016
 8017
 8018
 8019
 8020
 8021
 8022
 8023
 8024
 8025
 8026
 8027
 8028
 8029
 8030
 8031
 8032
 8033
 8034
 8035
 8036
 8037
 8038
 8039
 8040
 8041
 8042
 8043
 8044
 8045
 8046
 8047
 8048
 8049
 8050
 8051
 8052
 8053
 8054
 8055
 8056
 8057
 8058
 8059
 8060
 8061
 8062
 8063
 8064
 8065
 8066
 8067
 8068
 8069
 8070
 8071
 8072
 8073
 8074
 8075
 8076
 8077
 8078
 8079
 8080
 8081
 8082
 8083
 8084
 8085
 8086
 8087
 8088
 8089
 8090
 8091
 8092
 8093
 8094
 8095
 8096
 8097
 8098
 8099
 8100
 8101
 8102
 8103
 8104
 8105
 8106
 8107
 8108
 8109
 8110
 8111
 8112
 8113
 8114
 8115
 8116
 8117
 8118
 8119
 8120
 8121
 8122
 8123
 8124
 8125
 8126
 8127
 8128
 8129
 8130
 8131
 8132
 8133
 8134
 8135
 8136
 8137
 8138
 8139
 8140
 8141
 8142
 8143
 8144
 8145
 8146
 8147
 8148
 8149
 8150
 8151
 8152
 8153
 8154
 8155
 8156
 8157
 8158
 8159
 8160
 8161
 8162
 8163
 8164
 8165
 8166
 8167
 8168
 8169
 8170
 8171
 8172
 8173
 8174
 8175
 8176
 8177
 8178
 8179
 8180
 8181
 8182
 8183
 8184
 8185
 8186
 8187
 8188
 8189
 8190
 8191
 8192
 8193
 8194
 8195
 8196
 8197
 8198
 8199
 8200
 8201
 8202
 8203
 8204
 8205
 8206
 8207
 8208
 8209
 8210
 8211
 8212
 8213
 8214
 8215
 8216
 8217
 8218
 8219
 8220
 8221
 8222
 8223
 8224
 8225
 8226
 8227
 8228
 8229
 8230
 8231
 8232
 8233
 8234
 8235
 8236
 8237
 8238
 8239
 8240
 8241
 8242
 8243
 8244
 8245
 8246
 8247
 8248
 8249
 8250
 8251
 8252
 8253
 8254
 8255
 8256
 8257
 8258
 8259
 8260
 8261
 8262
 8263
 8264
 8265
 8266
 8267
 8268
 8269
 8270
 8271
 8272
 8273
 8274
 8275
 8276
 8277
 8278
 8279
 8280
 8281
 8282
 8283
 8284
 8285
 8286
 8287
 8288
 8289
 8290
 8291
 8292
 8293
 8294
 8295
 8296
 8297
 8298
 8299
 8300
 8301
 8302
 8303
 8304
 8305
 8306
 8307
 8308
 8309
 8310
 8311
 8312
 8313
 8314
 8315
 8316
 8317
 8318
 8319
 8320
 8321
 8322
 8323
 8324
 8325
 8326
 8327
 8328
 8329
 8330
 8331
 8332
 8333
 8334
 8335
 8336
 8337
 8338
 8339
 8340
 8341
 8342
 8343
 8344
 8345
 8346
 8347
 8348
 8349
 8350
 8351
 8352
 8353
 8354
 8355
 8356
 8357
 8358
 8359
 8360
 8361
 8362
 8363
 8364
 8365
 8366
 8367
 8368
 8369
 8370
 8371
 8372
 8373
 8374
 8375
 8376
 8377
 8378
 8379
 8380
 8381
 8382
 8383
 8384
 8385
 8386
 8387
 8388
 8389
 8390
 8391
 8392
 8393
 8394
 8395
 8396
 8397
 8398
 8399
 8400
 8401
 8402
 8403
 8404
 8405
 8406
 8407
 8408
 8409
 8410
 8411
 8412
 8413
 8414
 8415
 8416
 8417
 8418
 8419
 8420
 8421
 8422
 8423
 8424
 8425
 8426
 8427
 8428
 8429
 8430
 8431
 8432
 8433
 8434
 8435
 8436
 8437
 8438
 8439
 8440
 8441
 8442
 8443
 8444
 8445
 8446
 8447
 8448
 8449
 8450
 8451
 8452
 8453
 8454
 8455
 8456
 8457
 8458
 8459
 8460
 8461
 8462
 8463
 8464
 8465
 8466
 8467
 8468
 8469
 8470
 8471
 8472
 8473
 8474
 8475
 8476
 8477
 8478
 8479
 8480
 8481
 8482
 8483
 8484
 8485
 8486
 8487
 8488
 8489
 8490
 8491
 8492
 8493
 8494
 8495
 8496
 8497
 8498
 8499
 8500
 8501
 8502
 8503
 8504
 8505
 8506
 8507
 8508
 8509
 8510
 8511
 8512
 8513
 8514
 8515
 8516
 8517
 8518
 8519
 8520
 8521
 8522
 8523
 8524
 8525
 8526
 8527
 8528
 8529
 8530
 8531
 8532
 8533
 8534
 8535
 8536
 8537
 8538
 8539
 8540
 8541
 8542
 8543
 8544
 8545
 8546
 8547
 8548
 8549
 8550
 8551
 8552
 8553
 8554
 8555
 8556
 8557
 8558
 8559
 8560
 8561
 8562
 8563
 8564
 8565
 8566
 8567
 8568
 8569
 8570
 8571
 8572
 8573
 8574
 8575
 8576
 8577
 8578
 8579
 8580
 8581
 8582
 8583
 8584
 8585
 8586
 8587
 8588
 8589
 8590
 8591
 8592
 8593
 8594
 8595
 8596
 8597
 8598
 8599
 8600
 8601
 8602
 8603
 8604
 8605
 8606
 8607
 8608
 8609
 8610
 8611
 8612
 8613
 8614
 8615
 8616
 8617
 8618
 8619
 8620
 8621
 8622
 8623
 8624
 8625
 8626
 8627
 8628
 8629
 8630
 8631
 8632
 8633
 8634
 8635
 8636
 8637
 8638
 8639
 8640
 8641
 8642
 8643
 8644
 8645
 8646
 8647
 8648
 8649
 8650
 8651
 8652
 8653
 8654
 8655
 8656
 8657
 8658
 8659
 8660
 8661
 8662
 8663
 8664
 8665
 8666
 8667
 8668
 8669
 8670
 8671
 8672
 8673
 8674
 8675
 8676
 8677
 8678
 8679
 8680
 8681
 8682
 8683
 8684
 8685
 8686
 8687
 8688
 8689
 8690
 8691
 8692
 8693
 8694
 8695
 8696
 8697
 8698
 8699
 8700
 8701
 8702
 8703
 8704
 8705
 8706
 8707
 8708
 8709
 8710
 8711
 8712
 8713
 8714
 8715
 8716
 8717
 8718
 8719
 8720
 8721
 8722
 8723
 8724
 8725
 8726
 8727
 8728
 8729
 8730
 8731
 8732
 8733
 8734
 8735
 8736
 8737
 8738
 8739
 8740
 8741
 8742
 8743
 8744
 8745
 8746
 8747
 8748
 8749
 8750
 8751
 8752
 8753
 8754
 8755
 8756
 8757
 8758
 8759
 8760
 8761
 8762
 8763
 8764
 8765
 8766
 8767
 8768
 8769
 8770
 8771
 8772
 8773
 8774
 8775
 8776
 8777
 8778
 8779
 8780
 8781
 8782
 8783
 8784
 8785
 8786
 8787
 8788
 8789
 8790
 8791
 8792
 8793
 8794
 8795
 8796
 8797
 8798
 8799
 8800
 8801
 8802
 8803
 8804
 8805
 8806
 8807
 8808
 8809
 8810
 8811
 8812
 8813
 8814
 8815
 8816
 8817
 8818
 8819
 8820
 8821
 8822
 8823
 8824
 8825
 8826
 8827
 8828
 8829
 8830
 8831
 8832
 8833
 8834
 8835
 8836
 8837
 8838
 8839
 8840
 8841
 8842
 8843
 8844
 8845
 8846
 8847
 8848
 8849
 8850
 8851
 8852
 8853
 8854
 8855
 8856
 8857
 8858
 8859
 8860
 8861
 8862
 8863
 8864
 8865
 8866
 8867
 8868
 8869
 8870
 8871
 8872
 8873
 8874
 8875
 8876
 8877
 8878
 8879
 8880
 8881
 8882
 8883
 8884
 8885
 8886
 8887
 8888
 8889
 8890
 8891
 8892
 8893
 8894
 8895
 8896
 8897
 8898
 8899
 8900
 8901
 8902
 8903
 8904
 8905
 8906
 8907
 8908
 8909
 8910
 8911
 8912
 8913
 8914
 8915
 8916
 8917
 8918
 8919
 8920
 8921
 8922
 8923
 8924
 8925
 8926
 8927
 8928
 8929
 8930
 8931
 8932
 8933
 8934
 8935
 8936
 8937
 8938
 8939
 8940
 8941
 8942
 8943
 8944
 8945
 8946
 8947
 8948
 8949
 8950
 8951
 8952
 8953
 8954
 8955
 8956
 8957
 8958
 8959
 8960
 8961
 8962
 8963
 8964
 8965
 8966
 8967
 8968
 8969
 8970
 8971
 8972
 8973
 8974
 8975
 8976
 8977
 8978
 8979
 8980
 8981
 8982
 8983
 8984
 8985
 8986
 8987
 8988
 8989
 8990
 8991
 8992
 8993
 8994
 8995
 8996
 8997
 8998
 8999
 9000
 9001
 9002
 9003
 9004
 9005
 9006
 9007
 9008
 9009
 9010
 9011
 9012
 9013
 9014
 9015
 9016
 9017
 9018
 9019
 9020
 9021
 9022
 9023
 9024
 9025
 9026
 9027
 9028
 9029
 9030
 9031
 9032
 9033
 9034
 9035
 9036
 9037
 9038
 9039
 9040
 9041
 9042
 9043
 9044
 9045
 9046
 9047
 9048
 9049
 9050
 9051
 9052
 9053
 9054
 9055
 9056
 9057
 9058
 9059
 9060
 9061
 9062
 9063
 9064
 9065
 9066
 9067
 9068
 9069
 9070
 9071
 9072
 9073
 9074
 9075
 9076
 9077
 9078
 9079
 9080
 9081
 9082
 9083
 9084
 9085
 9086
 9087
 9088
 9089
 9090
 9091
 9092
 9093
 9094
 9095
 9096
 9097
 9098
 9099
 9100
 9101
 9102
 9103
 9104
 9105
 9106
 9107
 9108
 9109
 9110
 9111
 9112
 9113
 9114
 9115
 9116
 9117
 9118
 9119
 9120
 9121
 9122
 9123
 9124
 9125
 9126
 9127
 9128
 9129
 9130
 9131
 9132
 9133
 9134
 9135
 9136
 9137
 9138
 9139
 9140
 9141
 9142
 9143
 9144
 9145
 9146
 9147
 9148
 9149
 9150
 9151
 9152
 9153
 9154
 9155
 9156
 9157
 9158
 9159
 9160
 9161
 9162
 9163
 9164
 9165
 9166
 9167
 9168
 9169
 9170
 9171
 9172
 9173
 9174
 9175
 9176
 9177
 9178
 9179
 9180
 9181
 9182
 9183
 9184
 9185
 9186
 9187
 9188
 9189
 9190
 9191
 9192
 9193
 9194
 9195
 9196
 9197
 9198
 9199
 9200
 9201
 9202
 9203
 9204
 9205
 9206
 9207
 9208
 9209
 9210
 9211
 9212
 9213
 9214
 9215
 9216
 9217
 9218
 9219
 9220
 9221
 9222
 9223
 9224
 9225
 9226
 9227
 9228
 9229
 9230
 9231
 9232
 9233
 9234
 9235
 9236
 9237
 9238
 9239
 9240
 9241
 9242
 9243
 9244
 9245
 9246
 9247
 9248
 9249
 9250
 9251
 9252
 9253
 9254
 9255
 9256
 9257
 9258
 9259
 9260
 9261
 9262
 9263
 9264
 9265
 9266
 9267
 9268
 9269
 9270
 9271
 9272
 9273
 9274
 9275
 9276
 9277
 9278
 9279
 9280
 9281
 9282
 9283
 9284
 9285
 9286
 9287
 9288
 9289
 9290
 9291
 9292
 9293
 9294
 9295
 9296
 9297
 9298
 9299
 9300
 9301
 9302
 9303
 9304
 9305
 9306
 9307
 9308
 9309
 9310
 9311
 9312
 9313
 9314
 9315
 9316
 9317
 9318
 9319
 9320
 9321
 9322
 9323
 9324
 9325
 9326
 9327
 9328
 9329
 9330
 9331
 9332
 9333
 9334
 9335
 9336
 9337
 9338
 9339
 9340
 9341
 9342
 9343
 9344
 9345
 9346
 9347
 9348
 9349
 9350
 9351
 9352
 9353
 9354
 9355
 9356
 9357
 9358
 9359
 9360
 9361
 9362
 9363
 9364
 9365
 9366
 9367
 9368
 9369
 9370
 9371
 9372
 9373
 9374
 9375
 9376
 9377
 9378
 9379
 9380
 9381
 9382
 9383
 9384
 9385
 9386
 9387
 9388
 9389
 9390
 9391
 9392
 9393
 9394
 9395
 9396
 9397
 9398
 9399
 9400
 9401
 9402
 9403
 9404
 9405
 9406
 9407
 9408
 9409
 9410
 9411
 9412
 9413
 9414
 9415
 9416
 9417
 9418
 9419
 9420
 9421
 9422
 9423
 9424
 9425
 9426
 9427
 9428
 9429
 9430
 9431
 9432
 9433
 9434
 9435
 9436
 9437
 9438
 9439
 9440
 9441
 9442
 9443
 9444
 9445
 9446
 9447
 9448
 9449
 9450
 9451
 9452
 9453
 9454
 9455
 9456
 9457
 9458
 9459
 9460
 9461
 9462
 9463
 9464
 9465
 9466
 9467
 9468
 9469
 9470
 9471
 9472
 9473
 9474
 9475
 9476
 9477
 9478
 9479
 9480
 9481
 9482
 9483
 9484
 9485
 9486
 9487
 9488
 9489
 9490
 9491
 9492
 9493
 9494
 9495
 9496
 9497
 9498
 9499
 9500
 9501
 9502
 9503
 9504
 9505
 9506
 9507
 9508
 9509
 9510
 9511
 9512
 9513
 9514
 9515
 9516
 9517
 9518
 9519
 9520
 9521
 9522
 9523
 9524
 9525
 9526
 9527
 9528
 9529
 9530
 9531
 9532
 9533
 9534
 9535
 9536
 9537
 9538
 9539
 9540
 9541
 9542
 9543
 9544
 9545
 9546
 9547
 9548
 9549
 9550
 9551
 9552
 9553
 9554
 9555
 9556
 9557
 9558
 9559
 9560
 9561
 9562
 9563
 9564
 9565
 9566
 9567
 9568
 9569
 9570
 9571
 9572
 9573
 9574
 9575
 9576
 9577
 9578
 9579
 9580
 9581
 9582
 9583
 9584
 9585
 9586
 9587
 9588
 9589
 9590
 9591
 9592
 9593
 9594
 9595
 9596
 9597
 9598
 9599
 9600
 9601
 9602
 9603
 9604
 9605
 9606
 9607
 9608
 9609
 9610
 9611
 9612
 9613
 9614
 9615
 9616
 9617
 9618
 9619
 9620
 9621
 9622
 9623
 9624
 9625
 9626
 9627
 9628
 9629
 9630
 9631
 9632
 9633
 9634
 9635
 9636
 9637
 9638
 9639
 9640
 9641
 9642
 9643
 9644
 9645
 9646
 9647
 9648
 9649
 9650
 9651
 9652
 9653
 9654
 9655
 9656
 9657
 9658
 9659
 9660
 9661
 9662
 9663
 9664
 9665
 9666
 9667
 9668
 9669
 9670
 9671
 9672
 9673
 9674
 9675
 9676
 9677
 9678
 9679
 9680
 9681
 9682
 9683
 9684
 9685
 9686
 9687
 9688
 9689
 9690
 9691
 9692
 9693
 9694
 9695
 9696
 9697
 9698
 9699
 9700
 9701
 9702
 9703
 9704
 9705
 9706
 9707
 9708
 9709
 9710
 9711
 9712
 9713
 9714
 9715
 9716
 9717
 9718
 9719
 9720
 9721
 9722
 9723
 9724
 9725
 9726
 9727
 9728
 9729
 9730
 9731
 9732
 9733
 9734
 9735
 9736
 9737
 9738
 9739
 9740
 9741
 9742
 9743
 9744
 9745
 9746
 9747
 9748
 9749
 9750
 9751
 9752
 9753
 9754
 9755
 9756
 9757
 9758
 9759
 9760
 9761
 9762
 9763
 9764
 9765
 9766
 9767
 9768
 9769
 9770
 9771
 9772
 9773
 9774
 9775
 9776
 9777
 9778
 9779
 9780
 9781
 9782
 9783
 9784
 9785
 9786
 9787
 9788
 9789
 9790
 9791
 9792
 9793
 9794
 9795
 9796
 9797
 9798
 9799
 9800
 9801
 9802
 9803
 9804
 9805
 9806
 9807
 9808
 9809
 9810
 9811
 9812
 9813
 9814
 9815
 9816
 9817
 9818
 9819
 9820
 9821
 9822
 9823
 9824
 9825
 9826
 9827
 9828
 9829
 9830
 9831
 9832
 9833
 9834
 9835
 9836
 9837
 9838
 9839
 9840
 9841
 9842
 9843
 9844
 9845
 9846
 9847
 9848
 9849
 9850
 9851
 9852
 9853
 9854
 9855
 9856
 9857
 9858
 9859
 9860
 9861
 9862
 9863
 9864
 9865
 9866
 9867
 9868
 9869
 9870
 9871
 9872
 9873
 9874
 9875
 9876
 9877
 9878
 9879
 9880
 9881
 9882
 9883
 9884
 9885
 9886
 9887
 9888
 9889
 9890
 9891
 9892
 9893
 9894
 9895
 9896
 9897
 9898
 9899
 9900
 9901
 9902
 9903
 9904
 9905
 9906
 9907
 9908
 9909
 9910
 9911
 9912
 9913
 9914
 9915
 9916
 9917
 9918
 9919
 9920
 9921
 9922
 9923
 9924
 9925
 9926
 9927
 9928
 9929
 9930
 9931
 9932
 9933
 9934
 9935
 9936
 9937
 9938
 9939
 9940
 9941
 9942
 9943
 9944
 9945
 9946
 9947
 9948
 9949
 9950
 9951
 9952
 9953
 9954
 9955
 9956
 9957
 9958
 9959
 9960
 9961
 9962
 9963
 9964
 9965
 9966
 9967
 9968
 9969
 9970
 9971
 9972
 9973
 9974
 9975
 9976
 9977
 9978
 9979
 9980
 9981
 9982
 9983
 9984
 9985
 9986
 9987
 9988
 9989
 9990
 9991
 9992
 9993
 9994
 9995
 9996
 9997
 9998
 9999
10000
10001
10002
10003
10004
10005
10006
10007
10008
10009
10010
10011
10012
10013
10014
10015
10016
10017
10018
10019
10020
10021
10022
10023
10024
10025
10026
10027
10028
10029
10030
10031
10032
10033
10034
10035
10036
10037
10038
10039
10040
10041
10042
10043
10044
10045
10046
10047
10048
10049
10050
10051
10052
10053
10054
10055
10056
10057
10058
10059
10060
10061
10062
10063
10064
10065
10066
10067
10068
10069
10070
10071
10072
10073
10074
10075
10076
10077
10078
10079
10080
10081
10082
10083
10084
10085
10086
10087
10088
10089
10090
10091
10092
10093
10094
10095
10096
10097
10098
10099
10100
10101
10102
10103
10104
10105
10106
10107
10108
10109
10110
10111
10112
10113
10114
10115
10116
10117
10118
10119
10120
10121
10122
10123
10124
10125
10126
10127
10128
10129
10130
10131
10132
10133
10134
10135
10136
10137
10138
10139
10140
10141
10142
10143
10144
10145
10146
10147
10148
10149
10150
10151
10152
10153
10154
10155
10156
10157
10158
10159
10160
10161
10162
10163
10164
10165
10166
10167
10168
10169
10170
10171
10172
10173
10174
10175
10176
10177
10178
10179
10180
10181
10182
10183
10184
10185
10186
10187
10188
10189
10190
10191
10192
10193
10194
10195
10196
10197
10198
10199
10200
10201
10202
10203
10204
10205
10206
10207
10208
10209
10210
10211
10212
10213
10214
10215
10216
10217
10218
10219
10220
10221
10222
10223
10224
10225
10226
10227
10228
10229
10230
10231
10232
10233
10234
10235
10236
10237
10238
10239
10240
10241
10242
10243
10244
10245
10246
10247
10248
10249
10250
10251
10252
10253
10254
10255
10256
10257
10258
10259
10260
10261
10262
10263
10264
10265
10266
10267
10268
10269
10270
10271
10272
10273
10274
10275
10276
10277
10278
10279
10280
10281
10282
10283
10284
10285
10286
10287
10288
10289
10290
10291
10292
10293
10294
10295
10296
10297
10298
10299
10300
10301
10302
10303
10304
10305
10306
10307
10308
10309
10310
10311
10312
10313
10314
10315
10316
10317
10318
10319
10320
10321
10322
10323
10324
10325
10326
10327
10328
10329
10330
10331
10332
10333
10334
10335
10336
10337
10338
10339
10340
10341
10342
10343
10344
10345
10346
10347
10348
10349
10350
10351
10352
10353
10354
10355
10356
10357
10358
10359
10360
10361
10362
10363
10364
10365
10366
10367
10368
10369
10370
10371
10372
10373
10374
10375
10376
10377
10378
10379
10380
10381
10382
10383
10384
10385
10386
10387
10388
10389
10390
10391
10392
10393
10394
10395
10396
10397
10398
10399
10400
10401
10402
10403
10404
10405
10406
10407
10408
10409
10410
10411
10412
10413
10414
10415
10416
10417
10418
10419
10420
10421
10422
10423
10424
10425
10426
10427
10428
10429
10430
10431
10432
10433
10434
10435
10436
10437
10438
10439
10440
10441
10442
10443
10444
10445
10446
10447
10448
10449
10450
10451
10452
10453
10454
10455
10456
10457
10458
10459
10460
10461
10462
10463
10464
10465
10466
10467
10468
10469
10470
10471
10472
10473
10474
10475
10476
10477
10478
10479
10480
10481
10482
10483
10484
10485
10486
10487
10488
10489
10490
10491
10492
10493
10494
10495
10496
10497
10498
10499
10500
10501
10502
10503
10504
10505
10506
10507
10508
10509
10510
10511
10512
10513
10514
10515
10516
10517
10518
10519
10520
10521
10522
10523
10524
10525
10526
10527
10528
10529
10530
10531
10532
10533
10534
10535
10536
10537
10538
10539
10540
10541
10542
10543
10544
10545
10546
10547
10548
10549
10550
10551
10552
10553
10554
10555
10556
10557
10558
10559
10560
10561
10562
10563
10564
10565
10566
10567
10568
10569
10570
10571
10572
10573
10574
10575
10576
10577
10578
10579
10580
10581
10582
10583
10584
10585
10586
10587
10588
10589
10590
10591
10592
10593
10594
10595
10596
10597
10598
10599
10600
10601
10602
10603
10604
10605
10606
10607
10608
10609
10610
10611
10612
10613
10614
10615
10616
10617
10618
10619
10620
10621
10622
10623
10624
10625
10626
10627
10628
10629
10630
10631
10632
10633
10634
10635
10636
10637
10638
10639
10640
10641
10642
10643
10644
10645
10646
10647
10648
10649
10650
10651
10652
10653
10654
10655
10656
10657
10658
10659
10660
10661
10662
10663
10664
10665
10666
10667
10668
10669
10670
10671
10672
10673
10674
10675
10676
10677
10678
10679
10680
10681
10682
10683
10684
10685
10686
10687
10688
10689
10690
10691
10692
10693
10694
10695
10696
10697
10698
10699
10700
10701
10702
10703
10704
10705
10706
10707
10708
10709
10710
10711
10712
10713
10714
10715
10716
10717
10718
10719
10720
10721
10722
10723
10724
10725
10726
10727
10728
10729
10730
10731
10732
10733
10734
10735
10736
10737
10738
10739
10740
10741
10742
10743
10744
10745
10746
10747
10748
10749
10750
10751
10752
10753
10754
10755
10756
10757
10758
10759
10760
10761
10762
10763
10764
10765
10766
10767
10768
10769
10770
10771
10772
10773
10774
10775
10776
10777
10778
10779
10780
10781
10782
10783
10784
10785
10786
10787
10788
10789
10790
10791
10792
10793
10794
10795
10796
10797
10798
10799
10800
10801
10802
10803
10804
10805
10806
10807
10808
10809
10810
10811
10812
10813
10814
10815
10816
10817
10818
10819
10820
10821
10822
10823
10824
10825
10826
10827
10828
10829
10830
10831
10832
10833
10834
10835
10836
10837
10838
10839
10840
10841
10842
10843
10844
10845
10846
10847
10848
10849
10850
10851
10852
10853
10854
10855
10856
10857
10858
10859
10860
10861
10862
10863
10864
10865
10866
10867
10868
10869
10870
10871
10872
10873
10874
10875
10876
10877
10878
10879
10880
10881
10882
10883
10884
10885
10886
10887
10888
10889
10890
10891
10892
10893
10894
10895
10896
10897
10898
10899
10900
10901
10902
10903
10904
10905
10906
10907
10908
10909
10910
10911
10912
10913
10914
10915
10916
10917
10918
10919
10920
10921
10922
10923
10924
10925
10926
10927
10928
10929
10930
10931
10932
10933
10934
10935
10936
10937
10938
10939
10940
10941
10942
10943
10944
10945
10946
10947
10948
10949
10950
10951
10952
10953
10954
10955
10956
10957
10958
10959
10960
10961
10962
10963
10964
10965
10966
10967
10968
10969
10970
10971
10972
10973
10974
10975
10976
10977
10978
10979
10980
10981
10982
10983
10984
10985
10986
10987
10988
10989
10990
10991
10992
10993
10994
10995
10996
10997
10998
10999
11000
11001
11002
11003
11004
11005
11006
11007
11008
11009
11010
11011
11012
11013
11014
11015
11016
11017
11018
11019
11020
11021
11022
11023
11024
11025
11026
11027
11028
11029
11030
11031
11032
11033
11034
11035
11036
11037
11038
11039
11040
11041
11042
11043
11044
11045
11046
11047
11048
11049
11050
11051
11052
11053
11054
11055
11056
11057
11058
11059
11060
11061
11062
11063
11064
11065
11066
11067
11068
11069
11070
11071
11072
11073
11074
11075
11076
11077
11078
11079
11080
11081
11082
11083
11084
11085
11086
11087
11088
11089
11090
11091
11092
11093
11094
11095
11096
11097
11098
11099
11100
11101
11102
11103
11104
11105
11106
11107
11108
11109
11110
11111
11112
11113
11114
11115
11116
11117
11118
11119
11120
11121
11122
11123
11124
11125
11126
11127
11128
11129
11130
11131
11132
11133
11134
11135
11136
11137
11138
11139
11140
11141
11142
11143
11144
11145
11146
11147
11148
11149
11150
11151
11152
11153
11154
11155
11156
11157
11158
11159
11160
11161
11162
11163
11164
11165
11166
11167
11168
11169
11170
11171
11172
11173
11174
11175
11176
11177
11178
11179
11180
11181
11182
11183
11184
11185
11186
11187
11188
11189
11190
11191
11192
11193
11194
11195
11196
11197
11198
11199
11200
11201
11202
11203
11204
11205
11206
11207
11208
11209
11210
11211
11212
11213
11214
11215
11216
11217
11218
11219
11220
11221
11222
11223
11224
11225
11226
11227
11228
11229
11230
11231
11232
11233
11234
11235
11236
11237
11238
11239
11240
11241
11242
11243
11244
11245
11246
11247
11248
11249
11250
11251
11252
11253
11254
11255
11256
11257
11258
11259
11260
11261
11262
11263
11264
11265
11266
11267
11268
11269
11270
11271
11272
11273
11274
11275
11276
11277
11278
11279
11280
11281
11282
11283
11284
11285
11286
11287
11288
11289
11290
11291
11292
11293
11294
11295
11296
11297
11298
11299
11300
11301
11302
11303
11304
11305
11306
11307
11308
11309
11310
11311
11312
11313
11314
11315
11316
11317
11318
11319
11320
11321
11322
11323
11324
11325
11326
11327
11328
11329
11330
11331
11332
11333
11334
11335
11336
11337
11338
11339
11340
11341
11342
11343
11344
11345
11346
11347
11348
11349
11350
11351
11352
11353
11354
11355
11356
11357
11358
11359
11360
11361
11362
11363
11364
11365
11366
11367
11368
11369
11370
11371
11372
11373
11374
11375
11376
11377
11378
11379
11380
11381
11382
11383
11384
11385
11386
11387
11388
11389
11390
11391
11392
11393
11394
11395
11396
11397
11398
11399
11400
11401
11402
11403
11404
11405
11406
11407
11408
11409
11410
11411
11412
11413
11414
11415
11416
11417
11418
11419
11420
11421
11422
11423
11424
11425
11426
11427
11428
11429
11430
11431
11432
11433
11434
11435
11436
11437
11438
11439
11440
11441
11442
11443
11444
11445
11446
11447
11448
11449
11450
11451
11452
11453
11454
11455
11456
11457
11458
11459
11460
11461
11462
11463
11464
11465
11466
11467
11468
11469
11470
11471
11472
11473
11474
11475
11476
11477
11478
11479
11480
11481
11482
11483
11484
11485
11486
11487
11488
11489
11490
11491
11492
11493
11494
11495
11496
11497
11498
11499
11500
11501
11502
11503
11504
11505
11506
11507
11508
11509
11510
11511
11512
11513
11514
11515
11516
11517
11518
11519
11520
11521
11522
11523
11524
11525
11526
11527
11528
11529
11530
11531
11532
11533
11534
11535
11536
11537
11538
11539
11540
11541
11542
11543
11544
11545
11546
11547
11548
11549
11550
11551
11552
11553
11554
11555
11556
11557
11558
11559
11560
11561
11562
11563
11564
11565
11566
11567
11568
11569
11570
11571
11572
11573
11574
11575
11576
11577
11578
11579
11580
11581
11582
11583
11584
11585
11586
11587
11588
11589
11590
11591
11592
11593
11594
11595
11596
11597
11598
11599
11600
11601
11602
11603
11604
11605
11606
11607
11608
11609
11610
11611
11612
11613
11614
11615
11616
11617
11618
11619
11620
11621
11622
11623
11624
11625
11626
11627
11628
11629
11630
11631
11632
11633
11634
11635
11636
11637
11638
11639
11640
11641
11642
11643
11644
11645
11646
11647
11648
11649
11650
11651
11652
11653
11654
11655
11656
11657
11658
11659
11660
11661
11662
11663
11664
11665
11666
11667
11668
11669
11670
11671
11672
11673
11674
11675
11676
11677
11678
11679
11680
11681
11682
11683
11684
11685
11686
11687
11688
11689
11690
11691
11692
11693
11694
11695
11696
11697
11698
11699
11700
11701
11702
11703
11704
11705
11706
11707
11708
11709
11710
11711
11712
11713
11714
11715
11716
11717
11718
11719
11720
11721
11722
11723
11724
11725
11726
11727
11728
11729
11730
11731
11732
11733
11734
11735
11736
11737
11738
11739
11740
11741
11742
11743
11744
11745
11746
11747
11748
11749
11750
11751
11752
11753
11754
11755
11756
11757
11758
11759
11760
11761
11762
11763
11764
11765
11766
11767
11768
11769
11770
11771
11772
11773
11774
11775
11776
11777
11778
11779
11780
11781
11782
11783
11784
11785
11786
11787
11788
11789
11790
11791
11792
11793
11794
11795
11796
11797
11798
11799
11800
11801
11802
11803
11804
11805
11806
11807
11808
11809
11810
11811
11812
11813
11814
11815
11816
11817
11818
11819
11820
11821
11822
 
\input texinfo
@c -*-texinfo-*-

@c %**start of header
@setfilename guix.info
@documentencoding UTF-8
@settitle GNU Guix Reference Manual
@c %**end of header

@include version.texi

@copying
Copyright @copyright{} 2012, 2013, 2014, 2015, 2016 Ludovic Courtès@*
Copyright @copyright{} 2013, 2014, 2016 Andreas Enge@*
Copyright @copyright{} 2013 Nikita Karetnikov@*
Copyright @copyright{} 2015, 2016 Mathieu Lirzin@*
Copyright @copyright{} 2014 Pierre-Antoine Rault@*
Copyright @copyright{} 2015 Taylan Ulrich Bayırlı/Kammer@*
Copyright @copyright{} 2015, 2016 Leo Famulari@*
Copyright @copyright{} 2016 Ben Woodcroft@*
Copyright @copyright{} 2016 Chris Marusich@*
Copyright @copyright{} 2016 Efraim Flashner
Copyright @copyright{} 2016 Vincent Legoll

Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with no
Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.  A
copy of the license is included in the section entitled ``GNU Free
Documentation License''.
@end copying

@dircategory System administration
@direntry
* Guix: (guix).       Manage installed software and system configuration.
* guix package: (guix)Invoking guix package.  Installing, removing, and upgrading packages.
* guix build: (guix)Invoking guix build.      Building packages.
* guix gc: (guix)Invoking guix gc.            Reclaiming unused disk space.
* guix pull: (guix)Invoking guix pull.        Update the list of available packages.
* guix system: (guix)Invoking guix system.    Manage the operating system configuration.
@end direntry

@dircategory Software development
@direntry
* guix environment: (guix)Invoking guix environment. Building development environments with Guix.
@end direntry

@dircategory Emacs
@direntry
* Guix user interface: (guix)Emacs Interface. Package management from the comfort of Emacs.
@end direntry


@titlepage
@title GNU Guix Reference Manual
@subtitle Using the GNU Guix Functional Package Manager
@author The GNU Guix Developers

@page
@vskip 0pt plus 1filll
Edition @value{EDITION} @*
@value{UPDATED} @*

@insertcopying
@end titlepage

@contents

@c *********************************************************************
@node Top
@top GNU Guix

This document describes GNU Guix version @value{VERSION}, a functional
package management tool written for the GNU system.

@menu
* Introduction::                What is Guix about?
* Installation::                Installing Guix.
* Package Management::          Package installation, upgrade, etc.
* Emacs Interface::             Using Guix from Emacs.
* Programming Interface::       Using Guix in Scheme.
* Utilities::                   Package management commands.
* GNU Distribution::            Software for your friendly GNU system.
* Contributing::                Your help needed!

* Acknowledgments::             Thanks!
* GNU Free Documentation License::  The license of this manual.
* Concept Index::               Concepts.
* Programming Index::           Data types, functions, and variables.

@detailmenu
 --- The Detailed Node Listing ---

Installation

* Binary Installation::         Getting Guix running in no time!
* Requirements::                Software needed to build and run Guix.
* Running the Test Suite::      Testing Guix.
* Setting Up the Daemon::       Preparing the build daemon's environment.
* Invoking guix-daemon::        Running the build daemon.
* Application Setup::           Application-specific setup.

Setting Up the Daemon

* Build Environment Setup::     Preparing the isolated build environment.
* Daemon Offload Setup::        Offloading builds to remote machines.

Package Management

* Features::                    How Guix will make your life brighter.
* Invoking guix package::       Package installation, removal, etc.
* Substitutes::                 Downloading pre-built binaries.
* Packages with Multiple Outputs::  Single source package, multiple outputs.
* Invoking guix gc::            Running the garbage collector.
* Invoking guix pull::          Fetching the latest Guix and distribution.
* Invoking guix archive::       Exporting and importing store files.

Emacs Interface

* Initial Setup: Emacs Initial Setup.	Preparing @file{~/.emacs}.
* Package Management: Emacs Package Management.	Managing packages and generations.
* Licenses: Emacs Licenses.		Interface for licenses of Guix packages.
* Package Source Locations: Emacs Package Locations.	Interface for package location files.
* Popup Interface: Emacs Popup Interface.	Magit-like interface for guix commands.
* Prettify Mode: Emacs Prettify.	Abbreviating @file{/gnu/store/@dots{}} file names.
* Build Log Mode: Emacs Build Log.	Highlighting Guix build logs.
* Completions: Emacs Completions.	Completing @command{guix} shell command.
* Development: Emacs Development.	Tools for Guix developers.
* Hydra: Emacs Hydra.			Interface for Guix build farm.

Programming Interface

* Defining Packages::           Defining new packages.
* Build Systems::               Specifying how packages are built.
* The Store::                   Manipulating the package store.
* Derivations::                 Low-level interface to package derivations.
* The Store Monad::             Purely functional interface to the store.
* G-Expressions::               Manipulating build expressions.

Defining Packages

* package Reference::           The package data type.
* origin Reference::            The origin data type.

Utilities

* Invoking guix build::         Building packages from the command line.
* Invoking guix edit::          Editing package definitions.
* Invoking guix download::      Downloading a file and printing its hash.
* Invoking guix hash::          Computing the cryptographic hash of a file.
* Invoking guix import::        Importing package definitions.
* Invoking guix refresh::       Updating package definitions.
* Invoking guix lint::          Finding errors in package definitions.
* Invoking guix size::          Profiling disk usage.
* Invoking guix graph::         Visualizing the graph of packages.
* Invoking guix environment::   Setting up development environments.
* Invoking guix publish::       Sharing substitutes.
* Invoking guix challenge::     Challenging substitute servers.
* Invoking guix container::     Process isolation.

Invoking @command{guix build}

* Common Build Options::        Build options for most commands.
* Package Transformation Options::    Creating variants of packages.
* Additional Build Options::    Options specific to 'guix build'.

GNU Distribution

* System Installation::         Installing the whole operating system.
* System Configuration::        Configuring the operating system.
* Installing Debugging Files::  Feeding the debugger.
* Security Updates::            Deploying security fixes quickly.
* Package Modules::             Packages from the programmer's viewpoint.
* Packaging Guidelines::        Growing the distribution.
* Bootstrapping::               GNU/Linux built from scratch.
* Porting::                     Targeting another platform or kernel.

System Installation

* Limitations::                 What you can expect.
* Hardware Considerations::     Supported hardware.
* USB Stick Installation::      Preparing the installation medium.
* USB storage Installation in a VM:: Booting a VM with USB install image.
* Preparing for Installation::  Networking, partitioning, etc.
* Proceeding with the Installation::  The real thing.
* Building the Installation Image::  How this comes to be.

System Configuration

* Using the Configuration System::  Customizing your GNU system.
* operating-system Reference::  Detail of operating-system declarations.
* File Systems::                Configuring file system mounts.
* Mapped Devices::              Block device extra processing.
* User Accounts::               Specifying user accounts.
* Locales::                     Language and cultural convention settings.
* Services::                    Specifying system services.
* Setuid Programs::             Programs running with root privileges.
* X.509 Certificates::          Authenticating HTTPS servers.
* Name Service Switch::         Configuring libc's name service switch.
* Initial RAM Disk::            Linux-Libre bootstrapping.
* GRUB Configuration::          Configuring the boot loader.
* Invoking guix system::        Instantiating a system configuration.
* Running GuixSD in a VM::      How to run GuixSD in a virtual machine.
* Defining Services::           Adding new service definitions.

Services

* Base Services::               Essential system services.
* Scheduled Job Execution::     The mcron service.
* Networking Services::         Network setup, SSH daemon, etc.
* X Window::                    Graphical display.
* Desktop Services::            D-Bus and desktop services.
* Database Services::           SQL databases.
* Mail Services::               IMAP, POP3, SMTP, and all that.
* Web Services::                Web servers.
* Various Services::            Other services.

Defining Services

* Service Composition::         The model for composing services.
* Service Types and Services::  Types and services.
* Service Reference::           API reference.
* Shepherd Services::           A particular type of service.

Packaging Guidelines

* Software Freedom::            What may go into the distribution.
* Package Naming::              What's in a name?
* Version Numbers::             When the name is not enough.
* Synopses and Descriptions::   Helping users find the right package.
* Python Modules::              Taming the snake.
* Perl Modules::                Little pearls.
* Java Packages::               Coffee break.
* Fonts::                       Fond of fonts.

Contributing

* Building from Git::           The latest and greatest.
* Running Guix Before It Is Installed::  Hacker tricks.
* The Perfect Setup::           The right tools.
* Coding Style::                Hygiene of the contributor.
* Submitting Patches::          Share your work.

Coding Style

* Programming Paradigm::        How to compose your elements.
* Modules::                     Where to store your code?
* Data Types and Pattern Matching::  Implementing data structures.
* Formatting Code::             Writing conventions.

@end detailmenu
@end menu

@c *********************************************************************
@node Introduction
@chapter Introduction

@cindex purpose
GNU Guix@footnote{``Guix'' is pronounced like ``geeks'', or ``ɡiːks''
using the international phonetic alphabet (IPA).} is a package
management tool for the GNU system.  Guix makes it easy for unprivileged
users to install, upgrade, or remove packages, to roll back to a
previous package set, to build packages from source, and generally
assists with the creation and maintenance of software environments.

@cindex user interfaces
Guix provides a command-line package management interface
(@pxref{Invoking guix package}), a set of command-line utilities
(@pxref{Utilities}), a visual user interface in Emacs (@pxref{Emacs
Interface}), as well as Scheme programming interfaces
(@pxref{Programming Interface}).
@cindex build daemon
Its @dfn{build daemon} is responsible for building packages on behalf of
users (@pxref{Setting Up the Daemon}) and for downloading pre-built
binaries from authorized sources (@pxref{Substitutes}).

@cindex extensibility of the distribution
@cindex customization of packages
Guix includes package definitions for many GNU and non-GNU packages, all
of which @uref{https://www.gnu.org/philosophy/free-sw.html, respect the
user's computing freedom}.  It is @emph{extensible}: users can write
their own package definitions (@pxref{Defining Packages}) and make them
available as independent package modules (@pxref{Package Modules}).  It
is also @emph{customizable}: users can @emph{derive} specialized package
definitions from existing ones, including from the command line
(@pxref{Package Transformation Options}).

@cindex Guix System Distribution
@cindex GuixSD
You can install GNU@tie{}Guix on top of an existing GNU/Linux system
where it complements the available tools without interference
(@pxref{Installation}), or you can use it as part of the standalone
@dfn{Guix System Distribution} or GuixSD (@pxref{GNU Distribution}).
With GNU@tie{}GuixSD, you @emph{declare} all aspects of the operating
system configuration and Guix takes care of instantiating the
configuration in a transactional, reproducible, and stateless fashion
(@pxref{System Configuration}).

@cindex functional package management
Under the hood, Guix implements the @dfn{functional package management}
discipline pioneered by Nix (@pxref{Acknowledgments}).
In Guix, the package build and installation process is seen
as a @emph{function}, in the mathematical sense.  That function takes inputs,
such as build scripts, a compiler, and libraries, and
returns an installed package.  As a pure function, its result depends
solely on its inputs---for instance, it cannot refer to software or
scripts that were not explicitly passed as inputs.  A build function
always produces the same result when passed a given set of inputs.  It
cannot alter the environment of the running system in
any way; for instance, it cannot create, modify, or delete files outside
of its build and installation directories.  This is achieved by running
build processes in isolated environments (or @dfn{containers}), where only their
explicit inputs are visible.

@cindex store
The result of package build functions is @dfn{cached} in the file
system, in a special directory called @dfn{the store} (@pxref{The
Store}).  Each package is installed in a directory of its own in the
store---by default under @file{/gnu/store}.  The directory name contains
a hash of all the inputs used to build that package; thus, changing an
input yields a different directory name.

This approach is the foundation for the salient features of Guix: support
for transactional package upgrade and rollback, per-user installation, and
garbage collection of packages (@pxref{Features}).


@c *********************************************************************
@node Installation
@chapter Installation

GNU Guix is available for download from its website at
@url{http://www.gnu.org/software/guix/}.  This section describes the
software requirements of Guix, as well as how to install it and get
ready to use it.

Note that this section is concerned with the installation of the package
manager, which can be done on top of a running GNU/Linux system.  If,
instead, you want to install the complete GNU operating system,
@pxref{System Installation}.

@cindex foreign distro
When installed on a running GNU/Linux system---thereafter called a
@dfn{foreign distro}---GNU@tie{}Guix complements the available tools
without interference.  Its data lives exclusively in two directories,
usually @file{/gnu/store} and @file{/var/guix}; other files on your
system, such as @file{/etc}, are left untouched.

@menu
* Binary Installation::         Getting Guix running in no time!
* Requirements::                Software needed to build and run Guix.
* Running the Test Suite::      Testing Guix.
* Setting Up the Daemon::       Preparing the build daemon's environment.
* Invoking guix-daemon::        Running the build daemon.
* Application Setup::           Application-specific setup.
@end menu

@node Binary Installation
@section Binary Installation

This section describes how to install Guix on an arbitrary system from a
self-contained tarball providing binaries for Guix and for all its
dependencies.  This is often quicker than installing from source, which
is described in the next sections.  The only requirement is to have
GNU@tie{}tar and Xz.

Installing goes along these lines:

@enumerate
@item
Download the binary tarball from
@indicateurl{ftp://alpha.gnu.org/gnu/guix/guix-binary-@value{VERSION}.@var{system}.tar.xz},
where @var{system} is @code{x86_64-linux} for an @code{x86_64} machine
already running the kernel Linux, and so on.

Make sure to download the associated @file{.sig} file and to verify the
authenticity of the tarball against it, along these lines:

@example
$ wget ftp://alpha.gnu.org/gnu/guix/guix-binary-@value{VERSION}.@var{system}.tar.xz.sig
$ gpg --verify guix-binary-@value{VERSION}.@var{system}.tar.xz.sig
@end example

If that command fails because you do not have the required public key,
then run this command to import it:

@example
$ gpg --keyserver pgp.mit.edu --recv-keys 090B11993D9AEBB5
@end example

@noindent
and rerun the @code{gpg --verify} command.

@item
As @code{root}, run:

@example
# cd /tmp
# tar --warning=no-timestamp -xf \
     guix-binary-@value{VERSION}.@var{system}.tar.xz
# mv var/guix /var/ && mv gnu /
@end example

This creates @file{/gnu/store} (@pxref{The Store}) and @file{/var/guix}.
The latter contains a ready-to-use profile for @code{root} (see next
step.)

Do @emph{not} unpack the tarball on a working Guix system since that
would overwrite its own essential files.

The @code{--warning=no-timestamp} option makes sure GNU@tie{}tar does
not emit warnings about ``implausibly old time stamps'' (such
warnings were triggered by GNU@tie{}tar 1.26 and older; recent
versions are fine.)
They stem from the fact that all the
files in the archive have their modification time set to zero (which
means January 1st, 1970.)  This is done on purpose to make sure the
archive content is independent of its creation time, thus making it
reproducible.

@item
Make @code{root}'s profile available under @file{~/.guix-profile}:

@example
# ln -sf /var/guix/profiles/per-user/root/guix-profile \
         ~root/.guix-profile
@end example

@item
Create the group and user accounts for build users as explained below
(@pxref{Build Environment Setup}).

@item
Run the daemon, and set it to automatically start on boot.

If your host distro uses the systemd init system, this can be achieved
with these commands:

@example
# cp ~root/.guix-profile/lib/systemd/system/guix-daemon.service \
        /etc/systemd/system/
# systemctl start guix-daemon && systemctl enable guix-daemon
@end example

If your host distro uses the Upstart init system:

@example
# cp ~root/.guix-profile/lib/upstart/system/guix-daemon.conf /etc/init/
# start guix-daemon
@end example

Otherwise, you can still start the daemon manually with:

@example
# ~root/.guix-profile/bin/guix-daemon --build-users-group=guixbuild
@end example

@item
Make the @command{guix} command available to other users on the machine,
for instance with:

@example
# mkdir -p /usr/local/bin
# cd /usr/local/bin
# ln -s /var/guix/profiles/per-user/root/guix-profile/bin/guix
@end example

It is also a good idea to make the Info version of this manual available
there:

@example
# mkdir -p /usr/local/share/info
# cd /usr/local/share/info
# for i in /var/guix/profiles/per-user/root/guix-profile/share/info/* ;
  do ln -s $i ; done
@end example

That way, assuming @file{/usr/local/share/info} is in the search path,
running @command{info guix} will open this manual (@pxref{Other Info
Directories,,, texinfo, GNU Texinfo}, for more details on changing the
Info search path.)

@item
To use substitutes from @code{hydra.gnu.org} or one of its mirrors
(@pxref{Substitutes}), authorize them:

@example
# guix archive --authorize < ~root/.guix-profile/share/guix/hydra.gnu.org.pub
@end example
@end enumerate

This completes root-level install of Guix.  Each user will need to
perform additional steps to make their Guix envionment ready for use,
@pxref{Application Setup}.

You can confirm that Guix is working by installing a sample package into
the root profile:

@example
# guix package -i hello
@end example

The @code{guix} package must remain available in @code{root}'s profile,
or it would become subject to garbage collection---in which case you
would find yourself badly handicapped by the lack of the @command{guix}
command.  In other words, do not remove @code{guix} by running
@code{guix package -r guix}.

The binary installation tarball can be (re)produced and verified simply
by running the following command in the Guix source tree:

@example
make guix-binary.@var{system}.tar.xz
@end example


@node Requirements
@section Requirements

This section lists requirements when building Guix from source.  The
build procedure for Guix is the same as for other GNU software, and is
not covered here.  Please see the files @file{README} and @file{INSTALL}
in the Guix source tree for additional details.

GNU Guix depends on the following packages:

@itemize
@item @url{http://gnu.org/software/guile/, GNU Guile}, version 2.0.7 or later;
@item @url{http://gnupg.org/, GNU libgcrypt};
@item @url{http://www.gnu.org/software/make/, GNU Make}.
@end itemize

The following dependencies are optional:

@itemize
@item
Installing @uref{http://gnutls.org/, GnuTLS-Guile} will allow you to
access @code{https} URLs for substitutes, which is highly recommended
(@pxref{Substitutes}).  It also allows you to access HTTPS URLs with the
@command{guix download} command (@pxref{Invoking guix download}), the
@command{guix import pypi} command, and the @command{guix import cpan}
command.  @xref{Guile Preparations, how to install the GnuTLS bindings
for Guile,, gnutls-guile, GnuTLS-Guile}.

@item
Installing
@url{http://savannah.nongnu.org/projects/guile-json/, Guile-JSON} will
allow you to use the @command{guix import pypi} command (@pxref{Invoking
guix import}).  It is of
interest primarily for developers and not for casual users.
@end itemize

Unless @code{--disable-daemon} was passed to @command{configure}, the
following packages are also needed:

@itemize
@item @url{http://sqlite.org, SQLite 3};
@item @url{http://www.bzip.org, libbz2};
@item @url{http://gcc.gnu.org, GCC's g++}, with support for the
C++11 standard.
@end itemize

When configuring Guix on a system that already has a Guix installation,
be sure to specify the same state directory as the existing installation
using the @code{--localstatedir} option of the @command{configure}
script (@pxref{Directory Variables, @code{localstatedir},, standards,
GNU Coding Standards}).  The @command{configure} script protects against
unintended misconfiguration of @var{localstatedir} so you do not
inadvertently corrupt your store (@pxref{The Store}).

When a working installation of @url{http://nixos.org/nix/, the Nix package
manager} is available, you
can instead configure Guix with @code{--disable-daemon}.  In that case,
Nix replaces the three dependencies above.

Guix is compatible with Nix, so it is possible to share the same store
between both.  To do so, you must pass @command{configure} not only the
same @code{--with-store-dir} value, but also the same
@code{--localstatedir} value.  The latter is essential because it
specifies where the database that stores metadata about the store is
located, among other things.  The default values for Nix are
@code{--with-store-dir=/nix/store} and @code{--localstatedir=/nix/var}.
Note that @code{--disable-daemon} is not required if
your goal is to share the store with Nix.

@node Running the Test Suite
@section Running the Test Suite

After a successful @command{configure} and @code{make} run, it is a good
idea to run the test suite.  It can help catch issues with the setup or
environment, or bugs in Guix itself---and really, reporting test
failures is a good way to help improve the software.  To run the test
suite, type:

@example
make check
@end example

Test cases can run in parallel: you can use the @code{-j} option of
GNU@tie{}make to speed things up.  The first run may take a few minutes
on a recent machine; subsequent runs will be faster because the store
that is created for test purposes will already have various things in
cache.

It is also possible to run a subset of the tests by defining the
@code{TESTS} makefile variable as in this example:

@example
make check TESTS="tests/store.scm tests/cpio.scm"
@end example

By default, tests results are displayed at a file level.  In order to
see the details of every individual test cases, it is possible to define
the @code{SCM_LOG_DRIVER_FLAGS} makefile variable as in this example:

@example
make check TESTS="tests/base64.scm" SCM_LOG_DRIVER_FLAGS="--brief=no"
@end example

Upon failure, please email @email{bug-guix@@gnu.org} and attach the
@file{test-suite.log} file.  Please specify the Guix version being used
as well as version numbers of the dependencies (@pxref{Requirements}) in
your message.

