commit 3c459670690f90f85905d241d230a7541a41fe15
Author: Ludovic Courtès <ludo@gnu.org>
Date:   Tue Feb 18 15:10:28 2014 +0100

    dmd: Add '--pid' option.
    
    * modules/dmd.scm (main): Add '--pid' option and honor it.
    * tests/basic.sh: Run dmd with '--pid'.  Wait for the PID file to be
      available, for synchronization.
    * tests/respawn.sh: Likewise.
    * dmd.texi (Invoking dmd): Document '--pid'.

	Modified   dmd.texi
diff --git a/dmd.texi b/dmd.texi
index a970894..f7306db 100644
--- a/dmd.texi
+++ b/dmd.texi
@@ -369,6 +369,10 @@ Log output into @var{file}, or if @var{file} is not given,
 @code{/var/log/dmd.log} when running as superuser, @var{~/.dmd.log}
 otherwise.
 
+@item --pid[=@var{file}]
+When dmd is ready to accept connections, write its PID to @var{file} or
+to the standard output if @var{file} is omitted.
+
 @item -p [@var{file}]
 @itemx --persistency[=@var{file}]
 @c FIXME-CRITICAL
	Modified   modules/dmd.scm
diff --git a/modules/dmd.scm b/modules/dmd.scm
index df41eb3..bfa579f 100644
--- a/modules/dmd.scm
+++ b/modules/dmd.scm
@@ -1,5 +1,5 @@
 ;; dmd.scm -- Daemon managing Daemons (or Daemons-managing Daemon?)
-;; Copyright (C) 2013 Ludovic Courts <ludo@gnu.org>
+;; Copyright (C) 2013, 2014 Ludovic Courts <ludo@gnu.org>
 ;; Copyright (C) 2002, 2003 Wolfgang Jhrling <wolfgang@pro-linux.de>
 ;;
 ;; This file is part of GNU dmd.
@@ -23,6 +23,7 @@
   #:use-module (ice-9 readline) ;; Readline (for interactive use).
   #:use-module (oop goops)      ;; Defining classes and methods.
   #:use-module (srfi srfi-1)    ;; List library.
+  #:use-module (srfi srfi-26)
   #:use-module (dmd config)
   #:use-module (dmd support)
   #:use-module (dmd service)
@@ -54,6 +55,7 @@
 
   (let ((config-file default-config-file)
 	(socket-file default-socket-file)
+        (pid-file    #f)
 	(insecure #f)
 	(logfile default-logfile))
     ;; Process command line arguments.
@@ -99,6 +101,12 @@
 		    #:action (lambda (file)
 			       (set! logfile file)))
 		  (make <option>
+		    #:long "pid"
+		    #:takes-arg? #t #:optional-arg? #t #:arg-name "FILE"
+		    #:description "when ready write PID to FILE or stdout"
+		    #:action (lambda (file)
+			       (set! pid-file (or file #t))))
+		  (make <option>
 		    #:long "config" #:short #\c
 		    #:takes-arg? #t #:optional-arg? #f #:arg-name "FILE"
 		    #:description "read configuration from FILE"
@@ -173,6 +181,16 @@
               ;; EINTR, which happens anytime we receive a signal, such as
               ;; SIGCHLD.  Thus, wrap the 'accept' call.
               (accept (EINTR-safe accept)))
+
+          ;; Possibly write out our PID, which means we're ready to accept
+          ;; connections.  XXX: What if we daemonized already?
+          (match pid-file
+            ((? string? file)
+             (call-with-output-file pid-file
+               (cute display (getpid) <>)))
+            (#t (display (getpid)))
+            (_  #t))
+
           (let next-command ()
             (match (accept sock)
               ((command-source . client-address)
	Modified   tests/basic.sh
diff --git a/tests/basic.sh b/tests/basic.sh
index 0311f20..e9ad970 100644
--- a/tests/basic.sh
+++ b/tests/basic.sh
@@ -1,5 +1,5 @@
 # GNU dmd --- Test basic communication capabilities.
-# Copyright © 2013 Ludovic Courtès <ludo@gnu.org>
+# Copyright © 2013, 2014 Ludovic Courtès <ludo@gnu.org>
 #
 # This file is part of GNU dmd.
 #
@@ -23,11 +23,12 @@ socket="t-socket-$$"
 conf="t-conf-$$"
 log="t-log-$$"
 stamp="t-stamp-$$"
+pid="t-pid-$$"
 
 deco="deco -s $socket"
-dmd_pid=""
 
-trap "rm -f $socket $conf $stamp $log; test -z $dmd_pid || kill $dmd_pid" EXIT
+trap "rm -f $socket $conf $stamp $log $pid;
+      test -f $pid && kill \`cat $pid\` || true" EXIT
 
 cat > "$conf"<<EOF
 (use-modules (srfi srfi-26))
@@ -43,10 +44,14 @@ cat > "$conf"<<EOF
    #:respawn? #f))
 EOF
 
-dmd -I -s "$socket" -c "$conf" -l "$log" &
-dmd_pid=$!
+rm -f "$pid"
+dmd -I -s "$socket" -c "$conf" -l "$log" --pid="$pid" &
+
+# Wait till it's ready.
+while ! test -f "$pid" ; do : ; done
+
+dmd_pid="`cat $pid`"
 
-sleep 1				# XXX: wait till it's up
 kill -0 $dmd_pid
 test -S "$socket"
 $deco status dmd | grep -E '(Start.*dmd|Stop.*test)'
	Modified   tests/respawn.sh
diff --git a/tests/respawn.sh b/tests/respawn.sh
index 96fad66..161eead 100644
--- a/tests/respawn.sh
+++ b/tests/respawn.sh
@@ -1,5 +1,5 @@
 # GNU dmd --- Test respawnable services.
-# Copyright © 2013 Ludovic Courtès <ludo@gnu.org>
+# Copyright © 2013, 2014 Ludovic Courtès <ludo@gnu.org>
 #
 # This file is part of GNU dmd.
 #
@@ -25,11 +25,12 @@ log="t-log-$$"
 stamp="t-stamp-$$"
 service1_pid="t-service1-pid-$$"
 service2_pid="t-service2-pid-$$"
+pid="t-pid-$$"
 
 deco="deco -s $socket"
-dmd_pid=""
 
-trap "rm -f $socket $conf $stamp $log; test -z $dmd_pid || kill $dmd_pid ;
+trap "rm -f $socket $conf $stamp $log $pid $service1_pid $service2_pid ;
+  test -f $pid && kill \`cat $pid\` || true ;
   test -f $service1_pid && kill \`cat $service1_pid\` || true ;
   test -f $service2_pid && kill \`cat $service2_pid\` || true ;
   rm -f $service1_pid $service2_pid" EXIT
@@ -79,10 +80,14 @@ cat > "$conf"<<EOF
 (start 'test2)
 EOF
 
-dmd -I -s "$socket" -c "$conf" -l "$log" &
-dmd_pid=$!
+rm -f "$pid"
+dmd -I -s "$socket" -c "$conf" -l "$log" --pid="$pid" &
+
+# Wait till it's ready.
+wait_for_file "$pid"
+
+dmd_pid="`cat $pid`"
 
-sleep 1				# XXX: wait till it's up
 kill -0 $dmd_pid
 test -S "$socket"
 $deco status test1 | grep started