1CTAGS(1) Exuberant Ctags CTAGS(1)
2
6 ctags - Generate tag files for source code
7
11 ctags [options] [file(s)]
12 etags [options] [file(s)]
14
18 The ctags and etags programs (hereinafter collectively referred to as
19 ctags, except where distinguished) generate an index (or "tag") file
20 for a variety of language objects found in file(s). This tag file
21 allows these items to be quickly and easily located by a text editor or
22 other utility. A "tag" signifies a language object for which an index
23 entry is available (or, alternatively, the index entry created for that
24 object).
25 Alternatively, ctags can generate a cross reference file which lists,
27 in human readable form, information about the various source objects
28 found in a set of language files.
29 Tag index files are supported by numerous editors, which allow the user
31 to locate the object associated with a name appearing in a source file
32 and jump to the file and line which defines the name. Those known about
33 at the time of this release are:
34 Vi(1) and its derivatives (e.g. Elvis, Vim, Vile, Lemmy), CRiSP,
36 Emacs, FTE (Folding Text Editor), JED, jEdit, Mined, NEdit (Nirvana
37 Edit), TSE (The SemWare Editor), UltraEdit, WorkSpace, X2, Zeus
38 Ctags is capable of generating different kinds of tags for each of many
40 different languages. For a complete list of supported languages, the
41 names by which they are recognized, and the kinds of tags which are
42 generated for each, see the --list-languages and --list-kinds options.
43
47 Unless the --language-force option is specified, the language of each
48 source file is automatically selected based upon a mapping of file
49 names to languages. The mappings in effect for each language may be
50 display using the --list-maps option and may be changed using the
51 --langmap option. On platforms which support it, if the name of a file
52 is not mapped to a language and the file is executable, the first line
53 of the file is checked to see if the file is a "#!" script for a recog‐
54 nized language.
55 By default, all other files names are ignored. This permits running
57 ctags on all files in either a single directory (e.g. "ctags *"), or on
58 all files in an entire source directory tree (e.g. "ctags -R"), since
59 only those files whose names are mapped to languages will be scanned.
60 [The reason that .h extensions are mapped to C++ files rather than C
62 files is because it is common to use .h extensions in C++, and no harm
63 results in treating them as C++ files.]
64
68 Despite the wealth of available options, defaults are set so that ctags
69 is most commonly executed without any options (e.g. "ctags *", or
70 "ctags -R"), which will create a tag file in the current directory for
71 all recognized source files. The options described below are provided
72 merely to allow custom tailoring to meet special needs.
73 Note that spaces separating the single-letter options from their param‐
75 eters are optional.
76 Note also that the boolean parameters to the long form options (those
78 beginning with "--" and that take a "[=yes|no]" parameter) may be omit‐
79 ted, in which case "=yes" is implied. (e.g. --sort is equivalent to
80 --sort=yes). Note further that "=1" and "=on" are considered synonyms
81 for "=yes", and that "=0" and "=off" are considered synonyms for "=no".
82 Some options are either ignored or useful only when used while running
84 in etags mode (see -e option). Such options will be noted.
85 Most options may appear anywhere on the command line, affecting only
87 those files which follow the option. A few options, however, must
88 appear before the first file name and will be noted as such.
89 Options taking language names will accept those names in either upper
91 or lower case. See the --list-languages option for a complete list of
92 the built-in language names.
93 -a Equivalent to --append.
96 -B Use backward searching patterns (e.g. ?pattern?). [Ignored in
99 etags mode]
100 -e Enable etags mode, which will create a tag file for use with the
103 Emacs editor. Alternatively, if ctags is invoked by a name con‐
104 taining the string "etags" (either by renaming, or creating a link
105 to, the executable), etags mode will be enabled. This option must
106 appear before the first file name.