Guix also comes with a whole-system test suite that tests complete
GuixSD operating system instances.  It can only run on systems where
Guix is already installed, using:

@example
make check-system
@end example

@noindent
or, again, by defining @code{TESTS} to select a subset of tests to run:

@example
make check-system TESTS="basic mcron"
@end example

These system tests are defined in the @code{(gnu tests @dots{})}
modules.  They work by running the operating systems under test with
lightweight instrumentation in a virtual machine (VM).  They can be
computationally intensive or rather cheap, depending on whether
substitutes are available for their dependencies (@pxref{Substitutes}).
Some of them require a lot of storage space to hold VM images.

Again in case of test failures, please send @email{bug-guix@@gnu.org}
all the details.

@node Setting Up the Daemon
@section Setting Up the Daemon

@cindex daemon
Operations such as building a package or running the garbage collector
are all performed by a specialized process, the @dfn{build daemon}, on
behalf of clients.  Only the daemon may access the store and its
associated database.  Thus, any operation that manipulates the store
goes through the daemon.  For instance, command-line tools such as
@command{guix package} and @command{guix build} communicate with the
daemon (@i{via} remote procedure calls) to instruct it what to do.

The following sections explain how to prepare the build daemon's
environment.  See also @ref{Substitutes}, for information on how to allow
the daemon to download pre-built binaries.

@menu
* Build Environment Setup::     Preparing the isolated build environment.
* Daemon Offload Setup::        Offloading builds to remote machines.
@end menu

@node Build Environment Setup
@subsection Build Environment Setup

In a standard multi-user setup, Guix and its daemon---the
@command{guix-daemon} program---are installed by the system
administrator; @file{/gnu/store} is owned by @code{root} and
@command{guix-daemon} runs as @code{root}.  Unprivileged users may use
Guix tools to build packages or otherwise access the store, and the
daemon will do it on their behalf, ensuring that the store is kept in a
consistent state, and allowing built packages to be shared among users.

@cindex build users
When @command{guix-daemon} runs as @code{root}, you may not want package
build processes themselves to run as @code{root} too, for obvious
security reasons.  To avoid that, a special pool of @dfn{build users}
should be created for use by build processes started by the daemon.
These build users need not have a shell and a home directory: they will
just be used when the daemon drops @code{root} privileges in build
processes.  Having several such users allows the daemon to launch
distinct build processes under separate UIDs, which guarantees that they
do not interfere with each other---an essential feature since builds are
regarded as pure functions (@pxref{Introduction}).

On a GNU/Linux system, a build user pool may be created like this (using
Bash syntax and the @code{shadow} commands):

@c See http://lists.gnu.org/archive/html/bug-guix/2013-01/msg00239.html
@c for why `-G' is needed.
@example
# groupadd --system guixbuild
# for i in `seq -w 1 10`;
  do
    useradd -g guixbuild -G guixbuild           \
            -d /var/empty -s `which nologin`    \
            -c "Guix build user $i" --system    \
            guixbuilder$i;
  done
@end example

@noindent
The number of build users determines how many build jobs may run in
parallel, as specified by the @option{--max-jobs} option
(@pxref{Invoking guix-daemon, @option{--max-jobs}}).  To use
@command{guix system vm} and related commands, you may need to add the
build users to the @code{kvm} group so they can access @file{/dev/kvm},
using @code{-G guixbuild,kvm} instead of @code{-G guixbuild}
(@pxref{Invoking guix system}).

The @code{guix-daemon} program may then be run as @code{root} with the
following command@footnote{If your machine uses the systemd init system,
dropping the @file{@var{prefix}/lib/systemd/system/guix-daemon.service}
file in @file{/etc/systemd/system} will ensure that
@command{guix-daemon} is automatically started.  Similarly, if your
machine uses the Upstart init system, drop the
@file{@var{prefix}/lib/upstart/system/guix-daemon.conf}
file in @file{/etc/init}.}:

@example
# guix-daemon --build-users-group=guixbuild
@end example

@cindex chroot
@noindent
This way, the daemon starts build processes in a chroot, under one of
the @code{guixbuilder} users.  On GNU/Linux, by default, the chroot
environment contains nothing but:

@c Keep this list in sync with libstore/build.cc! -----------------------
@itemize
@item
a minimal @code{/dev} directory, created mostly independently from the
host @code{/dev}@footnote{``Mostly'', because while the set of files
that appear in the chroot's @code{/dev} is fixed, most of these files
can only be created if the host has them.};

@item
the @code{/proc} directory; it only shows the processes of the container
since a separate PID name space is used;

@item
@file{/etc/passwd} with an entry for the current user and an entry for
user @file{nobody};

@item
@file{/etc/group} with an entry for the user's group;

@item
@file{/etc/hosts} with an entry that maps @code{localhost} to
@code{127.0.0.1};

@item
a writable @file{/tmp} directory.
@end itemize

You can influence the directory where the daemon stores build trees
@i{via} the @code{TMPDIR} environment variable.  However, the build tree
within the chroot is always called @file{/tmp/guix-build-@var{name}.drv-0},
where @var{name} is the derivation name---e.g., @code{coreutils-8.24}.
This way, the value of @code{TMPDIR} does not leak inside build
environments, which avoids discrepancies in cases where build processes
capture the name of their build tree.

@vindex http_proxy
The daemon also honors the @code{http_proxy} environment variable for
HTTP downloads it performs, be it for fixed-output derivations
(@pxref{Derivations}) or for substitutes (@pxref{Substitutes}).

If you are installing Guix as an unprivileged user, it is still possible
to run @command{guix-daemon} provided you pass @code{--disable-chroot}.
However, build processes will not be isolated from one another, and not
from the rest of the system.  Thus, build processes may interfere with
each other, and may access programs, libraries, and other files
available on the system---making it much harder to view them as
@emph{pure} functions.


@node Daemon Offload Setup
@subsection Using the Offload Facility

@cindex offloading
@cindex build hook
When desired, the build daemon can @dfn{offload}
derivation builds to other machines
running Guix, using the @code{offload} @dfn{build hook}.  When that
feature is enabled, a list of user-specified build machines is read from
@file{/etc/guix/machines.scm}; every time a build is requested, for
instance via @code{guix build}, the daemon attempts to offload it to one
of the machines that satisfy the constraints of the derivation, in
particular its system type---e.g., @file{x86_64-linux}.  Missing
prerequisites for the build are copied over SSH to the target machine,
which then proceeds with the build; upon success the output(s) of the
build are copied back to the initial machine.

The @file{/etc/guix/machines.scm} file typically looks like this:

@example
(list (build-machine
        (name "eightysix.example.org")
        (system "x86_64-linux")
        (user "bob")
        (speed 2.))    ; incredibly fast!

      (build-machine
        (name "meeps.example.org")
        (system "mips64el-linux")
        (user "alice")
        (private-key
         (string-append (getenv "HOME")
                        "/.lsh/identity-for-guix"))))
@end example

@noindent
In the example above we specify a list of two build machines, one for
the @code{x86_64} architecture and one for the @code{mips64el}
architecture.

In fact, this file is---not surprisingly!---a Scheme file that is
evaluated when the @code{offload} hook is started.  Its return value
must be a list of @code{build-machine} objects.  While this example
shows a fixed list of build machines, one could imagine, say, using
DNS-SD to return a list of potential build machines discovered in the
local network (@pxref{Introduction, Guile-Avahi,, guile-avahi, Using
Avahi in Guile Scheme Programs}).  The @code{build-machine} data type is
detailed below.

@deftp {Data Type} build-machine
This data type represents build machines to which the daemon may offload
builds.  The important fields are:

@table @code

@item name
The host name of the remote machine.

@item system
The system type of the remote machine---e.g., @code{"x86_64-linux"}.

@item user
The user account to use when connecting to the remote machine over SSH.
Note that the SSH key pair must @emph{not} be passphrase-protected, to
allow non-interactive logins.

@end table

A number of optional fields may be specified:

@table @code

@item port
Port number of SSH server on the machine (default: 22).

@item private-key
The SSH private key file to use when connecting to the machine.

Currently offloading uses GNU@tie{}lsh as its SSH client
(@pxref{Invoking lsh,,, GNU lsh Manual}).  Thus, the key file here must
be an lsh key file.  This may change in the future, though.

@item parallel-builds
The number of builds that may run in parallel on the machine (1 by
default.)

@item speed
A ``relative speed factor''.  The offload scheduler will tend to prefer
machines with a higher speed factor.

@item features
A list of strings denoting specific features supported by the machine.
An example is @code{"kvm"} for machines that have the KVM Linux modules
and corresponding hardware support.  Derivations can request features by
name, and they will be scheduled on matching build machines.

@end table
@end deftp

The @code{guix} command must be in the search path on the build
machines, since offloading works by invoking the @code{guix archive} and
@code{guix build} commands.  In addition, the Guix modules must be in
@code{$GUILE_LOAD_PATH} on the build machine---you can check whether
this is the case by running:

@example
lsh build-machine guile -c "'(use-modules (guix config))'"
@end example

There is one last thing to do once @file{machines.scm} is in place.  As
explained above, when offloading, files are transferred back and forth
between the machine stores.  For this to work, you first need to
generate a key pair on each machine to allow the daemon to export signed
archives of files from the store (@pxref{Invoking guix archive}):

@example
# guix archive --generate-key
@end example

@noindent
Each build machine must authorize the key of the master machine so that
it accepts store items it receives from the master:

@example
# guix archive --authorize < master-public-key.txt
@end example

@noindent
Likewise, the master machine must authorize the key of each build machine.

All the fuss with keys is here to express pairwise mutual trust
relations between the master and the build machines.  Concretely, when
the master receives files from a build machine (and @i{vice versa}), its
build daemon can make sure they are genuine, have not been tampered
with, and that they are signed by an authorized key.


@node Invoking guix-daemon
@section Invoking @command{guix-daemon}

The @command{guix-daemon} program implements all the functionality to
access the store.  This includes launching build processes, running the
garbage collector, querying the availability of a build result, etc.  It
is normally run as @code{root} like this:

@example
# guix-daemon --build-users-group=guixbuild
@end example

@noindent
For details on how to set it up, @pxref{Setting Up the Daemon}.

@cindex chroot
@cindex container, build environment
@cindex build environment
@cindex reproducible builds
By default, @command{guix-daemon} launches build processes under
different UIDs, taken from the build group specified with
@code{--build-users-group}.  In addition, each build process is run in a
chroot environment that only contains the subset of the store that the
build process depends on, as specified by its derivation
(@pxref{Programming Interface, derivation}), plus a set of specific
system directories.  By default, the latter contains @file{/dev} and
@file{/dev/pts}.  Furthermore, on GNU/Linux, the build environment is a
@dfn{container}: in addition to having its own file system tree, it has
a separate mount name space, its own PID name space, network name space,
etc.  This helps achieve reproducible builds (@pxref{Features}).

When the daemon performs a build on behalf of the user, it creates a
build directory under @file{/tmp} or under the directory specified by
its @code{TMPDIR} environment variable; this directory is shared with
the container for the duration of the build.  Be aware that using a
directory other than @file{/tmp} can affect build results---for example,
with a longer directory name, a build process that uses Unix-domain
sockets might hit the name length limitation for @code{sun_path}, which
it would otherwise not hit.

The build directory is automatically deleted upon completion, unless the
build failed and the client specified @option{--keep-failed}
(@pxref{Invoking guix build, @option{--keep-failed}}).

The following command-line options are supported:

@table @code
@item --build-users-group=@var{group}
Take users from @var{group} to run build processes (@pxref{Setting Up
the Daemon, build users}).

@item --no-substitutes
@cindex substitutes
Do not use substitutes for build products.  That is, always build things
locally instead of allowing downloads of pre-built binaries
(@pxref{Substitutes}).

By default substitutes are used, unless the client---such as the
@command{guix package} command---is explicitly invoked with
@code{--no-substitutes}.

When the daemon runs with @code{--no-substitutes}, clients can still
explicitly enable substitution @i{via} the @code{set-build-options}
remote procedure call (@pxref{The Store}).

@item --substitute-urls=@var{urls}
@anchor{daemon-substitute-urls}
Consider @var{urls} the default whitespace-separated list of substitute
source URLs.  When this option is omitted,
@indicateurl{https://mirror.hydra.gnu.org https://hydra.gnu.org} is used
(@code{mirror.hydra.gnu.org} is a mirror of @code{hydra.gnu.org}).

This means that substitutes may be downloaded from @var{urls}, as long
as they are signed by a trusted signature (@pxref{Substitutes}).

@cindex build hook
@item --no-build-hook
Do not use the @dfn{build hook}.

The build hook is a helper program that the daemon can start and to
which it submits build requests.  This mechanism is used to offload
builds to other machines (@pxref{Daemon Offload Setup}).

@item --cache-failures
Cache build failures.  By default, only successful builds are cached.

When this option is used, @command{guix gc --list-failures} can be used
to query the set of store items marked as failed; @command{guix gc
--clear-failures} removes store items from the set of cached failures.
@xref{Invoking guix gc}.

@item --cores=@var{n}
@itemx -c @var{n}
Use @var{n} CPU cores to build each derivation; @code{0} means as many
as available.

The default value is @code{0}, but it may be overridden by clients, such
as the @code{--cores} option of @command{guix build} (@pxref{Invoking
guix build}).

The effect is to define the @code{NIX_BUILD_CORES} environment variable
in the build process, which can then use it to exploit internal
parallelism---for instance, by running @code{make -j$NIX_BUILD_CORES}.

@item --max-jobs=@var{n}
@itemx -M @var{n}
Allow at most @var{n} build jobs in parallel.  The default value is
@code{1}.  Setting it to @code{0} means that no builds will be performed
locally; instead, the daemon will offload builds (@pxref{Daemon Offload
Setup}), or simply fail.

@item --rounds=@var{N}
Build each derivation @var{n} times in a row, and raise an error if
consecutive build results are not bit-for-bit identical.  Note that this
setting can be overridden by clients such as @command{guix build}
(@pxref{Invoking guix build}).

When used in conjunction with @option{--keep-failed}, the differing
output is kept in the store, under @file{/gnu/store/@dots{}-check}.
This makes it easy to look for differences between the two results.

@item --debug
Produce debugging output.

This is useful to debug daemon start-up issues, but then it may be
overridden by clients, for example the @code{--verbosity} option of
@command{guix build} (@pxref{Invoking guix build}).

@item --chroot-directory=@var{dir}
Add @var{dir} to the build chroot.

Doing this may change the result of build processes---for instance if
they use optional dependencies found in @var{dir} when it is available,
and not otherwise.  For that reason, it is not recommended to do so.
Instead, make sure that each derivation declares all the inputs that it
needs.

@item --disable-chroot
Disable chroot builds.

Using this option is not recommended since, again, it would allow build
processes to gain access to undeclared dependencies.  It is necessary,
though, when @command{guix-daemon} is running under an unprivileged user
account.

@item --disable-log-compression
Disable compression of the build logs.

Unless @code{--lose-logs} is used, all the build logs are kept in the
@var{localstatedir}.  To save space, the daemon automatically compresses
them with bzip2 by default.  This option disables that.

@item --disable-deduplication
@cindex deduplication
Disable automatic file ``deduplication'' in the store.

By default, files added to the store are automatically ``deduplicated'':
if a newly added file is identical to another one found in the store,
the daemon makes the new file a hard link to the other file.  This can
noticeably reduce disk usage, at the expense of slightly increased
input/output load at the end of a build process.  This option disables
this optimization.

@item --gc-keep-outputs[=yes|no]
Tell whether the garbage collector (GC) must keep outputs of live
derivations.

When set to ``yes'', the GC will keep the outputs of any live derivation
available in the store---the @code{.drv} files.  The default is ``no'',
meaning that derivation outputs are kept only if they are GC roots.

@item --gc-keep-derivations[=yes|no]
Tell whether the garbage collector (GC) must keep derivations
corresponding to live outputs.

When set to ``yes'', as is the case by default, the GC keeps
derivations---i.e., @code{.drv} files---as long as at least one of their
outputs is live.  This allows users to keep track of the origins of
items in their store.  Setting it to ``no'' saves a bit of disk space.

Note that when both @code{--gc-keep-derivations} and
@code{--gc-keep-outputs} are used, the effect is to keep all the build
prerequisites (the sources, compiler, libraries, and other build-time
tools) of live objects in the store, regardless of whether these
prerequisites are live.  This is convenient for developers since it
saves rebuilds or downloads.

@item --impersonate-linux-2.6
On Linux-based systems, impersonate Linux 2.6.  This means that the
kernel's @code{uname} system call will report 2.6 as the release number.

This might be helpful to build programs that (usually wrongfully) depend
on the kernel version number.

@item --lose-logs
Do not keep build logs.  By default they are kept under
@code{@var{localstatedir}/guix/log}.

@item --system=@var{system}
Assume @var{system} as the current system type.  By default it is the
architecture/kernel pair found at configure time, such as
@code{x86_64-linux}.

@item --listen=@var{socket}
Listen for connections on @var{socket}, the file name of a Unix-domain
socket.  The default socket is
@file{@var{localstatedir}/daemon-socket/socket}.  This option is only
useful in exceptional circumstances, such as if you need to run several
daemons on the same machine.
@end table


@node Application Setup
@section Application Setup

@cindex foreign distro
When using Guix on top of GNU/Linux distribution other than GuixSD---a
so-called @dfn{foreign distro}---a few additional steps are needed to
get everything in place.  Here are some of them.

@subsection Locales

@anchor{locales-and-locpath}
@cindex locales, when not on GuixSD
@vindex LOCPATH
@vindex GUIX_LOCPATH
Packages installed @i{via} Guix will not use the locale data of the
host system.  Instead, you must first install one of the locale packages
available with Guix and then define the @code{GUIX_LOCPATH} environment
variable:

@example
$ guix package -i glibc-locales
$ export GUIX_LOCPATH=$HOME/.guix-profile/lib/locale
@end example

Note that the @code{glibc-locales} package contains data for all the
locales supported by the GNU@tie{}libc and weighs in at around
110@tie{}MiB.  Alternatively, the @code{glibc-utf8-locales} is smaller but
limited to a few UTF-8 locales.

The @code{GUIX_LOCPATH} variable plays a role similar to @code{LOCPATH}
(@pxref{Locale Names, @code{LOCPATH},, libc, The GNU C Library Reference
Manual}).  There are two important differences though:

@enumerate
@item
@code{GUIX_LOCPATH} is honored only by the libc in Guix, and not by the libc
provided by foreign distros.  Thus, using @code{GUIX_LOCPATH} allows you
to make sure the programs of the foreign distro will not end up loading
incompatible locale data.

@item
libc suffixes each entry of @code{GUIX_LOCPATH} with @code{/X.Y}, where
@code{X.Y} is the libc version---e.g., @code{2.22}.  This means that,
should your Guix profile contain a mixture of programs linked against
different libc version, each libc version will only try to load locale
data in the right format.
@end enumerate

This is important because the locale data format used by different libc
versions may be incompatible.

@subsection X11 Fonts

The majority of graphical applications use Fontconfig to locate and
load fonts and perform X11-client-side rendering.  The @code{fontconfig}
package in Guix looks for fonts in @file{$HOME/.guix-profile}
by default.  Thus, to allow graphical applications installed with Guix
to display fonts, you have to install fonts with Guix as well.
Essential font packages include @code{gs-fonts}, @code{font-dejavu}, and
@code{font-gnu-freefont-ttf}.

To display text written in Chinese languages, Japanese, or Korean in
graphical applications, consider installing
@code{font-adobe-source-han-sans} or @code{font-wqy-zenhei}.  The former
has multiple outputs, one per language family (@pxref{Packages with
Multiple Outputs}).  For instance, the following command installs fonts
for Chinese languages:

@example
guix package -i font-adobe-source-han-sans:cn
@end example

@subsection X.509 Certificates

The @code{nss-certs} package provides X.509 certificates, which allow
programs to authenticate Web servers accessed over HTTPS.

When using Guix on a foreign distro, you can install this package and
define the relevant environment variables so that packages know where to
look for certificates.  @pxref{X.509 Certificates}, for detailed
information.

@subsection Emacs Packages

When you install Emacs packages with Guix, the elisp files may be placed
either in @file{$HOME/.guix-profile/share/emacs/site-lisp/} or in
sub-directories of
@file{$HOME/.guix-profile/share/emacs/site-lisp/guix.d/}.  The latter
directory exists because potentially there may exist thousands of Emacs
packages and storing all their files in a single directory may be not
reliable (because of name conflicts).  So we think using a separate
directory for each package is a good idea.  It is very similar to how
the Emacs package system organizes the file structure (@pxref{Package
Files,,, emacs, The GNU Emacs Manual}).

By default, Emacs (installed with Guix) ``knows'' where these packages
are placed, so you do not need to perform any configuration.  If, for
some reason, you want to avoid auto-loading Emacs packages installed
with Guix, you can do so by running Emacs with @code{--no-site-file}
option (@pxref{Init File,,, emacs, The GNU Emacs Manual}).

@c TODO What else?

@c *********************************************************************
@node Package Management
@chapter Package Management

The purpose of GNU Guix is to allow users to easily install, upgrade, and
remove software packages, without having to know about their build
procedures or dependencies.  Guix also goes beyond this obvious set of
features.

This chapter describes the main features of Guix, as well as the package
management tools it provides.  Two user interfaces are provided for
routine package management tasks: A command-line interface described below
(@pxref{Invoking guix package, @code{guix package}}), as well as a visual user
interface in Emacs described in a subsequent chapter (@pxref{Emacs Interface}).

@menu
* Features::                    How Guix will make your life brighter.
* Invoking guix package::       Package installation, removal, etc.
* Substitutes::                 Downloading pre-built binaries.
* Packages with Multiple Outputs::  Single source package, multiple outputs.
* Invoking guix gc::            Running the garbage collector.
* Invoking guix pull::          Fetching the latest Guix and distribution.
* Invoking guix archive::       Exporting and importing store files.
@end menu

@node Features
@section Features

When using Guix, each package ends up in the @dfn{package store}, in its
own directory---something that resembles
@file{/gnu/store/xxx-package-1.2}, where @code{xxx} is a base32 string
(note that Guix comes with an Emacs extension to shorten those file
names, @pxref{Emacs Prettify}.)

Instead of referring to these directories, users have their own
@dfn{profile}, which points to the packages that they actually want to
use.  These profiles are stored within each user's home directory, at
@code{$HOME/.guix-profile}.

For example, @code{alice} installs GCC 4.7.2.  As a result,
@file{/home/alice/.guix-profile/bin/gcc} points to
@file{/gnu/store/@dots{}-gcc-4.7.2/bin/gcc}.  Now, on the same machine,
@code{bob} had already installed GCC 4.8.0.  The profile of @code{bob}
simply continues to point to
@file{/gnu/store/@dots{}-gcc-4.8.0/bin/gcc}---i.e., both versions of GCC
coexist on the same system without any interference.

The @command{guix package} command is the central tool to manage
packages (@pxref{Invoking guix package}).  It operates on the per-user
profiles, and can be used @emph{with normal user privileges}.

The command provides the obvious install, remove, and upgrade
operations.  Each invocation is actually a @emph{transaction}: either
the specified operation succeeds, or nothing happens.  Thus, if the
@command{guix package} process is terminated during the transaction,
or if a power outage occurs during the transaction, then the user's
profile remains in its previous state, and remains usable.

In addition, any package transaction may be @emph{rolled back}.  So, if,
for example, an upgrade installs a new version of a package that turns
out to have a serious bug, users may roll back to the previous instance
of their profile, which was known to work well.  Similarly, the global
system configuration on GuixSD is subject to
transactional upgrades and roll-back
(@pxref{Using the Configuration System}).

All packages in the package store may be @emph{garbage-collected}.
Guix can determine which packages are still referenced by user
profiles, and remove those that are provably no longer referenced
(@pxref{Invoking guix gc}).  Users may also explicitly remove old
generations of their profile so that the packages they refer to can be
collected.

@cindex reproducibility
@cindex reproducible builds
Finally, Guix takes a @dfn{purely functional} approach to package
management, as described in the introduction (@pxref{Introduction}).
Each @file{/gnu/store} package directory name contains a hash of all the
inputs that were used to build that package---compiler, libraries, build
scripts, etc.  This direct correspondence allows users to make sure a
given package installation matches the current state of their
distribution.  It also helps maximize @dfn{build reproducibility}:
thanks to the isolated build environments that are used, a given build
is likely to yield bit-identical files when performed on different
machines (@pxref{Invoking guix-daemon, container}).

@cindex substitutes
This foundation allows Guix to support @dfn{transparent binary/source
deployment}.  When a pre-built binary for a @file{/gnu/store} item is
available from an external source---a @dfn{substitute}, Guix just
downloads it and unpacks it;
otherwise, it builds the package from source, locally
(@pxref{Substitutes}).  Because build results are usually bit-for-bit
reproducible, users do not have to trust servers that provide
substitutes: they can force a local build and @emph{challenge} providers
(@pxref{Invoking guix challenge}).

Control over the build environment is a feature that is also useful for
developers.  The @command{guix environment} command allows developers of
a package to quickly set up the right development environment for their
package, without having to manually install the dependencies of the
package into their profile (@pxref{Invoking guix environment}).

@node Invoking guix package
@section Invoking @command{guix package}

The @command{guix package} command is the tool that allows users to
install, upgrade, and remove packages, as well as rolling back to
previous configurations.  It operates only on the user's own profile,
and works with normal user privileges (@pxref{Features}).  Its syntax
is:

@example
guix package @var{options}
@end example

Primarily, @var{options} specifies the operations to be performed during
the transaction.  Upon completion, a new profile is created, but
previous @dfn{generations} of the profile remain available, should the user
want to roll back.

For example, to remove @code{lua} and install @code{guile} and
@code{guile-cairo} in a single transaction:

@example
guix package -r lua -i guile guile-cairo
@end example

@command{guix package} also supports a @dfn{declarative approach}
whereby the user specifies the exact set of packages to be available and
passes it @i{via} the @option{--manifest} option
(@pxref{profile-manifest, @option{--manifest}}).

For each user, a symlink to the user's default profile is automatically
created in @file{$HOME/.guix-profile}.  This symlink always points to the
current generation of the user's default profile.  Thus, users can add
@file{$HOME/.guix-profile/bin} to their @code{PATH} environment
variable, and so on.
@cindex search paths
If you are not using the Guix System Distribution, consider adding the
following lines to your @file{~/.bash_profile} (@pxref{Bash Startup
Files,,, bash, The GNU Bash Reference Manual}) so that newly-spawned
shells get all the right environment variable definitions:

@example
GUIX_PROFILE="$HOME/.guix-profile" \
source "$HOME/.guix-profile/etc/profile"
@end example

In a multi-user setup, user profiles are stored in a place registered as
a @dfn{garbage-collector root}, which @file{$HOME/.guix-profile} points
to (@pxref{Invoking guix gc}).  That directory is normally
@code{@var{localstatedir}/profiles/per-user/@var{user}}, where
@var{localstatedir} is the value passed to @code{configure} as
@code{--localstatedir}, and @var{user} is the user name.  The
@file{per-user} directory is created when @command{guix-daemon} is
started, and the @var{user} sub-directory is created by @command{guix
package}.

The @var{options} can be among the following:

@table @code

@item --install=@var{package} @dots{}
@itemx -i @var{package} @dots{}
Install the specified @var{package}s.

Each @var{package} may specify either a simple package name, such as
@code{guile}, or a package name followed by an at-sign and version number,
such as @code{guile@@1.8.8} or simply @code{guile@@1.8} (in the latter
case, the newest version prefixed by @code{1.8} is selected.)

If no version number is specified, the
newest available version will be selected.  In addition, @var{package}
may contain a colon, followed by the name of one of the outputs of the
package, as in @code{gcc:doc} or @code{binutils@@2.22:lib}
(@pxref{Packages with Multiple Outputs}).  Packages with a corresponding
name (and optionally version) are searched for among the GNU
distribution modules (@pxref{Package Modules}).

@cindex propagated inputs
Sometimes packages have @dfn{propagated inputs}: these are dependencies
that automatically get installed along with the required package
(@pxref{package-propagated-inputs, @code{propagated-inputs} in
@code{package} objects}, for information about propagated inputs in
package definitions).

@anchor{package-cmd-propagated-inputs}
An example is the GNU MPC library: its C header files refer to those of
the GNU MPFR library, which in turn refer to those of the GMP library.
Thus, when installing MPC, the MPFR and GMP libraries also get installed
in the profile; removing MPC also removes MPFR and GMP---unless they had
also been explicitly installed by the user.

Besides, packages sometimes rely on the definition of environment
variables for their search paths (see explanation of
@code{--search-paths} below).  Any missing or possibly incorrect
environment variable definitions are reported here.

@item --install-from-expression=@var{exp}
@itemx -e @var{exp}
Install the package @var{exp} evaluates to.

@var{exp} must be a Scheme expression that evaluates to a
@code{<package>} object.  This option is notably useful to disambiguate
between same-named variants of a package, with expressions such as
@code{(@@ (gnu packages base) guile-final)}.

Note that this option installs the first output of the specified
package, which may be insufficient when needing a specific output of a
multiple-output package.

@item --install-from-file=@var{file}
@itemx -f @var{file}
Install the package that the code within @var{file} evaluates to.

As an example, @var{file} might contain a definition like this
(@pxref{Defining Packages}):

@example
@verbatiminclude package-hello.scm
@end example

Developers may find it useful to include such a @file{guix.scm} file
in the root of their project source tree that can be used to test
development snapshots and create reproducible development environments
(@pxref{Invoking guix environment}).

@item --remove=@var{package} @dots{}
@itemx -r @var{package} @dots{}
Remove the specified @var{package}s.

As for @code{--install}, each @var{package} may specify a version number
and/or output name in addition to the package name.  For instance,
@code{-r glibc:debug} would remove the @code{debug} output of
@code{glibc}.

@item --upgrade[=@var{regexp} @dots{}]
@itemx -u [@var{regexp} @dots{}]
Upgrade all the installed packages.  If one or more @var{regexp}s are
specified, upgrade only installed packages whose name matches a
@var{regexp}.  Also see the @code{--do-not-upgrade} option below.

Note that this upgrades package to the latest version of packages found
in the distribution currently installed.  To update your distribution,
you should regularly run @command{guix pull} (@pxref{Invoking guix
pull}).

@item --do-not-upgrade[=@var{regexp} @dots{}]
When used together with the @code{--upgrade} option, do @emph{not}
upgrade any packages whose name matches a @var{regexp}.  For example, to
upgrade all packages in the current profile except those containing the
substring ``emacs'':

@example
$ guix package --upgrade . --do-not-upgrade emacs
@end example

@item @anchor{profile-manifest}--manifest=@var{file}
@itemx -m @var{file}
@cindex profile declaration
@cindex profile manifest
Create a new generation of the profile from the manifest object
returned by the Scheme code in @var{file}.

This allows you to @emph{declare} the profile's contents rather than
constructing it through a sequence of @code{--install} and similar
commands.  The advantage is that @var{file} can be put under version
control, copied to different machines to reproduce the same profile, and
so on.

@c FIXME: Add reference to (guix profile) documentation when available.
@var{file} must return a @dfn{manifest} object, which is roughly a list
of packages:

@findex packages->manifest
@example
(use-package-modules guile emacs)

(packages->manifest
 (list emacs
       guile-2.0
       ;; Use a specific package output.
       (list guile-2.0 "debug")))
@end example

@item --roll-back
Roll back to the previous @dfn{generation} of the profile---i.e., undo
the last transaction.

When combined with options such as @code{--install}, roll back occurs
before any other actions.

When rolling back from the first generation that actually contains
installed packages, the profile is made to point to the @dfn{zeroth
generation}, which contains no files apart from its own metadata.

After having rolled back, installing, removing, or upgrading packages
overwrites previous future generations.  Thus, the history of the
generations in a profile is always linear.

@item --switch-generation=@var{pattern}
@itemx -S @var{pattern}
Switch to a particular generation defined by @var{pattern}.

@var{pattern} may be either a generation number or a number prefixed
with ``+'' or ``-''.  The latter means: move forward/backward by a
specified number of generations.  For example, if you want to return to
the latest generation after @code{--roll-back}, use
@code{--switch-generation=+1}.

The difference between @code{--roll-back} and
@code{--switch-generation=-1} is that @code{--switch-generation} will
not make a zeroth generation, so if a specified generation does not
exist, the current generation will not be changed.

@item --search-paths[=@var{kind}]
@cindex search paths
Report environment variable definitions, in Bash syntax, that may be
needed in order to use the set of installed packages.  These environment
variables are used to specify @dfn{search paths} for files used by some
of the installed packages.

For example, GCC needs the @code{CPATH} and @code{LIBRARY_PATH}
environment variables to be defined so it can look for headers and
libraries in the user's profile (@pxref{Environment Variables,,, gcc,
Using the GNU Compiler Collection (GCC)}).  If GCC and, say, the C
library are installed in the profile, then @code{--search-paths} will
suggest setting these variables to @code{@var{profile}/include} and
@code{@var{profile}/lib}, respectively.

The typical use case is to define these environment variables in the
shell:

@example
$ eval `guix package --search-paths`
@end example

@var{kind} may be one of @code{exact}, @code{prefix}, or @code{suffix},
meaning that the returned environment variable definitions will either
be exact settings, or prefixes or suffixes of the current value of these
variables.  When omitted, @var{kind} defaults to @code{exact}.

This option can also be used to compute the @emph{combined} search paths
of several profiles.  Consider this example:

@example
$ guix package -p foo -i guile
$ guix package -p bar -i guile-json
$ guix package -p foo -p bar --search-paths
@end example

The last command above reports about the @code{GUILE_LOAD_PATH}
variable, even though, taken individually, neither @file{foo} nor
@file{bar} would lead to that recommendation.


@item --profile=@var{profile}
@itemx -p @var{profile}
Use @var{profile} instead of the user's default profile.

@item --verbose
Produce verbose output.  In particular, emit the build log of the
environment on the standard error port.

@item --bootstrap
Use the bootstrap Guile to build the profile.  This option is only
useful to distribution developers.

@end table

In addition to these actions, @command{guix package} supports the
following options to query the current state of a profile, or the
availability of packages:

@table @option

@item --search=@var{regexp}
@itemx -s @var{regexp}
@cindex searching for packages
List the available packages whose name, synopsis, or description matches
@var{regexp}.  Print all the metadata of matching packages in
@code{recutils} format (@pxref{Top, GNU recutils databases,, recutils,
GNU recutils manual}).

This allows specific fields to be extracted using the @command{recsel}
command, for instance:

@example
$ guix package -s malloc | recsel -p name,version
name: glibc
version: 2.17

name: libgc
version: 7.2alpha6
@end example

Similarly, to show the name of all the packages available under the
terms of the GNU@tie{}LGPL version 3:

@example
$ guix package -s "" | recsel -p name -e 'license ~ "LGPL 3"'
name: elfutils

name: gmp
@dots{}
@end example

It is also possible to refine search results using several @code{-s}
flags.  For example, the following command returns a list of board
games:

@example
$ guix package -s '\<board\>' -s game | recsel -p name
name: gnubg
@dots{}
@end example

If we were to omit @code{-s game}, we would also get software packages
that deal with printed circuit boards; removing the angle brackets
around @code{board} would further add packages that have to do with
keyboards.

And now for a more elaborate example.  The following command searches
for cryptographic libraries, filters out Haskell, Perl, Python, and Ruby
libraries, and prints the name and synopsis of the matching packages:

@example
$ guix package -s crypto -s library | \
    recsel -e '! (name ~ "^(ghc|perl|python|ruby)")' -p name,synopsis
@end example

@noindent
@xref{Selection Expressions,,, recutils, GNU recutils manual}, for more
information on @dfn{selection expressions} for @code{recsel -e}.

@item --show=@var{package}
Show details about @var{package}, taken from the list of available packages, in
@code{recutils} format (@pxref{Top, GNU recutils databases,, recutils, GNU
recutils manual}).

@example
$ guix package --show=python | recsel -p name,version
name: python
version: 2.7.6

name: python
version: 3.3.5
@end example

You may also specify the full name of a package to only get details about a
specific version of it:
@example
$ guix package --show=python-3.3.5 | recsel -p name,version
name: python
version: 3.3.5
@end example



@item --list-installed[=@var{regexp}]
@itemx -I [@var{regexp}]
List the currently installed packages in the specified profile, with the
most recently installed packages shown last.  When @var{regexp} is
specified, list only installed packages whose name matches @var{regexp}.

For each installed package, print the following items, separated by
tabs: the package name, its version string, the part of the package that
is installed (for instance, @code{out} for the default output,
@code{include} for its headers, etc.), and the path of this package in
the store.

@item --list-available[=@var{regexp}]
@itemx -A [@var{regexp}]
List packages currently available in the distribution for this system
(@pxref{GNU Distribution}).  When @var{regexp} is specified, list only
installed packages whose name matches @var{regexp}.

For each package, print the following items separated by tabs: its name,
its version string, the parts of the package (@pxref{Packages with
Multiple Outputs}), and the source location of its definition.

@item --list-generations[=@var{pattern}]
@itemx -l [@var{pattern}]
Return a list of generations along with their creation dates; for each
generation, show the installed packages, with the most recently
installed packages shown last.  Note that the zeroth generation is never
shown.

For each installed package, print the following items, separated by
tabs: the name of a package, its version string, the part of the package
that is installed (@pxref{Packages with Multiple Outputs}), and the
location of this package in the store.

When @var{pattern} is used, the command returns only matching
generations.  Valid patterns include:

@itemize
@item @emph{Integers and comma-separated integers}.  Both patterns denote
generation numbers.  For instance, @code{--list-generations=1} returns
the first one.

And @code{--list-generations=1,8,2} outputs three generations in the
specified order.  Neither spaces nor trailing commas are allowed.

@item @emph{Ranges}.  @code{--list-generations=2..9} prints the
specified generations and everything in between.  Note that the start of
a range must be smaller than its end.

It is also possible to omit the endpoint.  For example,
@code{--list-generations=2..}, returns all generations starting from the
second one.

@item @emph{Durations}.  You can also get the last @emph{N}@tie{}days, weeks,
or months by passing an integer along with the first letter of the
duration.  For example, @code{--list-generations=20d} lists generations
that are up to 20 days old.
@end itemize

@item --delete-generations[=@var{pattern}]
@itemx -d [@var{pattern}]
When @var{pattern} is omitted, delete all generations except the current
one.

This command accepts the same patterns as @option{--list-generations}.
When @var{pattern} is specified, delete the matching generations.  When
@var{pattern} specifies a duration, generations @emph{older} than the
specified duration match.  For instance, @code{--delete-generations=1m}
deletes generations that are more than one month old.

If the current generation matches, it is @emph{not} deleted.  Also, the
zeroth generation is never deleted.

Note that deleting generations prevents rolling back to them.
Consequently, this command must be used with care.

@end table

Finally, since @command{guix package} may actually start build
processes, it supports all the common build options (@pxref{Common Build
Options}).  It also supports package transformation options, such as
@option{--with-source} (@pxref{Package Transformation Options}).
However, note that package transformations are lost when upgrading; to
preserve transformations across upgrades, you should define your own
package variant in a Guile module and add it to @code{GUIX_PACKAGE_PATH}
(@pxref{Defining Packages}).


@node Substitutes
@section Substitutes

@cindex substitutes
@cindex pre-built binaries
Guix supports transparent source/binary deployment, which means that it
can either build things locally, or download pre-built items from a
server.  We call these pre-built items @dfn{substitutes}---they are
substitutes for local build results.  In many cases, downloading a
substitute is much faster than building things locally.

Substitutes can be anything resulting from a derivation build
(@pxref{Derivations}).  Of course, in the common case, they are
pre-built package binaries, but source tarballs, for instance, which
also result from derivation builds, can be available as substitutes.

The @code{hydra.gnu.org} server is a front-end to a build farm that
builds packages from the GNU distribution continuously for some
architectures, and makes them available as substitutes (@pxref{Emacs
Hydra}, for information on how to query the continuous integration
server).  This is the
default source of substitutes; it can be overridden by passing the
@option{--substitute-urls} option either to @command{guix-daemon}
(@pxref{daemon-substitute-urls,, @code{guix-daemon --substitute-urls}})
or to client tools such as @command{guix package}
(@pxref{client-substitute-urls,, client @option{--substitute-urls}
option}).

Substitute URLs can be either HTTP or HTTPS@footnote{For HTTPS access,
the Guile bindings of GnuTLS must be installed.  @xref{Requirements}.}
HTTPS is recommended because communications are encrypted; conversely,
using HTTP makes all communications visible to an eavesdropper, who
could use the information gathered to determine, for instance, whether
your system has unpatched security vulnerabilities.

@cindex security
@cindex digital signatures
To allow Guix to download substitutes from @code{hydra.gnu.org} or a
mirror thereof, you
must add its public key to the access control list (ACL) of archive
imports, using the @command{guix archive} command (@pxref{Invoking guix
archive}).  Doing so implies that you trust @code{hydra.gnu.org} to not
be compromised and to serve genuine substitutes.

This public key is installed along with Guix, in
@code{@var{prefix}/share/guix/hydra.gnu.org.pub}, where @var{prefix} is
the installation prefix of Guix.  If you installed Guix from source,
make sure you checked the GPG signature of
@file{guix-@value{VERSION}.tar.gz}, which contains this public key file.
Then, you can run something like this:

@example
# guix archive --authorize < hydra.gnu.org.pub
@end example

Once this is in place, the output of a command like @code{guix build}
should change from something like:

@example
$ guix build emacs --dry-run
The following derivations would be built:
   /gnu/store/yr7bnx8xwcayd6j95r2clmkdl1qh688w-emacs-24.3.drv
   /gnu/store/x8qsh1hlhgjx6cwsjyvybnfv2i37z23w-dbus-1.6.4.tar.gz.drv
   /gnu/store/1ixwp12fl950d15h2cj11c73733jay0z-alsa-lib-1.0.27.1.tar.bz2.drv
   /gnu/store/nlma1pw0p603fpfiqy7kn4zm105r5dmw-util-linux-2.21.drv
@dots{}
@end example

@noindent
to something like:

@example
$ guix build emacs --dry-run
The following files would be downloaded:
   /gnu/store/pk3n22lbq6ydamyymqkkz7i69wiwjiwi-emacs-24.3
   /gnu/store/2ygn4ncnhrpr61rssa6z0d9x22si0va3-libjpeg-8d
   /gnu/store/71yz6lgx4dazma9dwn2mcjxaah9w77jq-cairo-1.12.16
   /gnu/store/7zdhgp0n1518lvfn8mb96sxqfmvqrl7v-libxrender-0.9.7
@dots{}
@end example

@noindent
This indicates that substitutes from @code{hydra.gnu.org} are usable and
will be downloaded, when possible, for future builds.

Guix ignores substitutes that are not signed, or that are not signed by
one of the keys listed in the ACL.  It also detects and raises an error
when attempting to use a substitute that has been tampered with.

@vindex http_proxy
Substitutes are downloaded over HTTP or HTTPS.
The @code{http_proxy} environment
variable can be set in the environment of @command{guix-daemon} and is
honored for downloads of substitutes.  Note that the value of
@code{http_proxy} in the environment where @command{guix build},
@command{guix package}, and other client commands are run has
@emph{absolutely no effect}.

When using HTTPS, the server's X.509 certificate is @emph{not} validated
(in other words, the server is not authenticated), contrary to what
HTTPS clients such as Web browsers usually do.  This is because Guix
authenticates substitute information itself, as explained above, which
is what we care about (whereas X.509 certificates are about
authenticating bindings between domain names and public keys.)

The substitute mechanism can be disabled globally by running
@code{guix-daemon} with @code{--no-substitutes} (@pxref{Invoking
guix-daemon}).  It can also be disabled temporarily by passing the
@code{--no-substitutes} option to @command{guix package}, @command{guix
build}, and other command-line tools.


@unnumberedsubsec On Trusting Binaries

Today, each individual's control over their own computing is at the
mercy of institutions, corporations, and groups with enough power and
determination to subvert the computing infrastructure and exploit its
weaknesses.  While using @code{hydra.gnu.org} substitutes can be
convenient, we encourage users to also build on their own, or even run
their own build farm, such that @code{hydra.gnu.org} is less of an
interesting target.  One way to help is by publishing the software you
build using @command{guix publish} so that others have one more choice
of server to download substitutes from (@pxref{Invoking guix publish}).

Guix has the foundations to maximize build reproducibility
(@pxref{Features}).  In most cases, independent builds of a given
package or derivation should yield bit-identical results.  Thus, through
a diverse set of independent package builds, we can strengthen the
integrity of our systems.  The @command{guix challenge} command aims to
help users assess substitute servers, and to assist developers in
finding out about non-deterministic package builds (@pxref{Invoking guix
challenge}).  Similarly, the @option{--check} option of @command{guix
build} allows users to check whether previously-installed substitutes
are genuine by rebuilding them locally (@pxref{build-check,
@command{guix build --check}}).

In the future, we want Guix to have support to publish and retrieve
binaries to/from other users, in a peer-to-peer fashion.  If you would
like to discuss this project, join us on @email{guix-devel@@gnu.org}.


@node Packages with Multiple Outputs
@section Packages with Multiple Outputs

@cindex multiple-output packages
@cindex package outputs

Often, packages defined in Guix have a single @dfn{output}---i.e., the
source package leads to exactly one directory in the store.  When running
@command{guix package -i glibc}, one installs the default output of the
GNU libc package; the default output is called @code{out}, but its name
can be omitted as shown in this command.  In this particular case, the
default output of @code{glibc} contains all the C header files, shared
libraries, static libraries, Info documentation, and other supporting
files.

Sometimes it is more appropriate to separate the various types of files
produced from a single source package into separate outputs.  For
instance, the GLib C library (used by GTK+ and related packages)
installs more than 20 MiB of reference documentation as HTML pages.
To save space for users who do not need it, the documentation goes to a
separate output, called @code{doc}.  To install the main GLib output,
which contains everything but the documentation, one would run:

@example
guix package -i glib
@end example

The command to install its documentation is:

@example
guix package -i glib:doc
@end example

Some packages install programs with different ``dependency footprints''.
For instance, the WordNet package installs both command-line tools and
graphical user interfaces (GUIs).  The former depend solely on the C
library, whereas the latter depend on Tcl/Tk and the underlying X
libraries.  In this case, we leave the command-line tools in the default
output, whereas the GUIs are in a separate output.  This allows users
who do not need the GUIs to save space.  The @command{guix size} command
can help find out about such situations (@pxref{Invoking guix size}).
@command{guix graph} can also be helpful (@pxref{Invoking guix graph}).

There are several such multiple-output packages in the GNU distribution.
Other conventional output names include @code{lib} for libraries and
possibly header files, @code{bin} for stand-alone programs, and
@code{debug} for debugging information (@pxref{Installing Debugging
Files}).  The outputs of a packages are listed in the third column of
the output of @command{guix package --list-available} (@pxref{Invoking
guix package}).


@node Invoking guix gc
@section Invoking @command{guix gc}

@cindex garbage collector
Packages that are installed, but not used, may be @dfn{garbage-collected}.
The @command{guix gc} command allows users to explicitly run the garbage
collector to reclaim space from the @file{/gnu/store} directory.  It is
the @emph{only} way to remove files from @file{/gnu/store}---removing
files or directories manually may break it beyond repair!

The garbage collector has a set of known @dfn{roots}: any file under
@file{/gnu/store} reachable from a root is considered @dfn{live} and
cannot be deleted; any other file is considered @dfn{dead} and may be
deleted.  The set of garbage collector roots includes default user
profiles, and may be augmented with @command{guix build --root}, for
example (@pxref{Invoking guix build}).

Prior to running @code{guix gc --collect-garbage} to make space, it is
often useful to remove old generations from user profiles; that way, old
package builds referenced by those generations can be reclaimed.  This
is achieved by running @code{guix package --delete-generations}
(@pxref{Invoking guix package}).

The @command{guix gc} command has three modes of operation: it can be
used to garbage-collect any dead files (the default), to delete specific
files (the @code{--delete} option), to print garbage-collector
information, or for more advanced queries.  The garbage collection
options are as follows:

@table @code
@item --collect-garbage[=@var{min}]
@itemx -C [@var{min}]
Collect garbage---i.e., unreachable @file{/gnu/store} files and
sub-directories.  This is the default operation when no option is
specified.

When @var{min} is given, stop once @var{min} bytes have been collected.
@var{min} may be a number of bytes, or it may include a unit as a
suffix, such as @code{MiB} for mebibytes and @code{GB} for gigabytes
(@pxref{Block size, size specifications,, coreutils, GNU Coreutils}).

When @var{min} is omitted, collect all the garbage.

@item --free-space=@var{free}
@itemx -F @var{free}
Collect garbage until @var{free} space is available under
@file{/gnu/store}, if possible; @var{free} denotes storage space, such
as @code{500MiB}, as described above.

When @var{free} or more is already available in @file{/gnu/store}, do
nothing and exit immediately.

@item --delete
@itemx -d
Attempt to delete all the store files and directories specified as
arguments.  This fails if some of the files are not in the store, or if
they are still live.

@item --list-failures
List store items corresponding to cached build failures.

This prints nothing unless the daemon was started with
@option{--cache-failures} (@pxref{Invoking guix-daemon,
@option{--cache-failures}}).

@item --clear-failures
Remove the specified store items from the failed-build cache.

Again, this option only makes sense when the daemon is started with
@option{--cache-failures}.  Otherwise, it does nothing.

@item --list-dead
Show the list of dead files and directories still present in the
store---i.e., files and directories no longer reachable from any root.

@item --list-live
Show the list of live store files and directories.

@end table

In addition, the references among existing store files can be queried:

@table @code

@item --references
@itemx --referrers
List the references (respectively, the referrers) of store files given
as arguments.

@item --requisites
@itemx -R
@cindex closure
List the requisites of the store files passed as arguments.  Requisites
include the store files themselves, their references, and the references
of these, recursively.  In other words, the returned list is the
@dfn{transitive closure} of the store files.

@xref{Invoking guix size}, for a tool to profile the size of the closure
of an element.  @xref{Invoking guix graph}, for a tool to visualize
the graph of references.

@end table

Lastly, the following options allow you to check the integrity of the
store and to control disk usage.

@table @option

@item --verify[=@var{options}]
@cindex integrity, of the store
@cindex integrity checking
Verify the integrity of the store.

By default, make sure that all the store items marked as valid in the
database of the daemon actually exist in @file{/gnu/store}.

When provided, @var{options} must be a comma-separated list containing one
or more of @code{contents} and @code{repair}.

When passing @option{--verify=contents}, the daemon computse the
content hash of each store item and compares it against its hash in the
database.  Hash mismatches are reported as data corruptions.  Because it
traverses @emph{all the files in the store}, this command can take a
long time, especially on systems with a slow disk drive.

@cindex repairing the store
Using @option{--verify=repair} or @option{--verify=contents,repair}
causes the daemon to try to repair corrupt store items by fetching
substitutes for them (@pxref{Substitutes}).  Because repairing is not
atomic, and thus potentially dangerous, it is available only to the
system administrator.

@item --optimize
@cindex deduplication
Optimize the store by hard-linking identical files---this is
@dfn{deduplication}.

The daemon performs deduplication after each successful build or archive
import, unless it was started with @code{--disable-deduplication}
(@pxref{Invoking guix-daemon, @code{--disable-deduplication}}).  Thus,
this option is primarily useful when the daemon was running with
@code{--disable-deduplication}.

@end table

@node Invoking guix pull
@section Invoking @command{guix pull}

Packages are installed or upgraded to the latest version available in
the distribution currently available on your local machine.  To update
that distribution, along with the Guix tools, you must run @command{guix
pull}: the command downloads the latest Guix source code and package
descriptions, and deploys it.

On completion, @command{guix package} will use packages and package
versions from this just-retrieved copy of Guix.  Not only that, but all
the Guix commands and Scheme modules will also be taken from that latest
version.  New @command{guix} sub-commands added by the update also
become available.

Any user can update their Guix copy using @command{guix pull}, and the
effect is limited to the user who run @command{guix pull}.  For
instance, when user @code{root} runs @command{guix pull}, this has no
effect on the version of Guix that user @code{alice} sees, and vice
versa@footnote{Under the hood, @command{guix pull} updates the
@file{~/.config/guix/latest} symbolic link to point to the latest Guix,
and the @command{guix} command loads code from there.}.

The @command{guix pull} command is usually invoked with no arguments,
but it supports the following options:

@table @code
@item --verbose
Produce verbose output, writing build logs to the standard error output.

@item --url=@var{url}
Download the source tarball of Guix from @var{url}.

By default, the tarball is taken from its canonical address at
@code{gnu.org}, for the stable branch of Guix.

@item --bootstrap
Use the bootstrap Guile to build the latest Guix.  This option is only
useful to Guix developers.
@end table


@node Invoking guix archive
@section Invoking @command{guix archive}

The @command{guix archive} command allows users to @dfn{export} files
from the store into a single archive, and to later @dfn{import} them.
In particular, it allows store files to be transferred from one machine
to the store on another machine.

To export store files as an archive to standard output, run:

@example
guix archive --export @var{options} @var{specifications}...
@end example

@var{specifications} may be either store file names or package
specifications, as for @command{guix package} (@pxref{Invoking guix
package}).  For instance, the following command creates an archive
containing the @code{gui} output of the @code{git} package and the main
output of @code{emacs}:

@example
guix archive --export git:gui /gnu/store/...-emacs-24.3 > great.nar
@end example

If the specified packages are not built yet, @command{guix archive}
automatically builds them.  The build process may be controlled with the
common build options (@pxref{Common Build Options}).

