.\" See section COPYING for copyright and redistribution information.
.TH ETAGS 1 "2021-03-30" "GNU Tools" "GNU"
.de BP
.sp
.ti -.2i
\(**
..

.SH NAME
etags, ctags \- generate tag file for Emacs, vi
.SH SYNOPSIS
.hy 0
.na
\fBetags\fP [\|\-aCDGIQRVh\|] [\|\-i \fIfile\fP\|] [\|\-l \fIlanguage\fP\|]
.if n .br
[\|\-o \fItagfile\fP\|] [\|\-r \fIregexp\fP\|]
[\|\-\-parse\-stdin=\fIfile\fP\|]
.br
[\|\-\-append\|] [\|\-\-no\-defines\|] [\|\-\-globals\|]
[\|\-\-no\-globals\|] [\|\-\-no\-line\-directive\|] [\|\-\-include=\fIfile\fP\|]
[\|\-\-ignore\-indentation\|] [\|\-\-language=\fIlanguage\fP\|]
[\|\-\-members\|] [\|\-\-no\-members\|] [\|\-\-output=\fItagfile\fP\|]
[\|\-\-class\-qualify\|]
[\|\-\-regex=\fIregexp\fP\|] [\|\-\-no\-regex\|]
[\|\-\-help\|] [\|\-\-version\|]
\fIfile\fP .\|.\|.

\fBctags\fP [\|\-aCdgIQRVh\|] [\|\-BtTuvwx\|] [\|\-l \fIlanguage\fP\|]
.if n .br
[\|\-o \fItagfile\fP\|] [\|\-r \fIregexp\fP\|]
[\|\-\-parse\-stdin=\fIfile\fP\|]
.br
[\|\-\-append\|] [\|\-\-backward\-search\|]
[\|\-\-cxref\|] [\|\-\-no\-defines\|] [\|\-\-globals\|]
[\|\-\-no\-globals\|] [\|\-\-no\-line\-directive\|] [\|\-\-ignore\-indentation\|]
[\|\-\-language=\fIlanguage\fP\|] [\|\-\-members\|] [\|\-\-no\-members\|]
[\|\-\-class\-qualify\|]
[\|\-\-output=\fItagfile\fP\|] [\|\-\-regex=\fIregexp\fP\|]
[\|\-\-update\|]
[\|\-\-help\|] [\|\-\-version\|]
\fIfile\fP .\|.\|.
.ad b
.hy 1
.SH DESCRIPTION
The \|\fBetags\fP\| program is used to create a tag table file, in a format
understood by
.BR emacs ( 1 )\c
\&; the \|\fBctags\fP\| program is used to create a similar table in a
format understood by
.BR vi ( 1 )\c
\&.  Both forms of the program understand
the syntax of C, Objective C, C++, Java, Fortran, Ada, Cobol, Erlang,
Forth, Go, HTML, LaTeX, Emacs Lisp/Common Lisp, Lua, Makefile, Mercury, Pascal,
Perl, Ruby, Rust, PHP, PostScript, Python, Prolog, Scheme and most
assembler\-like syntaxes.
Both forms read the files specified on the command line, and write a tag
table (defaults: \fBTAGS\fP for \fBetags\fP, \fBtags\fP for
\fBctags\fP) in the current working directory.
Files specified with relative file names will be recorded in the tag
table with file names relative to the directory where the tag table
resides.  If the tag table is in /dev or is the standard output,
however, the file names are made relative to the working directory.
Files specified with absolute file names will be recorded
with absolute file names.  Files generated from a source file\-\-like
a C file generated from a source Cweb file\-\-will be recorded with
the name of the source file.
Compressed files are supported using gzip, bzip2, xz, and zstd.
The programs recognize the language used in an input file based on its
file name and contents.  The \fB\-\-language\fP switch can be used to force
parsing of the file names following the switch according to the given
language, overriding guesses based on filename extensions.
.SH OPTIONS
Some options make sense only for the \fBvi\fP style tag files produced
by ctags;
\fBetags\fP does not recognize them.
The programs accept unambiguous abbreviations for long option names.
.TP
.B \-a, \-\-append
Append to existing tag file.  (For \fBvi\fP-format tag files, see also
\fB\-\-update\fP.)
.TP
.B \-B, \-\-backward\-search
Tag files written in the format expected by \fBvi\fP contain regular
expression search instructions; the \fB\-B\fP option writes them using
the delimiter "\|\fB?\fP\|", to search \fIbackwards\fP through files.
The default is to use the delimiter "\|\fB/\fP\|", to search \fIforwards\fP
through files.
Only \fBctags\fP accepts this option.
.TP
.B \-\-declarations
In C and derived languages, create tags for function declarations,
and create tags for extern variables unless \-\-no\-globals is used.
In Lisp, create tags for (defvar foo) declarations.
In Mercury, declarations start a line with "\|\fB:-\fP\|" and are always
tagged.  In addition, this option tags predicates or functions in first
rules of clauses, as in Prolog.
.TP
.B \-D, \-\-no\-defines
Do not create tag entries for C preprocessor constant definitions
and enum constants.
This may make the tags file much smaller if many header files are tagged.
.TP
.B \-\-globals
Create tag entries for global variables in Perl and Makefile.  This is
the default in C and derived languages.
.TP
.B \-\-no\-globals
Do not tag global variables in C and derived languages.  Typically this
reduces the file size by one fourth.
.TP
.B \-\-no\-line\-directive
Ignore \fB#line\fP preprocessor directives in C and derived languages.  The
default is to honor those directives, and record the tags as if the
file scanned was the one named in the \fB#line\fP directive.  This switch is
useful when the original file named by \fB#line\fP is no longer available.
.TP
\fB\-i\fP \fIfile\fP, \fB\-\-include=\fIfile\fP
Include a note in the tag file indicating that, when searching for a
tag, one should also consult the tags file \fIfile\fP after checking the
current file.  Only \fBetags\fP accepts this option.
.TP
.B \-I, \-\-ignore\-indentation
Don't rely on indentation as much as we normally do.  Currently, this
means not to assume that a closing brace in the first column is the
final brace of a function or structure definition in C and C++.
.TP
\fB\-l\fP \fIlanguage\fP, \fB\-\-language=\fIlanguage\fP
Parse the following files according to the given language.  More than
one such options may be intermixed with filenames.  Use \fB\-\-help\fP
to get a list of the available languages and their default filename
extensions.  For example, as Mercury and Objective-C have same
filename extension \fI.m\fP, a test based on contents tries to detect
the language.  If this test fails, \fB\-\-language=\fP\fImercury\fP or
\fB\-\-language=\fP\fIobjc\fP should be used.
The "auto" language can be used to restore automatic detection of language
based on the file name.  The "none" language may be used to disable language
parsing altogether; only regexp matching is done in this case (see the
\fB\-\-regex\fP option).
.TP
.B \-\-members
Create tag entries for variables that are members of structure-like
constructs in PHP.  This is the default for C and derived languages.
.TP
.B \-\-no\-members
Do not tag member variables.
.TP
.B \-\-packages\-only
Only tag packages in Ada files.
.TP
\fB\-\-parse\-stdin=\fIfile\fP
May be used (only once) in place of a file name on the command line.
\fBetags\fP will read from standard input and mark the produced tags
as belonging to the file \fBFILE\fP.
.TP
\fB\-Q, \-\-class\-qualify\fP
Qualify tag names with their class name in C++, ObjC, Java, and Perl.
This produces tag names of the form \fIclass\fP\fB::\fP\fImember\fP
for C++ and Perl,
\fIclass\fP\fB(\fP\fIcategory\fP\fB)\fP for Objective C, and \fIclass\fP\fB.\fP\fImember\fP for Java.
For Objective C, this also produces class methods qualified with
their arguments, as in \fIfoo\fP\fB:\fP\fIbar\fP\fB:\fP\fIbaz\fP\fB:\fP\fImore\fP.
.TP
\fB\-o\fP \fItagfile\fP, \fB\-\-output=\fItagfile\fP
Explicit name of file for tag table; for \fBetags\fP only, a file name
of \- means standard output; overrides default \fBTAGS\fP or \fBtags\fP.
(But ignored with \fB\-v\fP or \fB\-x\fP.)
.TP
\fB\-r\fP \fIregexp\fP, \fB\-\-regex=\fIregexp\fP