107 -f tagfile
110 Use the name specified by tagfile for the tag file (default is
111 "tags", or "TAGS" when running in etags mode). If tagfile is spec‐
112 ified as "-", then the tag file is written to standard output
113 instead. Ctags will stubbornly refuse to take orders if tagfile
114 exists and its first line contains something other than a valid
115 tags line. This will save your neck if you mistakenly type "ctags
116 -f *.c", which would otherwise overwrite your first C file with
117 the tags generated by the rest! It will also refuse to accept a
118 multi-character file name which begins with a '-' (dash) charac‐
119 ter, since this most likely means that you left out the tag file
120 name and this option tried to grab the next option as the file
121 name. If you really want to name your output tag file "-ugly",
122 specify it as "./-ugly". This option must appear before the first
123 file name. If this option is specified more than once, only the
124 last will apply.
125 -F Use forward searching patterns (e.g. /pattern/) (default).
128 [Ignored in etags mode]
129 -h list
132 Specifies a list of file extensions, separated by periods, which
133 are to be interpreted as include (or header) files. To indicate
134 files having no extension, use a period not followed by a non-
135 period character (e.g. ".", "..x", ".x."). This option only
136 affects how the scoping of a particular kinds of tags is inter‐
137 preted (i.e. whether or not they are considered as globally visi‐
138 ble or visible only within the file in which they are defined); it
139 does not map the extension to any particular language. Any tag
140 which is located in a non-include file and cannot be seen (e.g.
141 linked to) from another file is considered to have file-limited
142 (e.g. static) scope. No kind of tag appearing in an include file
143 will be considered to have file-limited scope. If the first char‐
144 acter in the list is a plus sign, then the extensions in the list
145 will be appended to the current list; otherwise, the list will
146 replace the current list. See, also, the --file-scope option. The
147 default list is ".h.H.hh.hpp.hxx.h++.inc.def". To restore the
148 default list, specify -h default. Note that if an extension sup‐
149 plied to this option is not already mapped to a particular lan‐
150 guage (see SOURCE FILES, above), you will also need to use either
151 the --langmap or --language-force option.
152 -I identifier-list
155 Specifies a list of identifiers which are to be specially handled
156 while parsing C and C++ source files. This option is specifically
157 provided to handle special cases arising through the use of pre‐
158 processor macros. When the identifiers listed are simple identi‐
159 fiers, these identifiers will be ignored during parsing of the
160 source files. If an identifier is suffixed with a '+' character,
161 ctags will also ignore any parenthesis-enclosed argument list
162 which may immediately follow the identifier in the source files.
163 If two identifiers are separated with the '=' character, the first
164 identifiers is replaced by the second identifiers for parsing pur‐
165 poses. The list of identifiers may be supplied directly on the
166 command line or read in from a separate file. If the first charac‐
167 ter of identifier-list is '@', '.' or a pathname separator ('/' or
168 '\'), or the first two characters specify a drive letter (e.g.
169 "C:"), the parameter identifier-list will be interpreted as a
170 filename from which to read a list of identifiers, one per input
171 line. Otherwise, identifier-list is a list of identifiers (or
172 identifier pairs) to be specially handled, each delimited by a
173 either a comma or by white space (in which case the list should be
174 quoted to keep the entire list as one command line argument). Mul‐
175 tiple -I options may be supplied. To clear the list of ignore
176 identifiers, supply a single dash ("-") for identifier-list.
177 This feature is useful when preprocessor macros are used in such a
179 way that they cause syntactic confusion due to their presence.
180 Indeed, this is the best way of working around a number of prob‐
181 lems caused by the presence of syntax-busting macros in source
182 files (see CAVEATS, below). Some examples will illustrate this
183 point.
184 int foo ARGDECL4(void *, ptr, long int, nbytes)
186 In the above example, the macro "ARGDECL4" would be mistakenly
189 interpreted to be the name of the function instead of the correct
190 name of "foo". Specifying -I ARGDECL4 results in the correct
191 behavior.
192 /* creates an RCS version string in module */
194 MODULE_VERSION("$Revision: 690 $")
195 In the above example the macro invocation looks too much like a
198 function definition because it is not followed by a semicolon
199 (indeed, it could even be followed by a global variable definition
200 that would look much like a K&R style function parameter declara‐
201 tion). In fact, this seeming function definition could possibly
202 even cause the rest of the file to be skipped over while trying to
203 complete the definition. Specifying -I MODULE_VERSION+ would avoid
204 such a problem.
