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ETAGS(1)			      GNU			      ETAGS(1)

NAME
       etags, ctags - generate tag file	for Emacs, vi

SYNOPSIS
       etags [-aCDGIQRVh] [-i file] [-l	language]
       [-o tagfile] [-r	regexp]	[--parse-stdin=file]
       [--append] [--no-defines] [--globals] [--no-globals]
       [--no-line-directive] [--include=file] [--ignore-indentation]
       [--language=language] [--members] [--no-members]	[--output=tagfile]
       [--class-qualify] [--regex=regexp] [--no-regex] [--help]	[--version]
       file ...

       ctags [-aCdgIQRVh] [-BtTuvwx] [-l language]
       [-o tagfile] [-r	regexp]	[--parse-stdin=file]
       [--append] [--backward-search] [--cxref]	[--no-defines] [--globals]
       [--no-globals] [--no-line-directive] [--ignore-indentation]
       [--language=language] [--members] [--no-members]	[--class-qualify]
       [--output=tagfile] [--regex=regexp] [--update] [--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 ta-
       ble  in a format	understood by vi(1).  Both forms of the	program	under-
       stand the syntax	of C, Objective	C, C++,	Java, Fortran, Ada, Cobol, Er-
       lang,  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:  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.
       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	--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 also
	      --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.	In Lisp, create	tags for  (defvar  foo)	 declarations.
	      In  Mercury,  declarations start a line with ":-"	and are	always
	      tagged.  In addition, this option	tags predicates	 or  functions
	      in first rules of	clauses, as in Prolog.

       -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.

       --globals
	      Create  tag  entries  for	global variables in Perl and Makefile.
	      This is the default in C and derived languages.

       --no-globals
	      Do not tag global	variables in C and derived  languages.	 Typi-
	      cally this reduces the file size by one fourth.

       --no-line-directive
	      Ignore #line 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 #line directive.
	      This switch is useful when the original file named by  #line  is
	      no longer	available.

       -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  col-
	      umn  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  de-
	      fault  filename  extensions.  For	example, as Mercury and	Objec-
	      tive-C have same filename	extension .m, a	test based on contents
	      tries  to	 detect	 the  language.	  If  this  test fails,	--lan-
	      guage=mercury or --language=objc 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 dis-
	      able  language  parsing altogether; only regexp matching is done
	      in this case (see	the --regex option).

       --members
	      Create tag entries for variables that are	members	of  structure-
	      like  constructs	in PHP.	 This is the default for C and derived
	      languages.

       --no-members
	      Do not tag member	variables.

       --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.

       -Q, --class-qualify
	      Qualify tag names	with their class name in C++, ObjC, Java,  and
	      Perl.  This produces tag names of	the form class::member for C++
	      and Perl,	class(category)	for Objective C, and class.member  for
	      Java.   For Objective C, this also produces class	methods	quali-
	      fied with	their arguments, as in foo:bar:baz:more.

       -o tagfile, --output=tagfile
	      Explicit name of file for	tag table; for etags only, a file name
	      of  -  means  standard  output;  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 op-
	      tion 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 use-
	      ful 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.  The following character escape  sequences
	      are supported: \a, \b, \d, \e, \f, \n, \r, \t, \v, which respec-
	      tively 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 char-
	      acter is needed inside the regular expression, it	must be	quoted
	      by preceding it with \.
	      The optional {language} prefix means that	the tag	should be cre-
	      ated 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  con-
	      tains  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]*\(ARCHITECTURE\|\	    CONFIGURA-
	      TION\) +[^ ]* +OF/' --regex='/[ \t]*\ \(ATTRIBUTE\|ENTITY\|FUNC-
	      TION\|PACKAGE\( BODY\)?\				      \|PROCE-
	      DURE\|PROCESS\|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 recognized languages.  This feature is par-
	      ticularly	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.

       -u, --update
	      Update  tag entries for files specified on command line, leaving
	      tag entries for other files in place.  Currently,	this is	imple-
	      mented  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 format)
	      to standard output.  Only	ctags accepts this option.

       -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.   Followed  by	 one  or  more	--lan-
	      guage=LANG prints	detailed information about how tags are	creat-
	      ed for LANG.

       -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 1992, 1999, 2001-2022 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  per-
       mission notice identical	to this	one.

       Permission is granted to	copy and distribute translations of this docu-
       ment into another language, under the  above  conditions	 for  modified
       versions,  except that this permission notice may be stated in a	trans-
       lation approved by the Free Software Foundation.

GNU Tools			  2021-03-30			      ETAGS(1)

NAME | SYNOPSIS | DESCRIPTION | OPTIONS | SEE ALSO | COPYING

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