Make tags based on regexp matching for the files following this option,
in addition to the tags made with the standard parsing based on
language. May be freely intermixed with filenames and the \fB\-R\fP
option.  The regexps are cumulative, i.e., each such option will add to
the previous ones.  The regexps are of one of the forms:
.br
	[\fB{\fP\fIlanguage\fP\fB}\fP]\fB/\fP\fItagregexp/\fP[\fInameregexp\fP\fB/\fP]\fImodifiers\fP
.br
	\fB@\fP\fIregexfile\fP
.br

where \fItagregexp\fP is used to match the tag.  It should not match
useless characters.  If the match is such that more characters than
needed are unavoidably matched by \fItagregexp\fP, it may be useful to
add a \fInameregexp\fP, to narrow down the tag scope.  \fBctags\fP
ignores regexps without a \fInameregexp\fP.  The syntax of regexps is
the same as in emacs.  The following character escape sequences are
supported: \\a, \\b, \\d, \\e, \\f, \\n, \\r, \\t, \\v, which
respectively stand for the ASCII characters BEL, BS, DEL, ESC, FF, NL,
CR, TAB, VT.
.br
The \fImodifiers\fP are a sequence of 0 or more characters among
\fIi\fP, which means to ignore case when matching; \fIm\fP, which means
that the \fItagregexp\fP will be matched against the whole file contents
at once, rather than line by line, and the matching sequence can match
multiple lines; and \fIs\fP, which implies \fIm\fP and means that the
dot character in \fItagregexp\fP matches the newline char as well.
.br
The separator, which is \fB/\fP in the examples, can be any character
different from space, tab, braces and \fB@\fP.  If the separator
character is needed inside the regular expression, it must be quoted
by preceding it with \fB\\\fP.
.br
The optional \fB{\fP\fIlanguage\fP\fB}\fP prefix means that the tag
should be
created only for files of language \fIlanguage\fP, and ignored
otherwise.  This is particularly useful when storing many predefined
regexps in a file.
.br
In its second form, \fIregexfile\fP is the name of a file that contains
a number of arguments to the \fI\-\-regex\=\fP option,
one per line.  Lines beginning with a space or tab are assumed
to be comments, and ignored.