205 CLASS Example {
207 // your content here
208 };
209 The example above uses "CLASS" as a preprocessor macro which
212 expands to something different for each platform. For instance
213 CLASS may be defined as "class __declspec(dllexport)" on Win32
214 platforms and simply "class" on UNIX. Normally, the absence of
215 the C++ keyword "class" would cause the source file to be incor‐
216 rectly parsed. Correct behavior can be restored by specifying -I
217 CLASS=class.
218 -L file
221 Read from file a list of file names for which tags should be gen‐
222 erated. If file is specified as "-", then file names are read
223 from standard input. File names read using this option are pro‐
224 cessed following file names appearing on the command line. Options
225 are also accepted in this input. If this option is specified more
226 than once, only the last will apply. Note: file is read in line-
227 oriented mode, where a new line is the only delimiter and non-
228 trailing white space is considered significant, in order that file
229 names containing spaces may be supplied (however, trailing white
230 space is stripped from lines); this can affect how options are
231 parsed if included in the input.
232 -n Equivalent to --excmd=number.
235 -N Equivalent to --excmd=pattern.
238 -o tagfile
241 Equivalent to -f tagfile.
242 -R Equivalent to --recurse.
245 -u Equivalent to --sort=no (i.e. "unsorted").
248 -V Equivalent to --verbose.
251 -w This option is silently ignored for backward-compatibility with
254 the ctags of SVR4 Unix.
255 -x Print a tabular, human-readable cross reference (xref) file to
258 standard output instead of generating a tag file. The information
259 contained in the output includes: the tag name; the kind of tag;
260 the line number, file name, and source line (with extra white
261 space condensed) of the file which defines the tag. No tag file is
262 written and all options affecting tag file output will be ignored.
263 Example applications for this feature are generating a listing of
264 all functions located in a source file (e.g. ctags -x --c-kinds=f
265 file), or generating a list of all externally visible global vari‐
266 ables located in a source file (e.g. ctags -x --c-kinds=v
267 --file-scope=no file). This option must appear before the first
268 file name.
269 --append[=yes|no]
272 Indicates whether tags generated from the specified files should
273 be appended to those already present in the tag file or should
274 replace them. This option is off by default. This option must
275 appear before the first file name.
276 --etags-include=file
279 Include a reference to file in the tag file. This option may be
280 specified as many times as desired. This supports Emacs' capabil‐
281 ity to use a tag file which "includes" other tag files. [Available
282 only in etags mode]
283 --exclude=[pattern]
286 Add pattern to a list of excluded files and directories. This
287 option may be specified as many times as desired. For each file
288 name considered by ctags, each pattern specified using this option
289 will be compared against both the complete path (e.g.
290 some/path/base.ext) and the base name (e.g. base.ext) of the file,
291 thus allowing patterns which match a given file name irrespective
292 of its path, or match only a specific path. If appropriate support
293 is available from the runtime library of your C compiler, then
294 pattern may contain the usual shell wildcards (not regular expres‐
295 sions) common on Unix (be sure to quote the option parameter to
296 protect the wildcards from being expanded by the shell before
297 being passed to ctags; also be aware that wildcards can match the
298 slash character, '/'). You can determine if shell wildcards are
299 available on your platform by examining the output of the --ver‐
300 sion option, which will include "+wildcards" in the compiled fea‐
301 ture list; otherwise, pattern is matched against file names using
302 a simple textual comparison.
303 If pattern begins with the character '@', then the rest of the
305 string is interpreted as a file name from which to read exclusion
306 patterns, one per line. If pattern is empty, the list of excluded
307 patterns is cleared. Note that at program startup, the default
308 exclude list contains "EIFGEN", "SCCS", "RCS", and "CVS", which
309 are names of directories for which it is generally not desirable
310 to descend while processing the --recurse option.
311 --excmd=type
314 Determines the type of EX command used to locate tags in the
315 source file. [Ignored in etags mode]
316 The valid values for type (either the entire word or the first
318 letter is accepted) are:
319 number Use only line numbers in the tag file for locating tags.