To transfer the @code{emacs} package to a machine connected over SSH,
one would run:

@example
guix archive --export -r emacs | ssh the-machine guix archive --import
@end example

@noindent
Similarly, a complete user profile may be transferred from one machine
to another like this:

@example
guix archive --export -r $(readlink -f ~/.guix-profile) | \
  ssh the-machine guix-archive --import
@end example

@noindent
However, note that, in both examples, all of @code{emacs} and the
profile as well as all of their dependencies are transferred (due to
@code{-r}), regardless of what is already available in the store on the
target machine.  The @code{--missing} option can help figure out which
items are missing from the target store.

Archives are stored in the ``Nix archive'' or ``Nar'' format, which is
comparable in spirit to `tar', but with a few noteworthy differences
that make it more appropriate for our purposes.  First, rather than
recording all Unix metadata for each file, the Nar format only mentions
the file type (regular, directory, or symbolic link); Unix permissions
and owner/group are dismissed.  Second, the order in which directory
entries are stored always follows the order of file names according to
the C locale collation order.  This makes archive production fully
deterministic.

When exporting, the daemon digitally signs the contents of the archive,
and that digital signature is appended.  When importing, the daemon
verifies the signature and rejects the import in case of an invalid
signature or if the signing key is not authorized.
@c FIXME: Add xref to daemon doc about signatures.

The main options are:

@table @code
@item --export
Export the specified store files or packages (see below.)  Write the
resulting archive to the standard output.

Dependencies are @emph{not} included in the output, unless
@code{--recursive} is passed.

@item -r
@itemx --recursive
When combined with @code{--export}, this instructs @command{guix
archive} to include dependencies of the given items in the archive.
Thus, the resulting archive is self-contained: it contains the closure
of the exported store items.

@item --import
Read an archive from the standard input, and import the files listed
therein into the store.  Abort if the archive has an invalid digital
signature, or if it is signed by a public key not among the authorized
keys (see @code{--authorize} below.)

@item --missing
Read a list of store file names from the standard input, one per line,
and write on the standard output the subset of these files missing from
the store.

@item --generate-key[=@var{parameters}]
@cindex signing, archives
Generate a new key pair for the daemon.  This is a prerequisite before
archives can be exported with @code{--export}.  Note that this operation
usually takes time, because it needs to gather enough entropy to
generate the key pair.

The generated key pair is typically stored under @file{/etc/guix}, in
@file{signing-key.pub} (public key) and @file{signing-key.sec} (private
key, which must be kept secret.)  When @var{parameters} is omitted,
an ECDSA key using the Ed25519 curve is generated, or, for Libgcrypt
versions before 1.6.0, it is a 4096-bit RSA key.
Alternatively, @var{parameters} can specify
@code{genkey} parameters suitable for Libgcrypt (@pxref{General
public-key related Functions, @code{gcry_pk_genkey},, gcrypt, The
Libgcrypt Reference Manual}).

@item --authorize
@cindex authorizing, archives
Authorize imports signed by the public key passed on standard input.
The public key must be in ``s-expression advanced format''---i.e., the
same format as the @file{signing-key.pub} file.

The list of authorized keys is kept in the human-editable file
@file{/etc/guix/acl}.  The file contains
@url{http://people.csail.mit.edu/rivest/Sexp.txt, ``advanced-format
s-expressions''} and is structured as an access-control list in the
@url{http://theworld.com/~cme/spki.txt, Simple Public-Key Infrastructure
(SPKI)}.

@item --extract=@var{directory}
@itemx -x @var{directory}
Read a single-item archive as served by substitute servers
(@pxref{Substitutes}) and extract it to @var{directory}.  This is a
low-level operation needed in only very narrow use cases; see below.

For example, the following command extracts the substitute for Emacs
served by @code{hydra.gnu.org} to @file{/tmp/emacs}:

@example
$ wget -O - \
  https://hydra.gnu.org/nar/@dots{}-emacs-24.5 \
  | bunzip2 | guix archive -x /tmp/emacs
@end example

Single-item archives are different from multiple-item archives produced
by @command{guix archive --export}; they contain a single store item,
and they do @emph{not} embed a signature.  Thus this operation does
@emph{no} signature verification and its output should be considered
unsafe.

The primary purpose of this operation is to facilitate inspection of
archive contents coming from possibly untrusted substitute servers.

@end table

@c *********************************************************************
@include emacs.texi

@c *********************************************************************
@node Programming Interface
@chapter Programming Interface

GNU Guix provides several Scheme programming interfaces (APIs) to
define, build, and query packages.  The first interface allows users to
write high-level package definitions.  These definitions refer to
familiar packaging concepts, such as the name and version of a package,
its build system, and its dependencies.  These definitions can then be
turned into concrete build actions.

Build actions are performed by the Guix daemon, on behalf of users.  In a
standard setup, the daemon has write access to the store---the
@file{/gnu/store} directory---whereas users do not.  The recommended
setup also has the daemon perform builds in chroots, under a specific
build users, to minimize interference with the rest of the system.

@cindex derivation
Lower-level APIs are available to interact with the daemon and the
store.  To instruct the daemon to perform a build action, users actually
provide it with a @dfn{derivation}.  A derivation is a low-level
representation of the build actions to be taken, and the environment in
which they should occur---derivations are to package definitions what
assembly is to C programs.  The term ``derivation'' comes from the fact
that build results @emph{derive} from them.

This chapter describes all these APIs in turn, starting from high-level
package definitions.

@menu
* Defining Packages::           Defining new packages.
* Build Systems::               Specifying how packages are built.
* The Store::                   Manipulating the package store.
* Derivations::                 Low-level interface to package derivations.
* The Store Monad::             Purely functional interface to the store.
* G-Expressions::               Manipulating build expressions.
@end menu

@node Defining Packages
@section Defining Packages

The high-level interface to package definitions is implemented in the
@code{(guix packages)} and @code{(guix build-system)} modules.  As an
example, the package definition, or @dfn{recipe}, for the GNU Hello
package looks like this:

@example
(define-module (gnu packages hello)
  #:use-module (guix packages)
  #:use-module (guix download)
  #:use-module (guix build-system gnu)
  #:use-module (guix licenses)
  #:use-module (gnu packages gawk))

(define-public hello
  (package
    (name "hello")
    (version "2.10")
    (source (origin
              (method url-fetch)
              (uri (string-append "mirror://gnu/hello/hello-" version
                                  ".tar.gz"))
              (sha256
               (base32
                "0ssi1wpaf7plaswqqjwigppsg5fyh99vdlb9kzl7c9lng89ndq1i"))))
    (build-system gnu-build-system)
    (arguments `(#:configure-flags '("--enable-silent-rules")))
    (inputs `(("gawk" ,gawk)))
    (synopsis "Hello, GNU world: An example GNU package")
    (description "Guess what GNU Hello prints!")
    (home-page "http://www.gnu.org/software/hello/")
    (license gpl3+)))
@end example

@noindent
Without being a Scheme expert, the reader may have guessed the meaning
of the various fields here.  This expression binds the variable
@code{hello} to a @code{<package>} object, which is essentially a record
(@pxref{SRFI-9, Scheme records,, guile, GNU Guile Reference Manual}).
This package object can be inspected using procedures found in the
@code{(guix packages)} module; for instance, @code{(package-name hello)}
returns---surprise!---@code{"hello"}.

With luck, you may be able to import part or all of the definition of
the package you are interested in from another repository, using the
@code{guix import} command (@pxref{Invoking guix import}).

In the example above, @var{hello} is defined in a module of its own,
@code{(gnu packages hello)}.  Technically, this is not strictly
necessary, but it is convenient to do so: all the packages defined in
modules under @code{(gnu packages @dots{})} are automatically known to
the command-line tools (@pxref{Package Modules}).

There are a few points worth noting in the above package definition:

@itemize
@item
The @code{source} field of the package is an @code{<origin>} object
(@pxref{origin Reference}, for the complete reference).
Here, the @code{url-fetch} method from @code{(guix download)} is used,
meaning that the source is a file to be downloaded over FTP or HTTP.

The @code{mirror://gnu} prefix instructs @code{url-fetch} to use one of
the GNU mirrors defined in @code{(guix download)}.

The @code{sha256} field specifies the expected SHA256 hash of the file
being downloaded.  It is mandatory, and allows Guix to check the
integrity of the file.  The @code{(base32 @dots{})} form introduces the
base32 representation of the hash.  You can obtain this information with
@code{guix download} (@pxref{Invoking guix download}) and @code{guix
hash} (@pxref{Invoking guix hash}).

@cindex patches
When needed, the @code{origin} form can also have a @code{patches} field
listing patches to be applied, and a @code{snippet} field giving a
Scheme expression to modify the source code.

@item
@cindex GNU Build System
The @code{build-system} field specifies the procedure to build the
package (@pxref{Build Systems}).  Here, @var{gnu-build-system}
represents the familiar GNU Build System, where packages may be
configured, built, and installed with the usual @code{./configure &&
make && make check && make install} command sequence.

@item
The @code{arguments} field specifies options for the build system
(@pxref{Build Systems}).  Here it is interpreted by
@var{gnu-build-system} as a request run @file{configure} with the
@code{--enable-silent-rules} flag.

@item
The @code{inputs} field specifies inputs to the build process---i.e.,
build-time or run-time dependencies of the package.  Here, we define an
input called @code{"gawk"} whose value is that of the @var{gawk}
variable; @var{gawk} is itself bound to a @code{<package>} object.

Note that GCC, Coreutils, Bash, and other essential tools do not need to
be specified as inputs here.  Instead, @var{gnu-build-system} takes care
of ensuring that they are present (@pxref{Build Systems}).

However, any other dependencies need to be specified in the
@code{inputs} field.  Any dependency not specified here will simply be
unavailable to the build process, possibly leading to a build failure.
@end itemize

@xref{package Reference}, for a full description of possible fields.

Once a package definition is in place, the
package may actually be built using the @code{guix build} command-line
tool (@pxref{Invoking guix build}).  You can easily jump back to the
package definition using the @command{guix edit} command
(@pxref{Invoking guix edit}).
@xref{Packaging Guidelines}, for
more information on how to test package definitions, and
@ref{Invoking guix lint}, for information on how to check a definition
for style conformance.

Finally, updating the package definition to a new upstream version
can be partly automated by the @command{guix refresh} command
(@pxref{Invoking guix refresh}).

Behind the scenes, a derivation corresponding to the @code{<package>}
object is first computed by the @code{package-derivation} procedure.
That derivation is stored in a @code{.drv} file under @file{/gnu/store}.
The build actions it prescribes may then be realized by using the
@code{build-derivations} procedure (@pxref{The Store}).

@deffn {Scheme Procedure} package-derivation @var{store} @var{package} [@var{system}]
Return the @code{<derivation>} object of @var{package} for @var{system}
(@pxref{Derivations}).

@var{package} must be a valid @code{<package>} object, and @var{system}
must be a string denoting the target system type---e.g.,
@code{"x86_64-linux"} for an x86_64 Linux-based GNU system.  @var{store}
must be a connection to the daemon, which operates on the store
(@pxref{The Store}).
@end deffn

@noindent
@cindex cross-compilation
Similarly, it is possible to compute a derivation that cross-builds a
package for some other system:

@deffn {Scheme Procedure} package-cross-derivation @var{store} @
            @var{package} @var{target} [@var{system}]
Return the @code{<derivation>} object of @var{package} cross-built from
@var{system} to @var{target}.

@var{target} must be a valid GNU triplet denoting the target hardware
and operating system, such as @code{"mips64el-linux-gnu"}
(@pxref{Configuration Names, GNU configuration triplets,, configure, GNU
Configure and Build System}).
@end deffn

@menu
* package Reference ::          The package data type.
* origin Reference::            The origin data type.
@end menu


@node package Reference
@subsection @code{package} Reference

This section summarizes all the options available in @code{package}
declarations (@pxref{Defining Packages}).

@deftp {Data Type} package
This is the data type representing a package recipe.

@table @asis
@item @code{name}
The name of the package, as a string.

@item @code{version}
The version of the package, as a string.

@item @code{source}
An object telling how the source code for the package should be
acquired.  Most of the time, this is an @code{origin} object, which
denotes a file fetched from the Internet (@pxref{origin Reference}).  It
can also be any other ``file-like'' object such as a @code{local-file},
which denotes a file from the local file system (@pxref{G-Expressions,
@code{local-file}}).

@item @code{build-system}
The build system that should be used to build the package (@pxref{Build
Systems}).

@item @code{arguments} (default: @code{'()})
The arguments that should be passed to the build system.  This is a
list, typically containing sequential keyword-value pairs.

@item @code{inputs} (default: @code{'()})
@itemx @code{native-inputs} (default: @code{'()})
@itemx @code{propagated-inputs} (default: @code{'()})
@cindex inputs, of packages
These fields list dependencies of the package.  Each one is a list of
tuples, where each tuple has a label for the input (a string) as its
first element, a package, origin, or derivation as its second element,
and optionally the name of the output thereof that should be used, which
defaults to @code{"out"} (@pxref{Packages with Multiple Outputs}, for
more on package outputs).  For example, the list below specifies three
inputs:

@example
`(("libffi" ,libffi)
  ("libunistring" ,libunistring)
  ("glib:bin" ,glib "bin"))  ;the "bin" output of Glib
@end example

@cindex cross compilation, package dependencies
The distinction between @code{native-inputs} and @code{inputs} is
necessary when considering cross-compilation.  When cross-compiling,
dependencies listed in @code{inputs} are built for the @emph{target}
architecture; conversely, dependencies listed in @code{native-inputs}
are built for the architecture of the @emph{build} machine.

@code{native-inputs} is typically used to list tools needed at
build time, but not at run time, such as Autoconf, Automake, pkg-config,
Gettext, or Bison.  @command{guix lint} can report likely mistakes in
this area (@pxref{Invoking guix lint}).

@anchor{package-propagated-inputs}
Lastly, @code{propagated-inputs} is similar to @code{inputs}, but the
specified packages will be automatically installed alongside the package
they belong to (@pxref{package-cmd-propagated-inputs, @command{guix
package}}, for information on how @command{guix package} deals with
propagated inputs.)

For example this is necessary when a C/C++ library needs headers of
another library to compile, or when a pkg-config file refers to another
one @i{via} its @code{Requires} field.

Another example where @code{propagated-inputs} is useful is for languages
that lack a facility to record the run-time search path akin to the
@code{RUNPATH} of ELF files; this includes Guile, Python, Perl, GHC, and
more.  To ensure that libraries written in those languages can find
library code they depend on at run time, run-time dependencies must be
listed in @code{propagated-inputs} rather than @code{inputs}.

@item @code{self-native-input?} (default: @code{#f})
This is a Boolean field telling whether the package should use itself as
a native input when cross-compiling.

@item @code{outputs} (default: @code{'("out")})
The list of output names of the package.  @xref{Packages with Multiple
Outputs}, for typical uses of additional outputs.

@item @code{native-search-paths} (default: @code{'()})
@itemx @code{search-paths} (default: @code{'()})
A list of @code{search-path-specification} objects describing
search-path environment variables honored by the package.

@item @code{replacement} (default: @code{#f})
This must be either @code{#f} or a package object that will be used as a
@dfn{replacement} for this package.  @xref{Security Updates, grafts},
for details.

@item @code{synopsis}
A one-line description of the package.

@item @code{description}
A more elaborate description of the package.

@item @code{license}
The license of the package; a value from @code{(guix licenses)},
or a list of such values.

@item @code{home-page}
The URL to the home-page of the package, as a string.

@item @code{supported-systems} (default: @var{%supported-systems})
The list of systems supported by the package, as strings of the form
@code{architecture-kernel}, for example @code{"x86_64-linux"}.

@item @code{maintainers} (default: @code{'()})
The list of maintainers of the package, as @code{maintainer} objects.

@item @code{location} (default: source location of the @code{package} form)
The source location of the package.  It is useful to override this when
inheriting from another package, in which case this field is not
automatically corrected.
@end table
@end deftp


@node origin Reference
@subsection @code{origin} Reference

This section summarizes all the options available in @code{origin}
declarations (@pxref{Defining Packages}).

@deftp {Data Type} origin
This is the data type representing a source code origin.

@table @asis
@item @code{uri}
An object containing the URI of the source.  The object type depends on
the @code{method} (see below).  For example, when using the
@var{url-fetch} method of @code{(guix download)}, the valid @code{uri}
values are: a URL represented as a string, or a list thereof.

@item @code{method}
A procedure that handles the URI.

Examples include:

@table @asis
@item @var{url-fetch} from @code{(guix download)}
download a file from the HTTP, HTTPS, or FTP URL specified in the
@code{uri} field;

@item @var{git-fetch} from @code{(guix git-download)}
clone the Git version control repository, and check out the revision
specified in the @code{uri} field as a @code{git-reference} object; a
@code{git-reference} looks like this:

@example
(git-reference
  (url "git://git.debian.org/git/pkg-shadow/shadow")
  (commit "v4.1.5.1"))
@end example
@end table

@item @code{sha256}
A bytevector containing the SHA-256 hash of the source.  Typically the
@code{base32} form is used here to generate the bytevector from a
base-32 string.

@item @code{file-name} (default: @code{#f})
The file name under which the source code should be saved.  When this is
@code{#f}, a sensible default value will be used in most cases.  In case
the source is fetched from a URL, the file name from the URL will be
used.  For version control checkouts, it is recommended to provide the
file name explicitly because the default is not very descriptive.

@item @code{patches} (default: @code{'()})
A list of file names containing patches to be applied to the source.

@item @code{snippet} (default: @code{#f})
A G-expression (@pxref{G-Expressions}) or S-expression that will be run
in the source directory.  This is a convenient way to modify the source,
sometimes more convenient than a patch.

@item @code{patch-flags} (default: @code{'("-p1")})
A list of command-line flags that should be passed to the @code{patch}
command.

@item @code{patch-inputs} (default: @code{#f})
Input packages or derivations to the patching process.  When this is
@code{#f}, the usual set of inputs necessary for patching are provided,
such as GNU@tie{}Patch.

@item @code{modules} (default: @code{'()})
A list of Guile modules that should be loaded during the patching
process and while running the code in the @code{snippet} field.

@item @code{patch-guile} (default: @code{#f})
The Guile package that should be used in the patching process.  When
this is @code{#f}, a sensible default is used.
@end table
@end deftp


@node Build Systems
@section Build Systems

@cindex build system
Each package definition specifies a @dfn{build system} and arguments for
that build system (@pxref{Defining Packages}).  This @code{build-system}
field represents the build procedure of the package, as well as implicit
dependencies of that build procedure.

Build systems are @code{<build-system>} objects.  The interface to
create and manipulate them is provided by the @code{(guix build-system)}
module, and actual build systems are exported by specific modules.

@cindex bag (low-level package representation)
Under the hood, build systems first compile package objects to
@dfn{bags}.  A @dfn{bag} is like a package, but with less
ornamentation---in other words, a bag is a lower-level representation of
a package, which includes all the inputs of that package, including some
that were implicitly added by the build system.  This intermediate
representation is then compiled to a derivation (@pxref{Derivations}).

Build systems accept an optional list of @dfn{arguments}.  In package
definitions, these are passed @i{via} the @code{arguments} field
(@pxref{Defining Packages}).  They are typically keyword arguments
(@pxref{Optional Arguments, keyword arguments in Guile,, guile, GNU
Guile Reference Manual}).  The value of these arguments is usually
evaluated in the @dfn{build stratum}---i.e., by a Guile process launched
by the daemon (@pxref{Derivations}).

The main build system is @var{gnu-build-system}, which implements the
standard build procedure for GNU and many other packages.  It
is provided by the @code{(guix build-system gnu)} module.

@defvr {Scheme Variable} gnu-build-system
@var{gnu-build-system} represents the GNU Build System, and variants
thereof (@pxref{Configuration, configuration and makefile conventions,,
standards, GNU Coding Standards}).

@cindex build phases
In a nutshell, packages using it are configured, built, and installed with
the usual @code{./configure && make && make check && make install}
command sequence.  In practice, a few additional steps are often needed.
All these steps are split up in separate @dfn{phases},
notably@footnote{Please see the @code{(guix build gnu-build-system)}
modules for more details about the build phases.}:

@table @code
@item unpack
Unpack the source tarball, and change the current directory to the
extracted source tree.  If the source is actually a directory, copy it
to the build tree, and enter that directory.

@item patch-source-shebangs
Patch shebangs encountered in source files so they refer to the right
store file names.  For instance, this changes @code{#!/bin/sh} to
@code{#!/gnu/store/@dots{}-bash-4.3/bin/sh}.

@item configure
Run the @file{configure} script with a number of default options, such
as @code{--prefix=/gnu/store/@dots{}}, as well as the options specified
by the @code{#:configure-flags} argument.

@item build
Run @code{make} with the list of flags specified with
@code{#:make-flags}.  If the @code{#:parallel-build?} argument is true
(the default), build with @code{make -j}.

@item check
Run @code{make check}, or some other target specified with
@code{#:test-target}, unless @code{#:tests? #f} is passed.  If the
@code{#:parallel-tests?} argument is true (the default), run @code{make
check -j}.

@item install
Run @code{make install} with the flags listed in @code{#:make-flags}.

@item patch-shebangs
Patch shebangs on the installed executable files.

@item strip
Strip debugging symbols from ELF files (unless @code{#:strip-binaries?}
is false), copying them to the @code{debug} output when available
(@pxref{Installing Debugging Files}).
@end table

@vindex %standard-phases
The build-side module @code{(guix build gnu-build-system)} defines
@var{%standard-phases} as the default list of build phases.
@var{%standard-phases} is a list of symbol/procedure pairs, where the
procedure implements the actual phase.

The list of phases used for a particular package can be changed with the
@code{#:phases} parameter.  For instance, passing:

@example
#:phases (modify-phases %standard-phases (delete 'configure))
@end example

means that all the phases described above will be used, except the
@code{configure} phase.

In addition, this build system ensures that the ``standard'' environment
for GNU packages is available.  This includes tools such as GCC, libc,
Coreutils, Bash, Make, Diffutils, grep, and sed (see the @code{(guix
build-system gnu)} module for a complete list).  We call these the
@dfn{implicit inputs} of a package, because package definitions do not
have to mention them.
@end defvr

Other @code{<build-system>} objects are defined to support other
conventions and tools used by free software packages.  They inherit most
of @var{gnu-build-system}, and differ mainly in the set of inputs
implicitly added to the build process, and in the list of phases
executed.  Some of these build systems are listed below.

@defvr {Scheme Variable} ant-build-system
This variable is exported by @code{(guix build-system ant)}.  It
implements the build procedure for Java packages that can be built with
@url{http://ant.apache.org/, Ant build tool}.

It adds both @code{ant} and the @dfn{Java Development Kit} (JDK) as
provided by the @code{icedtea} package to the set of inputs.  Different
packages can be specified with the @code{#:ant} and @code{#:jdk}
parameters, respectively.

When the original package does not provide a suitable Ant build file,
the parameter @code{#:jar-name} can be used to generate a minimal Ant
build file @file{build.xml} with tasks to build the specified jar
archive.

The parameter @code{#:build-target} can be used to specify the Ant task
that should be run during the @code{build} phase.  By default the
``jar'' task will be run.

@end defvr

@defvr {Scheme Variable} cmake-build-system
This variable is exported by @code{(guix build-system cmake)}.  It
implements the build procedure for packages using the
@url{http://www.cmake.org, CMake build tool}.

It automatically adds the @code{cmake} package to the set of inputs.
Which package is used can be specified with the @code{#:cmake}
parameter.

The @code{#:configure-flags} parameter is taken as a list of flags
passed to the @command{cmake} command.  The @code{#:build-type}
parameter specifies in abstract terms the flags passed to the compiler;
it defaults to @code{"RelWithDebInfo"} (short for ``release mode with
debugging information''), which roughly means that code is compiled with
@code{-O2 -g}, as is the case for Autoconf-based packages by default.
@end defvr

@defvr {Scheme Variable} glib-or-gtk-build-system
This variable is exported by @code{(guix build-system glib-or-gtk)}.  It
is intended for use with packages making use of GLib or GTK+.

This build system adds the following two phases to the ones defined by
@var{gnu-build-system}:

@table @code
@item glib-or-gtk-wrap
The phase @code{glib-or-gtk-wrap} ensures that programs in
@file{bin/} are able to find GLib ``schemas'' and
@uref{https://developer.gnome.org/gtk3/stable/gtk-running.html, GTK+
modules}.  This is achieved by wrapping the programs in launch scripts
that appropriately set the @code{XDG_DATA_DIRS} and @code{GTK_PATH}
environment variables.

It is possible to exclude specific package outputs from that wrapping
process by listing their names in the
@code{#:glib-or-gtk-wrap-excluded-outputs} parameter.  This is useful
when an output is known not to contain any GLib or GTK+ binaries, and
where wrapping would gratuitously add a dependency of that output on
GLib and GTK+.

@item glib-or-gtk-compile-schemas
The phase @code{glib-or-gtk-compile-schemas} makes sure that all
@uref{https://developer.gnome.org/gio/stable/glib-compile-schemas.html,
GSettings schemas} of GLib are compiled.  Compilation is performed by the
@command{glib-compile-schemas} program.  It is provided by the package
@code{glib:bin} which is automatically imported by the build system.
The @code{glib} package providing @command{glib-compile-schemas} can be
specified with the @code{#:glib} parameter.
@end table

Both phases are executed after the @code{install} phase.
@end defvr

@defvr {Scheme Variable} python-build-system
This variable is exported by @code{(guix build-system python)}.  It
implements the more or less standard build procedure used by Python
packages, which consists in running @code{python setup.py build} and
then @code{python setup.py install --prefix=/gnu/store/@dots{}}.

For packages that install stand-alone Python programs under @code{bin/},
it takes care of wrapping these programs so that their @code{PYTHONPATH}
environment variable points to all the Python libraries they depend on.

Which Python package is used to perform the build can be specified with
the @code{#:python} parameter.  This is a useful way to force a package
to be built for a specific version of the Python interpreter, which
might be necessary if the package is only compatible with a single
interpreter version.
@end defvr

@defvr {Scheme Variable} perl-build-system
This variable is exported by @code{(guix build-system perl)}.  It
implements the standard build procedure for Perl packages, which either
consists in running @code{perl Build.PL --prefix=/gnu/store/@dots{}},
followed by @code{Build} and @code{Build install}; or in running
@code{perl Makefile.PL PREFIX=/gnu/store/@dots{}}, followed by
@code{make} and @code{make install}, depending on which of
@code{Build.PL} or @code{Makefile.PL} is present in the package
distribution.  Preference is given to the former if both @code{Build.PL}
and @code{Makefile.PL} exist in the package distribution.  This
preference can be reversed by specifying @code{#t} for the
@code{#:make-maker?} parameter.

The initial @code{perl Makefile.PL} or @code{perl Build.PL} invocation
passes flags specified by the @code{#:make-maker-flags} or
@code{#:module-build-flags} parameter, respectively.

Which Perl package is used can be specified with @code{#:perl}.
@end defvr

@defvr {Scheme Variable} r-build-system
This variable is exported by @code{(guix build-system r)}.  It
implements the build procedure used by @uref{http://r-project.org, R}
packages, which essentially is little more than running @code{R CMD
INSTALL --library=/gnu/store/@dots{}} in an environment where
@code{R_LIBS_SITE} contains the paths to all R package inputs.  Tests
are run after installation using the R function
@code{tools::testInstalledPackage}.
@end defvr

@defvr {Scheme Variable} ruby-build-system
This variable is exported by @code{(guix build-system ruby)}.  It
implements the RubyGems build procedure used by Ruby packages, which
involves running @code{gem build} followed by @code{gem install}.

The @code{source} field of a package that uses this build system
typically references a gem archive, since this is the format that Ruby
developers use when releasing their software.  The build system unpacks
the gem archive, potentially patches the source, runs the test suite,
repackages the gem, and installs it.  Additionally, directories and
tarballs may be referenced to allow building unreleased gems from Git or
a traditional source release tarball.

Which Ruby package is used can be specified with the @code{#:ruby}
parameter.  A list of additional flags to be passed to the @command{gem}
command can be specified with the @code{#:gem-flags} parameter.
@end defvr

@defvr {Scheme Variable} waf-build-system
This variable is exported by @code{(guix build-system waf)}.  It
implements a build procedure around the @code{waf} script.  The common
phases---@code{configure}, @code{build}, and @code{install}---are
implemented by passing their names as arguments to the @code{waf}
script.

The @code{waf} script is executed by the Python interpreter.  Which
Python package is used to run the script can be specified with the
@code{#:python} parameter.
@end defvr

@defvr {Scheme Variable} haskell-build-system
This variable is exported by @code{(guix build-system haskell)}.  It
implements the Cabal build procedure used by Haskell packages, which
involves running @code{runhaskell Setup.hs configure
--prefix=/gnu/store/@dots{}} and @code{runhaskell Setup.hs build}.
Instead of installing the package by running @code{runhaskell Setup.hs
install}, to avoid trying to register libraries in the read-only
compiler store directory, the build system uses @code{runhaskell
Setup.hs copy}, followed by @code{runhaskell Setup.hs register}.  In
addition, the build system generates the package documentation by
running @code{runhaskell Setup.hs haddock}, unless @code{#:haddock? #f}
is passed.  Optional Haddock parameters can be passed with the help of
the @code{#:haddock-flags} parameter.  If the file @code{Setup.hs} is
not found, the build system looks for @code{Setup.lhs} instead.

Which Haskell compiler is used can be specified with the @code{#:haskell}
parameter which defaults to @code{ghc}.
@end defvr

@defvr {Scheme Variable} emacs-build-system
This variable is exported by @code{(guix build-system emacs)}.  It
implements an installation procedure similar to the packaging system
of Emacs itself (@pxref{Packages,,, emacs, The GNU Emacs Manual}).

It first creates the @code{@var{package}-autoloads.el} file, then it
byte compiles all Emacs Lisp files.  Differently from the Emacs
packaging system, the Info documentation files are moved to the standard
documentation directory and the @file{dir} file is deleted.  Each
package is installed in its own directory under
@file{share/emacs/site-lisp/guix.d}.
@end defvr

Lastly, for packages that do not need anything as sophisticated, a
``trivial'' build system is provided.  It is trivial in the sense that
it provides basically no support: it does not pull any implicit inputs,
and does not have a notion of build phases.

@defvr {Scheme Variable} trivial-build-system
This variable is exported by @code{(guix build-system trivial)}.

This build system requires a @code{#:builder} argument.  This argument
must be a Scheme expression that builds the package output(s)---as
with @code{build-expression->derivation} (@pxref{Derivations,
@code{build-expression->derivation}}).
@end defvr

@node The Store
@section The Store

@cindex store
@cindex store items
@cindex store paths

Conceptually, the @dfn{store} is the place where derivations that have
been built successfully are stored---by default, @file{/gnu/store}.
Sub-directories in the store are referred to as @dfn{store items} or
sometimes @dfn{store paths}.  The store has an associated database that
contains information such as the store paths referred to by each store
path, and the list of @emph{valid} store items---results of successful
builds.  This database resides in @file{@var{localstatedir}/guix/db},
where @var{localstatedir} is the state directory specified @i{via}
@option{--localstatedir} at configure time, usually @file{/var}.

The store is @emph{always} accessed by the daemon on behalf of its clients
(@pxref{Invoking guix-daemon}).  To manipulate the store, clients
connect to the daemon over a Unix-domain socket, send requests to it,
and read the result---these are remote procedure calls, or RPCs.

@quotation Note
Users must @emph{never} modify files under @file{/gnu/store} directly.
This would lead to inconsistencies and break the immutability
assumptions of Guix's functional model (@pxref{Introduction}).

@xref{Invoking guix gc, @command{guix gc --verify}}, for information on
how to check the integrity of the store and attempt recovery from
accidental modifications.
@end quotation

The @code{(guix store)} module provides procedures to connect to the
daemon, and to perform RPCs.  These are described below.

@deffn {Scheme Procedure} open-connection [@var{file}] [#:reserve-space? #t]
Connect to the daemon over the Unix-domain socket at @var{file}.  When
@var{reserve-space?} is true, instruct it to reserve a little bit of
extra space on the file system so that the garbage collector can still
operate should the disk become full.  Return a server object.

@var{file} defaults to @var{%default-socket-path}, which is the normal
location given the options that were passed to @command{configure}.
@end deffn

@deffn {Scheme Procedure} close-connection @var{server}
Close the connection to @var{server}.
@end deffn

@defvr {Scheme Variable} current-build-output-port
This variable is bound to a SRFI-39 parameter, which refers to the port
where build and error logs sent by the daemon should be written.
@end defvr

Procedures that make RPCs all take a server object as their first
argument.

@deffn {Scheme Procedure} valid-path? @var{server} @var{path}
@cindex invalid store items
Return @code{#t} when @var{path} designates a valid store item and
@code{#f} otherwise (an invalid item may exist on disk but still be
invalid, for instance because it is the result of an aborted or failed
build.)

A @code{&nix-protocol-error} condition is raised if @var{path} is not
prefixed by the store directory (@file{/gnu/store}).
@end deffn

@deffn {Scheme Procedure} add-text-to-store @var{server} @var{name} @var{text} [@var{references}]
Add @var{text} under file @var{name} in the store, and return its store
path.  @var{references} is the list of store paths referred to by the
resulting store path.
@end deffn

@deffn {Scheme Procedure} build-derivations @var{server} @var{derivations}
Build @var{derivations} (a list of @code{<derivation>} objects or
derivation paths), and return when the worker is done building them.
Return @code{#t} on success.
@end deffn

Note that the @code{(guix monads)} module provides a monad as well as
monadic versions of the above procedures, with the goal of making it
more convenient to work with code that accesses the store (@pxref{The
Store Monad}).

@c FIXME
@i{This section is currently incomplete.}

@node Derivations
@section Derivations

@cindex derivations
Low-level build actions and the environment in which they are performed
are represented by @dfn{derivations}.  A derivation contains the
following pieces of information:

@itemize
@item
The outputs of the derivation---derivations produce at least one file or
directory in the store, but may produce more.

@item
The inputs of the derivations, which may be other derivations or plain
files in the store (patches, build scripts, etc.)

@item
The system type targeted by the derivation---e.g., @code{x86_64-linux}.

@item
The file name of a build script in the store, along with the arguments
to be passed.

@item
A list of environment variables to be defined.

@end itemize

@cindex derivation path
Derivations allow clients of the daemon to communicate build actions to
the store.  They exist in two forms: as an in-memory representation,
both on the client- and daemon-side, and as files in the store whose
name end in @code{.drv}---these files are referred to as @dfn{derivation
paths}.  Derivations paths can be passed to the @code{build-derivations}
procedure to perform the build actions they prescribe (@pxref{The
Store}).

The @code{(guix derivations)} module provides a representation of
derivations as Scheme objects, along with procedures to create and
otherwise manipulate derivations.  The lowest-level primitive to create
a derivation is the @code{derivation} procedure:

@deffn {Scheme Procedure} derivation @var{store} @var{name} @var{builder} @
  @var{args} [#:outputs '("out")] [#:hash #f] [#:hash-algo #f] @
  [#:recursive? #f] [#:inputs '()] [#:env-vars '()] @
  [#:system (%current-system)] [#:references-graphs #f] @
  [#:allowed-references #f] [#:disallowed-references #f] @
  [#:leaked-env-vars #f] [#:local-build? #f] @
  [#:substitutable? #t]
Build a derivation with the given arguments, and return the resulting
@code{<derivation>} object.

When @var{hash} and @var{hash-algo} are given, a
@dfn{fixed-output derivation} is created---i.e., one whose result is
known in advance, such as a file download.  If, in addition,
@var{recursive?} is true, then that fixed output may be an executable
file or a directory and @var{hash} must be the hash of an archive
containing this output.

When @var{references-graphs} is true, it must be a list of file
name/store path pairs.  In that case, the reference graph of each store
path is exported in the build environment in the corresponding file, in
a simple text format.

When @var{allowed-references} is true, it must be a list of store items
or outputs that the derivation's output may refer to.  Likewise,
@var{disallowed-references}, if true, must be a list of things the
outputs may @emph{not} refer to.

When @var{leaked-env-vars} is true, it must be a list of strings
denoting environment variables that are allowed to ``leak'' from the
daemon's environment to the build environment.  This is only applicable
to fixed-output derivations---i.e., when @var{hash} is true.  The main
use is to allow variables such as @code{http_proxy} to be passed to
derivations that download files.

When @var{local-build?} is true, declare that the derivation is not a
good candidate for offloading and should rather be built locally
(@pxref{Daemon Offload Setup}).  This is the case for small derivations
where the costs of data transfers would outweigh the benefits.

When @var{substitutable?} is false, declare that substitutes of the
derivation's output should not be used (@pxref{Substitutes}).  This is
useful, for instance, when building packages that capture details of the
host CPU instruction set.
@end deffn

@noindent
Here's an example with a shell script as its builder, assuming
@var{store} is an open connection to the daemon, and @var{bash} points
to a Bash executable in the store:

@lisp
(use-modules (guix utils)
             (guix store)
             (guix derivations))

(let ((builder   ; add the Bash script to the store
        (add-text-to-store store "my-builder.sh"
                           "echo hello world > $out\n" '())))
  (derivation store "foo"
              bash `("-e" ,builder)
              #:inputs `((,bash) (,builder))
              #:env-vars '(("HOME" . "/homeless"))))
@result{} #<derivation /gnu/store/@dots{}-foo.drv => /gnu/store/@dots{}-foo>
@end lisp

As can be guessed, this primitive is cumbersome to use directly.  A
better approach is to write build scripts in Scheme, of course!  The
best course of action for that is to write the build code as a
``G-expression'', and to pass it to @code{gexp->derivation}.  For more
information, @pxref{G-Expressions}.

Once upon a time, @code{gexp->derivation} did not exist and constructing
derivations with build code written in Scheme was achieved with
@code{build-expression->derivation}, documented below.  This procedure
is now deprecated in favor of the much nicer @code{gexp->derivation}.

@deffn {Scheme Procedure} build-expression->derivation @var{store} @
       @var{name} @var{exp} @
       [#:system (%current-system)] [#:inputs '()] @
       [#:outputs '("out")] [#:hash #f] [#:hash-algo #f] @
       [#:recursive? #f] [#:env-vars '()] [#:modules '()] @
       [#:references-graphs #f] [#:allowed-references #f] @
       [#:disallowed-references #f] @
       [#:local-build? #f] [#:substitutable? #t] [#:guile-for-build #f]
Return a derivation that executes Scheme expression @var{exp} as a
builder for derivation @var{name}.  @var{inputs} must be a list of
@code{(name drv-path sub-drv)} tuples; when @var{sub-drv} is omitted,
@code{"out"} is assumed.  @var{modules} is a list of names of Guile
modules from the current search path to be copied in the store,
compiled, and made available in the load path during the execution of
@var{exp}---e.g., @code{((guix build utils) (guix build
gnu-build-system))}.

@var{exp} is evaluated in an environment where @code{%outputs} is bound
to a list of output/path pairs, and where @code{%build-inputs} is bound
to a list of string/output-path pairs made from @var{inputs}.
Optionally, @var{env-vars} is a list of string pairs specifying the name
and value of environment variables visible to the builder.  The builder
terminates by passing the result of @var{exp} to @code{exit}; thus, when
@var{exp} returns @code{#f}, the build is considered to have failed.

@var{exp} is built using @var{guile-for-build} (a derivation).  When
@var{guile-for-build} is omitted or is @code{#f}, the value of the
@code{%guile-for-build} fluid is used instead.

See the @code{derivation} procedure for the meaning of
@var{references-graphs}, @var{allowed-references},
@var{disallowed-references}, @var{local-build?}, and
@var{substitutable?}.
@end deffn

@noindent
Here's an example of a single-output derivation that creates a directory
containing one file:

@lisp
(let ((builder '(let ((out (assoc-ref %outputs "out")))
                  (mkdir out)    ; create /gnu/store/@dots{}-goo
                  (call-with-output-file (string-append out "/test")
                    (lambda (p)
                      (display '(hello guix) p))))))
  (build-expression->derivation store "goo" builder))

@result{} #<derivation /gnu/store/@dots{}-goo.drv => @dots{}>
@end lisp


@node The Store Monad
@section The Store Monad

@cindex monad

The procedures that operate on the store described in the previous
sections all take an open connection to the build daemon as their first
argument.  Although the underlying model is functional, they either have
side effects or depend on the current state of the store.

The former is inconvenient: the connection to the build daemon has to be
carried around in all those functions, making it impossible to compose
functions that do not take that parameter with functions that do.  The
latter can be problematic: since store operations have side effects
and/or depend on external state, they have to be properly sequenced.

@cindex monadic values
@cindex monadic functions
This is where the @code{(guix monads)} module comes in.  This module
provides a framework for working with @dfn{monads}, and a particularly
useful monad for our uses, the @dfn{store monad}.  Monads are a
construct that allows two things: associating ``context'' with values
(in our case, the context is the store), and building sequences of
computations (here computations include accesses to the store).  Values
in a monad---values that carry this additional context---are called
@dfn{monadic values}; procedures that return such values are called
@dfn{monadic procedures}.

Consider this ``normal'' procedure:

@example
(define (sh-symlink store)
  ;; Return a derivation that symlinks the 'bash' executable.
  (let* ((drv (package-derivation store bash))
         (out (derivation->output-path drv))
         (sh  (string-append out "/bin/bash")))
    (build-expression->derivation store "sh"
                                  `(symlink ,sh %output))))
@end example

Using @code{(guix monads)} and @code{(guix gexp)}, it may be rewritten
as a monadic function:

@example
(define (sh-symlink)
  ;; Same, but return a monadic value.
  (mlet %store-monad ((drv (package->derivation bash)))
    (gexp->derivation "sh"
                      #~(symlink (string-append #$drv "/bin/bash")
                                 #$output))))
@end example

There are several things to note in the second version: the @code{store}
parameter is now implicit and is ``threaded'' in the calls to the
@code{package->derivation} and @code{gexp->derivation} monadic
procedures, and the monadic value returned by @code{package->derivation}
is @dfn{bound} using @code{mlet} instead of plain @code{let}.

As it turns out, the call to @code{package->derivation} can even be
omitted since it will take place implicitly, as we will see later
(@pxref{G-Expressions}):

@example
(define (sh-symlink)
  (gexp->derivation "sh"
                    #~(symlink (string-append #$bash "/bin/bash")
                               #$output)))
@end example

@c See
@c <https://syntaxexclamation.wordpress.com/2014/06/26/escaping-continuations/>
@c for the funny quote.
Calling the monadic @code{sh-symlink} has no effect.  As someone once
said, ``you exit a monad like you exit a building on fire: by running''.
So, to exit the monad and get the desired effect, one must use
@code{run-with-store}:

@example
(run-with-store (open-connection) (sh-symlink))
@result{} /gnu/store/...-sh-symlink
@end example

Note that the @code{(guix monad-repl)} module extends the Guile REPL with
new ``meta-commands'' to make it easier to deal with monadic procedures:
@code{run-in-store}, and @code{enter-store-monad}.  The former is used
to ``run'' a single monadic value through the store:

@example
scheme@@(guile-user)> ,run-in-store (package->derivation hello)
$1 = #<derivation /gnu/store/@dots{}-hello-2.9.drv => @dots{}>
@end example

The latter enters a recursive REPL, where all the return values are
automatically run through the store:

@example
scheme@@(guile-user)> ,enter-store-monad
store-monad@@(guile-user) [1]> (package->derivation hello)
$2 = #<derivation /gnu/store/@dots{}-hello-2.9.drv => @dots{}>
store-monad@@(guile-user) [1]> (text-file "foo" "Hello!")
$3 = "/gnu/store/@dots{}-foo"
store-monad@@(guile-user) [1]> ,q
scheme@@(guile-user)>
@end example

@noindent
Note that non-monadic values cannot be returned in the
@code{store-monad} REPL.

The main syntactic forms to deal with monads in general are provided by
the @code{(guix monads)} module and are described below.

@deffn {Scheme Syntax} with-monad @var{monad} @var{body} ...
Evaluate any @code{>>=} or @code{return} forms in @var{body} as being
in @var{monad}.
@end deffn

@deffn {Scheme Syntax} return @var{val}
Return a monadic value that encapsulates @var{val}.
@end deffn

@deffn {Scheme Syntax} >>= @var{mval} @var{mproc} ...
@dfn{Bind} monadic value @var{mval}, passing its ``contents'' to monadic
procedures @var{mproc}@dots{}@footnote{This operation is commonly
referred to as ``bind'', but that name denotes an unrelated procedure in
Guile.  Thus we use this somewhat cryptic symbol inherited from the
Haskell language.}.  There can be one @var{mproc} or several of them, as
in this example:

@example
(run-with-state
    (with-monad %state-monad
      (>>= (return 1)
           (lambda (x) (return (+ 1 x)))
           (lambda (x) (return (* 2 x)))))
  'some-state)

@result{} 4
@result{} some-state
@end example
@end deffn

@deffn {Scheme Syntax} mlet @var{monad} ((@var{var} @var{mval}) ...) @
       @var{body} ...
@deffnx {Scheme Syntax} mlet* @var{monad} ((@var{var} @var{mval}) ...) @
       @var{body} ...
Bind the variables @var{var} to the monadic values @var{mval} in
@var{body}.  The form (@var{var} -> @var{val}) binds @var{var} to the
``normal'' value @var{val}, as per @code{let}.

@code{mlet*} is to @code{mlet} what @code{let*} is to @code{let}
(@pxref{Local Bindings,,, guile, GNU Guile Reference Manual}).
@end deffn

@deffn {Scheme System} mbegin @var{monad} @var{mexp} ...
Bind @var{mexp} and the following monadic expressions in sequence,
returning the result of the last expression.

This is akin to @code{mlet}, except that the return values of the
monadic expressions are ignored.  In that sense, it is analogous to
@code{begin}, but applied to monadic expressions.
@end deffn

@cindex state monad
The @code{(guix monads)} module provides the @dfn{state monad}, which
allows an additional value---the state---to be @emph{threaded} through
monadic procedure calls.

@defvr {Scheme Variable} %state-monad
The state monad.  Procedures in the state monad can access and change
the state that is threaded.

Consider the example below.  The @code{square} procedure returns a value
in the state monad.  It returns the square of its argument, but also
increments the current state value:

@example
(define (square x)
  (mlet %state-monad ((count (current-state)))
    (mbegin %state-monad
      (set-current-state (+ 1 count))
      (return (* x x)))))

(run-with-state (sequence %state-monad (map square (iota 3))) 0)
@result{} (0 1 4)
@result{} 3
@end example

When ``run'' through @var{%state-monad}, we obtain that additional state
value, which is the number of @code{square} calls.
@end defvr

@deffn {Monadic Procedure} current-state
Return the current state as a monadic value.
@end deffn

@deffn {Monadic Procedure} set-current-state @var{value}
Set the current state to @var{value} and return the previous state as a
monadic value.
@end deffn

@deffn {Monadic Procedure} state-push @var{value}
Push @var{value} to the current state, which is assumed to be a list,
and return the previous state as a monadic value.
@end deffn

@deffn {Monadic Procedure} state-pop
Pop a value from the current state and return it as a monadic value.
The state is assumed to be a list.
@end deffn

@deffn {Scheme Procedure} run-with-state @var{mval} [@var{state}]
Run monadic value @var{mval} starting with @var{state} as the initial
state.  Return two values: the resulting value, and the resulting state.
@end deffn

The main interface to the store monad, provided by the @code{(guix
store)} module, is as follows.

@defvr {Scheme Variable} %store-monad
The store monad---an alias for @var{%state-monad}.

Values in the store monad encapsulate accesses to the store.  When its
effect is needed, a value of the store monad must be ``evaluated'' by
passing it to the @code{run-with-store} procedure (see below.)
@end defvr

@deffn {Scheme Procedure} run-with-store @var{store} @var{mval} [#:guile-for-build] [#:system (%current-system)]
Run @var{mval}, a monadic value in the store monad, in @var{store}, an
open store connection.
@end deffn

@deffn {Monadic Procedure} text-file @var{name} @var{text} [@var{references}]
Return as a monadic value the absolute file name in the store of the file
containing @var{text}, a string.  @var{references} is a list of store items that the
resulting text file refers to; it defaults to the empty list.
@end deffn

@deffn {Monadic Procedure} interned-file @var{file} [@var{name}] @
         [#:recursive? #t] [#:select? (const #t)]
Return the name of @var{file} once interned in the store.  Use
@var{name} as its store name, or the basename of @var{file} if
@var{name} is omitted.

When @var{recursive?} is true, the contents of @var{file} are added
recursively; if @var{file} designates a flat file and @var{recursive?}
is true, its contents are added, and its permission bits are kept.

When @var{recursive?} is true, call @code{(@var{select?} @var{file}
@var{stat})} for each directory entry, where @var{file} is the entry's
absolute file name and @var{stat} is the result of @code{lstat}; exclude
entries for which @var{select?} does not return true.

The example below adds a file to the store, under two different names:

@example
(run-with-store (open-connection)
  (mlet %store-monad ((a (interned-file "README"))
                      (b (interned-file "README" "LEGU-MIN")))
    (return (list a b))))

@result{} ("/gnu/store/rwm@dots{}-README" "/gnu/store/44i@dots{}-LEGU-MIN")
@end example

@end deffn

The @code{(guix packages)} module exports the following package-related
monadic procedures:

@deffn {Monadic Procedure} package-file @var{package} [@var{file}] @
       [#:system (%current-system)] [#:target #f] @
       [#:output "out"]
Return as a monadic
value in the absolute file name of @var{file} within the @var{output}
directory of @var{package}.  When @var{file} is omitted, return the name
of the @var{output} directory of @var{package}.  When @var{target} is
true, use it as a cross-compilation target triplet.
@end deffn

@deffn {Monadic Procedure} package->derivation @var{package} [@var{system}]
@deffnx {Monadic Procedure} package->cross-derivation @var{package} @
          @var{target} [@var{system}]
Monadic version of @code{package-derivation} and
@code{package-cross-derivation} (@pxref{Defining Packages}).
@end deffn


@node G-Expressions
@section G-Expressions

@cindex G-expression
@cindex build code quoting
So we have ``derivations'', which represent a sequence of build actions
to be performed to produce an item in the store (@pxref{Derivations}).
These build actions are performed when asking the daemon to actually
build the derivations; they are run by the daemon in a container
(@pxref{Invoking guix-daemon}).

@cindex strata of code
It should come as no surprise that we like to write these build actions
in Scheme.  When we do that, we end up with two @dfn{strata} of Scheme
code@footnote{The term @dfn{stratum} in this context was coined by
Manuel Serrano et al.@: in the context of their work on Hop.  Oleg
Kiselyov, who has written insightful
@url{http://okmij.org/ftp/meta-programming/#meta-scheme, essays and code
on this topic}, refers to this kind of code generation as
@dfn{staging}.}: the ``host code''---code that defines packages, talks
to the daemon, etc.---and the ``build code''---code that actually
performs build actions, such as making directories, invoking
@command{make}, etc.

To describe a derivation and its build actions, one typically needs to
embed build code inside host code.  It boils down to manipulating build
code as data, and the homoiconicity of Scheme---code has a direct
representation as data---comes in handy for that.  But we need more than
the normal @code{quasiquote} mechanism in Scheme to construct build
expressions.

The @code{(guix gexp)} module implements @dfn{G-expressions}, a form of
S-expressions adapted to build expressions.  G-expressions, or
@dfn{gexps}, consist essentially of three syntactic forms: @code{gexp},
@code{ungexp}, and @code{ungexp-splicing} (or simply: @code{#~},
@code{#$}, and @code{#$@@}), which are comparable to
@code{quasiquote}, @code{unquote}, and @code{unquote-splicing},
respectively (@pxref{Expression Syntax, @code{quasiquote},, guile,
GNU Guile Reference Manual}).  However, there are major differences:

@itemize
@item
Gexps are meant to be written to a file and run or manipulated by other
processes.

@item
When a high-level object such as a package or derivation is unquoted
inside a gexp, the result is as if its output file name had been
introduced.

@item
Gexps carry information about the packages or derivations they refer to,
and these dependencies are automatically added as inputs to the build
processes that use them.
@end itemize

@cindex lowering, of high-level objects in gexps
This mechanism is not limited to package and derivation
objects: @dfn{compilers} able to ``lower'' other high-level objects to
derivations or files in the store can be defined,
such that these objects can also be inserted
into gexps.  For example, a useful type of high-level objects that can be
inserted in a gexp is ``file-like objects'', which make it easy to
add files to the store and to refer to them in
derivations and such (see @code{local-file} and @code{plain-file}
below.)

To illustrate the idea, here is an example of a gexp:

@example
(define build-exp
  #~(begin
      (mkdir #$output)
      (chdir #$output)
      (symlink (string-append #$coreutils "/bin/ls")
               "list-files")))
@end example

This gexp can be passed to @code{gexp->derivation}; we obtain a
derivation that builds a directory containing exactly one symlink to
@file{/gnu/store/@dots{}-coreutils-8.22/bin/ls}:

@example
(gexp->derivation "the-thing" build-exp)
@end example

As one would expect, the @code{"/gnu/store/@dots{}-coreutils-8.22"} string is
substituted to the reference to the @var{coreutils} package in the
actual build code, and @var{coreutils} is automatically made an input to
the derivation.  Likewise, @code{#$output} (equivalent to @code{(ungexp
output)}) is replaced by a string containing the directory name of the
output of the derivation.