.br
Here are some examples.  All the regexps are quoted to protect them
from shell interpretation.
.br

Tag the DEFVAR macros in the emacs source files:
.br
\fI\-\-regex\='/[ \\t]*DEFVAR_[A-Z_ \\t(]+"\\([^"]+\\)"/'\fP
.\"" This comment is to avoid confusion to Emacs syntax highlighting
.br

Tag VHDL files (this example is a single long line, broken here for
formatting reasons):
.br
\fI\-\-language\=none\ \-\-regex='/[\ \\t]*\\(ARCHITECTURE\\|\\
CONFIGURATION\\)\ +[^\ ]*\ +OF/'\ \-\-regex\='/[\ \\t]*\\
\\(ATTRIBUTE\\|ENTITY\\|FUNCTION\\|PACKAGE\\(\ BODY\\)?\\
\\|PROCEDURE\\|PROCESS\\|TYPE\\)[\ \\t]+\\([^\ \\t(]+\\)/\\3/'\fP
.br

Tag TCL files (this last example shows the usage of a \fItagregexp\fP):
.br
\fI\-\-lang\=none \-\-regex\='/proc[\ \\t]+\\([^\ \\t]+\\)/\\1/'\fP

.br
A regexp can be preceded by {\fIlang\fP}, thus restricting it to match
lines of files of the specified language.  Use \fBetags \-\-help\fP to obtain
a list of the recognized languages.  This feature is particularly useful inside
\fBregex files\fP.  A regex file contains one regex per line.  Empty lines,
and those lines beginning with space or tab are ignored.  Lines beginning
with @ are references to regex files whose name follows the @ sign.  Other
lines are considered regular expressions like those following \fB\-\-regex\fP.
.br
For example, the command
.br
\fIetags \-\-regex=@regex.file *.c\fP
.br
reads the regexes contained in the file regex.file.
.TP
.B \-R, \-\-no\-regex
Don't do any more regexp matching on the following files.  May be
freely intermixed with filenames and the \fB\-\-regex\fP option.
.TP
.B \-u, \-\-update
Update tag entries for \fIfiles\fP specified on command line, leaving
tag entries for other files in place.  Currently, this is implemented
by deleting the existing entries for the given files and then
rewriting the new entries at the end of the tags file.  It is often
faster to simply rebuild the entire tag file than to use this.
Only \fBctags\fP accepts this option.
.TP
.B \-v, \-\-vgrind
Instead of generating a tag file, write index (in \fBvgrind\fP format)
to standard output.  Only \fBctags\fP accepts this option.
.TP
.B \-x, \-\-cxref
Instead of generating a tag file, write a cross reference (in
\fBcxref\fP format) to standard output.  Only \fBctags\fP accepts this option.
.TP
.B \-h, \-H, \-\-help
Print usage information.  Followed by one or more \-\-language=LANG
prints detailed information about how tags are created for LANG.
.TP
.B \-V, \-\-version
Print the current version of the program (same as the version of the
emacs \fBetags\fP is shipped with).

.SH "SEE ALSO"
"\|\fBemacs\fP\|" entry in \fBinfo\fP; \fIGNU Emacs Manual\fP, Richard
Stallman.
.br
.BR cxref ( 1 ),
.BR emacs ( 1 ),
.BR vgrind ( 1 ),
.BR vi ( 1 ).

.SH COPYING
Copyright 1992, 1999, 2001-2021 Free Software Foundation, Inc.
.PP
Permission is granted to make and distribute verbatim copies of this
document provided the copyright notice and this permission notice are
preserved on all copies.
.PP
Permission is granted to copy and distribute modified versions of
this document under the conditions for verbatim copying, provided that
the entire resulting derived work is distributed under the terms of
a permission notice identical to this one.
.PP
Permission is granted to copy and distribute translations of this
document into another language, under the above conditions for
modified versions, except that this permission notice may be stated
in a translation approved by the Free Software Foundation.

.\" Local Variables:
.\" time-stamp-pattern: "3/.TH ETAGS 1 \"%Y-%02m-%02d\" \"GNU Tools\" \"GNU\"$"
.\" End: