etags
etags(1) GNU Tools etags(1)
NAME
etags, ctags - generate tag file for Emacs, vi
SYNOPSIS
etags [-aCDGImRVh] [-i file] [-l language]
[-o tagfile] [-r regexp]
[--append] [--no-defines] [--no-globals] [--include=file]
[--ignore-indentation] [--language=language] [--members]
[--output=tagfile] [--regex=regexp] [--no-regex]
[--ignore-case-regex=regexp] [--help] [--version] file ...
ctags [-aCdgImRVh] [-BtTuvwx] [-l language]
[-o tagfile] [-r regexp]
[--append] [--backward-search] [--cxref] [--defines]
[--forward-search] [--globals] [--ignore-indentation]
[--language=language] [--members] [--output=tagfile] [--regex=regexp]
[--ignore-case-regex=regexp] [--typedefs] [--typedefs-and-c++]
[--update] [--no-warn] [--help] [--version] file ...
DESCRIPTION
The etags program is used to create a tag table file, in a format un-
derstood by emacs(1); the ctags program is used to create a similar
table in a format understood by vi(1). Both forms of the program un-
derstand the syntax of C, Objective C, C++, Java, Fortran, Ada, Cobol,
Erlang, LaTeX, Emacs Lisp/Common Lisp, makefiles, Pascal, Perl,
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: TAGS for etags, tags for ctags) 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. Files specified with absolute file names
will be recorded with absolute file names. The programs recognize the
language used in an input file based on its file name and contents.
The --language 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.
OPTIONS
Some options make sense only for the vi style tag files produced by
ctags; etags does not recognize them. The programs accept unambiguous
abbreviations for long option names.
-a, --append
Append to existing tag file. (For vi-format tag files, see al-
so --update.)
-B, --backward-search
Tag files written in the format expected by vi contain regular
expression search instructions; the -B option writes them using
the delimiter ‘?’, to search backwards through files. The de-
fault is to use the delimiter ‘/’, to search forwards through
files. Only ctags accepts this option.
--declarations
In C and derived languages, create tags for function declara-
tions, and create tags for extern variables unless --no-globals
is used.
-d, --defines
Create tag entries for C preprocessor constant definitions and
enum constants, too. This is the default behavior for etags.
-D, --no-defines
Do not create tag entries for C preprocessor constant defini-
tions and enum constants. This may make the tags file much
smaller if many header files are tagged. This is the default
behavior for ctags.
-g, --globals
Create tag entries for global variables in C, C++, Objective C,
Java, and Perl. This is the default behavior for etags.
-G, --no-globals
Do not tag global variables. Typically this reduces the file
size by one fourth. This is the default behavior for ctags.
-i file, --include=file
Include a note in the tag file indicating that, when searching
for a tag, one should also consult the tags file file after
checking the current file. This options is only accepted by
etags.
-I, --ignore-indentation
Don’t rely on indentation as much as we normally do. Current-
ly, 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++.
-l language, --language=language
Parse the following files according to the given language.
More than one such options may be intermixed with filenames.
Use --help to get a list of the available languages and their
default filename extensions. 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 --regex option).
-m, --members
Create tag entries for variables that are members of structure-
like constructs in C++, Objective C, Java.
-M, --no-members
Do not tag member variables. This is the default behavior.
--packages-only
Only tag packages in Ada files.
-o tagfile, --output=tagfile
Explicit name of file for tag table; overrides default TAGS or
tags. (But ignored with -v or -x.)
-r regexp, --regex=regexp
--ignore-case-regex=regexp
Make tags based on regexp matching for each line of the files
following this option, in addition to the tags made with the
standard parsing based on language. When using --regex, case
is significant, while it is not with --ignore-case-regex. May
be freely intermixed with filenames and the -R option. The
regexps are cumulative, i.e. each option will add to the previ-
ous ones. The regexps are of the form:
/tagregexp[/nameregexp]/
where tagregexp is used to match the lines that must be tagged.
It should not match useless characters. If the match is such
that more characters than needed are unavoidably matched by
tagregexp, it may be useful to add a nameregexp, to narrow down
the tag scope. ctags ignores regexps without a nameregexp.
The syntax of regexps is the same as in emacs, augmented with
intervals of the form \{m,n\}, as in ed or grep.
Here are some examples. All the regexps are quoted to protect
them from shell interpretation.
Tag the DEFVAR macros in the emacs source files:
--regex=’/[ \t]*DEFVAR_[A-Z_ \t(]+"\([^"]+\)"’
Tag VHDL files (this example is a single long line, broken here
for formatting reasons):
--language=none --regex=’/[ \t]*\(ARCHITECTURE\|\ CONFIGURA-
TION\) +[^ ]* +OF/’ --regex=’/[ \t]*\ \(ATTRIBUTE\|ENTI-
TY\|FUNCTION\|PACKAGE\( BODY\)?\ \|PROCEDURE\|PRO-
CESS\|TYPE\)[ \t]+\([^ \t(]+\)/\3/’
Tag TCL files (this last example shows the usage of a tagreg-
exp):
--lang=none --regex=’/proc[ \t]+\([^ \t]+\)/\1/’
A regexp can be preceded by {lang}, thus restricting it to
match lines of files of the specified language. Use etags
--help to obtain a list of the recognised languages. This fea-
ture is particularly useful inside regex files. A regex file
contains one regex per line. Empty lines, and those lines be-
ginning 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 fol-
lowing --regex.
For example, the command
etags --regex=@regex.file *.c
reads the regexes contained in the file regex.file.
-R, --no-regex
Don’t do any more regexp matching on the following files. May
be freely intermixed with filenames and the --regex option.
-t, --typedefs
Record typedefs in C code as tags. Since this is the default
behaviour of etags, only ctags accepts this option.
-T, --typedefs-and-c++
Generate tag entries for typedefs, struct, enum, and union
tags, and C++ member functions. Since this is the default be-
haviour of etags, only ctags accepts this option.
-u, --update
Update tag entries for files specified on command line, leaving
tag entries for other files in place. Currently, this is im-
plemented 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 ctags accepts this option.
-v, --vgrind
Instead of generating a tag file, write index (in vgrind for-
mat) to standard output. Only ctags accepts this option.
-w, --no-warn
Suppress warning messages about duplicate entries. The etags
program does not check for duplicate entries, so this option is
not allowed with it.
-x, --cxref
Instead of generating a tag file, write a cross reference (in
cxref format) to standard output. Only ctags accepts this op-
tion.
-h, -H, --help
Print usage information.
-V, --version
Print the current version of the program (same as the version
of the emacs etags is shipped with).
SEE ALSO
‘emacs’ entry in info; GNU Emacs Manual, Richard Stallman.
cxref(1), emacs(1), vgrind(1), vi(1).
COPYING
Copyright (c) 1999, 2001 Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.1 or
any later version published by the Free Software Foundation; with no
Invariant Sections, with no Front-Cover Texts, and no Back-Cover
Texts.
This document is part of a collection distributed under the GNU Free
Documentation License. If you want to distribute this document sepa-
rately from the collection, you can do so by adding a copy of the li-
cense to the document, as described in section 6 of the license. A
copy of the license is included in the gfdl(1) man page, and in the
section entitled "GNU Free Documentation License" in the Emacs manual.
GNU Tools 08apr2001 etags(1)
