1ETAGS(1) GNU ETAGS(1)
2
6 etags, ctags - generate tag file for Emacs, vi
7
9 etags [-aCDGIQRVh] [-i file] [-l language]
10 [-o tagfile] [-r regexp] [--parse-stdin=file]
11 [--append] [--no-defines] [--globals] [--no-globals]
12 [--no-line-directive] [--include=file] [--ignore-indentation]
13 [--language=language] [--members] [--no-members] [--output=tagfile]
14 [--class-qualify] [--regex=regexp] [--no-regex] [--help] [--version]
15 file ...
16 ctags [-aCdgIQRVh] [-BtTuvwx] [-l language]
18 [-o tagfile] [-r regexp] [--parse-stdin=file]
19 [--append] [--backward-search] [--cxref] [--no-defines] [--globals]
20 [--no-globals] [--no-line-directive] [--ignore-indentation]
21 [--language=language] [--members] [--no-members] [--class-qualify]
22 [--output=tagfile] [--regex=regexp] [--update] [--help] [--version]
23 file ...
24
26 The etags program is used to create a tag table file, in a format un‐
27 derstood by emacs(1); the ctags program is used to create a similar ta‐
28 ble in a format understood by vi(1). Both forms of the program under‐
29 stand the syntax of C, Objective C, C++, Java, Fortran, Ada, Cobol, Er‐
30 lang, Forth, Go, HTML, LaTeX, Emacs Lisp/Common Lisp, Lua, Makefile,
31 Mercury, Pascal, Perl, Ruby, Rust, PHP, PostScript, Python, Prolog,
32 Scheme and most assembler-like syntaxes. Both forms read the files
33 specified on the command line, and write a tag table (defaults: TAGS
34 for etags, tags for ctags) in the current working directory. Files
35 specified with relative file names will be recorded in the tag table
36 with file names relative to the directory where the tag table resides.
37 If the tag table is in /dev or is the standard output, however, the
38 file names are made relative to the working directory. Files specified
39 with absolute file names will be recorded with absolute file names.
40 Files generated from a source file--like a C file generated from a
41 source Cweb file--will be recorded with the name of the source file.
42 Compressed files are supported using gzip, bzip2, xz, and zstd. The
43 programs recognize the language used in an input file based on its file
44 name and contents. The --language switch can be used to force parsing
45 of the file names following the switch according to the given language,
46 overriding guesses based on filename extensions.
47
49 Some options make sense only for the vi style tag files produced by
50 ctags; etags does not recognize them. The programs accept unambiguous
51 abbreviations for long option names.
52 -a, --append
54 Append to existing tag file. (For vi-format tag files, see also
55 --update.)
56 -B, --backward-search
58 Tag files written in the format expected by vi contain regular
59 expression search instructions; the -B option writes them using
60 the delimiter "?", to search backwards through files. The de‐
61 fault is to use the delimiter "/", to search forwards through
62 files. Only ctags accepts this option.
63 --declarations
65 In C and derived languages, create tags for function declara‐
66 tions, and create tags for extern variables unless --no-globals
67 is used. In Lisp, create tags for (defvar foo) declarations.
68 In Mercury, declarations start a line with ":-" and are always
69 tagged. In addition, this option tags predicates or functions
70 in first rules of clauses, as in Prolog.
71 -D, --no-defines
73 Do not create tag entries for C preprocessor constant defini‐
74 tions and enum constants. This may make the tags file much
75 smaller if many header files are tagged.
76 --globals
78 Create tag entries for global variables in Perl and Makefile.
79 This is the default in C and derived languages.
80 --no-globals
82 Do not tag global variables in C and derived languages. Typi‐
83 cally this reduces the file size by one fourth.
84 --no-line-directive
86 Ignore #line preprocessor directives in C and derived languages.
87 The default is to honor those directives, and record the tags as
88 if the file scanned was the one named in the #line directive.
89 This switch is useful when the original file named by #line is
90 no longer available.
91 -i file, --include=file
93 Include a note in the tag file indicating that, when searching
94 for a tag, one should also consult the tags file file after
95 checking the current file. Only etags accepts this option.
96 -I, --ignore-indentation
98 Don't rely on indentation as much as we normally do. Currently,
99 this means not to assume that a closing brace in the first col‐
100 umn is the final brace of a function or structure definition in
101 C and C++. This is important for code that doesn't observe the
102 GNU Coding conventions of placing only top-level braces in col‐
103 umn zero.
104 -l language, --language=language
106 Parse the following files according to the given language. More
107 than one such options may be intermixed with filenames. Use
108 --help to get a list of the available languages and their de‐
109 fault filename extensions. For example, as Mercury and Objec‐
110 tive-C have same filename extension .m, a test based on contents
111 tries to detect the language. If this test fails, --lan‐
112 guage=mercury or --language=objc should be used. The "auto"
113 language can be used to restore automatic detection of language
114 based on the file name. The "none" language may be used to dis‐
115 able language parsing altogether; only regexp matching is done
116 in this case (see the --regex option).
117 --members
119 Create tag entries for variables that are members of structure-
120 like constructs in PHP. This is the default for C and derived
121 languages.
122 --no-members
124 Do not tag member variables.
125 --packages-only
127 Only tag packages in Ada files.
128 --parse-stdin=file
130 May be used (only once) in place of a file name on the command
131 line. etags will read from standard input and mark the produced
132 tags as belonging to the file FILE.
133 -Q, --class-qualify
135 Qualify tag names with their class name in C++, ObjC, Java, and
136 Perl. This produces tag names of the form class::member for C++
137 and Perl, class(category) for Objective C, and class.member for
138 Java. For Objective C, this also produces class methods quali‐
139 fied with their arguments, as in foo:bar:baz:more.