322 This has four advantages:
323 1. Significantly reduces the size of the resulting tag
324 file.
325 2. Eliminates failures to find tags because the line
326 defining the tag has changed, causing the pattern
327 match to fail (note that some editors, such as vim,
328 are able to recover in many such instances).
329 3. Eliminates finding identical matching, but incorrect,
330 source lines (see BUGS, below).
331 4. Retains separate entries in the tag file for lines
332 which are identical in content. In pattern mode,
333 duplicate entries are dropped because the search pat‐
334 terns they generate are identical, making the dupli‐
335 cate entries useless.
336 However, this option has one significant drawback:
339 changes to the source files can cause the line numbers
340 recorded in the tag file to no longer correspond to the
341 lines in the source file, causing jumps to some tags to
342 miss the target definition by one or more lines. Basi‐
343 cally, this option is best used when the source code to
344 which it is applied is not subject to change. Selecting
345 this option type causes the following options to be
346 ignored: -BF.
347 pattern Use only search patterns for all tags, rather than the
350 line numbers usually used for macro definitions. This has
351 the advantage of not referencing obsolete line numbers
352 when lines have been added or removed since the tag file
353 was generated.
354 mixed In this mode, patterns are generally used with a few
357 exceptions. For C, line numbers are used for macro defi‐
358 nition tags. This was the default format generated by the
359 original ctags and is, therefore, retained as the default
360 for this option. For Fortran, line numbers are used for
361 common blocks because their corresponding source lines
362 are generally identical, making pattern searches useless
363 for finding all matches.
364 --extra=[+|-]flags
367 Specifies whether to include extra tag entries for certain kinds
368 of information. The parameter flags is a set of one-letter flags,
369 each representing one kind of extra tag entry to include in the
370 tag file. If flags is preceded by by either the '+' or '-' charac‐
371 ter, the effect of each flag is added to, or removed from, those
372 currently enabled; otherwise the flags replace any current set‐
373 tings. The meaning of each flag is as follows:
374 f Include an entry for the base file name of every source
377 file (e.g. "example.c"), which addresses the first line of
378 the file.
379 q Include an extra class-qualified tag entry for each tag
381 which is a member of a class (for languages for which this
382 information is extracted; currently C++, Eiffel, and Java).
383 The actual form of the qualified tag depends upon the lan‐
384 guage from which the tag was derived (using a form that is
385 most natural for how qualified calls are specified in the
386 language). For C++, it is in the form "class::member"; for
387 Eiffel and Java, it is in the form "class.member". This may
388 allow easier location of a specific tags when multiple
389 occurrences of a tag name occur in the tag file. Note, how‐
390 ever, that this could potentially more than double the size
391 of the tag file.
392 --fields=[+|-]flags
395 Specifies the available extension fields which are to be included
396 in the entries of the tag file (see TAG FILE FORMAT, below, for
397 more information). The parameter flags is a set of one-letter
398 flags, each representing one type of extension field to include,
399 with the following meanings (disabled by default unless indi‐
400 cated):
401 a Access (or export) of class members
404 f File-restricted scoping [enabled]
405 i Inheritance information
406 k Kind of tag as a single letter [enabled]
407 K Kind of tag as full name
408 l Language of source file containing tag
409 m Implementation information
410 n Line number of tag definition
411 s Scope of tag definition [enabled]
412 S Signature of routine (e.g. prototype or parameter list)
413 z Include the "kind:" key in kind field
414 t Type and name of a variable or typedef as "typeref:" field
415 [enabled]
416 Each letter or group of letters may be preceded by either '+' to
418 add it to the default set, or '-' to exclude it. In the absence of
419 any preceding '+' or '-' sign, only those kinds explicitly listed
420 in flags will be included in the output (i.e. overriding the
421 default set). This option is ignored if the option --format=1 has
422 been specified. The default value of this option is fkst.
423 --file-scope[=yes|no]
426 Indicates whether tags scoped only for a single file (i.e. tags
427 which cannot be seen outside of the file in which they are
428 defined, such as "static" tags) should be included in the output.