@cindex cross compilation
In a cross-compilation context, it is useful to distinguish between
references to the @emph{native} build of a package---that can run on the
host---versus references to cross builds of a package.  To that end, the
@code{#+} plays the same role as @code{#$}, but is a reference to a
native package build:

@example
(gexp->derivation "vi"
   #~(begin
       (mkdir #$output)
       (system* (string-append #+coreutils "/bin/ln")
                "-s"
                (string-append #$emacs "/bin/emacs")
                (string-append #$output "/bin/vi")))
   #:target "mips64el-linux")
@end example

@noindent
In the example above, the native build of @var{coreutils} is used, so
that @command{ln} can actually run on the host; but then the
cross-compiled build of @var{emacs} is referenced.

@cindex imported modules, for gexps
@findex with-imported-modules
Another gexp feature is @dfn{imported modules}: sometimes you want to be
able to use certain Guile modules from the ``host environment'' in the
gexp, so those modules should be imported in the ``build environment''.
The @code{with-imported-modules} form allows you to express that:

@example
(let ((build (with-imported-modules '((guix build utils))
               #~(begin
                   (use-modules (guix build utils))
                   (mkdir-p (string-append #$output "/bin"))))))
  (gexp->derivation "empty-dir"
                    #~(begin
                        #$build
                        (display "success!\n")
                        #t)))
@end example

@noindent
In this example, the @code{(guix build utils)} module is automatically
pulled into the isolated build environment of our gexp, such that
@code{(use-modules (guix build utils))} works as expected.

The syntactic form to construct gexps is summarized below.

@deffn {Scheme Syntax} #~@var{exp}
@deffnx {Scheme Syntax} (gexp @var{exp})
Return a G-expression containing @var{exp}.  @var{exp} may contain one
or more of the following forms:

@table @code
@item #$@var{obj}
@itemx (ungexp @var{obj})
Introduce a reference to @var{obj}.  @var{obj} may have one of the
supported types, for example a package or a
derivation, in which case the @code{ungexp} form is replaced by its
output file name---e.g., @code{"/gnu/store/@dots{}-coreutils-8.22}.

If @var{obj} is a list, it is traversed and references to supported
objects are substituted similarly.

If @var{obj} is another gexp, its contents are inserted and its
dependencies are added to those of the containing gexp.

If @var{obj} is another kind of object, it is inserted as is.

@item #$@var{obj}:@var{output}
@itemx (ungexp @var{obj} @var{output})
This is like the form above, but referring explicitly to the
@var{output} of @var{obj}---this is useful when @var{obj} produces
multiple outputs (@pxref{Packages with Multiple Outputs}).

@item #+@var{obj}
@itemx #+@var{obj}:output
@itemx (ungexp-native @var{obj})
@itemx (ungexp-native @var{obj} @var{output})
Same as @code{ungexp}, but produces a reference to the @emph{native}
build of @var{obj} when used in a cross compilation context.

@item #$output[:@var{output}]
@itemx (ungexp output [@var{output}])
Insert a reference to derivation output @var{output}, or to the main
output when @var{output} is omitted.

This only makes sense for gexps passed to @code{gexp->derivation}.

@item #$@@@var{lst}
@itemx (ungexp-splicing @var{lst})
Like the above, but splices the contents of @var{lst} inside the
containing list.

@item #+@@@var{lst}
@itemx (ungexp-native-splicing @var{lst})
Like the above, but refers to native builds of the objects listed in
@var{lst}.

@end table

G-expressions created by @code{gexp} or @code{#~} are run-time objects
of the @code{gexp?} type (see below.)
@end deffn

@deffn {Scheme Syntax} with-imported-modules @var{modules} @var{body}@dots{}
Mark the gexps defined in @var{body}@dots{} as requiring @var{modules}
in their execution environment.  @var{modules} must be a list of Guile
module names, such as @code{'((guix build utils) (guix build gremlin))}.

This form has @emph{lexical} scope: it has an effect on the gexps
directly defined in @var{body}@dots{}, but not on those defined, say, in
procedures called from @var{body}@dots{}.
@end deffn

@deffn {Scheme Procedure} gexp? @var{obj}
Return @code{#t} if @var{obj} is a G-expression.
@end deffn

G-expressions are meant to be written to disk, either as code building
some derivation, or as plain files in the store.  The monadic procedures
below allow you to do that (@pxref{The Store Monad}, for more
information about monads.)

@deffn {Monadic Procedure} gexp->derivation @var{name} @var{exp} @
       [#:system (%current-system)] [#:target #f] [#:graft? #t] @
       [#:hash #f] [#:hash-algo #f] @
       [#:recursive? #f] [#:env-vars '()] [#:modules '()] @
       [#:module-path @var{%load-path}] @
       [#:references-graphs #f] [#:allowed-references #f] @
       [#:disallowed-references #f] @
       [#:leaked-env-vars #f] @
       [#:script-name (string-append @var{name} "-builder")] @
       [#:local-build? #f] [#:substitutable? #t] [#:guile-for-build #f]
Return a derivation @var{name} that runs @var{exp} (a gexp) with
@var{guile-for-build} (a derivation) on @var{system}; @var{exp} is
stored in a file called @var{script-name}.  When @var{target} is true,
it is used as the cross-compilation target triplet for packages referred
to by @var{exp}.

@var{modules} is deprecated in favor of @code{with-imported-modules}.
Its meaning is to
make @var{modules} available in the evaluation context of @var{exp};
@var{modules} is a list of names of Guile modules searched in
@var{module-path} to be copied in the store, compiled, and made available in
the load path during the execution of @var{exp}---e.g., @code{((guix
build utils) (guix build gnu-build-system))}.

@var{graft?} determines whether packages referred to by @var{exp} should be grafted when
applicable.

When @var{references-graphs} is true, it must be a list of tuples of one of the
following forms:

@example
(@var{file-name} @var{package})
(@var{file-name} @var{package} @var{output})
(@var{file-name} @var{derivation})
(@var{file-name} @var{derivation} @var{output})
(@var{file-name} @var{store-item})
@end example

The right-hand-side of each element of @var{references-graphs} is automatically made
an input of the build process of @var{exp}.  In the build environment, each
@var{file-name} contains the reference graph of the corresponding item, in a simple
text format.

@var{allowed-references} must be either @code{#f} or a list of output names and packages.
In the latter case, the list denotes store items that the result is allowed to
refer to.  Any reference to another store item will lead to a build error.
Similarly for @var{disallowed-references}, which can list items that must not be
referenced by the outputs.

The other arguments are as for @code{derivation} (@pxref{Derivations}).
@end deffn

@cindex file-like objects
The @code{local-file}, @code{plain-file}, @code{computed-file},
@code{program-file}, and @code{scheme-file} procedures below return
@dfn{file-like objects}.  That is, when unquoted in a G-expression,
these objects lead to a file in the store.  Consider this G-expression:

@example
#~(system* (string-append #$glibc "/sbin/nscd") "-f"
           #$(local-file "/tmp/my-nscd.conf"))
@end example

The effect here is to ``intern'' @file{/tmp/my-nscd.conf} by copying it
to the store.  Once expanded, for instance @i{via}
@code{gexp->derivation}, the G-expression refers to that copy under
@file{/gnu/store}; thus, modifying or removing the file in @file{/tmp}
does not have any effect on what the G-expression does.
@code{plain-file} can be used similarly; it differs in that the file
content is directly passed as a string.

@deffn {Scheme Procedure} local-file @var{file} [@var{name}] @
   [#:recursive? #f] [#:select? (const #t)]
Return an object representing local file @var{file} to add to the store; this
object can be used in a gexp.  If @var{file} is a relative file name, it is looked
up relative to the source file where this form appears.  @var{file} will be added to
the store under @var{name}--by default the base name of @var{file}.

When @var{recursive?} is true, the contents of @var{file} are added recursively; if @var{file}
designates a flat file and @var{recursive?} is true, its contents are added, and its
permission bits are kept.

When @var{recursive?} is true, call @code{(@var{select?} @var{file}
@var{stat})} for each directory entry, where @var{file} is the entry's
absolute file name and @var{stat} is the result of @code{lstat}; exclude
entries for which @var{select?} does not return true.

This is the declarative counterpart of the @code{interned-file} monadic
procedure (@pxref{The Store Monad, @code{interned-file}}).
@end deffn

@deffn {Scheme Procedure} plain-file @var{name} @var{content}
Return an object representing a text file called @var{name} with the given
@var{content} (a string) to be added to the store.

This is the declarative counterpart of @code{text-file}.
@end deffn

@deffn {Scheme Procedure} computed-file @var{name} @var{gexp} @
          [#:options '(#:local-build? #t)]
Return an object representing the store item @var{name}, a file or
directory computed by @var{gexp}.  @var{options}
is a list of additional arguments to pass to @code{gexp->derivation}.

This is the declarative counterpart of @code{gexp->derivation}.
@end deffn

@deffn {Monadic Procedure} gexp->script @var{name} @var{exp}
Return an executable script @var{name} that runs @var{exp} using
@var{guile}, with @var{exp}'s imported modules in its search path.

The example below builds a script that simply invokes the @command{ls}
command:

@example
(use-modules (guix gexp) (gnu packages base))

(gexp->script "list-files"
              #~(execl (string-append #$coreutils "/bin/ls")
                       "ls"))
@end example

When ``running'' it through the store (@pxref{The Store Monad,
@code{run-with-store}}), we obtain a derivation that produces an
executable file @file{/gnu/store/@dots{}-list-files} along these lines:

@example
#!/gnu/store/@dots{}-guile-2.0.11/bin/guile -ds
!#
(execl (string-append "/gnu/store/@dots{}-coreutils-8.22"/bin/ls")
       "ls")
@end example
@end deffn

@deffn {Scheme Procedure} program-file @var{name} @var{exp} @
          [#:guile #f]
Return an object representing the executable store item @var{name} that
runs @var{gexp}.  @var{guile} is the Guile package used to execute that
script.

This is the declarative counterpart of @code{gexp->script}.
@end deffn

@deffn {Monadic Procedure} gexp->file @var{name} @var{exp} @
            [#:set-load-path? #t]
Return a derivation that builds a file @var{name} containing @var{exp}.
When @var{set-load-path?} is true, emit code in the resulting file to
set @code{%load-path} and @code{%load-compiled-path} to honor
@var{exp}'s imported modules.

The resulting file holds references to all the dependencies of @var{exp}
or a subset thereof.
@end deffn

@deffn {Scheme Procedure} scheme-file @var{name} @var{exp}
Return an object representing the Scheme file @var{name} that contains
@var{exp}.

This is the declarative counterpart of @code{gexp->file}.
@end deffn

@deffn {Monadic Procedure} text-file* @var{name} @var{text} @dots{}
Return as a monadic value a derivation that builds a text file
containing all of @var{text}.  @var{text} may list, in addition to
strings, objects of any type that can be used in a gexp: packages,
derivations, local file objects, etc.  The resulting store file holds
references to all these.

This variant should be preferred over @code{text-file} anytime the file
to create will reference items from the store.  This is typically the
case when building a configuration file that embeds store file names,
like this:

@example
(define (profile.sh)
  ;; Return the name of a shell script in the store that
  ;; initializes the 'PATH' environment variable.
  (text-file* "profile.sh"
              "export PATH=" coreutils "/bin:"
              grep "/bin:" sed "/bin\n"))
@end example

In this example, the resulting @file{/gnu/store/@dots{}-profile.sh} file
will reference @var{coreutils}, @var{grep}, and @var{sed}, thereby
preventing them from being garbage-collected during its lifetime.
@end deffn

@deffn {Scheme Procedure} mixed-text-file @var{name} @var{text} @dots{}
Return an object representing store file @var{name} containing
@var{text}.  @var{text} is a sequence of strings and file-like objects,
as in:

@example
(mixed-text-file "profile"
                 "export PATH=" coreutils "/bin:" grep "/bin")
@end example

This is the declarative counterpart of @code{text-file*}.
@end deffn

Of course, in addition to gexps embedded in ``host'' code, there are
also modules containing build tools.  To make it clear that they are
meant to be used in the build stratum, these modules are kept in the
@code{(guix build @dots{})} name space.

@cindex lowering, of high-level objects in gexps
Internally, high-level objects are @dfn{lowered}, using their compiler,
to either derivations or store items.  For instance, lowering a package
yields a derivation, and lowering a @code{plain-file} yields a store
item.  This is achieved using the @code{lower-object} monadic procedure.

@deffn {Monadic Procedure} lower-object @var{obj} [@var{system}] @
           [#:target #f]
Return as a value in @var{%store-monad} the derivation or store item
corresponding to @var{obj} for @var{system}, cross-compiling for
@var{target} if @var{target} is true.  @var{obj} must be an object that
has an associated gexp compiler, such as a @code{<package>}.
@end deffn


@c *********************************************************************
@node Utilities
@chapter Utilities

This section describes Guix command-line utilities.  Some of them are
primarily targeted at developers and users who write new package
definitions, while others are more generally useful.  They complement
the Scheme programming interface of Guix in a convenient way.

@menu
* Invoking guix build::         Building packages from the command line.
* Invoking guix edit::          Editing package definitions.
* Invoking guix download::      Downloading a file and printing its hash.
* Invoking guix hash::          Computing the cryptographic hash of a file.
* Invoking guix import::        Importing package definitions.
* Invoking guix refresh::       Updating package definitions.
* Invoking guix lint::          Finding errors in package definitions.
* Invoking guix size::          Profiling disk usage.
* Invoking guix graph::         Visualizing the graph of packages.
* Invoking guix environment::   Setting up development environments.
* Invoking guix publish::       Sharing substitutes.
* Invoking guix challenge::     Challenging substitute servers.
* Invoking guix container::     Process isolation.
@end menu

@node Invoking guix build
@section Invoking @command{guix build}

The @command{guix build} command builds packages or derivations and
their dependencies, and prints the resulting store paths.  Note that it
does not modify the user's profile---this is the job of the
@command{guix package} command (@pxref{Invoking guix package}).  Thus,
it is mainly useful for distribution developers.

The general syntax is:

@example
guix build @var{options} @var{package-or-derivation}@dots{}
@end example

As an example, the following command builds the latest versions of Emacs
and of Guile, displays their build logs, and finally displays the
resulting directories:

@example
guix build emacs guile
@end example

Similarly, the following command builds all the available packages:

@example
guix build --quiet --keep-going \
  `guix package -A | cut -f1,2 --output-delimiter=@@`
@end example

@var{package-or-derivation} may be either the name of a package found in
the software distribution such as @code{coreutils} or
@code{coreutils-8.20}, or a derivation such as
@file{/gnu/store/@dots{}-coreutils-8.19.drv}.  In the former case, a
package with the corresponding name (and optionally version) is searched
for among the GNU distribution modules (@pxref{Package Modules}).

Alternatively, the @code{--expression} option may be used to specify a
Scheme expression that evaluates to a package; this is useful when
disambiguating among several same-named packages or package variants is
needed.

There may be zero or more @var{options}.  The available options are
described in the subsections below.

@menu
* Common Build Options::        Build options for most commands.
* Package Transformation Options::    Creating variants of packages.
* Additional Build Options::    Options specific to 'guix build'.
@end menu

@node Common Build Options
@subsection Common Build Options

A number of options that control the build process are common to
@command{guix build} and other commands that can spawn builds, such as
@command{guix package} or @command{guix archive}.  These are the
following:

@table @code

@item --load-path=@var{directory}
@itemx -L @var{directory}
Add @var{directory} to the front of the package module search path
(@pxref{Package Modules}).

This allows users to define their own packages and make them visible to
the command-line tools.

@item --keep-failed
@itemx -K
Keep the build tree of failed builds.  Thus, if a build fails, its build
tree is kept under @file{/tmp}, in a directory whose name is shown at
the end of the build log.  This is useful when debugging build issues.

@item --keep-going
@itemx -k
Keep going when some of the derivations fail to build; return only once
all the builds have either completed or failed.

The default behavior is to stop as soon as one of the specified
derivations has failed.

@item --dry-run
@itemx -n
Do not build the derivations.

@item --fallback
When substituting a pre-built binary fails, fall back to building
packages locally.

@item --substitute-urls=@var{urls}
@anchor{client-substitute-urls}
Consider @var{urls} the whitespace-separated list of substitute source
URLs, overriding the default list of URLs of @command{guix-daemon}
(@pxref{daemon-substitute-urls,, @command{guix-daemon} URLs}).

This means that substitutes may be downloaded from @var{urls}, provided
they are signed by a key authorized by the system administrator
(@pxref{Substitutes}).

When @var{urls} is the empty string, substitutes are effectively
disabled.

@item --no-substitutes
Do not use substitutes for build products.  That is, always build things
locally instead of allowing downloads of pre-built binaries
(@pxref{Substitutes}).

@item --no-grafts
Do not ``graft'' packages.  In practice, this means that package updates
available as grafts are not applied.  @xref{Security Updates}, for more
information on grafts.

@item --rounds=@var{n}
Build each derivation @var{n} times in a row, and raise an error if
consecutive build results are not bit-for-bit identical.

This is a useful way to detect non-deterministic builds processes.
Non-deterministic build processes are a problem because they make it
practically impossible for users to @emph{verify} whether third-party
binaries are genuine.  @xref{Invoking guix challenge}, for more.

Note that, currently, the differing build results are not kept around,
so you will have to manually investigate in case of an error---e.g., by
stashing one of the build results with @code{guix archive --export}
(@pxref{Invoking guix archive}), then rebuilding, and finally comparing
the two results.

@item --no-build-hook
Do not attempt to offload builds @i{via} the ``build hook'' of the daemon
(@pxref{Daemon Offload Setup}).  That is, always build things locally
instead of offloading builds to remote machines.

@item --max-silent-time=@var{seconds}
When the build or substitution process remains silent for more than
@var{seconds}, terminate it and report a build failure.

@item --timeout=@var{seconds}
Likewise, when the build or substitution process lasts for more than
@var{seconds}, terminate it and report a build failure.

By default there is no timeout.  This behavior can be restored with
@code{--timeout=0}.

@item --verbosity=@var{level}
Use the given verbosity level.  @var{level} must be an integer between 0
and 5; higher means more verbose output.  Setting a level of 4 or more
may be helpful when debugging setup issues with the build daemon.

@item --cores=@var{n}
@itemx -c @var{n}
Allow the use of up to @var{n} CPU cores for the build.  The special
value @code{0} means to use as many CPU cores as available.

@item --max-jobs=@var{n}
@itemx -M @var{n}
Allow at most @var{n} build jobs in parallel.  @xref{Invoking
guix-daemon, @code{--max-jobs}}, for details about this option and the
equivalent @command{guix-daemon} option.

@end table

Behind the scenes, @command{guix build} is essentially an interface to
the @code{package-derivation} procedure of the @code{(guix packages)}
module, and to the @code{build-derivations} procedure of the @code{(guix
derivations)} module.

In addition to options explicitly passed on the command line,
@command{guix build} and other @command{guix} commands that support
building honor the @code{GUIX_BUILD_OPTIONS} environment variable.

@defvr {Environment Variable} GUIX_BUILD_OPTIONS
Users can define this variable to a list of command line options that
will automatically be used by @command{guix build} and other
@command{guix} commands that can perform builds, as in the example
below:

@example
$ export GUIX_BUILD_OPTIONS="--no-substitutes -c 2 -L /foo/bar"
@end example

These options are parsed independently, and the result is appended to
the parsed command-line options.
@end defvr


@node Package Transformation Options
@subsection Package Transformation Options

@cindex package variants
Another set of command-line options supported by @command{guix build}
and also @command{guix package} are @dfn{package transformation
options}.  These are options that make it possible to define @dfn{package
variants}---for instance, packages built from different source code.
This is a convenient way to create customized packages on the fly
without having to type in the definitions of package variants
(@pxref{Defining Packages}).

@table @code

@item --with-source=@var{source}
Use @var{source} as the source of the corresponding package.
@var{source} must be a file name or a URL, as for @command{guix
download} (@pxref{Invoking guix download}).

The ``corresponding package'' is taken to be the one specified on the
command line the name of which matches the base of @var{source}---e.g.,
if @var{source} is @code{/src/guile-2.0.10.tar.gz}, the corresponding
package is @code{guile}.  Likewise, the version string is inferred from
@var{source}; in the previous example, it is @code{2.0.10}.

This option allows users to try out versions of packages other than the
one provided by the distribution.  The example below downloads
@file{ed-1.7.tar.gz} from a GNU mirror and uses that as the source for
the @code{ed} package:

@example
guix build ed --with-source=mirror://gnu/ed/ed-1.7.tar.gz
@end example

As a developer, @code{--with-source} makes it easy to test release
candidates:

@example
guix build guile --with-source=../guile-2.0.9.219-e1bb7.tar.xz
@end example

@dots{} or to build from a checkout in a pristine environment:

@example
$ git clone git://git.sv.gnu.org/guix.git
$ guix build guix --with-source=./guix
@end example

@item --with-input=@var{package}=@var{replacement}
Replace dependency on @var{package} by a dependency on
@var{replacement}.  @var{package} must be a package name, and
@var{replacement} must be a package specification such as @code{guile}
or @code{guile@@1.8}.

For instance, the following command builds Guix, but replaces its
dependency on the current stable version of Guile with a dependency on
the development version of Guile, @code{guile-next}:

@example
guix build --with-input=guile=guile-next guix
@end example

This is a recursive, deep replacement.  So in this example, both
@code{guix} and its dependency @code{guile-json} (which also depends on
@code{guile}) get rebuilt against @code{guile-next}.

However, implicit inputs are left unchanged.
@end table

@node Additional Build Options
@subsection Additional Build Options

The command-line options presented below are specific to @command{guix
build}.

@table @code

@item --quiet
@itemx -q
Build quietly, without displaying the build log.  Upon completion, the
build log is kept in @file{/var} (or similar) and can always be
retrieved using the @option{--log-file} option.

@item --file=@var{file}
@itemx -f @var{file}

Build the package or derivation that the code within @var{file}
evaluates to.

As an example, @var{file} might contain a package definition like this
(@pxref{Defining Packages}):

@example
@verbatiminclude package-hello.scm
@end example

@item --expression=@var{expr}
@itemx -e @var{expr}
Build the package or derivation @var{expr} evaluates to.

For example, @var{expr} may be @code{(@@ (gnu packages guile)
guile-1.8)}, which unambiguously designates this specific variant of
version 1.8 of Guile.

Alternatively, @var{expr} may be a G-expression, in which case it is used
as a build program passed to @code{gexp->derivation}
(@pxref{G-Expressions}).

Lastly, @var{expr} may refer to a zero-argument monadic procedure
(@pxref{The Store Monad}).  The procedure must return a derivation as a
monadic value, which is then passed through @code{run-with-store}.

@item --source
@itemx -S
Build the source derivations of the packages, rather than the packages
themselves.

For instance, @code{guix build -S gcc} returns something like
@file{/gnu/store/@dots{}-gcc-4.7.2.tar.bz2}, which is the GCC
source tarball.

The returned source tarball is the result of applying any patches and
code snippets specified in the package @code{origin} (@pxref{Defining
Packages}).

@item --sources
Fetch and return the source of @var{package-or-derivation} and all their
dependencies, recursively.  This is a handy way to obtain a local copy
of all the source code needed to build @var{packages}, allowing you to
eventually build them even without network access.  It is an extension
of the @code{--source} option and can accept one of the following
optional argument values:

@table @code
@item package
This value causes the @code{--sources} option to behave in the same way
as the @code{--source} option.

@item all
Build the source derivations of all packages, including any source that
might be listed as @code{inputs}.  This is the default value.

@example
$ guix build --sources tzdata
The following derivations will be built:
   /gnu/store/@dots{}-tzdata2015b.tar.gz.drv
   /gnu/store/@dots{}-tzcode2015b.tar.gz.drv
@end example

@item transitive
Build the source derivations of all packages, as well of all transitive
inputs to the packages.  This can be used e.g. to
prefetch package source for later offline building.

@example
$ guix build --sources=transitive tzdata
The following derivations will be built:
   /gnu/store/@dots{}-tzcode2015b.tar.gz.drv
   /gnu/store/@dots{}-findutils-4.4.2.tar.xz.drv
   /gnu/store/@dots{}-grep-2.21.tar.xz.drv
   /gnu/store/@dots{}-coreutils-8.23.tar.xz.drv
   /gnu/store/@dots{}-make-4.1.tar.xz.drv
   /gnu/store/@dots{}-bash-4.3.tar.xz.drv
@dots{}
@end example

@end table

@item --system=@var{system}
@itemx -s @var{system}
Attempt to build for @var{system}---e.g., @code{i686-linux}---instead of
the system type of the build host.

An example use of this is on Linux-based systems, which can emulate
different personalities.  For instance, passing
@code{--system=i686-linux} on an @code{x86_64-linux} system allows users
to build packages in a complete 32-bit environment.

@item --target=@var{triplet}
@cindex cross-compilation
Cross-build for @var{triplet}, which must be a valid GNU triplet, such
as @code{"mips64el-linux-gnu"} (@pxref{Configuration Names, GNU
configuration triplets,, configure, GNU Configure and Build System}).

@anchor{build-check}
@item --check
@cindex determinism, checking
@cindex reproducibility, checking
Rebuild @var{package-or-derivation}, which are already available in the
store, and raise an error if the build results are not bit-for-bit
identical.

This mechanism allows you to check whether previously installed
substitutes are genuine (@pxref{Substitutes}), or whether the build result
of a package is deterministic.  @xref{Invoking guix challenge}, for more
background information and tools.

When used in conjunction with @option{--keep-failed}, the differing
output is kept in the store, under @file{/gnu/store/@dots{}-check}.
This makes it easy to look for differences between the two results.

@item --derivations
@itemx -d
Return the derivation paths, not the output paths, of the given
packages.

@item --root=@var{file}
@itemx -r @var{file}
Make @var{file} a symlink to the result, and register it as a garbage
collector root.

@item --log-file
Return the build log file names or URLs for the given
@var{package-or-derivation}, or raise an error if build logs are
missing.

This works regardless of how packages or derivations are specified.  For
instance, the following invocations are equivalent:

@example
guix build --log-file `guix build -d guile`
guix build --log-file `guix build guile`
guix build --log-file guile
guix build --log-file -e '(@@ (gnu packages guile) guile-2.0)'
@end example

If a log is unavailable locally, and unless @code{--no-substitutes} is
passed, the command looks for a corresponding log on one of the
substitute servers (as specified with @code{--substitute-urls}.)

So for instance, imagine you want to see the build log of GDB on MIPS,
but you are actually on an @code{x86_64} machine:

@example
$ guix build --log-file gdb -s mips64el-linux
https://hydra.gnu.org/log/@dots{}-gdb-7.10
@end example

You can freely access a huge library of build logs!
@end table


@node Invoking guix edit
@section Invoking @command{guix edit}

@cindex package definition, editing
So many packages, so many source files!  The @command{guix edit} command
facilitates the life of packagers by pointing their editor at the source
file containing the definition of the specified packages.  For instance:

@example
guix edit gcc@@4.9 vim
@end example

@noindent
launches the program specified in the @code{VISUAL} or in the
@code{EDITOR} environment variable to edit the recipe of GCC@tie{}4.9.3
and that of Vim.

If you are using Emacs, note that the Emacs user interface provides the
@kbd{M-x guix-edit} command and a similar functionality in the ``package
info'' and ``package list'' buffers created by the @kbd{M-x
guix-search-by-name} and similar commands (@pxref{Emacs Commands}).


@node Invoking guix download
@section Invoking @command{guix download}

When writing a package definition, developers typically need to download
a source tarball, compute its SHA256 hash, and write that
hash in the package definition (@pxref{Defining Packages}).  The
@command{guix download} tool helps with this task: it downloads a file
from the given URI, adds it to the store, and prints both its file name
in the store and its SHA256 hash.

The fact that the downloaded file is added to the store saves bandwidth:
when the developer eventually tries to build the newly defined package
with @command{guix build}, the source tarball will not have to be
downloaded again because it is already in the store.  It is also a
convenient way to temporarily stash files, which may be deleted
eventually (@pxref{Invoking guix gc}).

The @command{guix download} command supports the same URIs as used in
package definitions.  In particular, it supports @code{mirror://} URIs.
@code{https} URIs (HTTP over TLS) are supported @emph{provided} the
Guile bindings for GnuTLS are available in the user's environment; when
they are not available, an error is raised.  @xref{Guile Preparations,
how to install the GnuTLS bindings for Guile,, gnutls-guile,
GnuTLS-Guile}, for more information.

The following option is available:

@table @code
@item --format=@var{fmt}
@itemx -f @var{fmt}
Write the hash in the format specified by @var{fmt}.  For more
information on the valid values for @var{fmt}, @pxref{Invoking guix hash}.
@end table

@node Invoking guix hash
@section Invoking @command{guix hash}

The @command{guix hash} command computes the SHA256 hash of a file.
It is primarily a convenience tool for anyone contributing to the
distribution: it computes the cryptographic hash of a file, which can be
used in the definition of a package (@pxref{Defining Packages}).

The general syntax is:

@example
guix hash @var{option} @var{file}
@end example

@command{guix hash} has the following option:

@table @code

@item --format=@var{fmt}
@itemx -f @var{fmt}
Write the hash in the format specified by @var{fmt}.

Supported formats: @code{nix-base32}, @code{base32}, @code{base16}
(@code{hex} and @code{hexadecimal} can be used as well).

If the @option{--format} option is not specified, @command{guix hash}
will output the hash in @code{nix-base32}.  This representation is used
in the definitions of packages.

@item --recursive
@itemx -r
Compute the hash on @var{file} recursively.

In this case, the hash is computed on an archive containing @var{file},
including its children if it is a directory.  Some of the metadata of
@var{file} is part of the archive; for instance, when @var{file} is a
regular file, the hash is different depending on whether @var{file} is
executable or not.  Metadata such as time stamps has no impact on the
hash (@pxref{Invoking guix archive}).
@c FIXME: Replace xref above with xref to an ``Archive'' section when
@c it exists.

@end table

@node Invoking guix import
@section Invoking @command{guix import}

@cindex importing packages
@cindex package import
@cindex package conversion
The @command{guix import} command is useful for people who would like to
add a package to the distribution with as little work as
possible---a legitimate demand.  The command knows of a few
repositories from which it can ``import'' package metadata.  The result
is a package definition, or a template thereof, in the format we know
(@pxref{Defining Packages}).

The general syntax is:

@example
guix import @var{importer} @var{options}@dots{}
@end example

@var{importer} specifies the source from which to import package
metadata, and @var{options} specifies a package identifier and other
options specific to @var{importer}.  Currently, the available
``importers'' are:

@table @code
@item gnu
Import metadata for the given GNU package.  This provides a template
for the latest version of that GNU package, including the hash of its
source tarball, and its canonical synopsis and description.

Additional information such as the package dependencies and its
license needs to be figured out manually.

For example, the following command returns a package definition for
GNU@tie{}Hello:

@example
guix import gnu hello
@end example

Specific command-line options are:

@table @code
@item --key-download=@var{policy}
As for @code{guix refresh}, specify the policy to handle missing OpenPGP
keys when verifying the package signature.  @xref{Invoking guix
refresh, @code{--key-download}}.
@end table

@item pypi
@cindex pypi
Import metadata from the @uref{https://pypi.python.org/, Python Package
Index}@footnote{This functionality requires Guile-JSON to be installed.
@xref{Requirements}.}.  Information is taken from the JSON-formatted
description available at @code{pypi.python.org} and usually includes all
the relevant information, including package dependencies.  For maximum
efficiency, it is recommended to install the @command{unzip} utility, so
that the importer can unzip Python wheels and gather data from them.

The command below imports metadata for the @code{itsdangerous} Python
package:

@example
guix import pypi itsdangerous
@end example

@item gem
@cindex gem
Import metadata from @uref{https://rubygems.org/,
RubyGems}@footnote{This functionality requires Guile-JSON to be
installed.  @xref{Requirements}.}.  Information is taken from the
JSON-formatted description available at @code{rubygems.org} and includes
most relevant information, including runtime dependencies.  There are
some caveats, however.  The metadata doesn't distinguish between
synopses and descriptions, so the same string is used for both fields.
Additionally, the details of non-Ruby dependencies required to build
native extensions is unavailable and left as an exercise to the
packager.

The command below imports metadata for the @code{rails} Ruby package:

@example
guix import gem rails
@end example

@item cpan
@cindex CPAN
Import metadata from @uref{https://www.metacpan.org/, MetaCPAN}@footnote{This
functionality requires Guile-JSON to be installed.
@xref{Requirements}.}.
Information is taken from the JSON-formatted metadata provided through
@uref{https://api.metacpan.org/, MetaCPAN's API} and includes most
relevant information, such as module dependencies.  License information
should be checked closely.  If Perl is available in the store, then the
@code{corelist} utility will be used to filter core modules out of the
list of dependencies.

The command command below imports metadata for the @code{Acme::Boolean}
Perl module:

@example
guix import cpan Acme::Boolean
@end example

@item cran
@cindex CRAN
@cindex Bioconductor
Import metadata from @uref{http://cran.r-project.org/, CRAN}, the
central repository for the @uref{http://r-project.org, GNU@tie{}R
statistical and graphical environment}.

Information is extracted from the @code{DESCRIPTION} file of the package.

The command command below imports metadata for the @code{Cairo}
R package:

@example
guix import cran Cairo
@end example

When @code{--archive=bioconductor} is added, metadata is imported from
@uref{http://www.bioconductor.org/, Bioconductor}, a repository of R
packages for for the analysis and comprehension of high-throughput
genomic data in bioinformatics.

Information is extracted from the @code{DESCRIPTION} file of a package
published on the web interface of the Bioconductor SVN repository.

The command below imports metadata for the @code{GenomicRanges}
R package:

@example
guix import cran --archive=bioconductor GenomicRanges
@end example

@item nix
Import metadata from a local copy of the source of the
@uref{http://nixos.org/nixpkgs/, Nixpkgs distribution}@footnote{This
relies on the @command{nix-instantiate} command of
@uref{http://nixos.org/nix/, Nix}.}.  Package definitions in Nixpkgs are
typically written in a mixture of Nix-language and Bash code.  This
command only imports the high-level package structure that is written in
the Nix language.  It normally includes all the basic fields of a
package definition.

When importing a GNU package, the synopsis and descriptions are replaced
by their canonical upstream variant.

Usually, you will first need to do:

@example
export NIX_REMOTE=daemon
@end example

@noindent
so that @command{nix-instantiate} does not try to open the Nix database.

As an example, the command below imports the package definition of
LibreOffice (more precisely, it imports the definition of the package
bound to the @code{libreoffice} top-level attribute):

@example
guix import nix ~/path/to/nixpkgs libreoffice
@end example

@item hackage
@cindex hackage
Import metadata from the Haskell community's central package archive
@uref{https://hackage.haskell.org/, Hackage}.  Information is taken from
Cabal files and includes all the relevant information, including package
dependencies.

Specific command-line options are:

@table @code
@item --stdin
@itemx -s
Read a Cabal file from standard input.
@item --no-test-dependencies
@itemx -t
Do not include dependencies required only by the test suites.
@item --cabal-environment=@var{alist}
@itemx -e @var{alist}
@var{alist} is a Scheme alist defining the environment in which the
Cabal conditionals are evaluated.  The accepted keys are: @code{os},
@code{arch}, @code{impl} and a string representing the name of a flag.
The value associated with a flag has to be either the symbol
@code{true} or @code{false}.  The value associated with other keys
has to conform to the Cabal file format definition.  The default value
associated with the keys @code{os}, @code{arch} and @code{impl} is
@samp{linux}, @samp{x86_64} and @samp{ghc}, respectively.
@end table

The command below imports metadata for the latest version of the
@code{HTTP} Haskell package without including test dependencies and
specifying the value of the flag @samp{network-uri} as @code{false}:

@example
guix import hackage -t -e "'((\"network-uri\" . false))" HTTP
@end example

A specific package version may optionally be specified by following the
package name by an at-sign and a version number as in the following example:

@example
guix import hackage mtl@@2.1.3.1
@end example

@item elpa
@cindex elpa
Import metadata from an Emacs Lisp Package Archive (ELPA) package
repository (@pxref{Packages,,, emacs, The GNU Emacs Manual}).

Specific command-line options are:

@table @code
@item --archive=@var{repo}
@itemx -a @var{repo}
@var{repo} identifies the archive repository from which to retrieve the
information.  Currently the supported repositories and their identifiers
are:
@itemize -
@item
@uref{http://elpa.gnu.org/packages, GNU}, selected by the @code{gnu}
identifier.  This is the default.

@item
@uref{http://stable.melpa.org/packages, MELPA-Stable}, selected by the
@code{melpa-stable} identifier.

@item
@uref{http://melpa.org/packages, MELPA}, selected by the @code{melpa}
identifier.
@end itemize
@end table
@end table

The structure of the @command{guix import} code is modular.  It would be
useful to have more importers for other package formats, and your help
is welcome here (@pxref{Contributing}).

@node Invoking guix refresh
@section Invoking @command{guix refresh}

The primary audience of the @command{guix refresh} command is developers
of the GNU software distribution.  By default, it reports any packages
provided by the distribution that are outdated compared to the latest
upstream version, like this:

@example
$ guix refresh
gnu/packages/gettext.scm:29:13: gettext would be upgraded from 0.18.1.1 to 0.18.2.1
gnu/packages/glib.scm:77:12: glib would be upgraded from 2.34.3 to 2.37.0
@end example

It does so by browsing the FTP directory of each package and determining
the highest version number of the source tarballs therein.  The command
knows how to update specific types of packages: GNU packages, ELPA
packages, etc.---see the documentation for @option{--type} below.  The
are many packages, though, for which it lacks a method to determine
whether a new upstream release is available.  However, the mechanism is
extensible, so feel free to get in touch with us to add a new method!

When passed @code{--update}, it modifies distribution source files to
update the version numbers and source tarball hashes of those package
recipes (@pxref{Defining Packages}).  This is achieved by downloading
each package's latest source tarball and its associated OpenPGP
signature, authenticating the downloaded tarball against its signature
using @command{gpg}, and finally computing its hash.  When the public
key used to sign the tarball is missing from the user's keyring, an
attempt is made to automatically retrieve it from a public key server;
when this is successful, the key is added to the user's keyring; otherwise,
@command{guix refresh} reports an error.

The following options are supported:

@table @code

@item --expression=@var{expr}
@itemx -e @var{expr}
Consider the package @var{expr} evaluates to.

This is useful to precisely refer to a package, as in this example:

@example
guix refresh -l -e '(@@@@ (gnu packages commencement) glibc-final)'
@end example

This command lists the dependents of the ``final'' libc (essentially all
the packages.)

@item --update
@itemx -u
Update distribution source files (package recipes) in place.  This is
usually run from a checkout of the Guix source tree (@pxref{Running
Guix Before It Is Installed}):

@example
$ ./pre-inst-env guix refresh -s non-core
@end example

@xref{Defining Packages}, for more information on package definitions.

@item --select=[@var{subset}]
@itemx -s @var{subset}
Select all the packages in @var{subset}, one of @code{core} or
@code{non-core}.

The @code{core} subset refers to all the packages at the core of the
distribution---i.e., packages that are used to build ``everything
else''.  This includes GCC, libc, Binutils, Bash, etc.  Usually,
changing one of these packages in the distribution entails a rebuild of
all the others.  Thus, such updates are an inconvenience to users in
terms of build time or bandwidth used to achieve the upgrade.

The @code{non-core} subset refers to the remaining packages.  It is
typically useful in cases where an update of the core packages would be
inconvenient.

@item --type=@var{updater}
@itemx -t @var{updater}
Select only packages handled by @var{updater} (may be a comma-separated
list of updaters).  Currently, @var{updater} may be one of:

@table @code
@item gnu
the updater for GNU packages;
@item gnome
the updater for GNOME packages;
@item xorg
the updater for X.org packages;
@item elpa
the updater for @uref{http://elpa.gnu.org/, ELPA} packages;
@item cran
the updater for @uref{http://cran.r-project.org/, CRAN} packages;
@item bioconductor
the updater for @uref{http://www.bioconductor.org/, Bioconductor} R packages;
@item pypi
the updater for @uref{https://pypi.python.org, PyPI} packages.
@item gem
the updater for @uref{https://rubygems.org, RubyGems} packages.
@item github
the updater for @uref{https://github.com, GitHub} packages.
@item hackage
the updater for @uref{https://hackage.haskell.org, Hackage} packages.
@end table

For instance, the following command only checks for updates of Emacs
packages hosted at @code{elpa.gnu.org} and for updates of CRAN packages:

@example
$ guix refresh --type=elpa,cran
gnu/packages/statistics.scm:819:13: r-testthat would be upgraded from 0.10.0 to 0.11.0
gnu/packages/emacs.scm:856:13: emacs-auctex would be upgraded from 11.88.6 to 11.88.9
@end example

@end table

In addition, @command{guix refresh} can be passed one or more package
names, as in this example:

@example
$ ./pre-inst-env guix refresh -u emacs idutils gcc-4.8.4
@end example

@noindent
The command above specifically updates the @code{emacs} and
@code{idutils} packages.  The @code{--select} option would have no
effect in this case.

When considering whether to upgrade a package, it is sometimes
convenient to know which packages would be affected by the upgrade and
should be checked for compatibility.  For this the following option may
be used when passing @command{guix refresh} one or more package names:

@table @code

@item --list-updaters
@itemx -L
List available updaters and exit (see @option{--type} above.)

@item --list-dependent
@itemx -l
List top-level dependent packages that would need to be rebuilt as a
result of upgrading one or more packages.

@end table

Be aware that the @code{--list-dependent} option only
@emph{approximates} the rebuilds that would be required as a result of
an upgrade.  More rebuilds might be required under some circumstances.

@example
$ guix refresh --list-dependent flex
Building the following 120 packages would ensure 213 dependent packages are rebuilt:
hop-2.4.0 geiser-0.4 notmuch-0.18 mu-0.9.9.5 cflow-1.4 idutils-4.6 @dots{}
@end example

The command above lists a set of packages that could be built to check
for compatibility with an upgraded @code{flex} package.

The following options can be used to customize GnuPG operation:

@table @code

@item --gpg=@var{command}
Use @var{command} as the GnuPG 2.x command.  @var{command} is searched
for in @code{$PATH}.

@item --key-download=@var{policy}
Handle missing OpenPGP keys according to @var{policy}, which may be one
of:

@table @code
@item always
Always download missing OpenPGP keys from the key server, and add them
to the user's GnuPG keyring.

@item never
Never try to download missing OpenPGP keys.  Instead just bail out.

@item interactive
When a package signed with an unknown OpenPGP key is encountered, ask
the user whether to download it or not.  This is the default behavior.
@end table

@item --key-server=@var{host}
Use @var{host} as the OpenPGP key server when importing a public key.

@end table

The @code{github} updater uses the
@uref{https://developer.github.com/v3/, GitHub API} to query for new
releases.  When used repeatedly e.g. when refreshing all packages,
GitHub will eventually refuse to answer any further API requests.  By
default 60 API requests per hour are allowed, and a full refresh on all
GitHub packages in Guix requires more than this.  Authentication with
GitHub through the use of an API token alleviates these limits.  To use
an API token, set the environment variable @code{GUIX_GITHUB_TOKEN} to a
token procured from @uref{https://github.com/settings/tokens} or
otherwise.


@node Invoking guix lint
@section Invoking @command{guix lint}
The @command{guix lint} command is meant to help package developers avoid
common errors and use a consistent style.  It runs a number of checks on
a given set of packages in order to find common mistakes in their
definitions.  Available @dfn{checkers} include (see
@code{--list-checkers} for a complete list):

@table @code
@item synopsis
@itemx description
Validate certain typographical and stylistic rules about package
descriptions and synopses.

@item inputs-should-be-native
Identify inputs that should most likely be native inputs.

@item source
@itemx home-page
@itemx source-file-name
Probe @code{home-page} and @code{source} URLs and report those that are
invalid.  Check that the source file name is meaningful, e.g. is not
just a version number or ``git-checkout'', without a declared
@code{file-name} (@pxref{origin Reference}).

@item cve
@cindex security vulnerabilities
@cindex CVE, Common Vulnerabilities and Exposures
Report known vulnerabilities found in the Common Vulnerabilities and
Exposures (CVE) databases of the current and past year
@uref{https://nvd.nist.gov/download.cfm#CVE_FEED, published by the US
NIST}.

To view information about a particular vulnerability, visit pages such as:

@itemize
@item
@indicateurl{https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-YYYY-ABCD}
@item
@indicateurl{https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-YYYY-ABCD}
@end itemize

@noindent
where @code{CVE-YYYY-ABCD} is the CVE identifier---e.g.,
@code{CVE-2015-7554}.

Package developers can specify in package recipes the
@uref{https://nvd.nist.gov/cpe.cfm,Common Platform Enumeration (CPE)}
name and version of the package when they differ from the name that Guix
uses, as in this example:

@example
(package
  (name "grub")
  ;; @dots{}
  ;; CPE calls this package "grub2".
  (properties '((cpe-name . "grub2"))))
@end example

@item formatting
Warn about obvious source code formatting issues: trailing white space,
use of tabulations, etc.
@end table

The general syntax is:

@example
guix lint @var{options} @var{package}@dots{}
@end example

If no package is given on the command line, then all packages are checked.
The @var{options} may be zero or more of the following:

@table @code
@item --list-checkers
@itemx -l
List and describe all the available checkers that will be run on packages
and exit.

@item --checkers
@itemx -c
Only enable the checkers specified in a comma-separated list using the
names returned by @code{--list-checkers}.

@end table

@node Invoking guix size
@section Invoking @command{guix size}

The @command{guix size} command helps package developers profile the
disk usage of packages.  It is easy to overlook the impact of an
additional dependency added to a package, or the impact of using a
single output for a package that could easily be split (@pxref{Packages
with Multiple Outputs}).  Such are the typical issues that
@command{guix size} can highlight.

The command can be passed a package specification such as @code{gcc-4.8}
or @code{guile:debug}, or a file name in the store.  Consider this
example:

@example
$ guix size coreutils
store item                               total    self
/gnu/store/@dots{}-coreutils-8.23          70.0    13.9  19.8%
/gnu/store/@dots{}-gmp-6.0.0a              55.3     2.5   3.6%
/gnu/store/@dots{}-acl-2.2.52              53.7     0.5   0.7%
/gnu/store/@dots{}-attr-2.4.46             53.2     0.3   0.5%
/gnu/store/@dots{}-gcc-4.8.4-lib           52.9    15.7  22.4%
/gnu/store/@dots{}-glibc-2.21              37.2    37.2  53.1%
@end example

@cindex closure
The store items listed here constitute the @dfn{transitive closure} of
Coreutils---i.e., Coreutils and all its dependencies, recursively---as
would be returned by:

@example
$ guix gc -R /gnu/store/@dots{}-coreutils-8.23
@end example

Here the output shows three columns next to store items.  The first column,
labeled ``total'', shows the size in mebibytes (MiB) of the closure of
the store item---that is, its own size plus the size of all its
dependencies.  The next column, labeled ``self'', shows the size of the
item itself.  The last column shows the ratio of the size of the item
itself to the space occupied by all the items listed here.

In this example, we see that the closure of Coreutils weighs in at
70@tie{}MiB, half of which is taken by libc.  (That libc represents a
large fraction of the closure is not a problem @i{per se} because it is
always available on the system anyway.)

When the package passed to @command{guix size} is available in the
store, @command{guix size} queries the daemon to determine its
dependencies, and measures its size in the store, similar to @command{du
-ms --apparent-size} (@pxref{du invocation,,, coreutils, GNU
Coreutils}).

When the given package is @emph{not} in the store, @command{guix size}
reports information based on the available substitutes
(@pxref{Substitutes}).  This makes it possible it to profile disk usage of
store items that are not even on disk, only available remotely.

You can also specify several package names:

@example
$ guix size coreutils grep sed bash
store item                               total    self
/gnu/store/@dots{}-coreutils-8.24          77.8    13.8  13.4%
/gnu/store/@dots{}-grep-2.22               73.1     0.8   0.8%
/gnu/store/@dots{}-bash-4.3.42             72.3     4.7   4.6%
/gnu/store/@dots{}-readline-6.3            67.6     1.2   1.2%
@dots{}
total: 102.3 MiB
@end example

@noindent
In this example we see that the combination of the four packages takes
102.3@tie{}MiB in total, which is much less than the sum of each closure
since they have a lot of dependencies in common.

The available options are:

@table @option

@item --substitute-urls=@var{urls}
Use substitute information from @var{urls}.
@xref{client-substitute-urls, the same option for @code{guix build}}.

@item --map-file=@var{file}
Write a graphical map of disk usage in PNG format to @var{file}.

For the example above, the map looks like this:

@image{images/coreutils-size-map,5in,, map of Coreutils disk usage
produced by @command{guix size}}

This option requires that
@uref{http://wingolog.org/software/guile-charting/, Guile-Charting} be
installed and visible in Guile's module search path.  When that is not
the case, @command{guix size} fails as it tries to load it.

@item --system=@var{system}
@itemx -s @var{system}
Consider packages for @var{system}---e.g., @code{x86_64-linux}.

@end table

@node Invoking guix graph
@section Invoking @command{guix graph}

@cindex DAG
Packages and their dependencies form a @dfn{graph}, specifically a
directed acyclic graph (DAG).  It can quickly become difficult to have a
mental model of the package DAG, so the @command{guix graph} command
provides a visual representation of the DAG.  @command{guix graph}
emits a DAG representation in the input format of
@uref{http://www.graphviz.org/, Graphviz}, so its output can be passed
directly to the @command{dot} command of Graphviz.  The general
syntax is:

@example
guix graph @var{options} @var{package}@dots{}
@end example

For example, the following command generates a PDF file representing the
package DAG for the GNU@tie{}Core Utilities, showing its build-time
dependencies:

@example
guix graph coreutils | dot -Tpdf > dag.pdf
@end example

The output looks like this:

@image{images/coreutils-graph,2in,,Dependency graph of the GNU Coreutils}

Nice little graph, no?

But there is more than one graph!  The one above is concise: it is the
graph of package objects, omitting implicit inputs such as GCC, libc,
grep, etc.  It is often useful to have such a concise graph, but
sometimes one may want to see more details.  @command{guix graph} supports
several types of graphs, allowing you to choose the level of detail:

@table @code
@item package
This is the default type used in the example above.  It shows the DAG of
package objects, excluding implicit dependencies.  It is concise, but
filters out many details.

@item bag-emerged
This is the package DAG, @emph{including} implicit inputs.

For instance, the following command:

@example
guix graph --type=bag-emerged coreutils | dot -Tpdf > dag.pdf
@end example

... yields this bigger graph:

@image{images/coreutils-bag-graph,,5in,Detailed dependency graph of the GNU Coreutils}

At the bottom of the graph, we see all the implicit inputs of
@var{gnu-build-system} (@pxref{Build Systems, @code{gnu-build-system}}).

Now, note that the dependencies of these implicit inputs---that is, the
@dfn{bootstrap dependencies} (@pxref{Bootstrapping})---are not shown
here, for conciseness.

@item bag
Similar to @code{bag-emerged}, but this time including all the bootstrap
dependencies.

@item bag-with-origins
Similar to @code{bag}, but also showing origins and their dependencies.

@item derivations
This is the most detailed representation: It shows the DAG of
derivations (@pxref{Derivations}) and plain store items.  Compared to
the above representation, many additional nodes are visible, including
build scripts, patches, Guile modules, etc.

For this type of graph, it is also possible to pass a @file{.drv} file
name instead of a package name, as in:

@example
guix graph -t derivation `guix system build -d my-config.scm`
@end example
@end table

All the types above correspond to @emph{build-time dependencies}.  The
following graph type represents the @emph{run-time dependencies}:

@table @code
@item references
This is the graph of @dfn{references} of a package output, as returned
by @command{guix gc --references} (@pxref{Invoking guix gc}).

If the given package output is not available in the store, @command{guix
graph} attempts to obtain dependency information from substitutes.

Here you can also pass a store file name instead of a package name.  For
example, the command below produces the reference graph of your profile
(which can be big!):

@example
guix graph -t references `readlink -f ~/.guix-profile`
@end example
@end table

The available options are the following:

@table @option
@item --type=@var{type}
@itemx -t @var{type}
Produce a graph output of @var{type}, where @var{type} must be one of
the values listed above.

@item --list-types
List the supported graph types.

@item --expression=@var{expr}
@itemx -e @var{expr}
Consider the package @var{expr} evaluates to.

This is useful to precisely refer to a package, as in this example:

@example
guix graph -e '(@@@@ (gnu packages commencement) gnu-make-final)'
@end example
@end table


@node Invoking guix environment
@section Invoking @command{guix environment}

@cindex reproducible build environments
@cindex development environments
The purpose of @command{guix environment} is to assist hackers in
creating reproducible development environments without polluting their
package profile.  The @command{guix environment} tool takes one or more
packages, builds all of their inputs, and creates a shell
environment to use them.

The general syntax is:

@example
guix environment @var{options} @var{package}@dots{}
@end example

The following example spawns a new shell set up for the development of
GNU@tie{}Guile:

@example
guix environment guile
@end example

If the needed dependencies are not built yet, @command{guix environment}
automatically builds them.  The environment of the new shell is an augmented
version of the environment that @command{guix environment} was run in.
It contains the necessary search paths for building the given package
added to the existing environment variables.  To create a ``pure''
environment, in which the original environment variables have been unset,
use the @code{--pure} option@footnote{Users sometimes wrongfully augment
environment variables such as @code{PATH} in their @file{~/.bashrc}
file.  As a consequence, when @code{guix environment} launches it, Bash
may read @file{~/.bashrc}, thereby introducing ``impurities'' in these
environment variables.  It is an error to define such environment
variables in @file{.bashrc}; instead, they should be defined in
@file{.bash_profile}, which is sourced only by log-in shells.
@xref{Bash Startup Files,,, bash, The GNU Bash Reference Manual}, for
details on Bash start-up files.}.

@vindex GUIX_ENVIRONMENT
@command{guix environment} defines the @code{GUIX_ENVIRONMENT}
variable in the shell it spawns.  This allows users to, say, define a
specific prompt for development environments in their @file{.bashrc}
(@pxref{Bash Startup Files,,, bash, The GNU Bash Reference Manual}):

@example
if [ -n "$GUIX_ENVIRONMENT" ]
then
    export PS1="\u@@\h \w [dev]\$ "
fi
@end example

Additionally, more than one package may be specified, in which case the
union of the inputs for the given packages are used.  For example, the
command below spawns a shell where all of the dependencies of both Guile
and Emacs are available:

@example
guix environment guile emacs
@end example

Sometimes an interactive shell session is not desired.  An arbitrary
command may be invoked by placing the @code{--} token to separate the
command from the rest of the arguments:

@example
guix environment guile -- make -j4
@end example

In other situations, it is more convenient to specify the list of
packages needed in the environment.  For example, the following command
runs @command{python} from an environment containing Python@tie{}2.7 and
NumPy:

@example
guix environment --ad-hoc python2-numpy python-2.7 -- python
@end example

Furthermore, one might want the dependencies of a package and also some
additional packages that are not build-time or runtime dependencies, but
are useful when developing nonetheless.  Because of this, the
@code{--ad-hoc} flag is positional.  Packages appearing before
@code{--ad-hoc} are interpreted as packages whose dependencies will be
added to the environment.  Packages appearing after are interpreted as
packages that will be added to the environment directly.  For example,
the following command creates a Guix development environment that
additionally includes Git and strace:

@example
guix environment guix --ad-hoc git strace
@end example

Sometimes it is desirable to isolate the environment as much as
possible, for maximal purity and reproducibility.  In particular, when
using Guix on a host distro that is not GuixSD, it is desirable to
prevent access to @file{/usr/bin} and other system-wide resources from
the development environment.  For example, the following command spawns
a Guile REPL in a ``container'' where only the store and the current
working directory are mounted:

@example
guix environment --ad-hoc --container guile -- guile
@end example

@quotation Note
The @code{--container} option requires Linux-libre 3.19 or newer.
@end quotation

The available options are summarized below.

@table @code
@item --expression=@var{expr}
@itemx -e @var{expr}
Create an environment for the package or list of packages that
@var{expr} evaluates to.

For example, running:

@example
guix environment -e '(@@ (gnu packages maths) petsc-openmpi)'
@end example

starts a shell with the environment for this specific variant of the
PETSc package.

Running:

@example
guix environment --ad-hoc -e '(@@ (gnu) %base-packages)'
@end example

starts a shell with all the GuixSD base packages available.

The above commands only the use default output of the given packages.
To select other outputs, two element tuples can be specified:

@example
guix environment --ad-hoc -e '(list (@ (gnu packages bash) bash) "include")'
@end example

@item --load=@var{file}
@itemx -l @var{file}
Create an environment for the package or list of packages that the code
within @var{file} evaluates to.

As an example, @var{file} might contain a definition like this
(@pxref{Defining Packages}):

@example
@verbatiminclude environment-gdb.scm
@end example

@item --ad-hoc
Include all specified packages in the resulting environment, as if an
@i{ad hoc} package were defined with them as inputs.  This option is
useful for quickly creating an environment without having to write a
package expression to contain the desired inputs.

For instance, the command:

@example
guix environment --ad-hoc guile guile-sdl -- guile
@end example

runs @command{guile} in an environment where Guile and Guile-SDL are
available.

Note that this example implicitly asks for the default output of
@code{guile} and @code{guile-sdl}, but it is possible to ask for a
specific output---e.g., @code{glib:bin} asks for the @code{bin} output
of @code{glib} (@pxref{Packages with Multiple Outputs}).

This option may be composed with the default behavior of @command{guix
environment}.  Packages appearing before @code{--ad-hoc} are interpreted
as packages whose dependencies will be added to the environment, the
default behavior.  Packages appearing after are interpreted as packages
that will be added to the environment directly.

@item --pure
Unset existing environment variables when building the new environment.
This has the effect of creating an environment in which search paths
only contain package inputs.

@item --search-paths
Display the environment variable definitions that make up the
environment.

@item --system=@var{system}
@itemx -s @var{system}
Attempt to build for @var{system}---e.g., @code{i686-linux}.

@item --container
@itemx -C
@cindex container
Run @var{command} within an isolated container.  The current working
directory outside the container is mapped inside the container.
Additionally, a dummy home directory is created that matches the current
user's home directory, and @file{/etc/passwd} is configured accordingly.
The spawned process runs as the current user outside the container, but
has root privileges in the context of the container.

@item --network
@itemx -N
For containers, share the network namespace with the host system.
Containers created without this flag only have access to the loopback
device.

@item --expose=@var{source}[=@var{target}]
For containers, expose the file system @var{source} from the host system
as the read-only file system @var{target} within the container.  If
@var{target} is not specified, @var{source} is used as the target mount
point in the container.

The example below spawns a Guile REPL in a container in which the user's
home directory is accessible read-only via the @file{/exchange}
directory:

@example
guix environment --container --expose=$HOME=/exchange guile -- guile
@end example

@item --share=@var{source}[=@var{target}]
For containers, share the file system @var{source} from the host system
as the writable file system @var{target} within the container.  If
@var{target} is not specified, @var{source} is used as the target mount
point in the container.

The example below spawns a Guile REPL in a container in which the user's
home directory is accessible for both reading and writing via the
@file{/exchange} directory:

@example
guix environment --container --share=$HOME=/exchange guile -- guile
@end example
@end table

It also supports all of the common build options that @command{guix
build} supports (@pxref{Common Build Options}).

@node Invoking guix publish
@section Invoking @command{guix publish}

The purpose of @command{guix publish} is to enable users to easily share
their store with others, who can then use it as a substitute server
(@pxref{Substitutes}).

When @command{guix publish} runs, it spawns an HTTP server which allows
anyone with network access to obtain substitutes from it.  This means
that any machine running Guix can also act as if it were a build farm,
since the HTTP interface is compatible with Hydra, the software behind
the @code{hydra.gnu.org} build farm.

For security, each substitute is signed, allowing recipients to check
their authenticity and integrity (@pxref{Substitutes}).  Because
@command{guix publish} uses the signing key of the system, which is only
readable by the system administrator, it must be started as root; the
@code{--user} option makes it drop root privileges early on.

The signing key pair must be generated before @command{guix publish} is
launched, using @command{guix archive --generate-key} (@pxref{Invoking
guix archive}).

The general syntax is:

@example
guix publish @var{options}@dots{}
@end example

Running @command{guix publish} without any additional arguments will
spawn an HTTP server on port 8080:

@example
guix publish
@end example

Once a publishing server has been authorized (@pxref{Invoking guix
archive}), the daemon may download substitutes from it:

@example
guix-daemon --substitute-urls=http://example.org:8080
@end example

The following options are available:

@table @code
@item --port=@var{port}
@itemx -p @var{port}
Listen for HTTP requests on @var{port}.

@item --listen=@var{host}
Listen on the network interface for @var{host}.  The default is to
accept connections from any interface.

@item --user=@var{user}
@itemx -u @var{user}
Change privileges to @var{user} as soon as possible---i.e., once the
server socket is open and the signing key has been read.

@item --ttl=@var{ttl}
Produce @code{Cache-Control} HTTP headers that advertise a time-to-live
(TTL) of @var{ttl}.  @var{ttl} must denote a duration: @code{5d} means 5
days, @code{1m} means 1 month, and so on.

This allows the user's Guix to keep substitute information in cache for
@var{ttl}.  However, note that @code{guix publish} does not itself
guarantee that the store items it provides will indeed remain available
for as long as @var{ttl}.

@item --repl[=@var{port}]
@itemx -r [@var{port}]
Spawn a Guile REPL server (@pxref{REPL Servers,,, guile, GNU Guile
Reference Manual}) on @var{port} (37146 by default).  This is used
primarily for debugging a running @command{guix publish} server.
@end table

Enabling @command{guix publish} on a GuixSD system is a one-liner: just
add a call to @code{guix-publish-service} in the @code{services} field
of the @code{operating-system} declaration (@pxref{guix-publish-service,
@code{guix-publish-service}}).


@node Invoking guix challenge
@section Invoking @command{guix challenge}

@cindex reproducible builds
@cindex verifiable builds

Do the binaries provided by this server really correspond to the source
code it claims to build?  Is a package build process deterministic?
These are the questions the @command{guix challenge} command attempts to
answer.

The former is obviously an important question: Before using a substitute
server (@pxref{Substitutes}), one had better @emph{verify} that it
provides the right binaries, and thus @emph{challenge} it.  The latter
is what enables the former: If package builds are deterministic, then
independent builds of the package should yield the exact same result,
bit for bit; if a server provides a binary different from the one
obtained locally, it may be either corrupt or malicious.

We know that the hash that shows up in @file{/gnu/store} file names is
the hash of all the inputs of the process that built the file or
directory---compilers, libraries, build scripts,
etc. (@pxref{Introduction}).  Assuming deterministic build processes,
one store file name should map to exactly one build output.
@command{guix challenge} checks whether there is, indeed, a single
mapping by comparing the build outputs of several independent builds of
any given store item.

The command output looks like this:

@smallexample
$ guix challenge --substitute-urls="https://hydra.gnu.org https://guix.example.org"
updating list of substitutes from 'https://hydra.gnu.org'... 100.0%
updating list of substitutes from 'https://guix.example.org'... 100.0%
/gnu/store/@dots{}-openssl-1.0.2d contents differ:
  local hash: 0725l22r5jnzazaacncwsvp9kgf42266ayyp814v7djxs7nk963q
  https://hydra.gnu.org/nar/@dots{}-openssl-1.0.2d: 0725l22r5jnzazaacncwsvp9kgf42266ayyp814v7djxs7nk963q
  https://guix.example.org/nar/@dots{}-openssl-1.0.2d: 1zy4fmaaqcnjrzzajkdn3f5gmjk754b43qkq47llbyak9z0qjyim
/gnu/store/@dots{}-git-2.5.0 contents differ:
  local hash: 00p3bmryhjxrhpn2gxs2fy0a15lnip05l97205pgbk5ra395hyha
  https://hydra.gnu.org/nar/@dots{}-git-2.5.0: 069nb85bv4d4a6slrwjdy8v1cn4cwspm3kdbmyb81d6zckj3nq9f
  https://guix.example.org/nar/@dots{}-git-2.5.0: 0mdqa9w1p6cmli6976v4wi0sw9r4p5prkj7lzfd1877wk11c9c73
/gnu/store/@dots{}-pius-2.1.1 contents differ:
  local hash: 0k4v3m9z1zp8xzzizb7d8kjj72f9172xv078sq4wl73vnq9ig3ax
  https://hydra.gnu.org/nar/@dots{}-pius-2.1.1: 0k4v3m9z1zp8xzzizb7d8kjj72f9172xv078sq4wl73vnq9ig3ax
  https://guix.example.org/nar/@dots{}-pius-2.1.1: 1cy25x1a4fzq5rk0pmvc8xhwyffnqz95h2bpvqsz2mpvlbccy0gs
@end smallexample

@noindent
In this example, @command{guix challenge} first scans the store to
determine the set of locally-built derivations---as opposed to store
items that were downloaded from a substitute server---and then queries
all the substitute servers.  It then reports those store items for which
the servers obtained a result different from the local build.

@cindex non-determinism, in package builds
As an example, @code{guix.example.org} always gets a different answer.
Conversely, @code{hydra.gnu.org} agrees with local builds, except in the
case of Git.  This might indicate that the build process of Git is
non-deterministic, meaning that its output varies as a function of
various things that Guix does not fully control, in spite of building
packages in isolated environments (@pxref{Features}).  Most common
sources of non-determinism include the addition of timestamps in build
results, the inclusion of random numbers, and directory listings sorted
by inode number.  See @uref{https://reproducible-builds.org/docs/}, for
more information.

To find out what is wrong with this Git binary, we can do something along
these lines (@pxref{Invoking guix archive}):

@example
$ wget -q -O - https://hydra.gnu.org/nar/@dots{}-git-2.5.0 \
   | guix archive -x /tmp/git
$ diff -ur --no-dereference /gnu/store/@dots{}-git.2.5.0 /tmp/git
@end example

This command shows the difference between the files resulting from the
local build, and the files resulting from the build on
@code{hydra.gnu.org} (@pxref{Overview, Comparing and Merging Files,,
diffutils, Comparing and Merging Files}).  The @command{diff} command
works great for text files.  When binary files differ, a better option
is @uref{https://diffoscope.org/, Diffoscope}, a tool that helps
visualize differences for all kinds of files.

Once you have done that work, you can tell whether the differences are due
to a non-deterministic build process or to a malicious server.  We try
hard to remove sources of non-determinism in packages to make it easier
to verify substitutes, but of course, this is a process that
involves not just Guix, but a large part of the free software community.
In the meantime, @command{guix challenge} is one tool to help address
the problem.

If you are writing packages for Guix, you are encouraged to check
whether @code{hydra.gnu.org} and other substitute servers obtain the
same build result as you did with:

@example
$ guix challenge @var{package}
@end example

@noindent
where @var{package} is a package specification such as
@code{guile@@2.0} or @code{glibc:debug}.

The general syntax is:

@example
guix challenge @var{options} [@var{packages}@dots{}]
@end example

When a difference is found between the hash of a locally-built item and
that of a server-provided substitute, or among substitutes provided by
different servers, the command displays it as in the example above and
its exit code is 2 (other non-zero exit codes denote other kinds of
errors.)

The one option that matters is:

@table @code

@item --substitute-urls=@var{urls}
Consider @var{urls} the whitespace-separated list of substitute source
URLs to compare to.

@end table


@node Invoking guix container
@section Invoking @command{guix container}
@cindex container

@quotation Note
As of version @value{VERSION}, this tool is experimental.  The interface
is subject to radical change in the future.
@end quotation

The purpose of @command{guix container} is to manipulate processes
running within an isolated environment, commonly known as a
``container'', typically created by the @command{guix environment}
(@pxref{Invoking guix environment}) and @command{guix system container}
(@pxref{Invoking guix system}) commands.

The general syntax is:

@example
guix container @var{action} @var{options}@dots{}
@end example

@var{action} specifies the operation to perform with a container, and
@var{options} specifies the context-specific arguments for the action.

The following actions are available:

@table @code
@item exec
Execute a command within the context of a running container.

The syntax is:

@example
guix container exec @var{pid} @var{program} @var{arguments}@dots{}
@end example

@var{pid} specifies the process ID of the running container.
@var{program} specifies an executable file name within the root file
system of the container.  @var{arguments} are the additional options that
will be passed to @var{program}.

The following command launches an interactive login shell inside a
GuixSD container, started by @command{guix system container}, and whose
process ID is 9001:

@example
guix container exec 9001 /run/current-system/profile/bin/bash --login
@end example

Note that the @var{pid} cannot be the parent process of a container.  It
must be PID 1 of the container or one of its child processes.

@end table

@c *********************************************************************
@node GNU Distribution
@chapter GNU Distribution

@cindex Guix System Distribution
@cindex GuixSD
Guix comes with a distribution of the GNU system consisting entirely of
free software@footnote{The term ``free'' here refers to the
@url{http://www.gnu.org/philosophy/free-sw.html,freedom provided to
users of that software}.}.  The
distribution can be installed on its own (@pxref{System Installation}),
but it is also possible to install Guix as a package manager on top of
an installed GNU/Linux system (@pxref{Installation}).  To distinguish
between the two, we refer to the standalone distribution as the Guix
System Distribution, or GuixSD.

The distribution provides core GNU packages such as GNU libc, GCC, and
Binutils, as well as many GNU and non-GNU applications.  The complete
list of available packages can be browsed
@url{http://www.gnu.org/software/guix/packages,on-line} or by
running @command{guix package} (@pxref{Invoking guix package}):

@example
guix package --list-available
@end example

Our goal is to provide a practical 100% free software distribution of
Linux-based and other variants of GNU, with a focus on the promotion and
tight integration of GNU components, and an emphasis on programs and
tools that help users exert that freedom.

Packages are currently available on the following platforms:

@table @code

@item x86_64-linux
Intel/AMD @code{x86_64} architecture, Linux-Libre kernel;

@item i686-linux
Intel 32-bit architecture (IA32), Linux-Libre kernel;

@item armhf-linux
ARMv7-A architecture with hard float, Thumb-2 and NEON,
using the EABI hard-float application binary interface (ABI),
and Linux-Libre kernel.

@item mips64el-linux
little-endian 64-bit MIPS processors, specifically the Loongson series,
n32 ABI, and Linux-Libre kernel.

@end table

GuixSD itself is currently only available on @code{i686} and @code{x86_64}.

@noindent
For information on porting to other architectures or kernels,
@pxref{Porting}.

@menu
* System Installation::         Installing the whole operating system.
* System Configuration::        Configuring the operating system.
* Installing Debugging Files::  Feeding the debugger.
* Security Updates::            Deploying security fixes quickly.
* Package Modules::             Packages from the programmer's viewpoint.
* Packaging Guidelines::        Growing the distribution.
* Bootstrapping::               GNU/Linux built from scratch.
* Porting::                     Targeting another platform or kernel.
@end menu

Building this distribution is a cooperative effort, and you are invited
to join!  @xref{Contributing}, for information about how you can help.

@node System Installation
@section System Installation

@cindex Guix System Distribution
This section explains how to install the Guix System Distribution
on a machine.  The Guix package manager can
also be installed on top of a running GNU/Linux system,
@pxref{Installation}.

@ifinfo
@quotation Note
@c This paragraph is for people reading this from tty2 of the
@c installation image.
You are reading this documentation with an Info reader.  For details on
how to use it, hit the @key{RET} key (``return'' or ``enter'') on the
link that follows: @pxref{Top, Info reader,, info-stnd, Stand-alone GNU
Info}.  Hit @kbd{l} afterwards to come back here.

Alternately, run @command{info info} in another tty to keep the manual
available.
@end quotation
@end ifinfo

@menu
* Limitations::                 What you can expect.
* Hardware Considerations::     Supported hardware.
* USB Stick Installation::      Preparing the installation medium.
* USB storage Installation in a VM:: Booting a VM with USB install image.
* Preparing for Installation::  Networking, partitioning, etc.
* Proceeding with the Installation::  The real thing.
* Building the Installation Image::  How this comes to be.
@end menu

@node Limitations
@subsection Limitations

As of version @value{VERSION}, the Guix System Distribution (GuixSD) is
not production-ready.  It may contain bugs and lack important
features.  Thus, if you are looking for a stable production system that
respects your freedom as a computer user, a good solution at this point
is to consider @url{http://www.gnu.org/distros/free-distros.html, one of
the more established GNU/Linux distributions}.  We hope you can soon switch
to the GuixSD without fear, of course.  In the meantime, you can
also keep using your distribution and try out the package manager on top
of it (@pxref{Installation}).

Before you proceed with the installation, be aware of the following
noteworthy limitations applicable to version @value{VERSION}:

@itemize
@item
The installation process does not include a graphical user interface and
requires familiarity with GNU/Linux (see the following subsections to
get a feel of what that means.)

@item
Support for the Logical Volume Manager (LVM) is missing.

@item
Few system services are currently supported out-of-the-box
(@pxref{Services}).

@item
More than 3,200 packages are available, but you may
occasionally find that a useful package is missing.

@item
GNOME, Xfce, and Enlightenment are available (@pxref{Desktop Services}),
as well as a number of X11 window managers.  However, some graphical
applications may be missing, as well as KDE.
@end itemize

You have been warned!  But more than a disclaimer, this is an invitation
to report issues (and success stories!), and to join us in improving it.
@xref{Contributing}, for more info.


@node Hardware Considerations
@subsection Hardware Considerations

@cindex hardware support on GuixSD
GNU@tie{}GuixSD focuses on respecting the user's computing freedom.  It
builds around the kernel Linux-libre, which means that only hardware for
which free software drivers and firmware exist is supported.  Nowadays,
a wide range of off-the-shelf hardware is supported on
GNU/Linux-libre---from keyboards to graphics cards to scanners and
Ethernet controllers.  Unfortunately, there are still areas where
hardware vendors deny users control over their own computing, and such
hardware is not supported on GuixSD.

@cindex WiFi, hardware support
One of the main areas where free drivers or firmware are lacking is WiFi
devices.  WiFi devices known to work include those using Atheros chips
(AR9271 and AR7010), which corresponds to the @code{ath9k} Linux-libre
driver, and for which free firmware exists and is available
out-of-the-box on GuixSD, as part of @var{%base-firmware}
(@pxref{operating-system Reference, @code{firmware}}).

@cindex RYF, Respects Your Freedom
The @uref{https://www.fsf.org/, Free Software Foundation} runs
@uref{https://www.fsf.org/ryf, @dfn{Respects Your Freedom}} (RYF), a
certification program for hardware products that respect your freedom
and your privacy and ensure that you have control over your device.  We
encourage you to check the list of RYF-certified devices.

Another useful resource is the @uref{https://www.h-node.org/, H-Node}
web site.  It contains a catalog of hardware devices with information
about their support in GNU/Linux.


@node USB Stick Installation
@subsection USB Stick Installation

An installation image for USB sticks can be downloaded from
@indicateurl{ftp://alpha.gnu.org/gnu/guix/guixsd-usb-install-@value{VERSION}.@var{system}.xz},
where @var{system} is one of:

@table @code
@item x86_64-linux
for a GNU/Linux system on Intel/AMD-compatible 64-bit CPUs;

@item i686-linux
for a 32-bit GNU/Linux system on Intel-compatible CPUs.
@end table

This image contains a single partition with the tools necessary for an
installation.  It is meant to be copied @emph{as is} to a large-enough
USB stick.  It can also be used to install GuixSD in a QEmu virtual
machine (@pxref{USB storage Installation in a VM}).

To download and verify this image, follow these steps:

@enumerate
@item
Download the image & signature files using the @command{wget} command:

@example
wget ftp://alpha.gnu.org/gnu/guix/guixsd-usb-install-@value{VERSION}.@var{system}.xz
wget ftp://alpha.gnu.org/gnu/guix/guixsd-usb-install-@value{VERSION}.@var{system}.xz.sign
@end example

@item
Get the PGP key using the @command{gpg} command:

@example
gpg --keyserver keys.gnupg.net --recv-keys 3D9AEBB5
@end example

@item
Check download integrity using the @command{gpg} command:

@example
gpg --verify guixsd-usb-install-@value{VERSION}.@var{system}.xz.sig
@end example

@end enumerate

To copy the image to a USB stick, follow these steps:

@enumerate
@item
Decompress the image using the @command{xz} command:

@example
xz -d guixsd-usb-install-@value{VERSION}.@var{system}.xz
@end example

@item
Insert a USB stick of 1@tie{}GiB or more into your machine, and determine
its device name.  Assuming that the USB stick is known as @file{/dev/sdX},
copy the image with:

@example
dd if=guixsd-usb-install-@value{VERSION}.x86_64 of=/dev/sdX
@end example

Access to @file{/dev/sdX} usually requires root privileges.
@end enumerate

Once this is done, you should be able to reboot the system and boot from
the USB stick.  The latter usually requires you to get in the BIOS' boot
menu, where you can choose to boot from the USB stick.

@node USB storage Installation in a VM
@subsection USB storage Installation in a VM

To boot a QEmu virtual machine for installing GuixSD in a disk image, follow
these steps:

@enumerate
@item
Prepare a disk image file for the GuixSD system using the @command{dd} command:

@example
dd if=/dev/zero of=guixsd-x86_64-raw.img bs=1G count=5
@end example

@item
Or use the QEmu tool to create a qcow2 formatted image file using
the @command{qemu-img} command:

@example
qemu-img create -f qcow2 guixsd-x86_64-raw.img 5G
@end example

This will create a 5GB file.

@item
Ensure your running kernel has the required CONFIG_BRIDGE option for the
network to work properly in the virtual machine:

@example
zgrep CONFIG_BRIDGE= /proc/config.gz
CONFIG_BRIDGE=y
@end example

If it is compiled as a module & loaded, it will also work:

@example
zgrep CONFIG_BRIDGE= /proc/config.gz
CONFIG_BRIDGE=m
lsmod | grep ^bridge
bridge 117542 0
@end example

@item
Boot a virtual machine with the USB installation image

@example
qemu-system-x86_64 -m 1024 -smp 1 -net default -net nic,model=virtio -boot menu=on \
  -drive file=guixsd-x86_64-raw.img \
  -drive file=guixsd-usb-install-@value{VERSION}.@var{system}
@end example

In the VM console, quickly press the <F12> key to enter the boot menu.  Then
press the <2> key and the <ENTER> key to validate your selection.

@end enumerate

You're now root in the VM, proceed with the installation process.

@node Preparing for Installation
@subsection Preparing for Installation

Once you have successfully booted the image on the USB stick, you should
end up with a root prompt.  Several console TTYs are configured and can
be used to run commands as root.  TTY2 shows this documentation,
browsable using the Info reader commands (@pxref{Top,,, info-stnd,
Stand-alone GNU Info}).  The installation system runs the GPM mouse
daemon, which allows you to select text with the left mouse button and
to paste it with the middle button.

@quotation Note
Installation requires access to the Internet so that any missing
dependencies of your system configuration can be downloaded.  See the
``Networking'' section below.
@end quotation

The installation system includes many common tools needed for this task.
But it is also a full-blown GuixSD system, which means that you can
install additional packages, should you need it, using @command{guix
package} (@pxref{Invoking guix package}).

@subsubsection Keyboard Layout

@cindex keyboard layout
The installation image uses the US qwerty keyboard layout.  If you want
to change it, you can use the @command{loadkeys} command.  For example,
the following command selects the Dvorak keyboard layout:

@example
loadkeys dvorak
@end example

See the files under @file{/run/current-system/profile/share/keymaps} for
a list of available keyboard layouts.  Run @command{man loadkeys} for
more information.

@subsubsection Networking

Run the following command see what your network interfaces are called:

@example
ifconfig -a
@end example

@noindent
@dots{} or, using the GNU/Linux-specific @command{ip} command:

@example
ip a
@end example

@c http://cgit.freedesktop.org/systemd/systemd/tree/src/udev/udev-builtin-net_id.c#n20
Wired interfaces have a name starting with @samp{e}; for example, the
interface corresponding to the first on-board Ethernet controller is
called @samp{eno1}.  Wireless interfaces have a name starting with
@samp{w}, like @samp{w1p2s0}.

@table @asis
@item Wired connection
To configure a wired network run the following command, substituting
@var{interface} with the name of the wired interface you want to use.

@example
ifconfig @var{interface} up
@end example

@item Wireless connection
To configure wireless networking, you can create a configuration file
for the @command{wpa_supplicant} configuration tool (its location is not
important) using one of the available text editors such as
@command{zile}:

@example
zile wpa_supplicant.conf
@end example

As an example, the following stanza can go to this file and will work
for many wireless networks, provided you give the actual SSID and
passphrase for the network you are connecting to:

@example
network=@{
  ssid="@var{my-ssid}"
  key_mgmt=WPA-PSK
  psk="the network's secret passphrase"
@}
@end example

Start the wireless service and run it in the background with the
following command (substitute @var{interface} with the name of the
network interface you want to use):

@example
wpa_supplicant -c wpa_supplicant.conf -i @var{interface} -B
@end example

Run @command{man wpa_supplicant} for more information.
@end table

At this point, you need to acquire an IP address.  On a network where IP
addresses are automatically assigned @i{via} DHCP, you can run:

@example
dhclient -v @var{interface}
@end example

Try to ping a server to see if networking is up and running:

@example
ping -c 3 gnu.org
@end example

Setting up network access is almost always a requirement because the
image does not contain all the software and tools that may be needed.

@subsubsection Disk Partitioning

Unless this has already been done, the next step is to partition, and
then format the target partition(s).

The installation image includes several partitioning tools, including
Parted (@pxref{Overview,,, parted, GNU Parted User Manual}),
@command{fdisk}, and @command{cfdisk}.  Run it and set up your disk with
the partition layout you want:

@example
cfdisk
@end example

Once you are done partitioning the target hard disk drive, you have to
create a file system on the relevant partition(s)@footnote{Currently
GuixSD pretty much assumes an ext4 file system.  In particular, code
that reads partition UUIDs and labels only works with ext4.  This will
be fixed in the future.}.

Preferably, assign partitions a label so that you can easily and
reliably refer to them in @code{file-system} declarations (@pxref{File
Systems}).  This is typically done using the @code{-L} option of
@command{mkfs.ext4} and related commands.  So, assuming the target root
partition lives at @file{/dev/sda1}, a file system with the label
@code{my-root} can be created with:

@example
mkfs.ext4 -L my-root /dev/sda1
@end example

@c FIXME: Uncomment this once GRUB fully supports encrypted roots.
@c A typical command sequence may be:
@c
@c @example
@c # fdisk /dev/sdX
@c @dots{} Create partitions etc.@dots{}
@c # cryptsetup luksFormat /dev/sdX1
@c # cryptsetup open --type luks /dev/sdX1 my-partition
@c # mkfs.ext4 -L my-root /dev/mapper/my-partition
@c @end example

In addition to e2fsprogs, the suite of tools to manipulate
ext2/ext3/ext4 file systems, the installation image includes
Cryptsetup/LUKS for disk encryption.

Once that is done, mount the target root partition under @file{/mnt}
with a command like (again, assuming @file{/dev/sda1} is the root
partition):

@example
mount /dev/sda1 /mnt
@end example

Finally, if you plan to use one or more swap partitions (@pxref{Memory
Concepts, swap space,, libc, The GNU C Library Reference Manual}), make
sure to initialize them with @command{mkswap}.  Assuming you have one
swap partition on @file{/dev/sda2}, you would run:

@example
mkswap /dev/sda2
@end example

@node Proceeding with the Installation
@subsection Proceeding with the Installation

With the target partitions ready and the target root mounted on
@file{/mnt}, we're ready to go.  First, run:

@example
herd start cow-store /mnt
@end example

This makes @file{/gnu/store} copy-on-write, such that packages added to it
during the installation phase are written to the target disk on @file{/mnt}
rather than kept in memory.  This is necessary because the first phase of
the @command{guix system init} command (see below) entails downloads or
builds to @file{/gnu/store} which, initially, is an in-memory file system.

Next, you have to edit a file and
provide the declaration of the operating system to be installed.  To
that end, the installation system comes with two text editors: GNU nano
(@pxref{Top,,, nano, GNU nano Manual}), and GNU Zile, an Emacs clone.
We strongly recommend storing that file on the target root file system, say,
as @file{/mnt/etc/config.scm}.  Failing to do that, you will have lost your
configuration file once you have rebooted into the newly-installed system.

@xref{Using the Configuration System}, for an overview of the
configuration file.  The example configurations discussed in that
section are available under @file{/etc/configuration} in the
installation image.  Thus, to get started with a system configuration
providing a graphical display server (a ``desktop'' system), you can run
something along these lines:

@example
# mkdir /mnt/etc
# cp /etc/configuration/desktop.scm /mnt/etc/config.scm
# zile /mnt/etc/config.scm
@end example

You should pay attention to what your configuration file contains, and
in particular:

@itemize
@item
Make sure the @code{grub-configuration} form refers to the device you
want to install GRUB on.

@item
Be sure that your partition labels match the value of their respective
@code{device} fields in your @code{file-system} configuration, assuming
your @code{file-system} configuration sets the value of @code{title} to
@code{'label}.
@end itemize

Once you are done preparing the configuration file, the new system must
be initialized (remember that the target root file system is mounted
under @file{/mnt}):

@example
guix system init /mnt/etc/config.scm /mnt
@end example

@noindent
This copies all the necessary files and installs GRUB on
@file{/dev/sdX}, unless you pass the @option{--no-grub} option.  For
more information, @pxref{Invoking guix system}.  This command may trigger
downloads or builds of missing packages, which can take some time.

Once that command has completed---and hopefully succeeded!---you can run
@command{reboot} and boot into the new system.  The @code{root} password
in the new system is initially empty; other users' passwords need to be
initialized by running the @command{passwd} command as @code{root},
unless your configuration specifies otherwise
(@pxref{user-account-password, user account passwords}).

Join us on @code{#guix} on the Freenode IRC network or on
@file{guix-devel@@gnu.org} to share your experience---good or not so
good.

@node Building the Installation Image
@subsection Building the Installation Image

The installation image described above was built using the @command{guix
system} command, specifically:

@c FIXME: 1G is too much; see <http://bugs.gnu.org/23077>.
@example
guix system disk-image --image-size=1G gnu/system/install.scm
@end example

Have a look at @file{gnu/system/install.scm} in the source tree,
and see also @ref{Invoking guix system} for more information
about the installation image.

@node System Configuration
@section System Configuration

@cindex system configuration
The Guix System Distribution supports a consistent whole-system configuration
mechanism.  By that we mean that all aspects of the global system
configuration---such as the available system services, timezone and
locale settings, user accounts---are declared in a single place.  Such
a @dfn{system configuration} can be @dfn{instantiated}---i.e., effected.

One of the advantages of putting all the system configuration under the
control of Guix is that it supports transactional system upgrades, and
makes it possible to roll back to a previous system instantiation,
should something go wrong with the new one (@pxref{Features}).  Another
advantage is that it makes it easy to replicate the exact same configuration
across different machines, or at different points in time, without
having to resort to additional administration tools layered on top of
the own tools of the system.
@c Yes, we're talking of Puppet, Chef, & co. here.  ↑

This section describes this mechanism.  First we focus on the system
administrator's viewpoint---explaining how the system is configured and
instantiated.  Then we show how this mechanism can be extended, for
instance to support new system services.

@menu
* Using the Configuration System::  Customizing your GNU system.
* operating-system Reference::  Detail of operating-system declarations.
* File Systems::                Configuring file system mounts.
* Mapped Devices::              Block device extra processing.
* User Accounts::               Specifying user accounts.
* Locales::                     Language and cultural convention settings.
* Services::                    Specifying system services.
* Setuid Programs::             Programs running with root privileges.
* X.509 Certificates::          Authenticating HTTPS servers.
* Name Service Switch::         Configuring libc's name service switch.
* Initial RAM Disk::            Linux-Libre bootstrapping.
* GRUB Configuration::          Configuring the boot loader.
* Invoking guix system::        Instantiating a system configuration.
* Running GuixSD in a VM::      How to run GuixSD in a virtual machine.
* Defining Services::           Adding new service definitions.
@end menu

@node Using the Configuration System
@subsection Using the Configuration System

The operating system is configured by providing an
@code{operating-system} declaration in a file that can then be passed to
the @command{guix system} command (@pxref{Invoking guix system}).  A
simple setup, with the default system services, the default Linux-Libre
kernel, initial RAM disk, and boot loader looks like this:

@findex operating-system
@lisp
@include os-config-bare-bones.texi
@end lisp

This example should be self-describing.  Some of the fields defined
above, such as @code{host-name} and @code{bootloader}, are mandatory.
Others, such as @code{packages} and @code{services}, can be omitted, in
which case they get a default value.

Below we discuss the effect of some of the most important fields
(@pxref{operating-system Reference}, for details about all the available
fields), and how to @dfn{instantiate} the operating system using
@command{guix system}.

@unnumberedsubsubsec Globally-Visible Packages

@vindex %base-packages
The @code{packages} field lists packages that will be globally visible
on the system, for all user accounts---i.e., in every user's @code{PATH}
environment variable---in addition to the per-user profiles
(@pxref{Invoking guix package}).  The @var{%base-packages} variable
provides all the tools one would expect for basic user and administrator
tasks---including the GNU Core Utilities, the GNU Networking Utilities,
the GNU Zile lightweight text editor, @command{find}, @command{grep},
etc.  The example above adds tcpdump to those, taken from the @code{(gnu
packages admin)} module (@pxref{Package Modules}).

@findex specification->package
Referring to packages by variable name, like @var{tcpdump} above, has
the advantage of being unambiguous; it also allows typos and such to be
diagnosed right away as ``unbound variables''.  The downside is that one
needs to know which module defines which package, and to augment the
@code{use-package-modules} line accordingly.  To avoid that, one can use
the @code{specification->package} procedure of the @code{(gnu packages)}
module, which returns the best package for a given name or name and
version:

@lisp
(use-modules (gnu packages))

(operating-system
  ;; ...
  (packages (append (map specification->package
                         '("tcpdump" "htop" "gnupg@@2.0"))
                    %base-packages)))
@end lisp

@unnumberedsubsubsec System Services

@vindex %base-services
The @code{services} field lists @dfn{system services} to be made
available when the system starts (@pxref{Services}).
The @code{operating-system} declaration above specifies that, in
addition to the basic services, we want the @command{lshd} secure shell
daemon listening on port 2222 (@pxref{Networking Services,
@code{lsh-service}}).  Under the hood,
@code{lsh-service} arranges so that @code{lshd} is started with the
right command-line options, possibly with supporting configuration files
generated as needed (@pxref{Defining Services}).

@cindex customization, of services
@findex modify-services
Occasionally, instead of using the base services as is, you will want to
customize them.  To do this, use @code{modify-services} (@pxref{Service
Reference, @code{modify-services}}) to modify the list.

For example, suppose you want to modify @code{guix-daemon} and Mingetty
(the console log-in) in the @var{%base-services} list (@pxref{Base
Services, @code{%base-services}}).  To do that, you can write the
following in your operating system declaration:

@lisp
(define %my-services
  ;; My very own list of services.
  (modify-services %base-services
    (guix-service-type config =>
                       (guix-configuration
                        (inherit config)
                        (use-substitutes? #f)
                        (extra-options '("--gc-keep-derivations"))))
    (mingetty-service-type config =>
                           (mingetty-configuration
                            (inherit config)
                            (motd (plain-file "motd" "Howdy!"))))))

(operating-system
  ;; @dots{}
  (services %my-services))
@end lisp

This changes the configuration---i.e., the service parameters---of the
@code{guix-service-type} instance, and that of all the
@code{mingetty-service-type} instances in the @var{%base-services} list.
Observe how this is accomplished: first, we arrange for the original
configuration to be bound to the identifier @code{config} in the
@var{body}, and then we write the @var{body} so that it evaluates to the
desired configuration.  In particular, notice how we use @code{inherit}
to create a new configuration which has the same values as the old
configuration, but with a few modifications.

The configuration for a typical ``desktop'' usage, with the X11 display
server, GNOME and Xfce (users can choose which of these desktop
environments to use at the log-in screen by pressing @kbd{F1}), network
management, power management, and more, would look like this:

@lisp
@include os-config-desktop.texi
@end lisp

A graphical environment with a choice of lightweight window managers
instead of full-blown desktop environments would look like this:

@lisp
@include os-config-lightweight-desktop.texi
@end lisp

@xref{Desktop Services}, for the exact list of services provided by
@var{%desktop-services}.  @xref{X.509 Certificates}, for background
information about the @code{nss-certs} package that is used here.

Again, @var{%desktop-services} is just a list of service objects.  If
you want to remove services from there, you can do so using the
procedures for list filtering (@pxref{SRFI-1 Filtering and
Partitioning,,, guile, GNU Guile Reference Manual}).  For instance, the
following expression returns a list that contains all the services in
@var{%desktop-services} minus the Avahi service:

@example
(remove (lambda (service)
          (eq? (service-kind service) avahi-service-type))
        %desktop-services)
@end example

@unnumberedsubsubsec Instantiating the System

Assuming the @code{operating-system} declaration
is stored in the @file{my-system-config.scm}
file, the @command{guix system reconfigure my-system-config.scm} command
instantiates that configuration, and makes it the default GRUB boot
entry (@pxref{Invoking guix system}).

The normal way to change the system configuration is by updating this
file and re-running @command{guix system reconfigure}.  One should never
have to touch files in @command{/etc} or to run commands that modify the
system state such as @command{useradd} or @command{grub-install}.  In
fact, you must avoid that since that would not only void your warranty
but also prevent you from rolling back to previous versions of your
system, should you ever need to.

@cindex roll-back, of the operating system
Speaking of roll-back, each time you run @command{guix system
reconfigure}, a new @dfn{generation} of the system is created---without
modifying or deleting previous generations.  Old system generations get
an entry in the GRUB boot menu, allowing you to boot them in case
something went wrong with the latest generation.  Reassuring, no?  The
@command{guix system list-generations} command lists the system
generations available on disk.

@unnumberedsubsubsec The Programming Interface

At the Scheme level, the bulk of an @code{operating-system} declaration
is instantiated with the following monadic procedure (@pxref{The Store
Monad}):

@deffn {Monadic Procedure} operating-system-derivation os
Return a derivation that builds @var{os}, an @code{operating-system}
object (@pxref{Derivations}).

The output of the derivation is a single directory that refers to all
the packages, configuration files, and other supporting files needed to
instantiate @var{os}.
@end deffn

This procedure is provided by the @code{(gnu system)} module.  Along
with @code{(gnu services)} (@pxref{Services}), this module contains the
guts of GuixSD.  Make sure to visit it!


@node operating-system Reference
@subsection @code{operating-system} Reference

This section summarizes all the options available in
@code{operating-system} declarations (@pxref{Using the Configuration
System}).

@deftp {Data Type} operating-system
This is the data type representing an operating system configuration.
By that, we mean all the global system configuration, not per-user
configuration (@pxref{Using the Configuration System}).

@table @asis
@item @code{kernel} (default: @var{linux-libre})
The package object of the operating system kernel to use@footnote{Currently
only the Linux-libre kernel is supported.  In the future, it will be
possible to use the GNU@tie{}Hurd.}.

@item @code{kernel-arguments} (default: @code{'()})
List of strings or gexps representing additional arguments to pass on
the command-line of the kernel---e.g., @code{("console=ttyS0")}.

@item @code{bootloader}
The system bootloader configuration object.  @xref{GRUB Configuration}.

@item @code{initrd} (default: @code{base-initrd})
A two-argument monadic procedure that returns an initial RAM disk for
the Linux kernel.  @xref{Initial RAM Disk}.

@item @code{firmware} (default: @var{%base-firmware})
@cindex firmware
List of firmware packages loadable by the operating system kernel.

The default includes firmware needed for Atheros-based WiFi devices
(Linux-libre module @code{ath9k}).  @xref{Hardware Considerations}, for
more info on supported hardware.

@item @code{host-name}
The host name.

@item @code{hosts-file}
@cindex hosts file
A file-like object (@pxref{G-Expressions, file-like objects}) for use as
@file{/etc/hosts} (@pxref{Host Names,,, libc, The GNU C Library
Reference Manual}).  The default is a file with entries for
@code{localhost} and @var{host-name}.

@item @code{mapped-devices} (default: @code{'()})
A list of mapped devices.  @xref{Mapped Devices}.

@item @code{file-systems}
A list of file systems.  @xref{File Systems}.

@item @code{swap-devices} (default: @code{'()})
@cindex swap devices
A list of strings identifying devices to be used for ``swap space''
(@pxref{Memory Concepts,,, libc, The GNU C Library Reference Manual}).
For example, @code{'("/dev/sda3")}.

@item @code{users} (default: @code{%base-user-accounts})
@itemx @code{groups} (default: @var{%base-groups})
List of user accounts and groups.  @xref{User Accounts}.

@item @code{skeletons} (default: @code{(default-skeletons)})
A list target file name/file-like object tuples (@pxref{G-Expressions,
file-like objects}).  These are the skeleton files that will be added to
the home directory of newly-created user accounts.

For instance, a valid value may look like this:

@example
`((".bashrc" ,(plain-file "bashrc" "echo Hello\n"))
  (".guile" ,(plain-file "guile"
                         "(use-modules (ice-9 readline))
                          (activate-readline)")))
@end example

@item @code{issue} (default: @var{%default-issue})
A string denoting the contents of the @file{/etc/issue} file, which is
displayed when users log in on a text console.

@item @code{packages} (default: @var{%base-packages})
The set of packages installed in the global profile, which is accessible
at @file{/run/current-system/profile}.

The default set includes core utilities and it is good practice to
install non-core utilities in user profiles (@pxref{Invoking guix
package}).

@item @code{timezone}
A timezone identifying string---e.g., @code{"Europe/Paris"}.

You can run the @command{tzselect} command to find out which timezone
string corresponds to your region.  Choosing an invalid timezone name
causes @command{guix system} to fail.

@item @code{locale} (default: @code{"en_US.utf8"})
The name of the default locale (@pxref{Locale Names,,, libc, The GNU C
Library Reference Manual}).  @xref{Locales}, for more information.

@item @code{locale-definitions} (default: @var{%default-locale-definitions})
The list of locale definitions to be compiled and that may be used at
run time.  @xref{Locales}.

@item @code{locale-libcs} (default: @code{(list @var{glibc})})
The list of GNU@tie{}libc packages whose locale data and tools are used
to build the locale definitions.  @xref{Locales}, for compatibility
considerations that justify this option.

@item @code{name-service-switch} (default: @var{%default-nss})
Configuration of the libc name service switch (NSS)---a
@code{<name-service-switch>} object.  @xref{Name Service Switch}, for
details.

@item @code{services} (default: @var{%base-services})
A list of service objects denoting system services.  @xref{Services}.

@item @code{pam-services} (default: @code{(base-pam-services)})
@cindex PAM
@cindex pluggable authentication modules
Linux @dfn{pluggable authentication module} (PAM) services.
@c FIXME: Add xref to PAM services section.

@item @code{setuid-programs} (default: @var{%setuid-programs})
List of string-valued G-expressions denoting setuid programs.
@xref{Setuid Programs}.

@item @code{sudoers-file} (default: @var{%sudoers-specification})
@cindex sudoers file
The contents of the @file{/etc/sudoers} file as a file-like object
(@pxref{G-Expressions, @code{local-file} and @code{plain-file}}).

This file specifies which users can use the @command{sudo} command, what
they are allowed to do, and what privileges they may gain.  The default
is that only @code{root} and members of the @code{wheel} group may use
@code{sudo}.

@end table
@end deftp

@node File Systems
@subsection File Systems

The list of file systems to be mounted is specified in the
@code{file-systems} field of the operating system declaration
(@pxref{Using the Configuration System}).  Each file system is declared
using the @code{file-system} form, like this:

@example
(file-system
  (mount-point "/home")
  (device "/dev/sda3")
  (type "ext4"))
@end example

As usual, some of the fields are mandatory---those shown in the example
above---while others can be omitted.  These are described below.

@deftp {Data Type} file-system
Objects of this type represent file systems to be mounted.  They
contain the following members:

@table @asis
@item @code{type}
This is a string specifying the type of the file system---e.g.,
@code{"ext4"}.

@item @code{mount-point}
This designates the place where the file system is to be mounted.

@item @code{device}
This names the ``source'' of the file system.  By default it is the name
of a node under @file{/dev}, but its meaning depends on the @code{title}
field described below.

@item @code{title} (default: @code{'device})
This is a symbol that specifies how the @code{device} field is to be
interpreted.

When it is the symbol @code{device}, then the @code{device} field is
interpreted as a file name; when it is @code{label}, then @code{device}
is interpreted as a partition label name; when it is @code{uuid},
@code{device} is interpreted as a partition unique identifier (UUID).

UUIDs may be converted from their string representation (as shown by the
@command{tune2fs -l} command) using the @code{uuid} form@footnote{The
@code{uuid} form expects 16-byte UUIDs as defined in
@uref{https://tools.ietf.org/html/rfc4122, RFC@tie{}4122}.  This is the
form of UUID used by the ext2 family of file systems and others, but it
is different from ``UUIDs'' found in FAT file systems, for instance.},
like this:

@example
(file-system
  (mount-point "/home")
  (type "ext4")
  (title 'uuid)
  (device (uuid "4dab5feb-d176-45de-b287-9b0a6e4c01cb")))
@end example

The @code{label} and @code{uuid} options offer a way to refer to disk
partitions without having to hard-code their actual device
name@footnote{Note that, while it is tempting to use
@file{/dev/disk/by-uuid} and similar device names to achieve the same
result, this is not recommended: These special device nodes are created
by the udev daemon and may be unavailable at the time the device is
mounted.}.

However, when the source of a file system is a mapped device (@pxref{Mapped
Devices}), its @code{device} field @emph{must} refer to the mapped
device name---e.g., @file{/dev/mapper/root-partition}---and consequently
@code{title} must be set to @code{'device}.  This is required so that
the system knows that mounting the file system depends on having the
corresponding device mapping established.

@item @code{flags} (default: @code{'()})
This is a list of symbols denoting mount flags.  Recognized flags
include @code{read-only}, @code{bind-mount}, @code{no-dev} (disallow
access to special files), @code{no-suid} (ignore setuid and setgid
bits), and @code{no-exec} (disallow program execution.)

@item @code{options} (default: @code{#f})
This is either @code{#f}, or a string denoting mount options.

@item @code{mount?} (default: @code{#t})
This value indicates whether to automatically mount the file system when
the system is brought up.  When set to @code{#f}, the file system gets
an entry in @file{/etc/fstab} (read by the @command{mount} command) but
is not automatically mounted.

@item @code{needed-for-boot?} (default: @code{#f})
This Boolean value indicates whether the file system is needed when
booting.  If that is true, then the file system is mounted when the
initial RAM disk (initrd) is loaded.  This is always the case, for
instance, for the root file system.

@item @code{check?} (default: @code{#t})
This Boolean indicates whether the file system needs to be checked for
errors before being mounted.

@item @code{create-mount-point?} (default: @code{#f})
When true, the mount point is created if it does not exist yet.

@item @code{dependencies} (default: @code{'()})
This is a list of @code{<file-system>} objects representing file systems
that must be mounted before (and unmounted after) this one.

As an example, consider a hierarchy of mounts: @file{/sys/fs/cgroup} is
a dependency of @file{/sys/fs/cgroup/cpu} and
@file{/sys/fs/cgroup/memory}.

@end table
@end deftp

The @code{(gnu system file-systems)} exports the following useful
variables.

@defvr {Scheme Variable} %base-file-systems
These are essential file systems that are required on normal systems,
such as @var{%pseudo-terminal-file-system} and @var{%immutable-store} (see
below.)  Operating system declarations should always contain at least
these.
@end defvr

@defvr {Scheme Variable} %pseudo-terminal-file-system
This is the file system to be mounted as @file{/dev/pts}.  It supports
@dfn{pseudo-terminals} created @i{via} @code{openpty} and similar
functions (@pxref{Pseudo-Terminals,,, libc, The GNU C Library Reference
Manual}).  Pseudo-terminals are used by terminal emulators such as
@command{xterm}.
@end defvr

@defvr {Scheme Variable} %shared-memory-file-system
This file system is mounted as @file{/dev/shm} and is used to support
memory sharing across processes (@pxref{Memory-mapped I/O,
@code{shm_open},, libc, The GNU C Library Reference Manual}).
@end defvr

@defvr {Scheme Variable} %immutable-store
This file system performs a read-only ``bind mount'' of
@file{/gnu/store}, making it read-only for all the users including
@code{root}.  This prevents against accidental modification by software
running as @code{root} or by system administrators.

The daemon itself is still able to write to the store: it remounts it
read-write in its own ``name space.''
@end defvr

@defvr {Scheme Variable} %binary-format-file-system
The @code{binfmt_misc} file system, which allows handling of arbitrary
executable file types to be delegated to user space.  This requires the
@code{binfmt.ko} kernel module to be loaded.
@end defvr

@defvr {Scheme Variable} %fuse-control-file-system
The @code{fusectl} file system, which allows unprivileged users to mount
and unmount user-space FUSE file systems.  This requires the
@code{fuse.ko} kernel module to be loaded.
@end defvr

@node Mapped Devices
@subsection Mapped Devices

@cindex device mapping
@cindex mapped devices
The Linux kernel has a notion of @dfn{device mapping}: a block device,
such as a hard disk partition, can be @dfn{mapped} into another device,
with additional processing over the data that flows through
it@footnote{Note that the GNU@tie{}Hurd makes no difference between the
concept of a ``mapped device'' and that of a file system: both boil down
to @emph{translating} input/output operations made on a file to
operations on its backing store.  Thus, the Hurd implements mapped
devices, like file systems, using the generic @dfn{translator} mechanism
(@pxref{Translators,,, hurd, The GNU Hurd Reference Manual}).}.  A
typical example is encryption device mapping: all writes to the mapped
device are encrypted, and all reads are deciphered, transparently.

Mapped devices are declared using the @code{mapped-device} form:

@example
(mapped-device
  (source "/dev/sda3")
  (target "home")
  (type luks-device-mapping))
@end example

Or, better yet, like this:

@example
(mapped-device
  (source (uuid "cb67fc72-0d54-4c88-9d4b-b225f30b0f44"))
  (target "home")
  (type luks-device-mapping))
@end example

@cindex disk encryption
@cindex LUKS
This example specifies a mapping from @file{/dev/sda3} to
@file{/dev/mapper/home} using LUKS---the
@url{http://code.google.com/p/cryptsetup,Linux Unified Key Setup}, a
standard mechanism for disk encryption.  In the second example, the UUID
(unique identifier) is the LUKS UUID returned for the device by a
command like:

@example
cryptsetup luksUUID /dev/sdx9
@end example

The @file{/dev/mapper/home}
device can then be used as the @code{device} of a @code{file-system}
declaration (@pxref{File Systems}).  The @code{mapped-device} form is
detailed below.