140 -o tagfile, --output=tagfile
142 Explicit name of file for tag table; for etags only, a file name
143 of - means standard output; overrides default TAGS or tags.
144 (But ignored with -v or -x.)
145 -r regexp, --regex=regexp
147 Make tags based on regexp matching for the files following this
149 option, in addition to the tags made with the standard parsing
150 based on language. May be freely intermixed with filenames and
151 the -R option. The regexps are cumulative, i.e., each such op‐
152 tion will add to the previous ones. The regexps are of one of
153 the forms:
154 [{language}]/tagregexp/[nameregexp/]modifiers
155 @regexfile
156 where tagregexp is used to match the tag. It should not match
158 useless characters. If the match is such that more characters
159 than needed are unavoidably matched by tagregexp, it may be use‐
160 ful to add a nameregexp, to narrow down the tag scope. ctags
161 ignores regexps without a nameregexp. The syntax of regexps is
162 the same as in emacs. The following character escape sequences
163 are supported: \a, \b, \d, \e, \f, \n, \r, \t, \v, which respec‐
164 tively stand for the ASCII characters BEL, BS, DEL, ESC, FF, NL,
165 CR, TAB, VT.
166 The modifiers are a sequence of 0 or more characters among i,
167 which means to ignore case when matching; m, which means that
168 the tagregexp will be matched against the whole file contents at
169 once, rather than line by line, and the matching sequence can
170 match multiple lines; and s, which implies m and means that the
171 dot character in tagregexp matches the newline char as well.
172 The separator, which is / in the examples, can be any character
173 different from space, tab, braces and @. If the separator char‐
174 acter is needed inside the regular expression, it must be quoted
175 by preceding it with \.
176 The optional {language} prefix means that the tag should be cre‐
177 ated only for files of language language, and ignored otherwise.
178 This is particularly useful when storing many predefined regexps
179 in a file.
180 In its second form, regexfile is the name of a file that con‐
181 tains a number of arguments to the --regex= option, one per
182 line. Lines beginning with a space or tab are assumed to be
183 comments, and ignored.
184 Here are some examples. All the regexps are quoted to protect
186 them from shell interpretation.
187 Tag the DEFVAR macros in the emacs source files:
189 --regex='/[ \t]*DEFVAR_[A-Z_ \t(]+"\([^"]+\)"/'
190 Tag VHDL files (this example is a single long line, broken here
192 for formatting reasons):
193 --language=none --regex='/[ \t]*\(ARCHITECTURE\|\ CONFIGURA‐
194 TION\) +[^ ]* +OF/' --regex='/[ \t]*\ \(ATTRIBUTE\|ENTITY\|FUNC‐
195 TION\|PACKAGE\( BODY\)?\ \|PROCE‐
196 DURE\|PROCESS\|TYPE\)[ \t]+\([^ \t(]+\)/\3/'
197 Tag TCL files (this last example shows the usage of a tagreg‐
199 exp):
200 --lang=none --regex='/proc[ \t]+\([^ \t]+\)/\1/'
201 A regexp can be preceded by {lang}, thus restricting it to match
203 lines of files of the specified language. Use etags --help to
204 obtain a list of the recognized languages. This feature is par‐
205 ticularly useful inside regex files. A regex file contains one
206 regex per line. Empty lines, and those lines beginning with
207 space or tab are ignored. Lines beginning with @ are references
208 to regex files whose name follows the @ sign. Other lines are
209 considered regular expressions like those following --regex.
210 For example, the command
211 etags --regex=@regex.file *.c
212 reads the regexes contained in the file regex.file.
213 -R, --no-regex
215 Don't do any more regexp matching on the following files. May
216 be freely intermixed with filenames and the --regex option.
217 -u, --update
219 Update tag entries for files specified on command line, leaving
220 tag entries for other files in place. Currently, this is imple‐
221 mented by deleting the existing entries for the given files and
222 then rewriting the new entries at the end of the tags file. It
223 is often faster to simply rebuild the entire tag file than to
224 use this. Only ctags accepts this option.
225 -v, --vgrind
227 Instead of generating a tag file, write index (in vgrind format)
228 to standard output. Only ctags accepts this option.
229 -x, --cxref
231 Instead of generating a tag file, write a cross reference (in
232 cxref format) to standard output. Only ctags accepts this op‐
233 tion.
234 -h, -H, --help
236 Print usage information. Followed by one or more --lan‐
237 guage=LANG prints detailed information about how tags are creat‐
238 ed for LANG.
239 -V, --version
241 Print the current version of the program (same as the version of
242 the emacs etags is shipped with).
243
246 "emacs" entry in info; GNU Emacs Manual, Richard Stallman.
247 cxref(1), emacs(1), vgrind(1), vi(1).
248
251 Copyright 1992, 1999, 2001-2022 Free Software Foundation, Inc.
252 Permission is granted to make and distribute verbatim copies of this
254 document provided the copyright notice and this permission notice are
255 preserved on all copies.
256 Permission is granted to copy and distribute modified versions of this
258 document under the conditions for verbatim copying, provided that the
259 entire resulting derived work is distributed under the terms of a per‐
260 mission notice identical to this one.
261 Permission is granted to copy and distribute translations of this docu‐
263 ment into another language, under the above conditions for modified
264 versions, except that this permission notice may be stated in a trans‐
265 lation approved by the Free Software Foundation.
266GNU Tools 2022-06-10 ETAGS(1)