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etags, gnuctags - generate tag file for Emacs, vi
SYNOPSIS
etags [-aCDGImRVh] [-i file] [-l language]
[-o tagfile] [-r regexp] [--parse-stdin=file]
[--append] [--no-defines] [--no-globals] [--include=file] [--ignore-indentation] [--language=language]
[--members] [--output=tagfile] [--regex=regexp] [--no-regex] [--help] [--version] file ...
gnuctags [-aCdgImRVh] [-ABtTuvwx] [-l language]
[-o tagfile] [-r regexp] [--parse-stdin=file]
[--allow-duplicates] [--append] [--backward-search] [--cxref] [--defines] [--forward-search] [--globals]
[--ignore-indentation] [--language=language] [--members] [--output=tagfile] [--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 understood by emacs(1); the gnuctags program is
used to create a similar table in a format understood by vi(1). Both forms of the program understand the syntax
of C, Objective C, C++, Java, Fortran, Ada, Cobol, Erlang, HTML, LaTeX, Emacs Lisp/Common Lisp, Lua, makefile,
Pascal, Perl, 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: TAGS for etags, tags for gnuctags) 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, 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. 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 gnuctags; etags does not recognize them. The
programs accept unambiguous abbreviations for long option names.
-A, --allow-duplicates
Create entries for duplicate tags. Some editors accept tags files with entries for duplicate tags. Since
this is the default behavior of etags, only gnuctags accepts this option.
-a, --append
Append to existing tag file. (For vi-format tag files, see also --update.)
-B, --backward-search
Tag files written in the format expected by vi contain regular expression search instructions; the -B op-
tion writes them using the delimiter `?', to search backwards through files. The default is to use the
delimiter `/', to search forwards through files. Only gnuctags accepts this option.
--declarations
In C and derived languages, create tags for function declarations, 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. Since this is the de-
fault behavior of etags, only gnuctags accepts this option.
-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. Since this is the default behavior of gnuctags,
only etags accepts this option.
--globals
Create tag entries for global variables in C, C++, Objective C, Java, and Perl. Since this is the default
behavior of etags, only gnuctags accepts this option.
--no-globals
Do not tag global variables. Typically this reduces the file size by one fourth. Since this is the de-
fault behavior of gnuctags, only etags accepts this option.
-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. Only etags accepts this option.
-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++.
-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 exten-
sions. 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.
--parse-stdin=file
May be used (only once) in place of a file name on the command line. etags will read from standard input
and mark the produced tags as belonging to the file FILE.
-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
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 -R option. The
regexps are cumulative, i.e. each such option will add to the previous ones. The regexps are of one of
the forms:
[{language}]/tagregexp/[nameregexp/]modifiers
@regexfile
where tagregexp 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 tagregexp, it may be useful to add a namereg-
exp, to narrow down the tag scope. gnuctags ignores regexps without a nameregexp. 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.
The modifiers are a sequence of 0 or more characters among i, which means to ignore case when matching; m,
which means that the tagregexp will be matched against the whole file contents at once, rather than line
by line, and the matching sequence can match multiple lines; and s, which implies m and means that the dot
character in tagregexp matches the newline char as well.
The separator, which is / in the examples, can be any character different from space, tab, braces and @.
If the separator character is needed inside the regular expression, it must be quoted by preceding it with
\.
The optional {language} prefix means that the tag should be created only for files of language language,
and ignored otherwise. This is particularly useful when storing many predefined regexps in a file.
In its second form, regexfile is the name of a file that contains a number of arguments to the --regex=
option, one per line. Lines beginning with a space or tab are assumed to be comments, and ignored.
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]*\(ARCHITECTURE\|\ CONFIGURATION\) +[^ ]* +OF/' --regex='/[ \t]*\ \(AT-
TRIBUTE\|ENTITY\|FUNCTION\|PACKAGE\( BODY\)?\ \|PROCEDURE\|PROCESS\|TYPE\)[ \t]+\([^ \t(]+\)/\3/'
Tag TCL files (this last example shows the usage of a tagregexp):
--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 feature is particularly useful inside
regex files. 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 --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 behavior of etags, only gnuctags 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 behavior of etags, only gnuctags 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 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 gnuctags accepts this option.
-v, --vgrind
Instead of generating a tag file, write index (in vgrind format) to standard output. Only gnuctags ac-
cepts this option.
-w, --no-warn
Suppress warning messages about duplicate entries. The etags program does not check for duplicate en-
tries, 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
gnuctags accepts this option.
-h, -H, --help
Print usage information. Followed by one or more --language=LANG prints detailed information about how
tags are created for LANG.
-V, --version
Print the current version of the program (same as the version of the emacs etags is shipped with).
RELATED
`emacs' entry in info; GNU Emacs Manual, Richard Stallman.
ctags(1), cxref(1), emacs(1), gnuctags(1), vgrind(1), vi(1).
COPYING
Copyright (c) 1999, 2001, 2002, 2003, 2004, 2005, 2006 Free Software Foundation, Inc.
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.
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.
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.
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