@deftp {Data Type} mapped-device
Objects of this type represent device mappings that will be made when
the system boots up.

@table @code
@item source
This string specifies the name of the block device to be mapped, such as
@code{"/dev/sda3"}.

@item target
This string specifies the name of the mapping to be established.  For
example, specifying @code{"my-partition"} will lead to the creation of
the @code{"/dev/mapper/my-partition"} device.

@item type
This must be a @code{mapped-device-kind} object, which specifies how
@var{source} is mapped to @var{target}.
@end table
@end deftp

@defvr {Scheme Variable} luks-device-mapping
This defines LUKS block device encryption using the @command{cryptsetup}
command from the package with the same name.  It relies on the
@code{dm-crypt} Linux kernel module.
@end defvr

@node User Accounts
@subsection User Accounts

User accounts and groups are entirely managed through the
@code{operating-system} declaration.  They are specified with the
@code{user-account} and @code{user-group} forms:

@example
(user-account
  (name "alice")
  (group "users")
  (supplementary-groups '("wheel"   ;allow use of sudo, etc.
                          "audio"   ;sound card
                          "video"   ;video devices such as webcams
                          "cdrom")) ;the good ol' CD-ROM
  (comment "Bob's sister")
  (home-directory "/home/alice"))
@end example

When booting or upon completion of @command{guix system reconfigure},
the system ensures that only the user accounts and groups specified in
the @code{operating-system} declaration exist, and with the specified
properties.  Thus, account or group creations or modifications made by
directly invoking commands such as @command{useradd} are lost upon
reconfiguration or reboot.  This ensures that the system remains exactly
as declared.

@deftp {Data Type} user-account
Objects of this type represent user accounts.  The following members may
be specified:

@table @asis
@item @code{name}
The name of the user account.

@item @code{group}
This is the name (a string) or identifier (a number) of the user group
this account belongs to.

@item @code{supplementary-groups} (default: @code{'()})
Optionally, this can be defined as a list of group names that this
account belongs to.

@item @code{uid} (default: @code{#f})
This is the user ID for this account (a number), or @code{#f}.  In the
latter case, a number is automatically chosen by the system when the
account is created.

@item @code{comment} (default: @code{""})
A comment about the account, such as the account owner's full name.

@item @code{home-directory}
This is the name of the home directory for the account.

@item @code{shell} (default: Bash)
This is a G-expression denoting the file name of a program to be used as
the shell (@pxref{G-Expressions}).

@item @code{system?} (default: @code{#f})
This Boolean value indicates whether the account is a ``system''
account.  System accounts are sometimes treated specially; for instance,
graphical login managers do not list them.

@anchor{user-account-password}
@item @code{password} (default: @code{#f})
You would normally leave this field to @code{#f}, initialize user
passwords as @code{root} with the @command{passwd} command, and then let
users change it with @command{passwd}.  Passwords set with
@command{passwd} are of course preserved across reboot and
reconfiguration.

If you @emph{do} want to have a preset password for an account, then
this field must contain the encrypted password, as a string.
@xref{crypt,,, libc, The GNU C Library Reference Manual}, for more information
on password encryption, and @ref{Encryption,,, guile, GNU Guile Reference
Manual}, for information on Guile's @code{crypt} procedure.

@end table
@end deftp

User group declarations are even simpler:

@example
(user-group (name "students"))
@end example

@deftp {Data Type} user-group
This type is for, well, user groups.  There are just a few fields:

@table @asis
@item @code{name}
The name of the group.

@item @code{id} (default: @code{#f})
The group identifier (a number).  If @code{#f}, a new number is
automatically allocated when the group is created.

@item @code{system?} (default: @code{#f})
This Boolean value indicates whether the group is a ``system'' group.
System groups have low numerical IDs.

@item @code{password} (default: @code{#f})
What, user groups can have a password?  Well, apparently yes.  Unless
@code{#f}, this field specifies the password of the group.

@end table
@end deftp

For convenience, a variable lists all the basic user groups one may
expect:

@defvr {Scheme Variable} %base-groups
This is the list of basic user groups that users and/or packages expect
to be present on the system.  This includes groups such as ``root'',
``wheel'', and ``users'', as well as groups used to control access to
specific devices such as ``audio'', ``disk'', and ``cdrom''.
@end defvr

@defvr {Scheme Variable} %base-user-accounts
This is the list of basic system accounts that programs may expect to
find on a GNU/Linux system, such as the ``nobody'' account.

Note that the ``root'' account is not included here.  It is a
special-case and is automatically added whether or not it is specified.
@end defvr

@node Locales
@subsection Locales

@cindex locale
A @dfn{locale} defines cultural conventions for a particular language
and region of the world (@pxref{Locales,,, libc, The GNU C Library
Reference Manual}).  Each locale has a name that typically has the form
@code{@var{language}_@var{territory}.@var{codeset}}---e.g.,
@code{fr_LU.utf8} designates the locale for the French language, with
cultural conventions from Luxembourg, and using the UTF-8 encoding.

@cindex locale definition
Usually, you will want to specify the default locale for the machine
using the @code{locale} field of the @code{operating-system} declaration
(@pxref{operating-system Reference, @code{locale}}).

The selected locale is automatically added to the @dfn{locale
definitions} known to the system if needed, with its codeset inferred
from its name---e.g., @code{bo_CN.utf8} will be assumed to use the
@code{UTF-8} codeset.  Additional locale definitions can be specified in
the @code{locale-definitions} slot of @code{operating-system}---this is
useful, for instance, if the codeset could not be inferred from the
locale name.  The default set of locale definitions includes some widely
used locales, but not all the available locales, in order to save space.

For instance, to add the North Frisian locale for Germany, the value of
that field may be:

@example
(cons (locale-definition
        (name "fy_DE.utf8") (source "fy_DE"))
      %default-locale-definitions)
@end example

Likewise, to save space, one might want @code{locale-definitions} to
list only the locales that are actually used, as in:

@example
(list (locale-definition
        (name "ja_JP.eucjp") (source "ja_JP")
        (charset "EUC-JP")))
@end example

@vindex LOCPATH
The compiled locale definitions are available at
@file{/run/current-system/locale/X.Y}, where @code{X.Y} is the libc
version, which is the default location where the GNU@tie{}libc provided
by Guix looks for locale data.  This can be overridden using the
@code{LOCPATH} environment variable (@pxref{locales-and-locpath,
@code{LOCPATH} and locale packages}).

The @code{locale-definition} form is provided by the @code{(gnu system
locale)} module.  Details are given below.

@deftp {Data Type} locale-definition
This is the data type of a locale definition.

@table @asis

@item @code{name}
The name of the locale.  @xref{Locale Names,,, libc, The GNU C Library
Reference Manual}, for more information on locale names.

@item @code{source}
The name of the source for that locale.  This is typically the
@code{@var{language}_@var{territory}} part of the locale name.

@item @code{charset} (default: @code{"UTF-8"})
The ``character set'' or ``code set'' for that locale,
@uref{http://www.iana.org/assignments/character-sets, as defined by
IANA}.

@end table
@end deftp

@defvr {Scheme Variable} %default-locale-definitions
A list of commonly used UTF-8 locales, used as the default
value of the @code{locale-definitions} field of @code{operating-system}
declarations.

@cindex locale name
@cindex normalized codeset in locale names
These locale definitions use the @dfn{normalized codeset} for the part
that follows the dot in the name (@pxref{Using gettextized software,
normalized codeset,, libc, The GNU C Library Reference Manual}).  So for
instance it has @code{uk_UA.utf8} but @emph{not}, say,
@code{uk_UA.UTF-8}.
@end defvr

@subsubsection Locale Data Compatibility Considerations

@cindex incompatibility, of locale data
@code{operating-system} declarations provide a @code{locale-libcs} field
to specify the GNU@tie{}libc packages that are used to compile locale
declarations (@pxref{operating-system Reference}).  ``Why would I
care?'', you may ask.  Well, it turns out that the binary format of
locale data is occasionally incompatible from one libc version to
another.

@c See <https://sourceware.org/ml/libc-alpha/2015-09/msg00575.html>
@c and <https://lists.gnu.org/archive/html/guix-devel/2015-08/msg00737.html>.
For instance, a program linked against libc version 2.21 is unable to
read locale data produced with libc 2.22; worse, that program
@emph{aborts} instead of simply ignoring the incompatible locale
data@footnote{Versions 2.23 and later of GNU@tie{}libc will simply skip
the incompatible locale data, which is already an improvement.}.
Similarly, a program linked against libc 2.22 can read most, but not
all, the locale data from libc 2.21 (specifically, @code{LC_COLLATE}
data is incompatible); thus calls to @code{setlocale} may fail, but
programs will not abort.

The ``problem'' in GuixSD is that users have a lot of freedom: They can
choose whether and when to upgrade software in their profiles, and might
be using a libc version different from the one the system administrator
used to build the system-wide locale data.

Fortunately, unprivileged users can also install their own locale data
and define @var{GUIX_LOCPATH} accordingly (@pxref{locales-and-locpath,
@code{GUIX_LOCPATH} and locale packages}).

Still, it is best if the system-wide locale data at
@file{/run/current-system/locale} is built for all the libc versions
actually in use on the system, so that all the programs can access
it---this is especially crucial on a multi-user system.  To do that, the
administrator can specify several libc packages in the
@code{locale-libcs} field of @code{operating-system}:

@example
(use-package-modules base)

(operating-system
  ;; @dots{}
  (locale-libcs (list glibc-2.21 (canonical-package glibc))))
@end example

This example would lead to a system containing locale definitions for
both libc 2.21 and the current version of libc in
@file{/run/current-system/locale}.


@node Services
@subsection Services

@cindex system services
An important part of preparing an @code{operating-system} declaration is
listing @dfn{system services} and their configuration (@pxref{Using the
Configuration System}).  System services are typically daemons launched
when the system boots, or other actions needed at that time---e.g.,
configuring network access.

Services are managed by the GNU@tie{}Shepherd (@pxref{Introduction,,,
shepherd, The GNU Shepherd Manual}).  On a running system, the
@command{herd} command allows you to list the available services, show
their status, start and stop them, or do other specific operations
(@pxref{Jump Start,,, shepherd, The GNU Shepherd Manual}).  For example:

@example
# herd status
@end example

The above command, run as @code{root}, lists the currently defined
services.  The @command{herd doc} command shows a synopsis of the given
service:

@example
# herd doc nscd
Run libc's name service cache daemon (nscd).
@end example

The @command{start}, @command{stop}, and @command{restart} sub-commands
have the effect you would expect.  For instance, the commands below stop
the nscd service and restart the Xorg display server:

@example
# herd stop nscd
Service nscd has been stopped.
# herd restart xorg-server
Service xorg-server has been stopped.
Service xorg-server has been started.
@end example

The following sections document the available services, starting with
the core services, that may be used in an @code{operating-system}
declaration.

@menu
* Base Services::               Essential system services.
* Scheduled Job Execution::     The mcron service.
* Networking Services::         Network setup, SSH daemon, etc.
* X Window::                    Graphical display.
* Desktop Services::            D-Bus and desktop services.
* Database Services::           SQL databases.
* Mail Services::               IMAP, POP3, SMTP, and all that.
* Web Services::                Web servers.
* Various Services::            Other services.
@end menu

@node Base Services
@subsubsection Base Services

The @code{(gnu services base)} module provides definitions for the basic
services that one expects from the system.  The services exported by
this module are listed below.

@defvr {Scheme Variable} %base-services
This variable contains a list of basic services (@pxref{Service Types
and Services}, for more information on service objects) one would
expect from the system: a login service (mingetty) on each tty, syslogd,
the libc name service cache daemon (nscd), the udev device manager, and
more.

This is the default value of the @code{services} field of
@code{operating-system} declarations.  Usually, when customizing a
system, you will want to append services to @var{%base-services}, like
this:

@example
(cons* (avahi-service) (lsh-service) %base-services)
@end example
@end defvr

@deffn {Scheme Procedure} host-name-service @var{name}
Return a service that sets the host name to @var{name}.
@end deffn

@deffn {Scheme Procedure} mingetty-service @var{config}
Return a service to run mingetty according to @var{config}, a
@code{<mingetty-configuration>} object, which specifies the tty to run, among
other things.
@end deffn

@deftp {Data Type} mingetty-configuration
This is the data type representing the configuration of Mingetty, which
implements console log-in.

@table @asis

@item @code{tty}
The name of the console this Mingetty runs on---e.g., @code{"tty1"}.

@item @code{motd}
A file-like object containing the ``message of the day''.

@item @code{auto-login} (default: @code{#f})
When true, this field must be a string denoting the user name under
which the system automatically logs in.  When it is @code{#f}, a
user name and password must be entered to log in.

@item @code{login-program} (default: @code{#f})
This must be either @code{#f}, in which case the default log-in program
is used (@command{login} from the Shadow tool suite), or a gexp denoting
the name of the log-in program.

@item @code{login-pause?} (default: @code{#f})
When set to @code{#t} in conjunction with @var{auto-login}, the user
will have to press a key before the log-in shell is launched.

@item @code{mingetty} (default: @var{mingetty})
The Mingetty package to use.

@end table
@end deftp

@cindex name service cache daemon
@cindex nscd
@deffn {Scheme Procedure} nscd-service [@var{config}] [#:glibc glibc] @
                [#:name-services '()]
Return a service that runs the libc name service cache daemon (nscd) with the
given @var{config}---an @code{<nscd-configuration>} object.  @xref{Name
Service Switch}, for an example.
@end deffn

@defvr {Scheme Variable} %nscd-default-configuration
This is the default @code{<nscd-configuration>} value (see below) used
by @code{nscd-service}.  It uses the caches defined by
@var{%nscd-default-caches}; see below.
@end defvr

@deftp {Data Type} nscd-configuration
This is the data type representing the name service cache daemon (nscd)
configuration.

@table @asis

@item @code{name-services} (default: @code{'()})
List of packages denoting @dfn{name services} that must be visible to
the nscd---e.g., @code{(list @var{nss-mdns})}.

@item @code{glibc} (default: @var{glibc})
Package object denoting the GNU C Library providing the @command{nscd}
command.

@item @code{log-file} (default: @code{"/var/log/nscd.log"})
Name of the nscd log file.  This is where debugging output goes when
@code{debug-level} is strictly positive.

@item @code{debug-level} (default: @code{0})
Integer denoting the debugging levels.  Higher numbers mean that more
debugging output is logged.

@item @code{caches} (default: @var{%nscd-default-caches})
List of @code{<nscd-cache>} objects denoting things to be cached; see
below.

@end table
@end deftp

@deftp {Data Type} nscd-cache
Data type representing a cache database of nscd and its parameters.

@table @asis

@item @code{database}
This is a symbol representing the name of the database to be cached.
Valid values are @code{passwd}, @code{group}, @code{hosts}, and
@code{services}, which designate the corresponding NSS database
(@pxref{NSS Basics,,, libc, The GNU C Library Reference Manual}).

@item @code{positive-time-to-live}
@itemx @code{negative-time-to-live} (default: @code{20})
A number representing the number of seconds during which a positive or
negative lookup result remains in cache.

@item @code{check-files?} (default: @code{#t})
Whether to check for updates of the files corresponding to
@var{database}.

For instance, when @var{database} is @code{hosts}, setting this flag
instructs nscd to check for updates in @file{/etc/hosts} and to take
them into account.

@item @code{persistent?} (default: @code{#t})
Whether the cache should be stored persistently on disk.

@item @code{shared?} (default: @code{#t})
Whether the cache should be shared among users.

@item @code{max-database-size} (default: 32@tie{}MiB)
Maximum size in bytes of the database cache.

@c XXX: 'suggested-size' and 'auto-propagate?' seem to be expert
@c settings, so leave them out.

@end table
@end deftp

@defvr {Scheme Variable} %nscd-default-caches
List of @code{<nscd-cache>} objects used by default by
@code{nscd-configuration} (see above).

It enables persistent and aggressive caching of service and host name
lookups.  The latter provides better host name lookup performance,
resilience in the face of unreliable name servers, and also better
privacy---often the result of host name lookups is in local cache, so
external name servers do not even need to be queried.
@end defvr


@deffn {Scheme Procedure} syslog-service @
             [#:config-file @var{%default-syslog.conf}]
Return a service that runs @command{syslogd}.  If the configuration file
name @var{config-file} is not specified, use some reasonable default
settings.

@xref{syslogd invocation,,, inetutils, GNU Inetutils}, for more
information on the configuration file syntax.
@end deffn

@anchor{guix-configuration-type}
@deftp {Data Type} guix-configuration
This data type represents the configuration of the Guix build daemon.
@xref{Invoking guix-daemon}, for more information.

@table @asis
@item @code{guix} (default: @var{guix})
The Guix package to use.

@item @code{build-group} (default: @code{"guixbuild"})
Name of the group for build user accounts.

@item @code{build-accounts} (default: @code{10})
Number of build user accounts to create.

@item @code{authorize-key?} (default: @code{#t})
Whether to authorize the substitute key for @code{hydra.gnu.org}
(@pxref{Substitutes}).

@item @code{use-substitutes?} (default: @code{#t})
Whether to use substitutes.

@item @code{substitute-urls} (default: @var{%default-substitute-urls})
The list of URLs where to look for substitutes by default.

@item @code{extra-options} (default: @code{'()})
List of extra command-line options for @command{guix-daemon}.

@item @code{lsof} (default: @var{lsof})
@itemx @code{lsh} (default: @var{lsh})
The lsof and lsh packages to use.

@end table
@end deftp

@deffn {Scheme Procedure} guix-service @var{config}
Return a service that runs the Guix build daemon according to
@var{config}.
@end deffn

@deffn {Scheme Procedure} udev-service [#:udev udev]
Run @var{udev}, which populates the @file{/dev} directory dynamically.
@end deffn

@deffn {Scheme Procedure} urandom-seed-service @var{#f}
Save some entropy in @var{%random-seed-file} to seed @file{/dev/urandom}
when rebooting.
@end deffn

@defvr {Scheme Variable} %random-seed-file
This is the name of the file where some random bytes are saved by
@var{urandom-seed-service} to seed @file{/dev/urandom} when rebooting.
It defaults to @file{/var/lib/random-seed}.
@end defvr

@deffn {Scheme Procedure} console-keymap-service @var{files} ...
@cindex keyboard layout
Return a service to load console keymaps from @var{files} using
@command{loadkeys} command.  Most likely, you want to load some default
keymap, which can be done like this:

@example
(console-keymap-service "dvorak")
@end example

Or, for example, for a Swedish keyboard, you may need to combine
the following keymaps:
@example
(console-keymap-service "se-lat6" "se-fi-lat6")
@end example

Also you can specify a full file name (or file names) of your keymap(s).
See @code{man loadkeys} for details.

@end deffn

@deffn {Scheme Procedure} gpm-service [#:gpm @var{gpm}] @
          [#:options]
Run @var{gpm}, the general-purpose mouse daemon, with the given
command-line @var{options}.  GPM allows users to use the mouse in the console,
notably to select, copy, and paste text.  The default value of @var{options}
uses the @code{ps2} protocol, which works for both USB and PS/2 mice.

This service is not part of @var{%base-services}.
@end deffn

@anchor{guix-publish-service}
@deffn {Scheme Procedure} guix-publish-service [#:guix @var{guix}] @
           [#:port 80] [#:host "localhost"]
Return a service that runs @command{guix publish} listening on @var{host}
and @var{port} (@pxref{Invoking guix publish}).

This assumes that @file{/etc/guix} already contains a signing key pair as
created by @command{guix archive --generate-key} (@pxref{Invoking guix
archive}).  If that is not the case, the service will fail to start.
@end deffn

@anchor{rngd-service}
@deffn {Scheme Procedure} rngd-service [#:rng-tools @var{rng-tools}] @
            [#:device "/dev/hwrng"]
Return a service that runs the @command{rngd} program from @var{rng-tools}
to add @var{device} to the kernel's entropy pool.  The service will fail if
@var{device} does not exist.
@end deffn

@node Scheduled Job Execution
@subsubsection Scheduled Job Execution

@cindex cron
@cindex scheduling jobs
The @code{(gnu services mcron)} module provides an interface to
GNU@tie{}mcron, a daemon to run jobs at scheduled times (@pxref{Top,,,
mcron, GNU@tie{}mcron}).  GNU@tie{}mcron is similar to the traditional
Unix @command{cron} daemon; the main difference is that it is
implemented in Guile Scheme, which provides a lot of flexibility when
specifying the scheduling of jobs and their actions.

The example below defines an operating system that runs the
@command{updatedb} (@pxref{Invoking updatedb,,, find, Finding Files})
and the @command{guix gc} commands (@pxref{Invoking guix gc}) daily, as
well as the @command{mkid} command on behalf of an unprivileged user
(@pxref{mkid invocation,,, idutils, ID Database Utilities}).  It uses
gexps to introduce job definitions that are passed to mcron
(@pxref{G-Expressions}).

@lisp
(use-modules (guix) (gnu) (gnu services mcron))
(use-package-modules base idutils)

(define updatedb-job
  ;; Run 'updatedb' at 3AM every day.  Here we write the
  ;; job's action as a Scheme procedure.
  #~(job '(next-hour '(3))
         (lambda ()
           (execl (string-append #$findutils "/bin/updatedb")
                  "updatedb"
                  "--prunepaths=/tmp /var/tmp /gnu/store"))))

(define garbage-collector-job
  ;; Collect garbage 5 minutes after midnight every day.
  ;; The job's action is a shell command.
  #~(job "5 0 * * *"            ;Vixie cron syntax
         "guix gc -F 1G"))

(define idutils-jobs
  ;; Update the index database as user "charlie" at 12:15PM
  ;; and 19:15PM.  This runs from the user's home directory.
  #~(job '(next-minute-from (next-hour '(12 19)) '(15))
         (string-append #$idutils "/bin/mkid src")
         #:user "charlie"))

(operating-system
  ;; @dots{}
  (services (cons (mcron-service (list garbage-collector-job
                                       updatedb-job
                                       idutils-job))
                  %base-services)))
@end lisp

@xref{Guile Syntax, mcron job specifications,, mcron, GNU@tie{}mcron},
for more information on mcron job specifications.  Below is the
reference of the mcron service.

@deffn {Scheme Procedure} mcron-service @var{jobs} [#:mcron @var{mcron2}]
Return an mcron service running @var{mcron} that schedules @var{jobs}, a
list of gexps denoting mcron job specifications.

This is a shorthand for:
@example
  (service mcron-service-type
           (mcron-configuration (mcron mcron) (jobs jobs)))
@end example
@end deffn

@defvr {Scheme Variable} mcron-service-type
This is the type of the @code{mcron} service, whose value is an
@code{mcron-configuration} object.

This service type can be the target of a service extension that provides
it additional job specifications (@pxref{Service Composition}).  In
other words, it is possible to define services that provide addition
mcron jobs to run.
@end defvr

@deftp {Data Type} mcron-configuration
Data type representing the configuration of mcron.

@table @asis
@item @code{mcron} (default: @var{mcron2})
The mcron package to use.

@item @code{jobs}
This is a list of gexps (@pxref{G-Expressions}), where each gexp
corresponds to an mcron job specification (@pxref{Syntax, mcron job
specifications,, mcron, GNU@tie{}mcron}).
@end table
@end deftp


@node Networking Services
@subsubsection Networking Services

The @code{(gnu services networking)} module provides services to configure
the network interface.

@cindex DHCP, networking service
@deffn {Scheme Procedure} dhcp-client-service [#:dhcp @var{isc-dhcp}]
Return a service that runs @var{dhcp}, a Dynamic Host Configuration
Protocol (DHCP) client, on all the non-loopback network interfaces.
@end deffn

@deffn {Scheme Procedure} static-networking-service @var{interface} @var{ip} @
       [#:gateway #f] [#:name-servers @code{'()}]
Return a service that starts @var{interface} with address @var{ip}.  If
@var{gateway} is true, it must be a string specifying the default network
gateway.
@end deffn

@cindex wicd
@cindex network management
@deffn {Scheme Procedure} wicd-service [#:wicd @var{wicd}]
Return a service that runs @url{https://launchpad.net/wicd,Wicd}, a network
management daemon that aims to simplify wired and wireless networking.

This service adds the @var{wicd} package to the global profile, providing
several commands to interact with the daemon and configure networking:
@command{wicd-client}, a graphical user interface, and the @command{wicd-cli}
and @command{wicd-curses} user interfaces.
@end deffn

@cindex NetworkManager
@deffn {Scheme Procedure} network-manager-service @
       [#:network-manager @var{network-manager}]
Return a service that runs NetworkManager, a network connection manager
attempting to keep network connectivity active when available.
@end deffn

@cindex Connman
@deffn {Scheme Procedure} connman-service @
       [#:connman @var{connman}]
Return a service that runs @url{https://01.org/connman,Connman}, a network
connection manager.

This service adds the @var{connman} package to the global profile, providing
several the @command{connmanctl} command to interact with the daemon and
configure networking."
@end deffn

@deffn {Scheme Procedure} ntp-service [#:ntp @var{ntp}] @
  [#:name-service @var{%ntp-servers}]
Return a service that runs the daemon from @var{ntp}, the
@uref{http://www.ntp.org, Network Time Protocol package}.  The daemon will
keep the system clock synchronized with that of @var{servers}.
@end deffn

@defvr {Scheme Variable} %ntp-servers
List of host names used as the default NTP servers.
@end defvr

@deffn {Scheme Procedure} tor-service [@var{config-file}] [#:tor @var{tor}]
Return a service to run the @uref{https://torproject.org, Tor} anonymous
networking daemon.

The daemon runs as the @code{tor} unprivileged user.  It is passed
@var{config-file}, a file-like object, with an additional @code{User tor} line
and lines for hidden services added via @code{tor-hidden-service}.  Run
@command{man tor} for information about the configuration file.
@end deffn

@cindex hidden service
@deffn {Scheme Procedure} tor-hidden-service @var{name} @var{mapping}
Define a new Tor @dfn{hidden service} called @var{name} and implementing
@var{mapping}.  @var{mapping} is a list of port/host tuples, such as:

@example
 '((22 "127.0.0.1:22")
   (80 "127.0.0.1:8080"))
@end example

In this example, port 22 of the hidden service is mapped to local port 22, and
port 80 is mapped to local port 8080.

This creates a @file{/var/lib/tor/hidden-services/@var{name}} directory, where
the @file{hostname} file contains the @code{.onion} host name for the hidden
service.

See @uref{https://www.torproject.org/docs/tor-hidden-service.html.en, the Tor
project's documentation} for more information.
@end deffn

@deffn {Scheme Procedure} bitlbee-service [#:bitlbee bitlbee] @
         [#:interface "127.0.0.1"] [#:port 6667] @
         [#:extra-settings ""]
Return a service that runs @url{http://bitlbee.org,BitlBee}, a daemon that
acts as a gateway between IRC and chat networks.

The daemon will listen to the interface corresponding to the IP address
specified in @var{interface}, on @var{port}.  @code{127.0.0.1} means that only
local clients can connect, whereas @code{0.0.0.0} means that connections can
come from any networking interface.

In addition, @var{extra-settings} specifies a string to append to the
configuration file.
@end deffn

Furthermore, @code{(gnu services ssh)} provides the following service.

@deffn {Scheme Procedure} lsh-service [#:host-key "/etc/lsh/host-key"] @
       [#:daemonic? #t] [#:interfaces '()] [#:port-number 22] @
       [#:allow-empty-passwords? #f] [#:root-login? #f] @
       [#:syslog-output? #t] [#:x11-forwarding? #t] @
       [#:tcp/ip-forwarding? #t] [#:password-authentication? #t] @
       [#:public-key-authentication? #t] [#:initialize? #t]
Run the @command{lshd} program from @var{lsh} to listen on port @var{port-number}.
@var{host-key} must designate a file containing the host key, and readable
only by root.

When @var{daemonic?} is true, @command{lshd} will detach from the
controlling terminal and log its output to syslogd, unless one sets
@var{syslog-output?} to false.  Obviously, it also makes lsh-service
depend on existence of syslogd service.  When @var{pid-file?} is true,
@command{lshd} writes its PID to the file called @var{pid-file}.

When @var{initialize?} is true, automatically create the seed and host key
upon service activation if they do not exist yet.  This may take long and
require interaction.

When @var{initialize?} is false, it is up to the user to initialize the
randomness generator (@pxref{lsh-make-seed,,, lsh, LSH Manual}), and to create
a key pair with the private key stored in file @var{host-key} (@pxref{lshd
basics,,, lsh, LSH Manual}).

When @var{interfaces} is empty, lshd listens for connections on all the
network interfaces; otherwise, @var{interfaces} must be a list of host names
or addresses.

@var{allow-empty-passwords?} specifies whether to accept log-ins with empty
passwords, and @var{root-login?} specifies whether to accept log-ins as
root.

The other options should be self-descriptive.
@end deffn

@defvr {Scheme Variable} %facebook-host-aliases
This variable contains a string for use in @file{/etc/hosts}
(@pxref{Host Names,,, libc, The GNU C Library Reference Manual}).  Each
line contains a entry that maps a known server name of the Facebook
on-line service---e.g., @code{www.facebook.com}---to the local
host---@code{127.0.0.1} or its IPv6 equivalent, @code{::1}.

This variable is typically used in the @code{hosts-file} field of an
@code{operating-system} declaration (@pxref{operating-system Reference,
@file{/etc/hosts}}):

@example
(use-modules (gnu) (guix))

(operating-system
  (host-name "mymachine")
  ;; ...
  (hosts-file
    ;; Create a /etc/hosts file with aliases for "localhost"
    ;; and "mymachine", as well as for Facebook servers.
    (plain-file "hosts"
                (string-append (local-host-aliases host-name)
                               %facebook-host-aliases))))
@end example

This mechanism can prevent programs running locally, such as Web
browsers, from accessing Facebook.
@end defvr

The @code{(gnu services avahi)} provides the following definition.

@deffn {Scheme Procedure} avahi-service [#:avahi @var{avahi}] @
          [#:host-name #f] [#:publish? #t] [#:ipv4? #t] @
          [#:ipv6? #t] [#:wide-area? #f] @
          [#:domains-to-browse '()] [#:debug? #f]
Return a service that runs @command{avahi-daemon}, a system-wide
mDNS/DNS-SD responder that allows for service discovery and
"zero-configuration" host name lookups (see @uref{http://avahi.org/}), and
extends the name service cache daemon (nscd) so that it can resolve
@code{.local} host names using
@uref{http://0pointer.de/lennart/projects/nss-mdns/, nss-mdns}.  Additionally,
add the @var{avahi} package to the system profile so that commands such as
@command{avahi-browse} are directly usable.

If @var{host-name} is different from @code{#f}, use that as the host name to
publish for this machine; otherwise, use the machine's actual host name.

When @var{publish?} is true, publishing of host names and services is allowed;
in particular, avahi-daemon will publish the machine's host name and IP
address via mDNS on the local network.

When @var{wide-area?} is true, DNS-SD over unicast DNS is enabled.

Boolean values @var{ipv4?} and @var{ipv6?} determine whether to use IPv4/IPv6
sockets.
@end deffn


@node X Window
@subsubsection X Window

Support for the X Window graphical display system---specifically
Xorg---is provided by the @code{(gnu services xorg)} module.  Note that
there is no @code{xorg-service} procedure.  Instead, the X server is
started by the @dfn{login manager}, currently SLiM.

@deffn {Scheme Procedure} slim-service [#:allow-empty-passwords? #f] @
  [#:auto-login? #f] [#:default-user ""] [#:startx] @
  [#:theme @var{%default-slim-theme}] @
  [#:theme-name @var{%default-slim-theme-name}]
Return a service that spawns the SLiM graphical login manager, which in
turn starts the X display server with @var{startx}, a command as returned by
@code{xorg-start-command}.

@cindex X session

SLiM automatically looks for session types described by the @file{.desktop}
files in @file{/run/current-system/profile/share/xsessions} and allows users
to choose a session from the log-in screen using @kbd{F1}.  Packages such as
@var{xfce}, @var{sawfish}, and @var{ratpoison} provide @file{.desktop} files;
adding them to the system-wide set of packages automatically makes them
available at the log-in screen.

In addition, @file{~/.xsession} files are honored.  When available,
@file{~/.xsession} must be an executable that starts a window manager
and/or other X clients.

When @var{allow-empty-passwords?} is true, allow logins with an empty
password.  When @var{auto-login?} is true, log in automatically as
@var{default-user}.

If @var{theme} is @code{#f}, use the default log-in theme; otherwise
@var{theme} must be a gexp denoting the name of a directory containing the
theme to use.  In that case, @var{theme-name} specifies the name of the
theme.
@end deffn

@defvr {Scheme Variable} %default-theme
@defvrx {Scheme Variable} %default-theme-name
The G-Expression denoting the default SLiM theme and its name.
@end defvr

@deffn {Scheme Procedure} xorg-start-command [#:guile] @
  [#:configuration-file #f] [#:xorg-server @var{xorg-server}]
Return a derivation that builds a @var{guile} script to start the X server
from @var{xorg-server}.  @var{configuration-file} is the server configuration
file or a derivation that builds it; when omitted, the result of
@code{xorg-configuration-file} is used.

Usually the X server is started by a login manager.
@end deffn

@deffn {Scheme Procedure} xorg-configuration-file @
  [#:drivers '()] [#:resolutions '()] [#:extra-config '()]
Return a configuration file for the Xorg server containing search paths for
all the common drivers.

@var{drivers} must be either the empty list, in which case Xorg chooses a
graphics driver automatically, or a list of driver names that will be tried in
this order---e.g., @code{(\"modesetting\" \"vesa\")}.

Likewise, when @var{resolutions} is the empty list, Xorg chooses an
appropriate screen resolution; otherwise, it must be a list of
resolutions---e.g., @code{((1024 768) (640 480))}.

Last, @var{extra-config} is a list of strings or objects appended to the
@code{text-file*} argument list.  It is used to pass extra text to be added
verbatim to the configuration file.
@end deffn

@deffn {Scheme Procedure} screen-locker-service @var{package} [@var{name}]
Add @var{package}, a package for a screen-locker or screen-saver whose
command is @var{program}, to the set of setuid programs and add a PAM entry
for it.  For example:

@lisp
(screen-locker-service xlockmore "xlock")
@end lisp

makes the good ol' XlockMore usable.
@end deffn


@node Desktop Services
@subsubsection Desktop Services

The @code{(gnu services desktop)} module provides services that are
usually useful in the context of a ``desktop'' setup---that is, on a
machine running a graphical display server, possibly with graphical user
interfaces, etc.  It also defines services that provide specific desktop
environments like GNOME and XFCE.

To simplify things, the module defines a variable containing the set of
services that users typically expect on a machine with a graphical
environment and networking:

@defvr {Scheme Variable} %desktop-services
This is a list of services that builds upon @var{%base-services} and
adds or adjusts services for a typical ``desktop'' setup.

In particular, it adds a graphical login manager (@pxref{X Window,
@code{slim-service}}), screen lockers,
a network management tool (@pxref{Networking
Services, @code{wicd-service}}), energy and color management services,
the @code{elogind} login and seat manager, the Polkit privilege service,
the GeoClue location service, an NTP client (@pxref{Networking
Services}), the Avahi daemon, and has the name service switch service
configured to be able to use @code{nss-mdns} (@pxref{Name Service
Switch, mDNS}).
@end defvr

The @var{%desktop-services} variable can be used as the @code{services}
field of an @code{operating-system} declaration (@pxref{operating-system
Reference, @code{services}}).

Additionally, the @code{gnome-desktop-service} and
@code{xfce-desktop-service} procedures can add GNOME and/or XFCE to a
system.  To ``add GNOME'' means that system-level services like the
backlight adjustment helpers and the power management utilities are
added to the system, extending @code{polkit} and @code{dbus}
appropriately, allowing GNOME to operate with elevated privileges on a
limited number of special-purpose system interfaces.  Additionally,
adding a service made by @code{gnome-desktop-service} adds the GNOME
metapackage to the system profile.  Likewise, adding the XFCE service
not only adds the @code{xfce} metapackage to the system profile, but it
also gives the Thunar file manager the ability to open a ``root-mode''
file management window, if the user authenticates using the
administrator's password via the standard polkit graphical interface.

@deffn {Scheme Procedure} gnome-desktop-service
Return a service that adds the @code{gnome} package to the system
profile, and extends polkit with the actions from
@code{gnome-settings-daemon}.
@end deffn

@deffn {Scheme Procedure} xfce-desktop-service
Return a service that adds the @code{xfce} package to the system profile,
and extends polkit with the abilit for @code{thunar} to manipulate the
file system as root from within a user session, after the user has
authenticated with the administrator's password.
@end deffn

Because the GNOME and XFCE desktop services pull in so many packages,
the default @code{%desktop-services} variable doesn't include either of
them by default.  To add GNOME or XFCE, just @code{cons} them onto
@code{%desktop-services} in the @code{services} field of your
@code{operating-system}:

@example
(use-modules (gnu))
(use-service-modules desktop)
(operating-system
  ...
  ;; cons* adds items to the list given as its last argument.
  (services (cons* (gnome-desktop-service)
                   (xfce-desktop-service)
                   %desktop-services))
  ...)
@end example

These desktop environments will then be available as options in the
graphical login window.

The actual service definitions included in @code{%desktop-services} and
provided by @code{(gnu services dbus)} and @code{(gnu services desktop)}
are described below.

@deffn {Scheme Procedure} dbus-service [#:dbus @var{dbus}] [#:services '()]
Return a service that runs the ``system bus'', using @var{dbus}, with
support for @var{services}.

@uref{http://dbus.freedesktop.org/, D-Bus} is an inter-process communication
facility.  Its system bus is used to allow system services to communicate
and to be notified of system-wide events.

@var{services} must be a list of packages that provide an
@file{etc/dbus-1/system.d} directory containing additional D-Bus configuration
and policy files.  For example, to allow avahi-daemon to use the system bus,
@var{services} must be equal to @code{(list avahi)}.
@end deffn

@deffn {Scheme Procedure} elogind-service [#:config @var{config}]
Return a service that runs the @code{elogind} login and
seat management daemon.  @uref{https://github.com/andywingo/elogind,
Elogind} exposes a D-Bus interface that can be used to know which users
are logged in, know what kind of sessions they have open, suspend the
system, inhibit system suspend, reboot the system, and other tasks.

Elogind handles most system-level power events for a computer, for
example suspending the system when a lid is closed, or shutting it down
when the power button is pressed.

The @var{config} keyword argument specifies the configuration for
elogind, and should be the result of an @code{(elogind-configuration
(@var{parameter} @var{value})...)} invocation.  Available parameters and
their default values are:

@table @code
@item kill-user-processes?
@code{#f}
@item kill-only-users
@code{()}
@item kill-exclude-users
@code{("root")}
@item inhibit-delay-max-seconds
@code{5}
@item handle-power-key
@code{poweroff}
@item handle-suspend-key
@code{suspend}
@item handle-hibernate-key
@code{hibernate}
@item handle-lid-switch
@code{suspend}
@item handle-lid-switch-docked
@code{ignore}
@item power-key-ignore-inhibited?
@code{#f}
@item suspend-key-ignore-inhibited?
@code{#f}
@item hibernate-key-ignore-inhibited?
@code{#f}
@item lid-switch-ignore-inhibited?
@code{#t}
@item holdoff-timeout-seconds
@code{30}
@item idle-action
@code{ignore}
@item idle-action-seconds
@code{(* 30 60)}
@item runtime-directory-size-percent
@code{10}
@item runtime-directory-size
@code{#f}
@item remove-ipc?
@code{#t}
@item suspend-state
@code{("mem" "standby" "freeze")}
@item suspend-mode
@code{()}
@item hibernate-state
@code{("disk")}
@item hibernate-mode
@code{("platform" "shutdown")}
@item hybrid-sleep-state
@code{("disk")}
@item hybrid-sleep-mode
@code{("suspend" "platform" "shutdown")}
@end table
@end deffn

@deffn {Scheme Procedure} polkit-service @
                         [#:polkit @var{polkit}]
Return a service that runs the
@uref{http://www.freedesktop.org/wiki/Software/polkit/, Polkit privilege
management service}, which allows system administrators to grant access to
privileged operations in a structured way.  By querying the Polkit service, a
privileged system component can know when it should grant additional
capabilities to ordinary users.  For example, an ordinary user can be granted
the capability to suspend the system if the user is logged in locally.
@end deffn

@deffn {Scheme Procedure} upower-service [#:upower @var{upower}] @
                         [#:watts-up-pro? #f] @
                         [#:poll-batteries? #t] @
                         [#:ignore-lid? #f] @
                         [#:use-percentage-for-policy? #f] @
                         [#:percentage-low 10] @
                         [#:percentage-critical 3] @
                         [#:percentage-action 2] @
                         [#:time-low 1200] @
                         [#:time-critical 300] @
                         [#:time-action 120] @
                         [#:critical-power-action 'hybrid-sleep]
Return a service that runs @uref{http://upower.freedesktop.org/,
@command{upowerd}}, a system-wide monitor for power consumption and battery
levels, with the given configuration settings.  It implements the
@code{org.freedesktop.UPower} D-Bus interface, and is notably used by
GNOME.
@end deffn

@deffn {Scheme Procedure} udisks-service [#:udisks @var{udisks}]
Return a service for @uref{http://udisks.freedesktop.org/docs/latest/,
UDisks}, a @dfn{disk management} daemon that provides user interfaces with
notifications and ways to mount/unmount disks.  Programs that talk to UDisks
include the @command{udisksctl} command, part of UDisks, and GNOME Disks.
@end deffn

@deffn {Scheme Procedure} colord-service [#:colord @var{colord}]
Return a service that runs @command{colord}, a system service with a D-Bus
interface to manage the color profiles of input and output devices such as
screens and scanners.  It is notably used by the GNOME Color Manager graphical
tool.  See @uref{http://www.freedesktop.org/software/colord/, the colord web
site} for more information.
@end deffn

@deffn {Scheme Procedure} geoclue-application name [#:allowed? #t] [#:system? #f] [#:users '()]
Return a configuration allowing an application to access GeoClue
location data.  @var{name} is the Desktop ID of the application, without
the @code{.desktop} part.  If @var{allowed?} is true, the application
will have access to location information by default.  The boolean
@var{system?}  value indicates whether an application is a system component
or not.  Finally @var{users} is a list of UIDs of all users for which
this application is allowed location info access.  An empty users list
means that all users are allowed.
@end deffn

@defvr {Scheme Variable} %standard-geoclue-applications
The standard list of well-known GeoClue application configurations,
granting authority to the GNOME date-and-time utility to ask for the
current location in order to set the time zone, and allowing the
IceCat and Epiphany web browsers to request location information.
IceCat and Epiphany both query the user before allowing a web page to
know the user's location.
@end defvr

@deffn {Scheme Procedure} geoclue-service [#:colord @var{colord}] @
                         [#:whitelist '()] @
                         [#:wifi-geolocation-url "https://location.services.mozilla.com/v1/geolocate?key=geoclue"] @
                         [#:submit-data? #f]
                         [#:wifi-submission-url "https://location.services.mozilla.com/v1/submit?key=geoclue"] @
                         [#:submission-nick "geoclue"] @
                         [#:applications %standard-geoclue-applications]
Return a service that runs the GeoClue location service.  This service
provides a D-Bus interface to allow applications to request access to a
user's physical location, and optionally to add information to online
location databases.  See
@uref{https://wiki.freedesktop.org/www/Software/GeoClue/, the GeoClue
web site} for more information.
@end deffn

@deffn {Scheme Procedure} bluetooth-service [#:bluez @var{bluez}]
Return a service that runs the @command{bluetoothd} daemon, which manages
all the Bluetooth devices and provides a number of D-Bus interfaces.

Users need to be in the @code{lp} group to access the D-Bus service.
@end deffn

@node Database Services
@subsubsection Database Services

The @code{(gnu services databases)} module provides the following services.

@deffn {Scheme Procedure} postgresql-service [#:postgresql postgresql] @
       [#:config-file] [#:data-directory ``/var/lib/postgresql/data'']
Return a service that runs @var{postgresql}, the PostgreSQL database
server.

The PostgreSQL daemon loads its runtime configuration from
@var{config-file} and stores the database cluster in
@var{data-directory}.
@end deffn

@deffn {Scheme Procedure} mysql-service [#:config (mysql-configuration)]
Return a service that runs @command{mysqld}, the MySQL or MariaDB
database server.

The optional @var{config} argument specifies the configuration for
@command{mysqld}, which should be a @code{<mysql-configuraiton>} object.
@end deffn

@deftp {Data Type} mysql-configuration
Data type representing the configuration of @var{mysql-service}.

@table @asis
@item @code{mysql} (default: @var{mariadb})
Package object of the MySQL database server, can be either @var{mariadb}
or @var{mysql}.

For MySQL, a temorary root password will be displayed at activation time.
For MariaDB, the root password is empty.
@end table
@end deftp

@node Mail Services
@subsubsection Mail Services

The @code{(gnu services mail)} module provides Guix service definitions
for mail services.  Currently the only implemented service is Dovecot,
an IMAP, POP3, and LMTP server.

Guix does not yet have a mail transfer agent (MTA), although for some
lightweight purposes the @code{esmtp} relay-only MTA may suffice.  Help
is needed to properly integrate a full MTA, such as Postfix.  Patches
welcome!

To add an IMAP/POP3 server to a GuixSD system, add a
@code{dovecot-service} to the operating system definition:

@deffn {Scheme Procedure} dovecot-service [#:config (dovecot-configuration)]
Return a service that runs the Dovecot IMAP/POP3/LMTP mail server.
@end deffn

By default, Dovecot does not need much configuration; the default
configuration object created by @code{(dovecot-configuration)} will
suffice if your mail is delivered to @code{~/Maildir}.  A self-signed
certificate will be generated for TLS-protected connections, though
Dovecot will also listen on cleartext ports by default.  There are a
number of options, though, which mail administrators might need to change,
and as is the case with other services, Guix allows the system
administrator to specify these parameters via a uniform Scheme interface.

For example, to specify that mail is located at @code{maildir~/.mail},
one would instantiate the Dovecot service like this:

@example
(dovecot-service #:config
                 (dovecot-configuration
                  (mail-location "maildir:~/.mail")))
@end example

The available configuration parameters follow.  Each parameter
definition is preceded by its type; for example, @samp{string-list foo}
indicates that the @code{foo} parameter should be specified as a list of
strings.  There is also a way to specify the configuration as a string,
if you have an old @code{dovecot.conf} file that you want to port over
from some other system; see the end for more details.

@c The following documentation was initially generated by
@c (generate-documentation) in (gnu services mail).  Manually maintained
@c documentation is better, so we shouldn't hesitate to edit below as
@c needed.  However if the change you want to make to this documentation
@c can be done in an automated way, it's probably easier to change
@c (generate-documentation) than to make it below and have to deal with
@c the churn as dovecot updates.

Available @code{dovecot-configuration} fields are:

@deftypevr {@code{dovecot-configuration} parameter} package dovecot
The dovecot package.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} comma-separated-string-list listen
A list of IPs or hosts where to listen for connections.  @samp{*}
listens on all IPv4 interfaces, @samp{::} listens on all IPv6
interfaces.  If you want to specify non-default ports or anything more
complex, customize the address and port fields of the
@samp{inet-listener} of the specific services you are interested in.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} protocol-configuration-list protocols
List of protocols we want to serve.  Available protocols include
@samp{imap}, @samp{pop3}, and @samp{lmtp}.

Available @code{protocol-configuration} fields are:

@deftypevr {@code{protocol-configuration} parameter} string name
The name of the protocol.
@end deftypevr

@deftypevr {@code{protocol-configuration} parameter} string auth-socket-path
UNIX socket path to the master authentication server to find users.
This is used by imap (for shared users) and lda.
It defaults to @samp{"/var/run/dovecot/auth-userdb"}.
@end deftypevr

@deftypevr {@code{protocol-configuration} parameter} space-separated-string-list mail-plugins
Space separated list of plugins to load.
@end deftypevr

@deftypevr {@code{protocol-configuration} parameter} non-negative-integer mail-max-userip-connections
Maximum number of IMAP connections allowed for a user from each IP
address.  NOTE: The username is compared case-sensitively.
Defaults to @samp{10}.
@end deftypevr

@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} service-configuration-list services
List of services to enable.  Available services include @samp{imap},
@samp{imap-login}, @samp{pop3}, @samp{pop3-login}, @samp{auth}, and
@samp{lmtp}.

Available @code{service-configuration} fields are:

@deftypevr {@code{service-configuration} parameter} string kind
The service kind.  Valid values include @code{director},
@code{imap-login}, @code{pop3-login}, @code{lmtp}, @code{imap},
@code{pop3}, @code{auth}, @code{auth-worker}, @code{dict},
@code{tcpwrap}, @code{quota-warning}, or anything else.
@end deftypevr

@deftypevr {@code{service-configuration} parameter} listener-configuration-list listeners
Listeners for the service.  A listener is either a
@code{unix-listener-configuration}, a @code{fifo-listener-configuration}, or
an @code{inet-listener-configuration}.
Defaults to @samp{()}.

Available @code{unix-listener-configuration} fields are:

@deftypevr {@code{unix-listener-configuration} parameter} file-name path
The file name on which to listen.
@end deftypevr

@deftypevr {@code{unix-listener-configuration} parameter} string mode
The access mode for the socket.
Defaults to @samp{"0600"}.
@end deftypevr

@deftypevr {@code{unix-listener-configuration} parameter} string user
The user to own the socket.
Defaults to @samp{""}.
@end deftypevr

@deftypevr {@code{unix-listener-configuration} parameter} string group
The group to own the socket.
Defaults to @samp{""}.
@end deftypevr


Available @code{fifo-listener-configuration} fields are:

@deftypevr {@code{fifo-listener-configuration} parameter} file-name path
The file name on which to listen.
@end deftypevr

@deftypevr {@code{fifo-listener-configuration} parameter} string mode
The access mode for the socket.
Defaults to @samp{"0600"}.
@end deftypevr

@deftypevr {@code{fifo-listener-configuration} parameter} string user
The user to own the socket.
Defaults to @samp{""}.
@end deftypevr

@deftypevr {@code{fifo-listener-configuration} parameter} string group
The group to own the socket.
Defaults to @samp{""}.
@end deftypevr


Available @code{inet-listener-configuration} fields are:

@deftypevr {@code{inet-listener-configuration} parameter} string protocol
The protocol to listen for.
@end deftypevr

@deftypevr {@code{inet-listener-configuration} parameter} string address
The address on which to listen, or empty for all addresses.
Defaults to @samp{""}.
@end deftypevr

@deftypevr {@code{inet-listener-configuration} parameter} non-negative-integer port
The port on which to listen.
@end deftypevr

@deftypevr {@code{inet-listener-configuration} parameter} boolean ssl?
Whether to use SSL for this service; @samp{yes}, @samp{no}, or
@samp{required}.
Defaults to @samp{#t}.
@end deftypevr

@end deftypevr

@deftypevr {@code{service-configuration} parameter} non-negative-integer service-count
Number of connections to handle before starting a new process.
Typically the only useful values are 0 (unlimited) or 1.  1 is more
secure, but 0 is faster.  <doc/wiki/LoginProcess.txt>.
Defaults to @samp{1}.
@end deftypevr

@deftypevr {@code{service-configuration} parameter} non-negative-integer process-min-avail
Number of processes to always keep waiting for more connections.
Defaults to @samp{0}.
@end deftypevr

@deftypevr {@code{service-configuration} parameter} non-negative-integer vsz-limit
If you set @samp{service-count 0}, you probably need to grow
this.
Defaults to @samp{256000000}.
@end deftypevr

@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} dict-configuration dict
Dict configuration, as created by the @code{dict-configuration}
constructor.

Available @code{dict-configuration} fields are:

@deftypevr {@code{dict-configuration} parameter} free-form-fields entries
A list of key-value pairs that this dict should hold.
Defaults to @samp{()}.
@end deftypevr

@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} passdb-configuration-list passdbs
A list of passdb configurations, each one created by the
@code{passdb-configuration} constructor.

Available @code{passdb-configuration} fields are:

@deftypevr {@code{passdb-configuration} parameter} string driver
The driver that the passdb should use.  Valid values include
@samp{pam}, @samp{passwd}, @samp{shadow}, @samp{bsdauth}, and
@samp{static}.
Defaults to @samp{"pam"}.
@end deftypevr

@deftypevr {@code{passdb-configuration} parameter} free-form-args args
A list of key-value args to the passdb driver.
Defaults to @samp{()}.
@end deftypevr

@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} userdb-configuration-list userdbs
List of userdb configurations, each one created by the
@code{userdb-configuration} constructor.

Available @code{userdb-configuration} fields are:

@deftypevr {@code{userdb-configuration} parameter} string driver
The driver that the userdb should use.  Valid values include
@samp{passwd} and @samp{static}.
Defaults to @samp{"passwd"}.
@end deftypevr

@deftypevr {@code{userdb-configuration} parameter} free-form-args args
A list of key-value args to the userdb driver.
Defaults to @samp{()}.
@end deftypevr

@deftypevr {@code{userdb-configuration} parameter} free-form-args override-fields
Override fields from passwd.
Defaults to @samp{()}.
@end deftypevr

@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} plugin-configuration plugin-configuration
Plug-in configuration, created by the @code{plugin-configuration}
constructor.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} list-of-namespace-configuration namespaces
List of namespaces.  Each item in the list is created by the
@code{namespace-configuration} constructor.

Available @code{namespace-configuration} fields are:

@deftypevr {@code{namespace-configuration} parameter} string name
Name for this namespace.
@end deftypevr

@deftypevr {@code{namespace-configuration} parameter} string type
Namespace type: @samp{private}, @samp{shared} or @samp{public}.
Defaults to @samp{"private"}.
@end deftypevr

@deftypevr {@code{namespace-configuration} parameter} string separator
Hierarchy separator to use. You should use the same separator for
all namespaces or some clients get confused.  @samp{/} is usually a good
one.  The default however depends on the underlying mail storage
format.
Defaults to @samp{""}.
@end deftypevr

@deftypevr {@code{namespace-configuration} parameter} string prefix
Prefix required to access this namespace.  This needs to be
different for all namespaces. For example @samp{Public/}.
Defaults to @samp{""}.
@end deftypevr

@deftypevr {@code{namespace-configuration} parameter} string location
Physical location of the mailbox. This is in the same format as
mail_location, which is also the default for it.
Defaults to @samp{""}.
@end deftypevr

@deftypevr {@code{namespace-configuration} parameter} boolean inbox?
There can be only one INBOX, and this setting defines which
namespace has it.
Defaults to @samp{#f}.
@end deftypevr

@deftypevr {@code{namespace-configuration} parameter} boolean hidden?
If namespace is hidden, it's not advertised to clients via NAMESPACE
extension. You'll most likely also want to set @samp{list? #f}.  This is mostly
useful when converting from another server with different namespaces
which you want to deprecate but still keep working.  For example you can
create hidden namespaces with prefixes @samp{~/mail/}, @samp{~%u/mail/}
and @samp{mail/}.
Defaults to @samp{#f}.
@end deftypevr

@deftypevr {@code{namespace-configuration} parameter} boolean list?
Show the mailboxes under this namespace with the LIST command. This
makes the namespace visible for clients that do not support the NAMESPACE
extension.  The special @code{children} value lists child mailboxes, but
hides the namespace prefix.
Defaults to @samp{#t}.
@end deftypevr

@deftypevr {@code{namespace-configuration} parameter} boolean subscriptions?
Namespace handles its own subscriptions.  If set to @code{#f}, the
parent namespace handles them.  The empty prefix should always have this
as @code{#t}).
Defaults to @samp{#t}.
@end deftypevr

@deftypevr {@code{namespace-configuration} parameter} mailbox-configuration-list mailboxes
List of predefined mailboxes in this namespace.
Defaults to @samp{()}.

Available @code{mailbox-configuration} fields are:

@deftypevr {@code{mailbox-configuration} parameter} string name
Name for this mailbox.
@end deftypevr

@deftypevr {@code{mailbox-configuration} parameter} string auto
@samp{create} will automatically create this mailbox.
@samp{subscribe} will both create and subscribe to the mailbox.
Defaults to @samp{"no"}.
@end deftypevr

@deftypevr {@code{mailbox-configuration} parameter} space-separated-string-list special-use
List of IMAP @code{SPECIAL-USE} attributes as specified by RFC 6154.
Valid values are @code{\All}, @code{\Archive}, @code{\Drafts},
@code{\Flagged}, @code{\Junk}, @code{\Sent}, and @code{\Trash}.
Defaults to @samp{()}.
@end deftypevr

@end deftypevr

@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} file-name base-dir
Base directory where to store runtime data.
Defaults to @samp{"/var/run/dovecot/"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string login-greeting
Greeting message for clients.
Defaults to @samp{"Dovecot ready."}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-trusted-networks
List of trusted network ranges.  Connections from these IPs are
allowed to override their IP addresses and ports (for logging and for
authentication checks).  @samp{disable-plaintext-auth} is also ignored
for these networks.  Typically you would specify your IMAP proxy servers
here.
Defaults to @samp{()}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-access-sockets
List of login access check sockets (e.g. tcpwrap).
Defaults to @samp{()}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} boolean verbose-proctitle?
Show more verbose process titles (in ps).  Currently shows user name
and IP address.  Useful for seeing who is actually using the IMAP
processes (e.g. shared mailboxes or if the same uid is used for multiple
accounts).
Defaults to @samp{#f}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} boolean shutdown-clients?
Should all processes be killed when Dovecot master process shuts down.
Setting this to @code{#f} means that Dovecot can be upgraded without
forcing existing client connections to close (although that could also
be a problem if the upgrade is e.g. due to a security fix).
Defaults to @samp{#t}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} non-negative-integer doveadm-worker-count
If non-zero, run mail commands via this many connections to doveadm
server, instead of running them directly in the same process.
Defaults to @samp{0}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string doveadm-socket-path
UNIX socket or host:port used for connecting to doveadm server.
Defaults to @samp{"doveadm-server"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list import-environment
List of environment variables that are preserved on Dovecot startup
and passed down to all of its child processes.  You can also give
key=value pairs to always set specific settings.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} boolean disable-plaintext-auth?
Disable LOGIN command and all other plaintext authentications unless
SSL/TLS is used (LOGINDISABLED capability).  Note that if the remote IP
matches the local IP (i.e. you're connecting from the same computer),
the connection is considered secure and plaintext authentication is
allowed.  See also ssl=required setting.
Defaults to @samp{#t}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} non-negative-integer auth-cache-size
Authentication cache size (e.g. @samp{#e10e6}).  0 means it's disabled.
Note that bsdauth, PAM and vpopmail require @samp{cache-key} to be set
for caching to be used.
Defaults to @samp{0}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string auth-cache-ttl
Time to live for cached data.  After TTL expires the cached record
is no longer used, *except* if the main database lookup returns internal
failure.  We also try to handle password changes automatically: If
user's previous authentication was successful, but this one wasn't, the
cache isn't used.  For now this works only with plaintext
authentication.
Defaults to @samp{"1 hour"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string auth-cache-negative-ttl
TTL for negative hits (user not found, password mismatch).
0 disables caching them completely.
Defaults to @samp{"1 hour"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list auth-realms
List of realms for SASL authentication mechanisms that need them.
You can leave it empty if you don't want to support multiple realms.
Many clients simply use the first one listed here, so keep the default
realm first.
Defaults to @samp{()}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string auth-default-realm
Default realm/domain to use if none was specified.  This is used for
both SASL realms and appending @@domain to username in plaintext
logins.
Defaults to @samp{""}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string auth-username-chars
List of allowed characters in username.  If the user-given username
contains a character not listed in here, the login automatically fails.
This is just an extra check to make sure user can't exploit any
potential quote escaping vulnerabilities with SQL/LDAP databases.  If
you want to allow all characters, set this value to empty.
Defaults to @samp{"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ01234567890.-_@@"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string auth-username-translation
Username character translations before it's looked up from
databases.  The value contains series of from -> to characters.  For
example @samp{#@@/@@} means that @samp{#} and @samp{/} characters are
translated to @samp{@@}.
Defaults to @samp{""}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string auth-username-format
Username formatting before it's looked up from databases.  You can
use the standard variables here, e.g. %Lu would lowercase the username,
%n would drop away the domain if it was given, or @samp{%n-AT-%d} would
change the @samp{@@} into @samp{-AT-}.  This translation is done after
@samp{auth-username-translation} changes.
Defaults to @samp{"%Lu"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string auth-master-user-separator
If you want to allow master users to log in by specifying the master
username within the normal username string (i.e. not using SASL
mechanism's support for it), you can specify the separator character
here.  The format is then <username><separator><master username>.
UW-IMAP uses @samp{*} as the separator, so that could be a good
choice.
Defaults to @samp{""}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string auth-anonymous-username
Username to use for users logging in with ANONYMOUS SASL
mechanism.
Defaults to @samp{"anonymous"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} non-negative-integer auth-worker-max-count
Maximum number of dovecot-auth worker processes.  They're used to
execute blocking passdb and userdb queries (e.g. MySQL and PAM).
They're automatically created and destroyed as needed.
Defaults to @samp{30}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string auth-gssapi-hostname
Host name to use in GSSAPI principal names.  The default is to use
the name returned by gethostname().  Use @samp{$ALL} (with quotes) to
allow all keytab entries.
Defaults to @samp{""}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string auth-krb5-keytab
Kerberos keytab to use for the GSSAPI mechanism.  Will use the
system default (usually /etc/krb5.keytab) if not specified.  You may
need to change the auth service to run as root to be able to read this
file.
Defaults to @samp{""}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} boolean auth-use-winbind?
Do NTLM and GSS-SPNEGO authentication using Samba's winbind daemon
and @samp{ntlm-auth} helper.
<doc/wiki/Authentication/Mechanisms/Winbind.txt>.
Defaults to @samp{#f}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} file-name auth-winbind-helper-path
Path for Samba's @samp{ntlm-auth} helper binary.
Defaults to @samp{"/usr/bin/ntlm_auth"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string auth-failure-delay
Time to delay before replying to failed authentications.
Defaults to @samp{"2 secs"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} boolean auth-ssl-require-client-cert?
Require a valid SSL client certificate or the authentication
fails.
Defaults to @samp{#f}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} boolean auth-ssl-username-from-cert?
Take the username from client's SSL certificate, using
@code{X509_NAME_get_text_by_NID()} which returns the subject's DN's
CommonName.
Defaults to @samp{#f}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list auth-mechanisms
List of wanted authentication mechanisms.  Supported mechanisms are:
@samp{plain}, @samp{login}, @samp{digest-md5}, @samp{cram-md5},
@samp{ntlm}, @samp{rpa}, @samp{apop}, @samp{anonymous}, @samp{gssapi},
@samp{otp}, @samp{skey}, and @samp{gss-spnego}.  NOTE: See also
@samp{disable-plaintext-auth} setting.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list director-servers
List of IPs or hostnames to all director servers, including ourself.
Ports can be specified as ip:port.  The default port is the same as what
director service's @samp{inet-listener} is using.
Defaults to @samp{()}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list director-mail-servers
List of IPs or hostnames to all backend mail servers.  Ranges are
allowed too, like 10.0.0.10-10.0.0.30.
Defaults to @samp{()}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string director-user-expire
How long to redirect users to a specific server after it no longer
has any connections.
Defaults to @samp{"15 min"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} non-negative-integer director-doveadm-port
TCP/IP port that accepts doveadm connections (instead of director
connections) If you enable this, you'll also need to add
@samp{inet-listener} for the port.
Defaults to @samp{0}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string director-username-hash
How the username is translated before being hashed.  Useful values
include %Ln if user can log in with or without @@domain, %Ld if mailboxes
are shared within domain.
Defaults to @samp{"%Lu"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string log-path
Log file to use for error messages.  @samp{syslog} logs to syslog,
@samp{/dev/stderr} logs to stderr.
Defaults to @samp{"syslog"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string info-log-path
Log file to use for informational messages.  Defaults to
@samp{log-path}.
Defaults to @samp{""}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string debug-log-path
Log file to use for debug messages.  Defaults to
@samp{info-log-path}.
Defaults to @samp{""}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string syslog-facility
Syslog facility to use if you're logging to syslog.  Usually if you
don't want to use @samp{mail}, you'll use local0..local7.  Also other
standard facilities are supported.
Defaults to @samp{"mail"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} boolean auth-verbose?
Log unsuccessful authentication attempts and the reasons why they
failed.
Defaults to @samp{#f}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} boolean auth-verbose-passwords?
In case of password mismatches, log the attempted password.  Valid
values are no, plain and sha1.  sha1 can be useful for detecting brute
force password attempts vs.  user simply trying the same password over
and over again.  You can also truncate the value to n chars by appending
":n" (e.g. sha1:6).
Defaults to @samp{#f}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} boolean auth-debug?
Even more verbose logging for debugging purposes.  Shows for example
SQL queries.
Defaults to @samp{#f}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} boolean auth-debug-passwords?
In case of password mismatches, log the passwords and used scheme so
the problem can be debugged.  Enabling this also enables
@samp{auth-debug}.
Defaults to @samp{#f}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} boolean mail-debug?
Enable mail process debugging.  This can help you figure out why
Dovecot isn't finding your mails.
Defaults to @samp{#f}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} boolean verbose-ssl?
Show protocol level SSL errors.
Defaults to @samp{#f}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string log-timestamp
Prefix for each line written to log file.  % codes are in
strftime(3) format.
Defaults to @samp{"\"%b %d %H:%M:%S \""}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-log-format-elements
List of elements we want to log.  The elements which have a
non-empty variable value are joined together to form a comma-separated
string.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string login-log-format
Login log format.  %s contains @samp{login-log-format-elements}
string, %$ contains the data we want to log.
Defaults to @samp{"%$: %s"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string mail-log-prefix
Log prefix for mail processes.  See doc/wiki/Variables.txt for list
of possible variables you can use.
Defaults to @samp{"\"%s(%u): \""}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string deliver-log-format
Format to use for logging mail deliveries.  You can use variables:
@table @code
@item %$
Delivery status message (e.g. @samp{saved to INBOX})
@item %m
Message-ID
@item %s
Subject
@item %f
From address
@item %p
Physical size
@item %w
Virtual size.
@end table
Defaults to @samp{"msgid=%m: %$"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string mail-location
Location for users' mailboxes.  The default is empty, which means
that Dovecot tries to find the mailboxes automatically.  This won't work
if the user doesn't yet have any mail, so you should explicitly tell
Dovecot the full location.

If you're using mbox, giving a path to the INBOX
file (e.g. /var/mail/%u) isn't enough.  You'll also need to tell Dovecot
where the other mailboxes are kept.  This is called the "root mail
directory", and it must be the first path given in the
@samp{mail-location} setting.

There are a few special variables you can use, eg.:

@table @samp
@item %u
username
@item %n
user part in user@@domain, same as %u if there's no domain
@item %d
domain part in user@@domain, empty if there's no domain
@item %h
home director
@end table

See doc/wiki/Variables.txt for full list.  Some examples:
@table @samp
@item maildir:~/Maildir
@item mbox:~/mail:INBOX=/var/mail/%u
@item mbox:/var/mail/%d/%1n/%n:INDEX=/var/indexes/%d/%1n/%
@end table
Defaults to @samp{""}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string mail-uid
System user and group used to access mails.  If you use multiple,
userdb can override these by returning uid or gid fields.  You can use
either numbers or names.  <doc/wiki/UserIds.txt>.
Defaults to @samp{""}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string mail-gid

Defaults to @samp{""}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string mail-privileged-group
Group to enable temporarily for privileged operations.  Currently
this is used only with INBOX when either its initial creation or
dotlocking fails.  Typically this is set to "mail" to give access to
/var/mail.
Defaults to @samp{""}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string mail-access-groups
Grant access to these supplementary groups for mail processes.
Typically these are used to set up access to shared mailboxes.  Note
that it may be dangerous to set these if users can create
symlinks (e.g. if "mail" group is set here, ln -s /var/mail ~/mail/var
could allow a user to delete others' mailboxes, or ln -s
/secret/shared/box ~/mail/mybox would allow reading it).
Defaults to @samp{""}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} boolean mail-full-filesystem-access?
Allow full filesystem access to clients.  There's no access checks
other than what the operating system does for the active UID/GID.  It
works with both maildir and mboxes, allowing you to prefix mailboxes
names with e.g. /path/ or ~user/.
Defaults to @samp{#f}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} boolean mmap-disable?
Don't use mmap() at all.  This is required if you store indexes to
shared filesystems (NFS or clustered filesystem).
Defaults to @samp{#f}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} boolean dotlock-use-excl?
Rely on @samp{O_EXCL} to work when creating dotlock files.  NFS
supports @samp{O_EXCL} since version 3, so this should be safe to use
nowadays by default.
Defaults to @samp{#t}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string mail-fsync
When to use fsync() or fdatasync() calls:
@table @code
@item optimized
Whenever necessary to avoid losing important data
@item always
Useful with e.g. NFS when write()s are delayed
@item never
Never use it (best performance, but crashes can lose data).
@end table
Defaults to @samp{"optimized"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} boolean mail-nfs-storage?
Mail storage exists in NFS.  Set this to yes to make Dovecot flush
NFS caches whenever needed.  If you're using only a single mail server
this isn't needed.
Defaults to @samp{#f}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} boolean mail-nfs-index?
Mail index files also exist in NFS.  Setting this to yes requires
@samp{mmap-disable? #t} and @samp{fsync-disable? #f}.
Defaults to @samp{#f}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string lock-method
Locking method for index files.  Alternatives are fcntl, flock and
dotlock.  Dotlocking uses some tricks which may create more disk I/O
than other locking methods.  NFS users: flock doesn't work, remember to
change @samp{mmap-disable}.
Defaults to @samp{"fcntl"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} file-name mail-temp-dir
Directory in which LDA/LMTP temporarily stores incoming mails >128
kB.
Defaults to @samp{"/tmp"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} non-negative-integer first-valid-uid
Valid UID range for users.  This is mostly to make sure that users can't
log in as daemons or other system users.  Note that denying root logins is
hardcoded to dovecot binary and can't be done even if @samp{first-valid-uid}
is set to 0.
Defaults to @samp{500}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} non-negative-integer last-valid-uid

Defaults to @samp{0}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} non-negative-integer first-valid-gid
Valid GID range for users.  Users having non-valid GID as primary group ID
aren't allowed to log in.  If user belongs to supplementary groups with
non-valid GIDs, those groups are not set.
Defaults to @samp{1}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} non-negative-integer last-valid-gid

Defaults to @samp{0}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-max-keyword-length
Maximum allowed length for mail keyword name.  It's only forced when
trying to create new keywords.
Defaults to @samp{50}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} colon-separated-file-name-list valid-chroot-dirs
List of directories under which chrooting is allowed for mail
processes (i.e. /var/mail will allow chrooting to /var/mail/foo/bar
too).  This setting doesn't affect @samp{login-chroot}
@samp{mail-chroot} or auth chroot settings.  If this setting is empty,
"/./" in home dirs are ignored.  WARNING: Never add directories here
which local users can modify, that may lead to root exploit.  Usually
this should be done only if you don't allow shell access for users.
<doc/wiki/Chrooting.txt>.
Defaults to @samp{()}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string mail-chroot
Default chroot directory for mail processes.  This can be overridden
for specific users in user database by giving /./ in user's home
directory (e.g. /home/./user chroots into /home).  Note that usually
there is no real need to do chrooting, Dovecot doesn't allow users to
access files outside their mail directory anyway.  If your home
directories are prefixed with the chroot directory, append "/." to
@samp{mail-chroot}.  <doc/wiki/Chrooting.txt>.
Defaults to @samp{""}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} file-name auth-socket-path
UNIX socket path to master authentication server to find users.
This is used by imap (for shared users) and lda.
Defaults to @samp{"/var/run/dovecot/auth-userdb"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} file-name mail-plugin-dir
Directory where to look up mail plugins.
Defaults to @samp{"/usr/lib/dovecot"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mail-plugins
List of plugins to load for all services.  Plugins specific to IMAP,
LDA, etc. are added to this list in their own .conf files.
Defaults to @samp{()}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-cache-min-mail-count
The minimum number of mails in a mailbox before updates are done to
cache file.  This allows optimizing Dovecot's behavior to do less disk
writes at the cost of more disk reads.
Defaults to @samp{0}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string mailbox-idle-check-interval
When IDLE command is running, mailbox is checked once in a while to
see if there are any new mails or other changes.  This setting defines
the minimum time to wait between those checks.  Dovecot can also use
dnotify, inotify and kqueue to find out immediately when changes
occur.
Defaults to @samp{"30 secs"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} boolean mail-save-crlf?
Save mails with CR+LF instead of plain LF.  This makes sending those
mails take less CPU, especially with sendfile() syscall with Linux and
FreeBSD.  But it also creates a bit more disk I/O which may just make it
slower.  Also note that if other software reads the mboxes/maildirs,
they may handle the extra CRs wrong and cause problems.
Defaults to @samp{#f}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} boolean maildir-stat-dirs?
By default LIST command returns all entries in maildir beginning
with a dot.  Enabling this option makes Dovecot return only entries
which are directories.  This is done by stat()ing each entry, so it
causes more disk I/O.
 (For systems setting struct @samp{dirent->d_type} this check is free
and it's done always regardless of this setting).
Defaults to @samp{#f}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} boolean maildir-copy-with-hardlinks?
When copying a message, do it with hard links whenever possible.
This makes the performance much better, and it's unlikely to have any
side effects.
Defaults to @samp{#t}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} boolean maildir-very-dirty-syncs?
Assume Dovecot is the only MUA accessing Maildir: Scan cur/
directory only when its mtime changes unexpectedly or when we can't find
the mail otherwise.
Defaults to @samp{#f}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mbox-read-locks
Which locking methods to use for locking mbox.  There are four
available:

@table @code
@item dotlock
Create <mailbox>.lock file.  This is the oldest and most NFS-safe
solution.  If you want to use /var/mail/ like directory, the users will
need write access to that directory.
@item dotlock-try
Same as dotlock, but if it fails because of permissions or because there
isn't enough disk space, just skip it.
@item fcntl
Use this if possible.  Works with NFS too if lockd is used.
@item flock
May not exist in all systems.  Doesn't work with NFS.
@item lockf
May not exist in all systems.  Doesn't work with NFS.
@end table

You can use multiple locking methods; if you do the order they're declared
in is important to avoid deadlocks if other MTAs/MUAs are using multiple
locking methods as well.  Some operating systems don't allow using some of
them simultaneously.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mbox-write-locks

@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string mbox-lock-timeout
Maximum time to wait for lock (all of them) before aborting.
Defaults to @samp{"5 mins"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string mbox-dotlock-change-timeout
If dotlock exists but the mailbox isn't modified in any way,
override the lock file after this much time.
Defaults to @samp{"2 mins"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} boolean mbox-dirty-syncs?
When mbox changes unexpectedly we have to fully read it to find out
what changed.  If the mbox is large this can take a long time.  Since
the change is usually just a newly appended mail, it'd be faster to
simply read the new mails.  If this setting is enabled, Dovecot does
this but still safely fallbacks to re-reading the whole mbox file
whenever something in mbox isn't how it's expected to be.  The only real
downside to this setting is that if some other MUA changes message
flags, Dovecot doesn't notice it immediately.  Note that a full sync is
done with SELECT, EXAMINE, EXPUNGE and CHECK commands.
Defaults to @samp{#t}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} boolean mbox-very-dirty-syncs?
Like @samp{mbox-dirty-syncs}, but don't do full syncs even with SELECT,
EXAMINE, EXPUNGE or CHECK commands.  If this is set,
@samp{mbox-dirty-syncs} is ignored.
Defaults to @samp{#f}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} boolean mbox-lazy-writes?
Delay writing mbox headers until doing a full write sync (EXPUNGE
and CHECK commands and when closing the mailbox).  This is especially
useful for POP3 where clients often delete all mails.  The downside is
that our changes aren't immediately visible to other MUAs.
Defaults to @samp{#t}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mbox-min-index-size
If mbox size is smaller than this (e.g. 100k), don't write index
files.  If an index file already exists it's still read, just not
updated.
Defaults to @samp{0}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mdbox-rotate-size
Maximum dbox file size until it's rotated.
Defaults to @samp{2000000}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string mdbox-rotate-interval
Maximum dbox file age until it's rotated.  Typically in days.  Day
begins from midnight, so 1d = today, 2d = yesterday, etc.  0 = check
disabled.
Defaults to @samp{"1d"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} boolean mdbox-preallocate-space?
When creating new mdbox files, immediately preallocate their size to
@samp{mdbox-rotate-size}.  This setting currently works only in Linux
with some filesystems (ext4, xfs).
Defaults to @samp{#f}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-dir
sdbox and mdbox support saving mail attachments to external files,
which also allows single instance storage for them.  Other backends
don't support this for now.

WARNING: This feature hasn't been tested much yet.  Use at your own risk.

Directory root where to store mail attachments.  Disabled, if empty.
Defaults to @samp{""}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-attachment-min-size
Attachments smaller than this aren't saved externally.  It's also
possible to write a plugin to disable saving specific attachments
externally.
Defaults to @samp{128000}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-fs
Filesystem backend to use for saving attachments:
@table @code
@item posix
No SiS done by Dovecot (but this might help FS's own deduplication)
@item sis posix
SiS with immediate byte-by-byte comparison during saving
@item sis-queue posix
SiS with delayed comparison and deduplication.
@end table
Defaults to @samp{"sis posix"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-hash
Hash format to use in attachment filenames.  You can add any text and
variables: @code{%@{md4@}}, @code{%@{md5@}}, @code{%@{sha1@}},
@code{%@{sha256@}}, @code{%@{sha512@}}, @code{%@{size@}}.  Variables can be
truncated, e.g. @code{%@{sha256:80@}} returns only first 80 bits.
Defaults to @samp{"%@{sha1@}"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-process-limit

Defaults to @samp{100}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-client-limit

Defaults to @samp{1000}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-vsz-limit
Default VSZ (virtual memory size) limit for service processes.
This is mainly intended to catch and kill processes that leak memory
before they eat up everything.
Defaults to @samp{256000000}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string default-login-user
Login user is internally used by login processes.  This is the most
untrusted user in Dovecot system.  It shouldn't have access to anything
at all.
Defaults to @samp{"dovenull"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string default-internal-user
Internal user is used by unprivileged processes.  It should be
separate from login user, so that login processes can't disturb other
processes.
Defaults to @samp{"dovecot"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string ssl?
SSL/TLS support: yes, no, required.  <doc/wiki/SSL.txt>.
Defaults to @samp{"required"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string ssl-cert
PEM encoded X.509 SSL/TLS certificate (public key).
Defaults to @samp{"</etc/dovecot/default.pem"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string ssl-key
PEM encoded SSL/TLS private key.  The key is opened before
dropping root privileges, so keep the key file unreadable by anyone but
root.
Defaults to @samp{"</etc/dovecot/private/default.pem"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string ssl-key-password
If key file is password protected, give the password here.
Alternatively give it when starting dovecot with -p parameter.  Since
this file is often world-readable, you may want to place this setting
instead to a different.
Defaults to @samp{""}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string ssl-ca
PEM encoded trusted certificate authority.  Set this only if you
intend to use @samp{ssl-verify-client-cert? #t}.  The file should
contain the CA certificate(s) followed by the matching
CRL(s).  (e.g. @samp{ssl-ca </etc/ssl/certs/ca.pem}).
Defaults to @samp{""}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} boolean ssl-require-crl?
Require that CRL check succeeds for client certificates.
Defaults to @samp{#t}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} boolean ssl-verify-client-cert?
Request client to send a certificate.  If you also want to require
it, set @samp{auth-ssl-require-client-cert? #t} in auth section.
Defaults to @samp{#f}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string ssl-cert-username-field
Which field from certificate to use for username.  commonName and
x500UniqueIdentifier are the usual choices.  You'll also need to set
@samp{auth-ssl-username-from-cert? #t}.
Defaults to @samp{"commonName"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} hours ssl-parameters-regenerate
How often to regenerate the SSL parameters file.  Generation is
quite CPU intensive operation.  The value is in hours, 0 disables
regeneration entirely.
Defaults to @samp{168}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string ssl-protocols
SSL protocols to use.
Defaults to @samp{"!SSLv2"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string ssl-cipher-list
SSL ciphers to use.
Defaults to @samp{"ALL:!LOW:!SSLv2:!EXP:!aNULL"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string ssl-crypto-device
SSL crypto device to use, for valid values run "openssl engine".
Defaults to @samp{""}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string postmaster-address
Address to use when sending rejection mails.
Default is postmaster@@<your domain>.  %d expands to recipient domain.
Defaults to @samp{""}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string hostname
Hostname to use in various parts of sent mails (e.g. in Message-Id)
and in LMTP replies.  Default is the system's real hostname@@domain.
Defaults to @samp{""}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} boolean quota-full-tempfail?
If user is over quota, return with temporary failure instead of
bouncing the mail.
Defaults to @samp{#f}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} file-name sendmail-path
Binary to use for sending mails.
Defaults to @samp{"/usr/sbin/sendmail"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string submission-host
If non-empty, send mails via this SMTP host[:port] instead of
sendmail.
Defaults to @samp{""}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string rejection-subject
Subject: header to use for rejection mails.  You can use the same
variables as for @samp{rejection-reason} below.
Defaults to @samp{"Rejected: %s"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string rejection-reason
Human readable error message for rejection mails.  You can use
variables:

@table @code
@item %n
CRLF
@item %r
reason
@item %s
original subject
@item %t
recipient
@end table
Defaults to @samp{"Your message to <%t> was automatically rejected:%n%r"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string recipient-delimiter
Delimiter character between local-part and detail in email
address.
Defaults to @samp{"+"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string lda-original-recipient-header
Header where the original recipient address (SMTP's RCPT TO:
address) is taken from if not available elsewhere.  With dovecot-lda -a
parameter overrides this.  A commonly used header for this is
X-Original-To.
Defaults to @samp{""}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} boolean lda-mailbox-autocreate?
Should saving a mail to a nonexistent mailbox automatically create
it?.
Defaults to @samp{#f}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} boolean lda-mailbox-autosubscribe?
Should automatically created mailboxes be also automatically
subscribed?.
Defaults to @samp{#f}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} non-negative-integer imap-max-line-length
Maximum IMAP command line length.  Some clients generate very long
command lines with huge mailboxes, so you may need to raise this if you
get "Too long argument" or "IMAP command line too large" errors
often.
Defaults to @samp{64000}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string imap-logout-format
IMAP logout format string:
@table @code
@item %i
total number of bytes read from client
@item %o
total number of bytes sent to client.
@end table
Defaults to @samp{"in=%i out=%o"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string imap-capability
Override the IMAP CAPABILITY response.  If the value begins with '+',
add the given capabilities on top of the defaults (e.g. +XFOO XBAR).
Defaults to @samp{""}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string imap-idle-notify-interval
How long to wait between "OK Still here" notifications when client
is IDLEing.
Defaults to @samp{"2 mins"}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string imap-id-send
ID field names and values to send to clients.  Using * as the value
makes Dovecot use the default value.  The following fields have default
values currently: name, version, os, os-version, support-url,
support-email.
Defaults to @samp{""}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string imap-id-log
ID fields sent by client to log.  * means everything.
Defaults to @samp{""}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list imap-client-workarounds
Workarounds for various client bugs:

@table @code
@item delay-newmail
Send EXISTS/RECENT new mail notifications only when replying to NOOP and
CHECK commands.  Some clients ignore them otherwise, for example OSX
Mail (<v2.1).  Outlook Express breaks more badly though, without this it
may show user "Message no longer in server" errors.  Note that OE6
still breaks even with this workaround if synchronization is set to
"Headers Only".

@item tb-extra-mailbox-sep
Thunderbird gets somehow confused with LAYOUT=fs (mbox and dbox) and
adds extra @samp{/} suffixes to mailbox names.  This option causes Dovecot to
ignore the extra @samp{/} instead of treating it as invalid mailbox name.

@item tb-lsub-flags
Show \Noselect flags for LSUB replies with LAYOUT=fs (e.g. mbox).
This makes Thunderbird realize they aren't selectable and show them
greyed out, instead of only later giving "not selectable" popup error.
@end table
Defaults to @samp{()}.
@end deftypevr

@deftypevr {@code{dovecot-configuration} parameter} string imap-urlauth-host
Host allowed in URLAUTH URLs sent by client.  "*" allows all.
Defaults to @samp{""}.
@end deftypevr


Whew!  Lots of configuration options.  The nice thing about it though is
that GuixSD has a complete interface to Dovecot's configuration
language.  This allows not only a nice way to declare configurations,
but also offers reflective capabilities as well: users can write code to
inspect and transform configurations from within Scheme.

However, it could be that you just want to get a @code{dovecot.conf} up
and running.  In that case, you can pass an
@code{opaque-dovecot-configuration} as the @code{#:config} paramter to
@code{dovecot-service}.  As its name indicates, an opaque configuration
does not have easy reflective capabilities.

Available @code{opaque-dovecot-configuration} fields are:

@deftypevr {@code{opaque-dovecot-configuration} parameter} package dovecot
The dovecot package.
@end deftypevr

@deftypevr {@code{opaque-dovecot-configuration} parameter} string string
The contents of the @code{dovecot.conf}, as a string.
@end deftypevr

For example, if your @code{dovecot.conf} is just the empty string, you
could instantiate a dovecot service like this:

@example
(dovecot-service #:config
                 (opaque-dovecot-configuration
                  (string "")))
@end example

@node Web Services
@subsubsection Web Services

The @code{(gnu services web)} module provides the following service:

@deffn {Scheme Procedure} nginx-service [#:nginx nginx] @
       [#:log-directory ``/var/log/nginx''] @
       [#:run-directory ``/var/run/nginx''] @
       [#:config-file]

Return a service that runs @var{nginx}, the nginx web server.

The nginx daemon loads its runtime configuration from @var{config-file}.
Log files are written to @var{log-directory} and temporary runtime data
files are written to @var{run-directory}.  For proper operation, these
arguments should match what is in @var{config-file} to ensure that the
directories are created when the service is activated.

@end deffn

@node Various Services
@subsubsection Various Services

The @code{(gnu services lirc)} module provides the following service.

@deffn {Scheme Procedure} lirc-service [#:lirc lirc] @
       [#:device #f] [#:driver #f] [#:config-file #f] @
       [#:extra-options '()]
Return a service that runs @url{http://www.lirc.org,LIRC}, a daemon that
decodes infrared signals from remote controls.

Optionally, @var{device}, @var{driver} and @var{config-file}
(configuration file name) may be specified.  See @command{lircd} manual
for details.

Finally, @var{extra-options} is a list of additional command-line options
passed to @command{lircd}.
@end deffn

@subsubsection Dictionary Services
The @code{(gnu services dict)} module provides the following service:

@deffn {Scheme Procedure} dicod-service [#:config (dicod-configuration)]
Return a service that runs the @command{dicod} daemon, an implementation
of DICT server (@pxref{Dicod,,, dico, GNU Dico Manual}).

The optional @var{config} argument specifies the configuration for
@command{dicod}, which should be a @code{<dicod-configuration>} object, by
default it serves the GNU Collaborative International Dictonary of English.

You can add @command{open localhost} to your @file{~/.dico} file to make
@code{localhost} the default server for @command{dico} client
(@pxref{Initialization File,,, dico, GNU Dico Manual}).
@end deffn

@deftp {Data Type} dicod-configuration
Data type representing the configuration of dicod.

@table @asis
@item @code{dico} (default: @var{dico})
Package object of the GNU Dico dictionary server.

@item @code{interfaces} (default: @var{'("localhost")})
This is the list of IP addresses and ports and possibly socket file
names to listen to (@pxref{Server Settings, @code{listen} directive,,
dico, GNU Dico Manual}).

@item @code{databases} (default: @var{(list %dicod-database:gcide)})
List of @code{<dicod-database>} objects denoting dictionaries to be served.
@end table
@end deftp

@deftp {Data Type} dicod-database
Data type representing a dictionary database.

@table @asis
@item @code{name}
Name of the database, will be used in DICT commands.

@item @code{module}
Name of the dicod module used by this database
(@pxref{Modules,,, dico, GNU Dico Manual}).

@item @code{options}
List of strings or gexps representing the arguments for the module handler
(@pxref{Handlers,,, dico, GNU Dico Manual}).
@end table
@end deftp

@defvr {Scheme Variable} %dicod-database:gcide
A @code{<dicod-database>} object serving the GNU Collaborative International
Dictonary of English using the @code{gcide} package.
@end defvr

@node Setuid Programs
@subsection Setuid Programs

@cindex setuid programs
Some programs need to run with ``root'' privileges, even when they are
launched by unprivileged users.  A notorious example is the
@command{passwd} program, which users can run to change their
password, and which needs to access the @file{/etc/passwd} and
@file{/etc/shadow} files---something normally restricted to root, for
obvious security reasons.  To address that, these executables are
@dfn{setuid-root}, meaning that they always run with root privileges
(@pxref{How Change Persona,,, libc, The GNU C Library Reference Manual},
for more info about the setuid mechanism.)

The store itself @emph{cannot} contain setuid programs: that would be a
security issue since any user on the system can write derivations that
populate the store (@pxref{The Store}).  Thus, a different mechanism is
used: instead of changing the setuid bit directly on files that are in
the store, we let the system administrator @emph{declare} which programs
should be setuid root.

The @code{setuid-programs} field of an @code{operating-system}
declaration contains a list of G-expressions denoting the names of
programs to be setuid-root (@pxref{Using the Configuration System}).
For instance, the @command{passwd} program, which is part of the Shadow
package, can be designated by this G-expression (@pxref{G-Expressions}):

@example
#~(string-append #$shadow "/bin/passwd")
@end example

A default set of setuid programs is defined by the
@code{%setuid-programs} variable of the @code{(gnu system)} module.

@defvr {Scheme Variable} %setuid-programs
A list of G-expressions denoting common programs that are setuid-root.

The list includes commands such as @command{passwd}, @command{ping},
@command{su}, and @command{sudo}.
@end defvr

Under the hood, the actual setuid programs are created in the
@file{/run/setuid-programs} directory at system activation time.  The
files in this directory refer to the ``real'' binaries, which are in the
store.

@node X.509 Certificates
@subsection X.509 Certificates

@cindex HTTPS, certificates
@cindex X.509 certificates
@cindex TLS
Web servers available over HTTPS (that is, HTTP over the transport-layer
security mechanism, TLS) send client programs an @dfn{X.509 certificate}
that the client can then use to @emph{authenticate} the server.  To do
that, clients verify that the server's certificate is signed by a
so-called @dfn{certificate authority} (CA).  But to verify the CA's
signature, clients must have first acquired the CA's certificate.

Web browsers such as GNU@tie{}IceCat include their own set of CA
certificates, such that they are able to verify CA signatures
out-of-the-box.

However, most other programs that can talk HTTPS---@command{wget},
@command{git}, @command{w3m}, etc.---need to be told where CA
certificates can be found.

@cindex @code{nss-certs}
In GuixSD, this is done by adding a package that provides certificates
to the @code{packages} field of the @code{operating-system} declaration
(@pxref{operating-system Reference}).  GuixSD includes one such package,
@code{nss-certs}, which is a set of CA certificates provided as part of
Mozilla's Network Security Services.

Note that it is @emph{not} part of @var{%base-packages}, so you need to
explicitly add it.  The @file{/etc/ssl/certs} directory, which is where
most applications and libraries look for certificates by default, points
to the certificates installed globally.

Unprivileged users, including users of Guix on a foreign distro,
can also install their own certificate package in
their profile.  A number of environment variables need to be defined so
that applications and libraries know where to find them.  Namely, the
OpenSSL library honors the @code{SSL_CERT_DIR} and @code{SSL_CERT_FILE}
variables.  Some applications add their own environment variables; for
instance, the Git version control system honors the certificate bundle
pointed to by the @code{GIT_SSL_CAINFO} environment variable.  Thus, you
would typically run something like:

@example
$ guix package -i nss-certs
$ export SSL_CERT_DIR="$HOME/.guix-profile/etc/ssl/certs"
$ export SSL_CERT_FILE="$HOME/.guix-profile/etc/ssl/certs/ca-certificates.crt"
$ export GIT_SSL_CAINFO="$SSL_CERT_FILE"
@end example

@node Name Service Switch
@subsection Name Service Switch

@cindex name service switch
@cindex NSS
The @code{(gnu system nss)} module provides bindings to the
configuration file of the libc @dfn{name service switch} or @dfn{NSS}
(@pxref{NSS Configuration File,,, libc, The GNU C Library Reference
Manual}).  In a nutshell, the NSS is a mechanism that allows libc to be
extended with new ``name'' lookup methods for system databases, which
includes host names, service names, user accounts, and more (@pxref{Name
Service Switch, System Databases and Name Service Switch,, libc, The GNU
C Library Reference Manual}).

The NSS configuration specifies, for each system database, which lookup
method is to be used, and how the various methods are chained
together---for instance, under which circumstances NSS should try the
next method in the list.  The NSS configuration is given in the
@code{name-service-switch} field of @code{operating-system} declarations
(@pxref{operating-system Reference, @code{name-service-switch}}).

@cindex nss-mdns
@cindex .local, host name lookup
As an example, the declaration below configures the NSS to use the
@uref{http://0pointer.de/lennart/projects/nss-mdns/, @code{nss-mdns}
back-end}, which supports host name lookups over multicast DNS (mDNS)
for host names ending in @code{.local}:

@example
(name-service-switch
   (hosts (list %files    ;first, check /etc/hosts

                ;; If the above did not succeed, try
                ;; with 'mdns_minimal'.
                (name-service
                  (name "mdns_minimal")

                  ;; 'mdns_minimal' is authoritative for
                  ;; '.local'.  When it returns "not found",
                  ;; no need to try the next methods.
                  (reaction (lookup-specification
                             (not-found => return))))

                ;; Then fall back to DNS.
                (name-service
                  (name "dns"))

                ;; Finally, try with the "full" 'mdns'.
                (name-service
                  (name "mdns")))))
@end example

Do not worry: the @code{%mdns-host-lookup-nss} variable (see below)
contains this configuration, so you will not have to type it if all you
want is to have @code{.local} host lookup working.

Note that, in this case, in addition to setting the
@code{name-service-switch} of the @code{operating-system} declaration,
you also need to use @code{avahi-service} (@pxref{Networking Services,
@code{avahi-service}}), or @var{%desktop-services}, which includes it
(@pxref{Desktop Services}).  Doing this makes @code{nss-mdns} accessible
to the name service cache daemon (@pxref{Base Services,
@code{nscd-service}}).

For convenience, the following variables provide typical NSS
configurations.

@defvr {Scheme Variable} %default-nss
This is the default name service switch configuration, a
@code{name-service-switch} object.
@end defvr

@defvr {Scheme Variable} %mdns-host-lookup-nss
This is the name service switch configuration with support for host name
lookup over multicast DNS (mDNS) for host names ending in @code{.local}.
@end defvr

The reference for name service switch configuration is given below.  It
is a direct mapping of the configuration file format of the C library , so
please refer to the C library manual for more information (@pxref{NSS
Configuration File,,, libc, The GNU C Library Reference Manual}).
Compared to the configuration file format of libc NSS, it has the advantage
not only of adding this warm parenthetic feel that we like, but also
static checks: you will know about syntax errors and typos as soon as you
run @command{guix system}.

@deftp {Data Type} name-service-switch

This is the data type representation the configuration of libc's name
service switch (NSS).  Each field below represents one of the supported
system databases.

@table @code
@item aliases
@itemx ethers
@itemx group
@itemx gshadow
@itemx hosts
@itemx initgroups
@itemx netgroup
@itemx networks
@itemx password
@itemx public-key
@itemx rpc
@itemx services
@itemx shadow
The system databases handled by the NSS.  Each of these fields must be a
list of @code{<name-service>} objects (see below).
@end table
@end deftp

@deftp {Data Type} name-service

This is the data type representing an actual name service and the
associated lookup action.

@table @code
@item name
A string denoting the name service (@pxref{Services in the NSS
configuration,,, libc, The GNU C Library Reference Manual}).

Note that name services listed here must be visible to nscd.  This is
achieved by passing the @code{#:name-services} argument to
@code{nscd-service} the list of packages providing the needed name
services (@pxref{Base Services, @code{nscd-service}}).

@item reaction
An action specified using the @code{lookup-specification} macro
(@pxref{Actions in the NSS configuration,,, libc, The GNU C Library
Reference Manual}).  For example:

@example
(lookup-specification (unavailable => continue)
                      (success => return))
@end example
@end table
@end deftp

@node Initial RAM Disk
@subsection Initial RAM Disk

@cindex initial RAM disk (initrd)
@cindex initrd (initial RAM disk)
For bootstrapping purposes, the Linux-Libre kernel is passed an
@dfn{initial RAM disk}, or @dfn{initrd}.  An initrd contains a temporary
root file system as well as an initialization script.  The latter is
responsible for mounting the real root file system, and for loading any
kernel modules that may be needed to achieve that.

The @code{initrd} field of an @code{operating-system} declaration allows
you to specify which initrd you would like to use.  The @code{(gnu
system linux-initrd)} module provides two ways to build an initrd: the
high-level @code{base-initrd} procedure, and the low-level
@code{expression->initrd} procedure.

The @code{base-initrd} procedure is intended to cover most common uses.
For example, if you want to add a bunch of kernel modules to be loaded
at boot time, you can define the @code{initrd} field of the operating
system declaration like this:

@example
(initrd (lambda (file-systems . rest)
          ;; Create a standard initrd that has modules "foo.ko"
          ;; and "bar.ko", as well as their dependencies, in
          ;; addition to the modules available by default.
          (apply base-initrd file-systems
                 #:extra-modules '("foo" "bar")
                 rest)))
@end example

The @code{base-initrd} procedure also handles common use cases that
involves using the system as a QEMU guest, or as a ``live'' system with
volatile root file system.

The initial RAM disk produced by @code{base-initrd} honors several
options passed on the Linux kernel command line (that is, arguments
passed @i{via} the @code{linux} command of GRUB, or the
@code{-append} option) of QEMU, notably:

@table @code
@item --load=@var{boot}
Tell the initial RAM disk to load @var{boot}, a file containing a Scheme
program, once it has mounted the root file system.

GuixSD uses this option to yield control to a boot program that runs the
service activation programs and then spawns the GNU@tie{}Shepherd, the
initialization system.

@item --root=@var{root}
Mount @var{root} as the root file system.  @var{root} can be a
device name like @code{/dev/sda1}, a partition label, or a partition
UUID.

@item --system=@var{system}
Have @file{/run/booted-system} and @file{/run/current-system} point to
@var{system}.

@item modprobe.blacklist=@var{modules}@dots{}
@cindex module, black-listing
@cindex black list, of kernel modules
Instruct the initial RAM disk as well as the @command{modprobe} command
(from the kmod package) to refuse to load @var{modules}.  @var{modules}
must be a comma-separated list of module names---e.g.,
@code{usbkbd,9pnet}.

@item --repl
Start a read-eval-print loop (REPL) from the initial RAM disk before it
tries to load kernel modules and to mount the root file system.  Our
marketing team calls it @dfn{boot-to-Guile}.  The Schemer in you will
love it.  @xref{Using Guile Interactively,,, guile, GNU Guile Reference
Manual}, for more information on Guile's REPL.

@end table

Now that you know all the features that initial RAM disks produced by
@code{base-initrd} provide, here is how to use it and customize it
further.

@deffn {Monadic Procedure} base-initrd @var{file-systems} @
       [#:qemu-networking? #f] [#:virtio? #t] [#:volatile-root? #f] @
       [#:extra-modules '()] [#:mapped-devices '()]
Return a monadic derivation that builds a generic initrd.  @var{file-systems} is
a list of file systems to be mounted by the initrd, possibly in addition to
the root file system specified on the kernel command line via @code{--root}.
@var{mapped-devices} is a list of device mappings to realize before
@var{file-systems} are mounted (@pxref{Mapped Devices}).

When @var{qemu-networking?} is true, set up networking with the standard QEMU
parameters.  When @var{virtio?} is true, load additional modules so that the
initrd can be used as a QEMU guest with para-virtualized I/O drivers.

When @var{volatile-root?} is true, the root file system is writable but any changes
to it are lost.

The initrd is automatically populated with all the kernel modules necessary
for @var{file-systems} and for the given options.  However, additional kernel
modules can be listed in @var{extra-modules}.  They will be added to the initrd, and
loaded at boot time in the order in which they appear.
@end deffn

Needless to say, the initrds we produce and use embed a
statically-linked Guile, and the initialization program is a Guile
program.  That gives a lot of flexibility.  The
@code{expression->initrd} procedure builds such an initrd, given the
program to run in that initrd.

@deffn {Monadic Procedure} expression->initrd @var{exp} @
       [#:guile %guile-static-stripped] [#:name "guile-initrd"]
Return a derivation that builds a Linux initrd (a gzipped cpio archive)
containing @var{guile} and that evaluates @var{exp}, a G-expression,
upon booting.  All the derivations referenced by @var{exp} are
automatically copied to the initrd.
@end deffn

@node GRUB Configuration
@subsection GRUB Configuration

@cindex GRUB
@cindex boot loader

The operating system uses GNU@tie{}GRUB as its boot loader
(@pxref{Overview, overview of GRUB,, grub, GNU GRUB Manual}).  It is
configured using a @code{grub-configuration} declaration.  This data type
is exported by the @code{(gnu system grub)} module and described below.

@deftp {Data Type} grub-configuration
The type of a GRUB configuration declaration.

@table @asis

@item @code{device}
This is a string denoting the boot device.  It must be a device name
understood by the @command{grub-install} command, such as
@code{/dev/sda} or @code{(hd0)} (@pxref{Invoking grub-install,,, grub,
GNU GRUB Manual}).

@item @code{menu-entries} (default: @code{()})
A possibly empty list of @code{menu-entry} objects (see below), denoting
entries to appear in the GRUB boot menu, in addition to the current
system entry and the entry pointing to previous system generations.

@item @code{default-entry} (default: @code{0})
The index of the default boot menu entry.  Index 0 is for the entry of the
current system.

@item @code{timeout} (default: @code{5})
The number of seconds to wait for keyboard input before booting.  Set to
0 to boot immediately, and to -1 to wait indefinitely.

@item @code{theme} (default: @var{%default-theme})
The @code{grub-theme} object describing the theme to use.
@end table

@end deftp

Should you want to list additional boot menu entries @i{via} the
@code{menu-entries} field above, you will need to create them with the
@code{menu-entry} form:

@deftp {Data Type} menu-entry
The type of an entry in the GRUB boot menu.

@table @asis

@item @code{label}
The label to show in the menu---e.g., @code{"GNU"}.

@item @code{linux}
The Linux kernel to boot.

@item @code{linux-arguments} (default: @code{()})
The list of extra Linux kernel command-line arguments---e.g.,
@code{("console=ttyS0")}.

@item @code{initrd}
A G-Expression or string denoting the file name of the initial RAM disk
to use (@pxref{G-Expressions}).

@end table
@end deftp

@c FIXME: Write documentation once it's stable.
Themes are created using the @code{grub-theme} form, which is not
documented yet.

@defvr {Scheme Variable} %default-theme
This is the default GRUB theme used by the operating system, with a
fancy background image displaying the GNU and Guix logos.
@end defvr


@node Invoking guix system
@subsection Invoking @code{guix system}

Once you have written an operating system declaration as seen in the
previous section, it can be @dfn{instantiated} using the @command{guix
system} command.  The synopsis is:

@example
guix system @var{options}@dots{} @var{action} @var{file}
@end example

@var{file} must be the name of a file containing an
@code{operating-system} declaration.  @var{action} specifies how the
operating system is instantiated.  Currently the following values are
supported:

@table @code
@item reconfigure
Build the operating system described in @var{file}, activate it, and
switch to it@footnote{This action is usable only on systems already
running GuixSD.}.

This effects all the configuration specified in @var{file}: user
accounts, system services, global package list, setuid programs, etc.
The command starts system services specified in @var{file} that are not
currently running; if a service is currently running, it does not
attempt to upgrade it since this would not be possible without stopping it
first.

It also adds a GRUB menu entry for the new OS configuration, and moves
entries for older configurations to a submenu---unless
@option{--no-grub} is passed.

@quotation Note
@c The paragraph below refers to the problem discussed at
@c <http://lists.gnu.org/archive/html/guix-devel/2014-08/msg00057.html>.
It is highly recommended to run @command{guix pull} once before you run
@command{guix system reconfigure} for the first time (@pxref{Invoking
guix pull}).  Failing to do that you would see an older version of Guix
once @command{reconfigure} has completed.
@end quotation

@item build
Build the derivation of the operating system, which includes all the
configuration files and programs needed to boot and run the system.
This action does not actually install anything.

@item init
Populate the given directory with all the files necessary to run the
operating system specified in @var{file}.  This is useful for first-time
installations of GuixSD.  For instance:

@example
guix system init my-os-config.scm /mnt
@end example

copies to @file{/mnt} all the store items required by the configuration
specified in @file{my-os-config.scm}.  This includes configuration
files, packages, and so on.  It also creates other essential files
needed for the system to operate correctly---e.g., the @file{/etc},
@file{/var}, and @file{/run} directories, and the @file{/bin/sh} file.

This command also installs GRUB on the device specified in
@file{my-os-config}, unless the @option{--no-grub} option was passed.

@item vm
@cindex virtual machine
@cindex VM
@anchor{guix system vm}
Build a virtual machine that contains the operating system declared in
@var{file}, and return a script to run that virtual machine (VM).
Arguments given to the script are passed to QEMU.

The VM shares its store with the host system.

Additional file systems can be shared between the host and the VM using
the @code{--share} and @code{--expose} command-line options: the former
specifies a directory to be shared with write access, while the latter
provides read-only access to the shared directory.

The example below creates a VM in which the user's home directory is
accessible read-only, and where the @file{/exchange} directory is a
read-write mapping of @file{$HOME/tmp} on the host:

@example
guix system vm my-config.scm \
   --expose=$HOME --share=$HOME/tmp=/exchange
@end example

On GNU/Linux, the default is to boot directly to the kernel; this has
the advantage of requiring only a very tiny root disk image since the
store of the host can then be mounted.

The @code{--full-boot} option forces a complete boot sequence, starting
with the bootloader.  This requires more disk space since a root image
containing at least the kernel, initrd, and bootloader data files must
be created.  The @code{--image-size} option can be used to specify the
size of the image.