429 See, also, the -h option. This option is enabled by default.
430 --filter[=yes|no]
433 Causes ctags to behave as a filter, reading source file names from
434 standard input and printing their tags to standard output on a
435 file-by-file basis. If --sorted is enabled, tags are sorted only
436 within the source file in which they are defined. File names are
437 read from standard input in line-oriented input mode (see note for
438 -L option) and only after file names listed on the command line or
439 from any file supplied using the -L option. When this option is
440 enabled, the options -f, -o, and --totals are ignored. This option
441 is quite esoteric and is disabled by default. This option must
442 appear before the first file name.
443 --filter-terminator=string
446 Specifies a string to print to standard output following the tags
447 for each file name parsed when the --filter option is enabled.
448 This may permit an application reading the output of ctags to
449 determine when the output for each file is finished. Note that if
450 the file name read is a directory and --recurse is enabled, this
451 string will be printed only one once at the end of all tags found
452 for by descending the directory. This string will always be sepa‐
453 rated from the last tag line for the file by its terminating new‐
454 line. This option is quite esoteric and is empty by default. This
455 option must appear before the first file name.
456 --format=level
459 Change the format of the output tag file. Currently the only valid
460 values for level are 1 or 2. Level 1 specifies the original tag
461 file format and level 2 specifies a new extended format containing
462 extension fields (but in a manner which retains backward-compati‐
463 bility with original vi(1) implementations). The default level is
464 2. This option must appear before the first file name. [Ignored in
465 etags mode]
466 --help
469 Prints to standard output a detailed usage description, and then
470 exits.
471 --if0[=yes|no]
474 Indicates a preference as to whether code within an "#if 0" branch
475 of a preprocessor conditional should be examined for non-macro
476 tags (macro tags are always included). Because the intent of this
477 construct is to disable code, the default value of this option is
478 no. Note that this indicates a preference only and does not guar‐
479 antee skipping code within an "#if 0" branch, since the fall-back
480 algorithm used to generate tags when preprocessor conditionals are
481 too complex follows all branches of a conditional. This option is
482 disabled by default.
483 --<LANG>-kinds=[+|-]kinds
486 Specifies a list of language-specific kinds of tags (or kinds) to
487 include in the output file for a particular language, where <LANG>
488 is case-insensitive and is one of the built-in language names (see
489 the --list-languages option for a complete list). The parameter
490 kinds is a group of one-letter flags designating kinds of tags
491 (particular to the language) to either include or exclude from the
492 output. The specific sets of flags recognized for each language,
493 their meanings and defaults may be list using the --list-kinds
494 option. Each letter or group of letters may be preceded by either
495 '+' to add it to, or '-' to remove it from, the default set. In
496 the absence of any preceding '+' or '-' sign, only those kinds
497 explicitly listed in kinds will be included in the output (i.e.
498 overriding the default for the specified language).
499 As an example for the C language, in order to add prototypes and
501 external variable declarations to the default set of tag kinds,
502 but exclude macros, use --c-kinds=+px-d; to include only tags for
503 functions, use --c-kinds=f.
504 --langdef=name
507 Defines a new user-defined language, name, to be parsed with regu‐
508 lar expressions. Once defined, name may be used in other options
509 taking language names. The typical use of this option is to first
510 define the language, then map file names to it using --langmap,
511 then specify regular expressions using --regex-<LANG> to define
512 how its tags are found.
513 --langmap=map[,map[...]]
516 Controls how file names are mapped to languages (see the
517 --list-maps option). Each comma-separated map consists of the lan‐
518 guage name (either a built-in or user-defined language), a colon,
519 and a list of file extensions and/or file name patterns. A file
520 extension is specified by preceding the extension with a period
521 (e.g. ".c"). A file name pattern is specified by enclosing the
522 pattern in parentheses (e.g. "([Mm]akefile)"). If appropriate sup‐
523 port is available from the runtime library of your C compiler,
524 then the file name pattern may contain the usual shell wildcards
525 common on Unix (be sure to quote the option parameter to protect
526 the wildcards from being expanded by the shell before being passed
527 to ctags). You can determine if shell wildcards are available on
528 your platform by examining the output of the --version option,
529 which will include "+wildcards" in the compiled feature list; oth‐
530 erwise, the file name patterns are matched against file names
531 using a simple textual comparison. When mapping a file extension,
532 it will first be unmapped from any other languages.