@item vm-image
@itemx disk-image
Return a virtual machine or disk image of the operating system declared
in @var{file} that stands alone.  Use the @option{--image-size} option
to specify the size of the image.

When using @code{vm-image}, the returned image is in qcow2 format, which
the QEMU emulator can efficiently use. @xref{Running GuixSD in a VM},
for more information on how to run the image in a virtual machine.

When using @code{disk-image}, a raw disk image is produced; it can be
copied as is to a USB stick, for instance.  Assuming @code{/dev/sdc} is
the device corresponding to a USB stick, one can copy the image to it
using the following command:

@example
# dd if=$(guix system disk-image my-os.scm) of=/dev/sdc
@end example

@item container
Return a script to run the operating system declared in @var{file}
within a container.  Containers are a set of lightweight isolation
mechanisms provided by the kernel Linux-libre.  Containers are
substantially less resource-demanding than full virtual machines since
the kernel, shared objects, and other resources can be shared with the
host system; this also means they provide thinner isolation.

Currently, the script must be run as root in order to support more than
a single user and group.  The container shares its store with the host
system.

As with the @code{vm} action (@pxref{guix system vm}), additional file
systems to be shared between the host and container can be specified
using the @option{--share} and @option{--expose} options:

@example
guix system container my-config.scm \
   --expose=$HOME --share=$HOME/tmp=/exchange
@end example

@quotation Note
This option requires Linux-libre 3.19 or newer.
@end quotation

@end table

@var{options} can contain any of the common build options (@pxref{Common
Build Options}).  In addition, @var{options} can contain one of the
following:

@table @option
@item --system=@var{system}
@itemx -s @var{system}
Attempt to build for @var{system} instead of the host system type.
This works as per @command{guix build} (@pxref{Invoking guix build}).

@item --derivation
@itemx -d
Return the derivation file name of the given operating system without
building anything.

@item --image-size=@var{size}
For the @code{vm-image} and @code{disk-image} actions, create an image
of the given @var{size}.  @var{size} may be a number of bytes, or it may
include a unit as a suffix (@pxref{Block size, size specifications,,
coreutils, GNU Coreutils}).

@item --on-error=@var{strategy}
Apply @var{strategy} when an error occurs when reading @var{file}.
@var{strategy} may be one of the following:

@table @code
@item nothing-special
Report the error concisely and exit.  This is the default strategy.

@item backtrace
Likewise, but also display a backtrace.

@item debug
Report the error and enter Guile's debugger.  From there, you can run
commands such as @code{,bt} to get a backtrace, @code{,locals} to
display local variable values, and more generally inspect the state of the
program.  @xref{Debug Commands,,, guile, GNU Guile Reference Manual}, for
a list of available debugging commands.
@end table
@end table

@quotation Note
All the actions above, except @code{build} and @code{init},
can use KVM support in the Linux-libre kernel.  Specifically, if the
machine has hardware virtualization support, the corresponding
KVM kernel module should be loaded, and the @file{/dev/kvm} device node
must exist and be readable and writable by the user and by the
build users of the daemon (@pxref{Build Environment Setup}).
@end quotation

Once you have built, configured, re-configured, and re-re-configured
your GuixSD installation, you may find it useful to list the operating
system generations available on disk---and that you can choose from the
GRUB boot menu:

@table @code

@item list-generations
List a summary of each generation of the operating system available on
disk, in a human-readable way.  This is similar to the
@option{--list-generations} option of @command{guix package}
(@pxref{Invoking guix package}).

Optionally, one can specify a pattern, with the same syntax that is used
in @command{guix package --list-generations}, to restrict the list of
generations displayed.  For instance, the following command displays
generations that are up to 10 days old:

@example
$ guix system list-generations 10d
@end example

@end table

The @command{guix system} command has even more to offer!  The following
sub-commands allow you to visualize how your system services relate to
each other:

@anchor{system-extension-graph}
@table @code

@item extension-graph
Emit in Dot/Graphviz format to standard output the @dfn{service
extension graph} of the operating system defined in @var{file}
(@pxref{Service Composition}, for more information on service
extensions.)

The command:

@example
$ guix system extension-graph @var{file} | dot -Tpdf > services.pdf
@end example

produces a PDF file showing the extension relations among services.

@anchor{system-shepherd-graph}
@item shepherd-graph
Emit in Dot/Graphviz format to standard output the @dfn{dependency
graph} of shepherd services of the operating system defined in
@var{file}.  @xref{Shepherd Services}, for more information and for an
example graph.

@end table

@node Running GuixSD in a VM
@subsection Running GuixSD in a Virtual Machine

One way to run GuixSD in a virtual machine (VM) is to build a GuixSD
virtual machine image using @command{guix system vm-image}
(@pxref{Invoking guix system}).  The returned image is in qcow2 format,
which the @uref{http://qemu.org/, QEMU emulator} can efficiently use.

To run the image in QEMU, copy it out of the store (@pxref{The Store})
and give yourself permission to write to the copy.  When invoking QEMU,
you must choose a system emulator that is suitable for your hardware
platform.  Here is a minimal QEMU invocation that will boot the result
of @command{guix system vm-image} on x86_64 hardware:

@example
$ qemu-system-x86_64 \
   -net user -net nic,model=virtio \
   -enable-kvm -m 256 /tmp/qemu-image
@end example

Here is what each of these options means:

@table @code
@item qemu-system-x86_64
This specifies the hardware platform to emulate.  This should match the
host.

@item -net user
Enable the unprivileged user-mode network stack.  The guest OS can
access the host but not vice versa.  This is the simplest way to get the
guest OS online.  If you do not choose a network stack, the boot will
fail.

@item -net nic,model=virtio
You must create a network interface of a given model.  If you do not
create a NIC, the boot will fail.  Assuming your hardware platform is
x86_64, you can get a list of available NIC models by running
@command{qemu-system-x86_64 -net nic,model=help}.

@item -enable-kvm
If your system has hardware virtualization extensions, enabling the
virtual machine support (KVM) of the Linux kernel will make things run
faster.

@item -m 256
RAM available to the guest OS, in mebibytes.  Defaults to 128@tie{}MiB,
which may be insufficent for some operations.

@item /tmp/qemu-image
The file name of the qcow2 image.
@end table

@node Defining Services
@subsection Defining Services

The previous sections show the available services and how one can combine
them in an @code{operating-system} declaration.  But how do we define
them in the first place?  And what is a service anyway?

@menu
* Service Composition::         The model for composing services.
* Service Types and Services::  Types and services.
* Service Reference::           API reference.
* Shepherd Services::           A particular type of service.
@end menu

@node Service Composition
@subsubsection Service Composition

@cindex services
@cindex daemons
Here we define a @dfn{service} as, broadly, something that extends the
functionality of the operating system.  Often a service is a process---a
@dfn{daemon}---started when the system boots: a secure shell server, a
Web server, the Guix build daemon, etc.  Sometimes a service is a daemon
whose execution can be triggered by another daemon---e.g., an FTP server
started by @command{inetd} or a D-Bus service activated by
@command{dbus-daemon}.  Occasionally, a service does not map to a
daemon.  For instance, the ``account'' service collects user accounts
and makes sure they exist when the system runs; the ``udev'' service
collects device management rules and makes them available to the eudev
daemon; the @file{/etc} service populates the @file{/etc} directory
of the system.

@cindex service extensions
GuixSD services are connected by @dfn{extensions}.  For instance, the
secure shell service @emph{extends} the Shepherd---the GuixSD
initialization system, running as PID@tie{}1---by giving it the command
lines to start and stop the secure shell daemon (@pxref{Networking
Services, @code{lsh-service}}); the UPower service extends the D-Bus
service by passing it its @file{.service} specification, and extends the
udev service by passing it device management rules (@pxref{Desktop
Services, @code{upower-service}}); the Guix daemon service extends the
Shepherd by passing it the command lines to start and stop the daemon,
and extends the account service by passing it a list of required build
user accounts (@pxref{Base Services}).

All in all, services and their ``extends'' relations form a directed
acyclic graph (DAG).  If we represent services as boxes and extensions
as arrows, a typical system might provide something like this:

@image{images/service-graph,,5in,Typical service extension graph.}

@cindex system service
At the bottom, we see the @dfn{system service}, which produces the
directory containing everything to run and boot the system, as returned
by the @command{guix system build} command.  @xref{Service Reference},
to learn about the other service types shown here.
@xref{system-extension-graph, the @command{guix system extension-graph}
command}, for information on how to generate this representation for a
particular operating system definition.

@cindex service types
Technically, developers can define @dfn{service types} to express these
relations.  There can be any number of services of a given type on the
system---for instance, a system running two instances of the GNU secure
shell server (lsh) has two instances of @var{lsh-service-type}, with
different parameters.

The following section describes the programming interface for service
types and services.

@node Service Types and Services
@subsubsection Service Types and Services

A @dfn{service type} is a node in the DAG described above.  Let us start
with a simple example, the service type for the Guix build daemon
(@pxref{Invoking guix-daemon}):

@example
(define guix-service-type
  (service-type
   (name 'guix)
   (extensions
    (list (service-extension shepherd-root-service-type guix-shepherd-service)
          (service-extension account-service-type guix-accounts)
          (service-extension activation-service-type guix-activation)))))
@end example

@noindent
It defines two things:

@enumerate
@item
A name, whose sole purpose is to make inspection and debugging easier.

@item
A list of @dfn{service extensions}, where each extension designates the
target service type and a procedure that, given the parameters of the
service, returns a list of objects to extend the service of that type.

Every service type has at least one service extension.  The only
exception is the @dfn{boot service type}, which is the ultimate service.
@end enumerate

In this example, @var{guix-service-type} extends three services:

@table @var
@item shepherd-root-service-type
The @var{guix-shepherd-service} procedure defines how the Shepherd
service is extended.  Namely, it returns a @code{<shepherd-service>}
object that defines how @command{guix-daemon} is started and stopped
(@pxref{Shepherd Services}).

@item account-service-type
This extension for this service is computed by @var{guix-accounts},
which returns a list of @code{user-group} and @code{user-account}
objects representing the build user accounts (@pxref{Invoking
guix-daemon}).

@item activation-service-type
Here @var{guix-activation} is a procedure that returns a gexp, which is
a code snippet to run at ``activation time''---e.g., when the service is
booted.
@end table

A service of this type is instantiated like this:

@example
(service guix-service-type
         (guix-configuration
           (build-accounts 5)
           (use-substitutes? #f)))
@end example

The second argument to the @code{service} form is a value representing
the parameters of this specific service instance.
@xref{guix-configuration-type, @code{guix-configuration}}, for
information about the @code{guix-configuration} data type.

@var{guix-service-type} is quite simple because it extends other
services but is not extensible itself.

@c @subsubsubsection Extensible Service Types

The service type for an @emph{extensible} service looks like this:

@example
(define udev-service-type
  (service-type (name 'udev)
                (extensions
                 (list (service-extension shepherd-root-service-type
                                          udev-shepherd-service)))

                (compose concatenate)       ;concatenate the list of rules
                (extend (lambda (config rules)
                          (match config
                            (($ <udev-configuration> udev initial-rules)
                             (udev-configuration
                              (udev udev)   ;the udev package to use
                              (rules (append initial-rules rules)))))))))
@end example

This is the service type for the
@uref{https://wiki.gentoo.org/wiki/Project:Eudev, eudev device
management daemon}.  Compared to the previous example, in addition to an
extension of @var{shepherd-root-service-type}, we see two new fields:

@table @code
@item compose
This is the procedure to @dfn{compose} the list of extensions to
services of this type.

Services can extend the udev service by passing it lists of rules; we
compose those extensions simply by concatenating them.

@item extend
This procedure defines how the value of the service is @dfn{extended} with
the composition of the extensions.

Udev extensions are composed into a list of rules, but the udev service
value is itself a @code{<udev-configuration>} record.  So here, we
extend that record by appending the list of rules it contains to the
list of contributed rules.
@end table

There can be only one instance of an extensible service type such as
@var{udev-service-type}.  If there were more, the
@code{service-extension} specifications would be ambiguous.

Still here?  The next section provides a reference of the programming
interface for services.

@node Service Reference
@subsubsection Service Reference

We have seen an overview of service types (@pxref{Service Types and
Services}).  This section provides a reference on how to manipulate
services and service types.  This interface is provided by the
@code{(gnu services)} module.

@deffn {Scheme Procedure} service @var{type} @var{value}
Return a new service of @var{type}, a @code{<service-type>} object (see
below.)  @var{value} can be any object; it represents the parameters of
this particular service instance.
@end deffn

@deffn {Scheme Procedure} service? @var{obj}
Return true if @var{obj} is a service.
@end deffn

@deffn {Scheme Procedure} service-kind @var{service}
Return the type of @var{service}---i.e., a @code{<service-type>} object.
@end deffn

@deffn {Scheme Procedure} service-parameters @var{service}
Return the value associated with @var{service}.  It represents its
parameters.
@end deffn

Here is an example of how a service is created and manipulated:

@example
(define s
  (service nginx-service-type
           (nginx-configuration
            (nginx nginx)
            (log-directory log-directory)
            (run-directory run-directory)
            (file config-file))))

(service? s)
@result{} #t

(eq? (service-kind s) nginx-service-type)
@result{} #t
@end example

The @code{modify-services} form provides a handy way to change the
parameters of some of the services of a list such as
@var{%base-services} (@pxref{Base Services, @code{%base-services}}).  It
evalutes to a list of services.  Of course, you could always use
standard list combinators such as @code{map} and @code{fold} to do that
(@pxref{SRFI-1, List Library,, guile, GNU Guile Reference Manual});
@code{modify-services} simply provides a more concise form for this
common pattern.

@deffn {Scheme Syntax} modify-services @var{services} @
  (@var{type} @var{variable} => @var{body}) @dots{}

Modify the services listed in @var{services} according to the given
clauses.  Each clause has the form:

@example
(@var{type} @var{variable} => @var{body})
@end example

where @var{type} is a service type---e.g.,
@code{guix-service-type}---and @var{variable} is an identifier that is
bound within the @var{body} to the service parameters---e.g., a
@code{guix-configuration} instance---of the original service of that
@var{type}.

The @var{body} should evaluate to the new service parameters, which will
be used to configure the new service.  This new service will replace the
original in the resulting list.  Because a service's service parameters
are created using @code{define-record-type*}, you can write a succint
@var{body} that evaluates to the new service parameters by using the
@code{inherit} feature that @code{define-record-type*} provides.

@xref{Using the Configuration System}, for example usage.

@end deffn

Next comes the programming interface for service types.  This is
something you want to know when writing new service definitions, but not
necessarily when simply looking for ways to customize your
@code{operating-system} declaration.

@deftp {Data Type} service-type
@cindex service type
This is the representation of a @dfn{service type} (@pxref{Service Types
and Services}).

@table @asis
@item @code{name}
This is a symbol, used only to simplify inspection and debugging.

@item @code{extensions}
A non-empty list of @code{<service-extension>} objects (see below).

@item @code{compose} (default: @code{#f})
If this is @code{#f}, then the service type denotes services that cannot
be extended---i.e., services that do not receive ``values'' from other
services.

Otherwise, it must be a one-argument procedure.  The procedure is called
by @code{fold-services} and is passed a list of values collected from
extensions.  It must return a value that is a valid parameter value for
the service instance.

@item @code{extend} (default: @code{#f})
If this is @code{#f}, services of this type cannot be extended.

Otherwise, it must be a two-argument procedure: @code{fold-services}
calls it, passing it the initial value of the service as the first argument
and the result of applying @code{compose} to the extension values as the
second argument.
@end table

@xref{Service Types and Services}, for examples.
@end deftp

@deffn {Scheme Procedure} service-extension @var{target-type} @
                              @var{compute}
Return a new extension for services of type @var{target-type}.
@var{compute} must be a one-argument procedure: @code{fold-services}
calls it, passing it the value associated with the service that provides
the extension; it must return a valid value for the target service.
@end deffn

@deffn {Scheme Procedure} service-extension? @var{obj}
Return true if @var{obj} is a service extension.
@end deffn

At the core of the service abstraction lies the @code{fold-services}
procedure, which is responsible for ``compiling'' a list of services
down to a single directory that contains everything needed to boot and
run the system---the directory shown by the @command{guix system build}
command (@pxref{Invoking guix system}).  In essence, it propagates
service extensions down the service graph, updating each node parameters
on the way, until it reaches the root node.

@deffn {Scheme Procedure} fold-services @var{services} @
                            [#:target-type @var{system-service-type}]
Fold @var{services} by propagating their extensions down to the root of
type @var{target-type}; return the root service adjusted accordingly.
@end deffn

Lastly, the @code{(gnu services)} module also defines several essential
service types, some of which are listed below.

@defvr {Scheme Variable} system-service-type
This is the root of the service graph.  It produces the system directory
as returned by the @command{guix system build} command.
@end defvr

@defvr {Scheme Variable} boot-service-type
The type of the ``boot service'', which produces the @dfn{boot script}.
The boot script is what the initial RAM disk runs when booting.
@end defvr

@defvr {Scheme Variable} etc-service-type
The type of the @file{/etc} service.  This service can be extended by
passing it name/file tuples such as:

@example
(list `("issue" ,(plain-file "issue" "Welcome!\n")))
@end example

In this example, the effect would be to add an @file{/etc/issue} file
pointing to the given file.
@end defvr

@defvr {Scheme Variable} setuid-program-service-type
Type for the ``setuid-program service''.  This service collects lists of
executable file names, passed as gexps, and adds them to the set of
setuid-root programs on the system (@pxref{Setuid Programs}).
@end defvr

@defvr {Scheme Variable} profile-service-type
Type of the service that populates the @dfn{system profile}---i.e., the
programs under @file{/run/current-system/profile}.  Other services can
extend it by passing it lists of packages to add to the system profile.
@end defvr


@node Shepherd Services
@subsubsection Shepherd Services

@cindex PID 1
@cindex init system
The @code{(gnu services shepherd)} module provides a way to define
services managed by the GNU@tie{}Shepherd, which is the GuixSD
initialization system---the first process that is started when the
system boots, also known as PID@tie{}1
(@pxref{Introduction,,, shepherd, The GNU Shepherd Manual}).

Services in the Shepherd can depend on each other.  For instance, the
SSH daemon may need to be started after the syslog daemon has been
started, which in turn can only happen once all the file systems have
been mounted.  The simple operating system defined earlier (@pxref{Using
the Configuration System}) results in a service graph like this:

@image{images/shepherd-graph,,5in,Typical shepherd service graph.}

You can actually generate such a graph for any operating system
definition using the @command{guix system shepherd-graph} command
(@pxref{system-shepherd-graph, @command{guix system shepherd-graph}}).

The @var{%shepherd-root-service} is a service object representing
PID@tie{}1, of type @var{shepherd-root-service-type}; it can be extended
by passing it lists of @code{<shepherd-service>} objects.

@deftp {Data Type} shepherd-service
The data type representing a service managed by the Shepherd.

@table @asis
@item @code{provision}
This is a list of symbols denoting what the service provides.

These are the names that may be passed to @command{herd start},
@command{herd status}, and similar commands (@pxref{Invoking herd,,,
shepherd, The GNU Shepherd Manual}).  @xref{Slots of services, the
@code{provides} slot,, shepherd, The GNU Shepherd Manual}, for details.

@item @code{requirements} (default: @code{'()})
List of symbols denoting the Shepherd services this one depends on.

@item @code{respawn?} (default: @code{#t})
Whether to restart the service when it stops, for instance when the
underlying process dies.

@item @code{start}
@itemx @code{stop} (default: @code{#~(const #f)})
The @code{start} and @code{stop} fields refer to the Shepherd's
facilities to start and stop processes (@pxref{Service De- and
Constructors,,, shepherd, The GNU Shepherd Manual}).  They are given as
G-expressions that get expanded in the Shepherd configuration file
(@pxref{G-Expressions}).

@item @code{documentation}
A documentation string, as shown when running:

@example
herd doc @var{service-name}
@end example

where @var{service-name} is one of the symbols in @var{provision}
(@pxref{Invoking herd,,, shepherd, The GNU Shepherd Manual}).

@item @code{modules} (default: @var{%default-modules})
This is the list of modules that must be in scope when @code{start} and
@code{stop} are evaluated.

@end table
@end deftp

@defvr {Scheme Variable} shepherd-root-service-type
The service type for the Shepherd ``root service''---i.e., PID@tie{}1.

This is the service type that extensions target when they want to create
shepherd services (@pxref{Service Types and Services}, for an example).
Each extension must pass a list of @code{<shepherd-service>}.
@end defvr

@defvr {Scheme Variable} %shepherd-root-service
This service represents PID@tie{}1.
@end defvr


@node Installing Debugging Files
@section Installing Debugging Files

@cindex debugging files
Program binaries, as produced by the GCC compilers for instance, are
typically written in the ELF format, with a section containing
@dfn{debugging information}.  Debugging information is what allows the
debugger, GDB, to map binary code to source code; it is required to
debug a compiled program in good conditions.

The problem with debugging information is that is takes up a fair amount
of disk space.  For example, debugging information for the GNU C Library
weighs in at more than 60 MiB.  Thus, as a user, keeping all the
debugging info of all the installed programs is usually not an option.
Yet, space savings should not come at the cost of an impediment to
debugging---especially in the GNU system, which should make it easier
for users to exert their computing freedom (@pxref{GNU Distribution}).

Thankfully, the GNU Binary Utilities (Binutils) and GDB provide a
mechanism that allows users to get the best of both worlds: debugging
information can be stripped from the binaries and stored in separate
files.  GDB is then able to load debugging information from those files,
when they are available (@pxref{Separate Debug Files,,, gdb, Debugging
with GDB}).

The GNU distribution takes advantage of this by storing debugging
information in the @code{lib/debug} sub-directory of a separate package
output unimaginatively called @code{debug} (@pxref{Packages with
Multiple Outputs}).  Users can choose to install the @code{debug} output
of a package when they need it.  For instance, the following command
installs the debugging information for the GNU C Library and for GNU
Guile:

@example
guix package -i glibc:debug guile:debug
@end example

GDB must then be told to look for debug files in the user's profile, by
setting the @code{debug-file-directory} variable (consider setting it
from the @file{~/.gdbinit} file, @pxref{Startup,,, gdb, Debugging with
GDB}):

@example
(gdb) set debug-file-directory ~/.guix-profile/lib/debug
@end example

From there on, GDB will pick up debugging information from the
@code{.debug} files under @file{~/.guix-profile/lib/debug}.

In addition, you will most likely want GDB to be able to show the source
code being debugged.  To do that, you will have to unpack the source
code of the package of interest (obtained with @code{guix build
--source}, @pxref{Invoking guix build}), and to point GDB to that source
directory using the @code{directory} command (@pxref{Source Path,
@code{directory},, gdb, Debugging with GDB}).

@c XXX: keep me up-to-date
The @code{debug} output mechanism in Guix is implemented by the
@code{gnu-build-system} (@pxref{Build Systems}).  Currently, it is
opt-in---debugging information is available only for the packages
with definitions explicitly declaring a @code{debug} output.  This may be
changed to opt-out in the future if our build farm servers can handle
the load.  To check whether a package has a @code{debug} output, use
@command{guix package --list-available} (@pxref{Invoking guix package}).


@node Security Updates
@section Security Updates

@cindex security updates
@cindex security vulnerabilities
Occasionally, important security vulnerabilities are discovered in software
packages and must be patched.  Guix developers try hard to keep track of
known vulnerabilities and to apply fixes as soon as possible in the
@code{master} branch of Guix (we do not yet provide a ``stable'' branch
containing only security updates.)  The @command{guix lint} tool helps
developers find out about vulnerable versions of software packages in the
distribution:

@smallexample
$ guix lint -c cve
gnu/packages/base.scm:652:2: glibc-2.21: probably vulnerable to CVE-2015-1781, CVE-2015-7547
gnu/packages/gcc.scm:334:2: gcc-4.9.3: probably vulnerable to CVE-2015-5276
gnu/packages/image.scm:312:2: openjpeg-2.1.0: probably vulnerable to CVE-2016-1923, CVE-2016-1924
@dots{}
@end smallexample

@xref{Invoking guix lint}, for more information.

@quotation Note
As of version @value{VERSION}, the feature described below is considered
``beta''.
@end quotation

Guix follows a functional
package management discipline (@pxref{Introduction}), which implies
that, when a package is changed, @emph{every package that depends on it}
must be rebuilt.  This can significantly slow down the deployment of
fixes in core packages such as libc or Bash, since basically the whole
distribution would need to be rebuilt.  Using pre-built binaries helps
(@pxref{Substitutes}), but deployment may still take more time than
desired.

@cindex grafts
To address this, Guix implements @dfn{grafts}, a mechanism that allows
for fast deployment of critical updates without the costs associated
with a whole-distribution rebuild.  The idea is to rebuild only the
package that needs to be patched, and then to ``graft'' it onto packages
explicitly installed by the user and that were previously referring to
the original package.  The cost of grafting is typically very low, and
order of magnitudes lower than a full rebuild of the dependency chain.

@cindex replacements of packages, for grafts
For instance, suppose a security update needs to be applied to Bash.
Guix developers will provide a package definition for the ``fixed''
Bash, say @var{bash-fixed}, in the usual way (@pxref{Defining
Packages}).  Then, the original package definition is augmented with a
@code{replacement} field pointing to the package containing the bug fix:

@example
(define bash
  (package
    (name "bash")
    ;; @dots{}
    (replacement bash-fixed)))
@end example

From there on, any package depending directly or indirectly on Bash---as
reported by @command{guix gc --requisites} (@pxref{Invoking guix
gc})---that is installed is automatically ``rewritten'' to refer to
@var{bash-fixed} instead of @var{bash}.  This grafting process takes
time proportional to the size of the package, usually less than a
minute for an ``average'' package on a recent machine.  Grafting is
recursive: when an indirect dependency requires grafting, then grafting
``propagates'' up to the package that the user is installing.

Currently, the graft and the package it replaces (@var{bash-fixed} and
@var{bash} in the example above) must have the exact same @code{name}
and @code{version} fields.  This restriction mostly comes from the fact
that grafting works by patching files, including binary files, directly.
Other restrictions may apply: for instance, when adding a graft to a
package providing a shared library, the original shared library and its
replacement must have the same @code{SONAME} and be binary-compatible.

The @option{--no-grafts} command-line option allows you to forcefully
avoid grafting (@pxref{Common Build Options, @option{--no-grafts}}).
Thus, the command:

@example
guix build bash --no-grafts
@end example

@noindent
returns the store file name of the original Bash, whereas:

@example
guix build bash
@end example

@noindent
returns the store file name of the ``fixed'', replacement Bash.  This
allows you to distinguish between the two variants of Bash.

To verify which Bash your whole profile refers to, you can run
(@pxref{Invoking guix gc}):

@example
guix gc -R `readlink -f ~/.guix-profile` | grep bash
@end example

@noindent
@dots{} and compare the store file names that you get with those above.
Likewise for a complete GuixSD system generation:

@example
guix gc -R `guix system build my-config.scm` | grep bash
@end example

Lastly, to check which Bash running processes are using, you can use the
@command{lsof} command:

@example
lsof | grep /gnu/store/.*bash
@end example


@node Package Modules
@section Package Modules

From a programming viewpoint, the package definitions of the
GNU distribution are provided by Guile modules in the @code{(gnu packages
@dots{})} name space@footnote{Note that packages under the @code{(gnu
packages @dots{})} module name space are not necessarily ``GNU
packages''.  This module naming scheme follows the usual Guile module
naming convention: @code{gnu} means that these modules are distributed
as part of the GNU system, and @code{packages} identifies modules that
define packages.}  (@pxref{Modules, Guile modules,, guile, GNU Guile
Reference Manual}).  For instance, the @code{(gnu packages emacs)}
module exports a variable named @code{emacs}, which is bound to a
@code{<package>} object (@pxref{Defining Packages}).

The @code{(gnu packages @dots{})} module name space is
automatically scanned for packages by the command-line tools.  For
instance, when running @code{guix package -i emacs}, all the @code{(gnu
packages @dots{})} modules are scanned until one that exports a package
object whose name is @code{emacs} is found.  This package search
facility is implemented in the @code{(gnu packages)} module.

@cindex customization, of packages
@cindex package module search path
Users can store package definitions in modules with different
names---e.g., @code{(my-packages emacs)}@footnote{Note that the file
name and module name must match.  For instance, the @code{(my-packages
emacs)} module must be stored in a @file{my-packages/emacs.scm} file
relative to the load path specified with @option{--load-path} or
@code{GUIX_PACKAGE_PATH}.  @xref{Modules and the File System,,,
guile, GNU Guile Reference Manual}, for details.}.  These package definitions
will not be visible by default.  Users can invoke commands such as
@command{guix package} and @command{guix build} with the
@code{-e} option so that they know where to find the package.  Better
yet, they can use the
@code{-L} option of these commands to make those modules visible
(@pxref{Invoking guix build, @code{--load-path}}), or define the
@code{GUIX_PACKAGE_PATH} environment variable.  This environment
variable makes it easy to extend or customize the distribution and is
honored by all the user interfaces.

@defvr {Environment Variable} GUIX_PACKAGE_PATH
This is a colon-separated list of directories to search for additional
package modules.  Directories listed in this variable take precedence
over the own modules of the distribution.
@end defvr

The distribution is fully @dfn{bootstrapped} and @dfn{self-contained}:
each package is built based solely on other packages in the
distribution.  The root of this dependency graph is a small set of
@dfn{bootstrap binaries}, provided by the @code{(gnu packages
bootstrap)} module.  For more information on bootstrapping,
@pxref{Bootstrapping}.

@node Packaging Guidelines
@section Packaging Guidelines

The GNU distribution is nascent and may well lack some of your favorite
packages.  This section describes how you can help make the distribution
grow.  @xref{Contributing}, for additional information on how you can
help.

Free software packages are usually distributed in the form of
@dfn{source code tarballs}---typically @file{tar.gz} files that contain
all the source files.  Adding a package to the distribution means
essentially two things: adding a @dfn{recipe} that describes how to
build the package, including a list of other packages required to build
it, and adding @dfn{package metadata} along with that recipe, such as a
description and licensing information.

In Guix all this information is embodied in @dfn{package definitions}.
Package definitions provide a high-level view of the package.  They are
written using the syntax of the Scheme programming language; in fact,
for each package we define a variable bound to the package definition,
and export that variable from a module (@pxref{Package Modules}).
However, in-depth Scheme knowledge is @emph{not} a prerequisite for
creating packages.  For more information on package definitions,
@pxref{Defining Packages}.

Once a package definition is in place, stored in a file in the Guix
source tree, it can be tested using the @command{guix build} command
(@pxref{Invoking guix build}).  For example, assuming the new package is
called @code{gnew}, you may run this command from the Guix build tree
(@pxref{Running Guix Before It Is Installed}):

@example
./pre-inst-env guix build gnew --keep-failed
@end example

Using @code{--keep-failed} makes it easier to debug build failures since
it provides access to the failed build tree.  Another useful
command-line option when debugging is @code{--log-file}, to access the
build log.

If the package is unknown to the @command{guix} command, it may be that
the source file contains a syntax error, or lacks a @code{define-public}
clause to export the package variable.  To figure it out, you may load
the module from Guile to get more information about the actual error:

@example
./pre-inst-env guile -c '(use-modules (gnu packages gnew))'
@end example

Once your package builds correctly, please send us a patch
(@pxref{Contributing}).  Well, if you need help, we will be happy to
help you too.  Once the patch is committed in the Guix repository, the
new package automatically gets built on the supported platforms by
@url{http://hydra.gnu.org/jobset/gnu/master, our continuous integration
system}.

@cindex substituter
Users can obtain the new package definition simply by running
@command{guix pull} (@pxref{Invoking guix pull}).  When
@code{hydra.gnu.org} is done building the package, installing the
package automatically downloads binaries from there
(@pxref{Substitutes}).  The only place where human intervention is
needed is to review and apply the patch.


@menu
* Software Freedom::            What may go into the distribution.
* Package Naming::              What's in a name?
* Version Numbers::             When the name is not enough.
* Synopses and Descriptions::   Helping users find the right package.
* Python Modules::              Taming the snake.
* Perl Modules::                Little pearls.
* Java Packages::               Coffee break.
* Fonts::                       Fond of fonts.
@end menu

@node Software Freedom
@subsection Software Freedom

@c Adapted from http://www.gnu.org/philosophy/philosophy.html.

The GNU operating system has been developed so that users can have
freedom in their computing.  GNU is @dfn{free software}, meaning that
users have the @url{http://www.gnu.org/philosophy/free-sw.html,four
essential freedoms}: to run the program, to study and change the program
in source code form, to redistribute exact copies, and to distribute
modified versions.  Packages found in the GNU distribution provide only
software that conveys these four freedoms.

In addition, the GNU distribution follow the
@url{http://www.gnu.org/distros/free-system-distribution-guidelines.html,free
software distribution guidelines}.  Among other things, these guidelines
reject non-free firmware, recommendations of non-free software, and
discuss ways to deal with trademarks and patents.

Some otherwise free upstream package sources contain a small and optional
subset that violates the above guidelines, for instance because this subset
is itself non-free code.  When that happens, the offending items are removed
with appropriate patches or code snippets in the @code{origin} form of the
package (@pxref{Defining Packages}).  This way, @code{guix
build --source} returns the ``freed'' source rather than the unmodified
upstream source.


@node Package Naming
@subsection Package Naming

A package has actually two names associated with it:
First, there is the name of the @emph{Scheme variable}, the one following
@code{define-public}.  By this name, the package can be made known in the
Scheme code, for instance as input to another package.  Second, there is
the string in the @code{name} field of a package definition.  This name
is used by package management commands such as
@command{guix package} and @command{guix build}.

Both are usually the same and correspond to the lowercase conversion of
the project name chosen upstream, with underscores replaced with
hyphens.  For instance, GNUnet is available as @code{gnunet}, and
SDL_net as @code{sdl-net}.

We do not add @code{lib} prefixes for library packages, unless these are
already part of the official project name.  But @pxref{Python
Modules} and @ref{Perl Modules} for special rules concerning modules for
the Python and Perl languages.

Font package names are handled differently, @pxref{Fonts}.


@node Version Numbers
@subsection Version Numbers

We usually package only the latest version of a given free software
project.  But sometimes, for instance for incompatible library versions,
two (or more) versions of the same package are needed.  These require
different Scheme variable names.  We use the name as defined
in @ref{Package Naming}
for the most recent version; previous versions use the same name, suffixed
by @code{-} and the smallest prefix of the version number that may
distinguish the two versions.

The name inside the package definition is the same for all versions of a
package and does not contain any version number.

For instance, the versions 2.24.20 and 3.9.12 of GTK+ may be packaged as follows:

@example
(define-public gtk+
  (package
    (name "gtk+")
    (version "3.9.12")
    ...))
(define-public gtk+-2
  (package
    (name "gtk+")
    (version "2.24.20")
    ...))
@end example
If we also wanted GTK+ 3.8.2, this would be packaged as
@example
(define-public gtk+-3.8
  (package
    (name "gtk+")
    (version "3.8.2")
    ...))
@end example

@c See <https://lists.gnu.org/archive/html/guix-devel/2016-01/msg00425.html>,
@c for a discussion of what follows.
@cindex version number, for VCS snapshots
Occasionally, we package snapshots of upstream's version control system
(VCS) instead of formal releases.  This should remain exceptional,
because it is up to upstream developers to clarify what the stable
release is.  Yet, it is sometimes necessary.  So, what should we put in
the @code{version} field?

Clearly, we need to make the commit identifier of the VCS snapshot
visible in the version string, but we also need to make sure that the
version string is monotonically increasing so that @command{guix package
--upgrade} can determine which version is newer.  Since commit
identifiers, notably with Git, are not monotonically increasing, we add
a revision number that we increase each time we upgrade to a newer
snapshot.  The resulting version string looks like this:

@example
2.0.11-3.cabba9e
  ^    ^    ^
  |    |    `-- upstream commit ID
  |    |
  |    `--- Guix package revision
  |
latest upstream version
@end example

It is a good idea to strip commit identifiers in the @code{version}
field to, say, 7 digits.  It avoids an aesthetic annoyance (assuming
aesthetics have a role to play here) as well as problems related to OS
limits such as the maximum shebang length (127 bytes for the Linux
kernel.)  It is best to use the full commit identifiers in
@code{origin}s, though, to avoid ambiguities.  A typical package
definition may look like this:

@example
(define my-package
  (let ((commit "c3f29bc928d5900971f65965feaae59e1272a3f7"))
    (package
      (version (string-append "0.9-1."
                              (string-take commit 7)))
      (source (origin
                (method git-fetch)
                (uri (git-reference
                      (url "git://example.org/my-package.git")
                      (commit commit)))
                (sha256 (base32 "1mbikn@dots{}"))
                (file-name (string-append "my-package-" version
                                          "-checkout"))))
      ;; @dots{}
      )))
@end example

@node Synopses and Descriptions
@subsection Synopses and Descriptions

As we have seen before, each package in GNU@tie{}Guix includes a
synopsis and a description (@pxref{Defining Packages}).  Synopses and
descriptions are important: They are what @command{guix package
--search} searches, and a crucial piece of information to help users
determine whether a given package suits their needs.  Consequently,
packagers should pay attention to what goes into them.

Synopses must start with a capital letter and must not end with a
period.  They must not start with ``a'' or ``the'', which usually does
not bring anything; for instance, prefer ``File-frobbing tool'' over ``A
tool that frobs files''.  The synopsis should say what the package
is---e.g., ``Core GNU utilities (file, text, shell)''---or what it is
used for---e.g., the synopsis for GNU@tie{}grep is ``Print lines
matching a pattern''.

Keep in mind that the synopsis must be meaningful for a very wide
audience.  For example, ``Manipulate alignments in the SAM format''
might make sense for a seasoned bioinformatics researcher, but might be
fairly unhelpful or even misleading to a non-specialized audience.  It
is a good idea to come up with a synopsis that gives an idea of the
application domain of the package.  In this example, this might give
something like ``Manipulate nucleotide sequence alignments'', which
hopefully gives the user a better idea of whether this is what they are
looking for.

Descriptions should take between five and ten lines.  Use full
sentences, and avoid using acronyms without first introducing them.
Please avoid marketing phrases such as ``world-leading'',
``industrial-strength'', and ``next-generation'', and avoid superlatives
like ``the most advanced''---they are not helpful to users looking for a
package and may even sound suspicious.  Instead, try to be factual,
mentioning use cases and features.

@cindex Texinfo markup, in package descriptions
Descriptions can include Texinfo markup, which is useful to introduce
ornaments such as @code{@@code} or @code{@@dfn}, bullet lists, or
hyperlinks (@pxref{Overview,,, texinfo, GNU Texinfo}).  However you
should be careful when using some characters for example @samp{@@} and
curly braces which are the basic special characters in Texinfo
(@pxref{Special Characters,,, texinfo, GNU Texinfo}).  User interfaces
such as @command{guix package --show} take care of rendering it
appropriately.

Synopses and descriptions are translated by volunteers
@uref{http://translationproject.org/domain/guix-packages.html, at the
Translation Project} so that as many users as possible can read them in
their native language.  User interfaces search them and display them in
the language specified by the current locale.

Translation is a lot of work so, as a packager, please pay even more
attention to your synopses and descriptions as every change may entail
additional work for translators.  In order to help them, it is possible
to make recommendations or instructions visible to them by inserting
special comments like this (@pxref{xgettext Invocation,,, gettext, GNU
Gettext}):

@example
;; TRANSLATORS: "X11 resize-and-rotate" should not be translated.
(description "ARandR is designed to provide a simple visual front end
for the X11 resize-and-rotate (RandR) extension. @dots{}")
@end example


@node Python Modules
@subsection Python Modules

We currently package Python 2 and Python 3, under the Scheme variable names
@code{python-2} and @code{python} as explained in @ref{Version Numbers}.
To avoid confusion and naming clashes with other programming languages, it
seems desirable that the name of a package for a Python module contains
the word @code{python}.

Some modules are compatible with only one version of Python, others with both.
If the package Foo compiles only with Python 3, we name it
@code{python-foo}; if it compiles only with Python 2, we name it
@code{python2-foo}. If it is compatible with both versions, we create two
packages with the corresponding names.

If a project already contains the word @code{python}, we drop this;
for instance, the module python-dateutil is packaged under the names
@code{python-dateutil} and @code{python2-dateutil}.  If the project name
starts with @code{py} (e.g. @code{pytz}), we keep it and prefix it as
described above.


@node Perl Modules
@subsection Perl Modules

Perl programs standing for themselves are named as any other package,
using the lowercase upstream name.
For Perl packages containing a single class, we use the lowercase class name,
replace all occurrences of @code{::} by dashes and prepend the prefix
@code{perl-}.
So the class @code{XML::Parser} becomes @code{perl-xml-parser}.
Modules containing several classes keep their lowercase upstream name and
are also prepended by @code{perl-}.  Such modules tend to have the word
@code{perl} somewhere in their name, which gets dropped in favor of the
prefix.  For instance, @code{libwww-perl} becomes @code{perl-libwww}.


@node Java Packages
@subsection Java Packages

Java programs standing for themselves are named as any other package,
using the lowercase upstream name.

To avoid confusion and naming clashes with other programming languages,
it is desirable that the name of a package for a Java package is
prefixed with @code{java-}.  If a project already contains the word
@code{java}, we drop this; for instance, the package @code{ngsjava} is
packaged under the name @code{java-ngs}.

For Java packages containing a single class or a small class hierarchy,
we use the lowercase class name, replace all occurrences of @code{.} by
dashes and prepend the prefix @code{java-}.  So the class
@code{apache.commons.cli} becomes package
@code{java-apache-commons-cli}.


@node Fonts
@subsection Fonts

For fonts that are in general not installed by a user for typesetting
purposes, or that are distributed as part of a larger software package,
we rely on the general packaging rules for software; for instance, this
applies to the fonts delivered as part of the X.Org system or fonts that
are part of TeX Live.

To make it easier for a user to search for fonts, names for other packages
containing only fonts are constructed as follows, independently of the
upstream package name.

The name of a package containing only one font family starts with
@code{font-}; it is followed by the foundry name and a dash @code{-}
if the foundry is known, and the font family name, in which spaces are
replaced by dashes (and as usual, all upper case letters are transformed
to lower case).
For example, the Gentium font family by SIL is packaged under the name
@code{font-sil-gentium}.

For a package containing several font families, the name of the collection
is used in the place of the font family name.
For instance, the Liberation fonts consist of three families,
Liberation Sans, Liberation Serif and Liberation Mono.
These could be packaged separately under the names
@code{font-liberation-sans} and so on; but as they are distributed together
under a common name, we prefer to package them together as
@code{font-liberation}.

In the case where several formats of the same font family or font collection
are packaged separately, a short form of the format, prepended by a dash,
is added to the package name.  We use @code{-ttf} for TrueType fonts,
@code{-otf} for OpenType fonts and @code{-type1} for PostScript Type 1
fonts.



@node Bootstrapping
@section Bootstrapping

@c Adapted from the ELS 2013 paper.

@cindex bootstrapping

Bootstrapping in our context refers to how the distribution gets built
``from nothing''.  Remember that the build environment of a derivation
contains nothing but its declared inputs (@pxref{Introduction}).  So
there's an obvious chicken-and-egg problem: how does the first package
get built?  How does the first compiler get compiled?  Note that this is
a question of interest only to the curious hacker, not to the regular
user, so you can shamelessly skip this section if you consider yourself
a ``regular user''.

@cindex bootstrap binaries
The GNU system is primarily made of C code, with libc at its core.  The
GNU build system itself assumes the availability of a Bourne shell and
command-line tools provided by GNU Coreutils, Awk, Findutils, `sed', and
`grep'.  Furthermore, build programs---programs that run
@code{./configure}, @code{make}, etc.---are written in Guile Scheme
(@pxref{Derivations}).  Consequently, to be able to build anything at
all, from scratch, Guix relies on pre-built binaries of Guile, GCC,
Binutils, libc, and the other packages mentioned above---the
@dfn{bootstrap binaries}.

These bootstrap binaries are ``taken for granted'', though we can also
re-create them if needed (more on that later).

@unnumberedsubsec Preparing to Use the Bootstrap Binaries

@c As of Emacs 24.3, Info-mode displays the image, but since it's a
@c large image, it's hard to scroll.  Oh well.
@image{images/bootstrap-graph,6in,,Dependency graph of the early bootstrap derivations}

The figure above shows the very beginning of the dependency graph of the
distribution, corresponding to the package definitions of the @code{(gnu
packages bootstrap)} module.  A similar figure can be generated with
@command{guix graph} (@pxref{Invoking guix graph}), along the lines of:

@example
guix graph -t derivation \
  -e '(@@@@ (gnu packages bootstrap) %bootstrap-gcc)' \
  | dot -Tps > t.ps
@end example

At this level of detail, things are
slightly complex.  First, Guile itself consists of an ELF executable,
along with many source and compiled Scheme files that are dynamically
loaded when it runs.  This gets stored in the @file{guile-2.0.7.tar.xz}
tarball shown in this graph.  This tarball is part of Guix's ``source''
distribution, and gets inserted into the store with @code{add-to-store}
(@pxref{The Store}).

But how do we write a derivation that unpacks this tarball and adds it
to the store?  To solve this problem, the @code{guile-bootstrap-2.0.drv}
derivation---the first one that gets built---uses @code{bash} as its
builder, which runs @code{build-bootstrap-guile.sh}, which in turn calls
@code{tar} to unpack the tarball.  Thus, @file{bash}, @file{tar},
@file{xz}, and @file{mkdir} are statically-linked binaries, also part of
the Guix source distribution, whose sole purpose is to allow the Guile
tarball to be unpacked.

Once @code{guile-bootstrap-2.0.drv} is built, we have a functioning
Guile that can be used to run subsequent build programs.  Its first task
is to download tarballs containing the other pre-built binaries---this
is what the @code{.tar.xz.drv} derivations do.  Guix modules such as
@code{ftp-client.scm} are used for this purpose.  The
@code{module-import.drv} derivations import those modules in a directory
in the store, using the original layout.  The
@code{module-import-compiled.drv} derivations compile those modules, and
write them in an output directory with the right layout.  This
corresponds to the @code{#:modules} argument of
@code{build-expression->derivation} (@pxref{Derivations}).

Finally, the various tarballs are unpacked by the
derivations @code{gcc-bootstrap-0.drv}, @code{glibc-bootstrap-0.drv},
etc., at which point we have a working C tool chain.


@unnumberedsubsec Building the Build Tools

Bootstrapping is complete when we have a full tool chain that does not
depend on the pre-built bootstrap tools discussed above.  This
no-dependency requirement is verified by checking whether the files of
the final tool chain contain references to the @file{/gnu/store}
directories of the bootstrap inputs.  The process that leads to this
``final'' tool chain is described by the package definitions found in
the @code{(gnu packages commencement)} module.

The @command{guix graph} command allows us to ``zoom out'' compared to
the graph above, by looking at the level of package objects instead of
individual derivations---remember that a package may translate to
several derivations, typically one derivation to download its source,
one to build the Guile modules it needs, and one to actually build the
package from source.  The command:

@example
guix graph -t bag \
  -e '(@@@@ (gnu packages commencement)
          glibc-final-with-bootstrap-bash)' | dot -Tps > t.ps
@end example

@noindent
produces the dependency graph leading to the ``final'' C
library@footnote{You may notice the @code{glibc-intermediate} label,
suggesting that it is not @emph{quite} final, but as a good
approximation, we will consider it final.}, depicted below.

@image{images/bootstrap-packages,6in,,Dependency graph of the early packages}

@c See <http://lists.gnu.org/archive/html/gnu-system-discuss/2012-10/msg00000.html>.
The first tool that gets built with the bootstrap binaries is
GNU@tie{}Make---noted @code{make-boot0} above---which is a prerequisite
for all the following packages.  From there Findutils and Diffutils get
built.

Then come the first-stage Binutils and GCC, built as pseudo cross
tools---i.e., with @code{--target} equal to @code{--host}.  They are
used to build libc.  Thanks to this cross-build trick, this libc is
guaranteed not to hold any reference to the initial tool chain.

From there the final Binutils and GCC (not shown above) are built.
GCC uses @code{ld}
from the final Binutils, and links programs against the just-built libc.
This tool chain is used to build the other packages used by Guix and by
the GNU Build System: Guile, Bash, Coreutils, etc.

And voilà!  At this point we have the complete set of build tools that
the GNU Build System expects.  These are in the @code{%final-inputs}
variable of the @code{(gnu packages commencement)} module, and are
implicitly used by any package that uses @code{gnu-build-system}
(@pxref{Build Systems, @code{gnu-build-system}}).


@unnumberedsubsec Building the Bootstrap Binaries

Because the final tool chain does not depend on the bootstrap binaries,
those rarely need to be updated.  Nevertheless, it is useful to have an
automated way to produce them, should an update occur, and this is what
the @code{(gnu packages make-bootstrap)} module provides.

The following command builds the tarballs containing the bootstrap
binaries (Guile, Binutils, GCC, libc, and a tarball containing a mixture
of Coreutils and other basic command-line tools):

@example
guix build bootstrap-tarballs
@end example

The generated tarballs are those that should be referred to in the
@code{(gnu packages bootstrap)} module mentioned at the beginning of
this section.

Still here?  Then perhaps by now you've started to wonder: when do we
reach a fixed point?  That is an interesting question!  The answer is
unknown, but if you would like to investigate further (and have
significant computational and storage resources to do so), then let us
know.

@node Porting
@section Porting to a New Platform

As discussed above, the GNU distribution is self-contained, and
self-containment is achieved by relying on pre-built ``bootstrap
binaries'' (@pxref{Bootstrapping}).  These binaries are specific to an
operating system kernel, CPU architecture, and application binary
interface (ABI).  Thus, to port the distribution to a platform that is
not yet supported, one must build those bootstrap binaries, and update
the @code{(gnu packages bootstrap)} module to use them on that platform.

Fortunately, Guix can @emph{cross compile} those bootstrap binaries.
When everything goes well, and assuming the GNU tool chain supports the
target platform, this can be as simple as running a command like this
one:

@example
guix build --target=armv5tel-linux-gnueabi bootstrap-tarballs
@end example

For this to work, the @code{glibc-dynamic-linker} procedure in
@code{(gnu packages bootstrap)} must be augmented to return the right
file name for libc's dynamic linker on that platform; likewise,
@code{system->linux-architecture} in @code{(gnu packages linux)} must be
taught about the new platform.

Once these are built, the @code{(gnu packages bootstrap)} module needs
to be updated to refer to these binaries on the target platform.  That
is, the hashes and URLs of the bootstrap tarballs for the new platform
must be added alongside those of the currently supported platforms.  The
bootstrap Guile tarball is treated specially: it is expected to be
available locally, and @file{gnu/local.mk} has rules do download it for
the supported architectures; a rule for the new platform must be added
as well.

In practice, there may be some complications.  First, it may be that the
extended GNU triplet that specifies an ABI (like the @code{eabi} suffix
above) is not recognized by all the GNU tools.  Typically, glibc
recognizes some of these, whereas GCC uses an extra @code{--with-abi}
configure flag (see @code{gcc.scm} for examples of how to handle this).
Second, some of the required packages could fail to build for that
platform.  Lastly, the generated binaries could be broken for some
reason.

@c *********************************************************************
@include contributing.texi

@c *********************************************************************
@node Acknowledgments
@chapter Acknowledgments

Guix is based on the @uref{http://nixos.org/nix/, Nix package manager},
which was designed and
implemented by Eelco Dolstra, with contributions from other people (see
the @file{nix/AUTHORS} file in Guix.)  Nix pioneered functional package
management, and promoted unprecedented features, such as transactional
package upgrades and rollbacks, per-user profiles, and referentially
transparent build processes.  Without this work, Guix would not exist.

The Nix-based software distributions, Nixpkgs and NixOS, have also been
an inspiration for Guix.

GNU@tie{}Guix itself is a collective work with contributions from a
number of people.  See the @file{AUTHORS} file in Guix for more
information on these fine people.  The @file{THANKS} file lists people
who have helped by reporting bugs, taking care of the infrastructure,
providing artwork and themes, making suggestions, and more---thank you!


@c *********************************************************************
@node GNU Free Documentation License
@appendix GNU Free Documentation License

@include fdl-1.3.texi

@c *********************************************************************
@node Concept Index
@unnumbered Concept Index
@printindex cp

@node Programming Index
@unnumbered Programming Index
@syncodeindex tp fn
@syncodeindex vr fn
@printindex fn

@bye

@c Local Variables:
@c ispell-local-dictionary: "american";
@c End:

debug log:

solving 04de780 ...
found 04de780 in https://yhetil.org/guix/1468419848-15393-2-git-send-email-vincent.legoll@gmail.com/
found 67ece1d in https://git.savannah.gnu.org/cgit/guix.git
preparing index
index prepared:
100644 67ece1d23f6a2b453e03eaa2642b06fa79afe4af	doc/guix.texi

applying [1/1] https://yhetil.org/guix/1468419848-15393-2-git-send-email-vincent.legoll@gmail.com/
diff --git a/doc/guix.texi b/doc/guix.texi
index 67ece1d..04de780 100644

Checking patch doc/guix.texi...
Applied patch doc/guix.texi cleanly.

index at:
100644 04de7808baa111c49b034a95f9d35b75a19b62ce	doc/guix.texi

(*) Git path names are given by the tree(s) the blob belongs to.
    Blobs themselves have no identifier aside from the hash of its contents.^

Code repositories for project(s) associated with this external index

	https://git.savannah.gnu.org/cgit/guix.git

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.