533 If the first character in a map is a plus sign, then the exten‐
535 sions and file name patterns in that map will be appended to the
536 current map for that language; otherwise, the map will replace the
537 current map. For example, to specify that only files with exten‐
538 sions of .c and .x are to be treated as C language files, use
539 "--langmap=c:.c.x"; to also add files with extensions of .j as
540 Java language files, specify "--langmap=c:.c.x,java:+.j". To map
541 makefiles (e.g. files named either "Makefile", "makefile", or hav‐
542 ing the extension ".mak") to a language called "make", specify
543 "--langmap=make:([Mm]akefile).mak". To map files having no exten‐
544 sion, specify a period not followed by a non-period character
545 (e.g. ".", "..x", ".x."). To clear the mapping for a particular
546 language (thus inhibiting automatic generation of tags for that
547 language), specify an empty extension list (e.g. "--langmap=for‐
548 tran:"). To restore the default language mappings for all a par‐
549 ticular language, supply the keyword "default" for the mapping.
550 To specify restore the default language mappings for all lan‐
551 guages, specify "--langmap=default". Note that file extensions are
552 tested before file name patterns when inferring the language of a
553 file.
554 --language-force=language
557 By default, ctags automatically selects the language of a source
558 file, ignoring those files whose language cannot be determined
559 (see SOURCE FILES, above). This option forces the specified lan‐
560 guage (case-insensitive; either built-in or user-defined) to be
561 used for every supplied file instead of automatically selecting
562 the language based upon its extension. In addition, the special
563 value auto indicates that the language should be automatically
564 selected (which effectively disables this option).
565 --languages=[+|-]list
568 Specifies the languages for which tag generation is enabled, with
569 list containing a comma-separated list of language names (case-
570 insensitive; either built-in or user-defined). If the first lan‐
571 guage of list is not preceded by either a '+' or '-', the current
572 list will be cleared before adding or removing the languages in
573 list. Until a '-' is encountered, each language in the list will
574 be added to the current list. As either the '+' or '-' is encoun‐
575 tered in the list, the languages following it are added or removed
576 from the current list, respectively. Thus, it becomes simple to
577 replace the current list with a new one, or to add or remove lan‐
578 guages from the current list. The actual list of files for which
579 tags will be generated depends upon the language extension mapping
580 in effect (see the --langmap option). Note that all languages,
581 including user-defined languages are enabled unless explicitly
582 disabled using this option. Language names included in list may be
583 any built-in language or one previously defined with --langdef.
584 The default is "all", which is also accepted as a valid argument.
585 See the --list-languages option for a complete list of the built-
586 in language names.
587 --license
590 Prints a summary of the software license to standard output, and
591 then exits.
592 --line-directives[=yes|no]
595 Specifies whether "#line" directives should be recognized. These
596 are present in the output of preprocessors and contain the line
597 number, and possibly the file name, of the original source file(s)
598 from which the preprocessor output file was generated. When
599 enabled, this option will cause ctags to generate tag entries
600 marked with the file names and line numbers of their locations
601 original source file(s), instead of their actual locations in the
602 preprocessor output. The actual file names placed into the tag
603 file will have the same leading path components as the preproces‐
604 sor output file, since it is assumed that the original source
605 files are located relative to the preprocessor output file
606 (unless, of course, the #line directive specifies an absolute
607 path). This option is off by default. Note: This option is gener‐
608 ally only useful when used together with the --excmd=number (-n)
609 option. Also, you may have to use either the --langmap or --lan‐
610 guage-force option if the extension of the preprocessor output
611 file is not known to ctags.
612 --links[=yes|no]
615 Indicates whether symbolic links (if supported) should be fol‐
616 lowed. When disabled, symbolic links are ignored. This option is
617 on by default.
618 --list-kinds[=language|all]
621 Lists the tag kinds recognized for either the specified language
622 or all languages, and then exits. Each kind of tag recorded in the
623 tag file is represented by a one-letter flag, which is also used
624 to filter the tags placed into the output through use of the
625 --<LANG>-kinds option. Note that some languages and/or tag kinds
626 may be implemented using regular expressions and may not be avail‐
627 able if regex support is not compiled into ctags (see the
628 --regex-<LANG> option). Each kind listed is enabled unless fol‐
629 lowed by "[off]".
630 --list-maps[=language|all]
633 Lists the file extensions and file name patterns which associate a
634 file name with a language for either the specified language or all
635 languages, and then exits. See the --langmap option, and SOURCE
636 FILES, above.
637 --list-languages
640 Lists the names of the languages understood by ctags, and then
641 exits. These language names are case insensitive and may be used
642 in the --language-force, --languages, --<LANG>-kinds, and
643 --regex-<LANG> options.
644 --options=file
647 Read additional options from file. The file should contain one
648 option per line. As a special case, if --options=NONE is specified
649 as the first option on the command line, it will disable the auto‐
650 matic reading of any configuration options from either a file or
651 the environment (see FILES).
652 --recurse[=yes|no]
655 Recurse into directories encountered in the list of supplied
656 files. If the list of supplied files is empty and no file list is
657 specified with the -L option, then the current directory (i.e.
658 ".") is assumed. Symbolic links are followed. If you don't like
659 these behaviors, either explicitly specify the files or pipe the
660 output of find(1) into ctags -L- instead. Note: This option is not
661 supported on all platforms at present. It is available if the
662 output of the --help option includes this option. See, also, the
663 --exclude to limit recursion.
664 --regex-<LANG>=/regexp/replacement/[kind-spec/][flags]
667 The /regexp/replacement/ pair define a regular expression replace‐
668 ment pattern, similar in style to sed substitution commands, with
669 which to generate tags from source files mapped to the named lan‐
670 guage, <LANG>, (case-insensitive; either a built-in or user-
671 defined language). The regular expression, regexp, defines an
672 extended regular expression (roughly that used by egrep(1)), which
673 is used to locate a single source line containing a tag and may
674 specify tab characters using \t. When a matching line is found, a
675 tag will be generated for the name defined by replacement, which
676 generally will contain the special back-references \1 through \9
677 to refer to matching sub-expression groups within regexp. The '/'
678 separator characters shown in the parameter to the option can
679 actually be replaced by any character. Note that whichever separa‐
680 tor character is used will have to be escaped with a backslash
681 ('\') character wherever it is used in the parameter as something
682 other than a separator. The regular expression defined by this
683 option is added to the current list of regular expressions for the
684 specified language unless the parameter is omitted, in which case
685 the current list is cleared.
686 Unless modified by flags, regexp is interpreted as a Posix
688 extended regular expression. The replacement should expand for all
689 matching lines to a non-empty string of characters, or a warning
690 message will be reported. An optional kind specifier for tags
691 matching regexp may follow replacement, which will determine what
692 kind of tag is reported in the "kind" extension field (see TAG
693 FILE FORMAT, below). The full form of kind-spec is in the form of
694 a single letter, a comma, a name (without spaces), a comma, a
695 description, followed by a separator, which specify the short and
696 long forms of the kind value and its textual description (dis‐
697 played using --list-kinds). Either the kind name and/or the
698 description may be omitted. If kind-spec is omitted, it defaults
699 to "r,regex". Finally, flags are one or more single-letter charac‐
700 ters having the following effect upon the interpretation of reg‐
701 exp:
702 b The pattern is interpreted as a Posix basic regular expres‐
705 sion.
706 e The pattern is interpreted as a Posix extended regular
708 expression (default).
709 i The regular expression is to be applied in a case-insensi‐
711 tive manner.
712 Note that this option is available only if ctags was compiled with
714 support for regular expressions, which depends upon your platform.
715 You can determine if support for regular expressions is compiled
716 in by examining the output of the --version option, which will
717 include "+regex" in the compiled feature list.
718 For more information on the regular expressions used by ctags, see
720 either the regex(5,7) man page, or the GNU info documentation for
721 regex (e.g. "info regex").
722 --sort[=yes|no|foldcase]
725 Indicates whether the tag file should be sorted on the tag name
726 (default is yes). Note that the original vi(1) required sorted
727 tags. The foldcase value specifies case insensitive (or case-
728 folded) sorting. Fast binary searches of tag files sorted with
729 case-folding will require special support from tools using tag
730 files, such as that found in the ctags readtags library, or Vim
731 version 6.2 or higher (using "set ignorecase"). This option must
732 appear before the first file name. [Ignored in etags mode]
733 --tag-relative[=yes|no]
736 Indicates that the file paths recorded in the tag file should be
737 relative to the directory containing the tag file, rather than
738 relative to the current directory, unless the files supplied on
739 the command line are specified with absolute paths. This option
740 must appear before the first file name. The default is yes when
741 running in etags mode (see the -e option), no otherwise.
742 --totals[=yes|no]
745 Prints statistics about the source files read and the tag file
746 written during the current invocation of ctags. This option is off
747 by default. This option must appear before the first file name.
748 --verbose[=yes|no]
751 Enable verbose mode. This prints out information on option pro‐
752 cessing and a brief message describing what action is being taken
753 for each file considered by ctags. Normally, ctags does not read
754 command line arguments until after options are read from the con‐
755 figuration files (see FILES, below) and the CTAGS environment
756 variable. However, if this option is the first argument on the
757 command line, it will take effect before any options are read from
758 these sources. The default is no.
759 --version
762 Prints a version identifier for ctags to standard output, and then
763 exits. This is guaranteed to always contain the string "Exuberant
764 Ctags".
765
769 As ctags considers each file name in turn, it tries to determine the
770 language of the file by applying the following three tests in order: if
771 the file extension has been mapped to a language, if the file name
772 matches a shell pattern mapped to a language, and finally if the file
773 is executable and its first line specifies an interpreter using the
774 Unix-style "#!" specification (if supported on the platform). If a lan‐
775 guage was identified, the file is opened and then the appropriate lan‐
776 guage parser is called to operate on the currently open file. The
777 parser parses through the file and adds an entry to the tag file for
778 each language object it is written to handle. See TAG FILE FORMAT,
779 below, for details on these entries.
780 This implementation of ctags imposes no formatting requirements on C
782 code as do legacy implementations. Older implementations of ctags
783 tended to rely upon certain formatting assumptions in order to help it
784 resolve coding dilemmas caused by preprocessor conditionals.
785 In general, ctags tries to be smart about conditional preprocessor
787 directives. If a preprocessor conditional is encountered within a
788 statement which defines a tag, ctags follows only the first branch of
789 that conditional (except in the special case of "#if 0", in which case
790 it follows only the last branch). The reason for this is that failing
791 to pursue only one branch can result in ambiguous syntax, as in the
792 following example:
793 #ifdef TWO_ALTERNATIVES
795 struct {
796 #else
797 union {
798 #endif
799 short a;
800 long b;
801 }
802 Both branches cannot be followed, or braces become unbalanced and ctags
804 would be unable to make sense of the syntax.
805 If the application of this heuristic fails to properly parse a file,
807 generally due to complicated and inconsistent pairing within the condi‐
808 tionals, ctags will retry the file using a different heuristic which
809 does not selectively follow conditional preprocessor branches, but
810 instead falls back to relying upon a closing brace ("}") in column 1 as
811 indicating the end of a block once any brace imbalance results from
812 following a #if conditional branch.
813 Ctags will also try to specially handle arguments lists enclosed in
815 double sets of parentheses in order to accept the following conditional
816 construct:
817 extern void foo __ARGS((int one, char two));
819 Any name immediately preceding the "((" will be automatically ignored
821 and the previous name will be used.
822 C++ operator definitions are specially handled. In order for consis‐
824 tency with all types of operators (overloaded and conversion), the
825 operator name in the tag file will always be preceded by the string
826 "operator " (i.e. even if the actual operator definition was written as
827 "operator<<").
828 After creating or appending to the tag file, it is sorted by the tag
830 name, removing identical tag lines.
831
835 When not running in etags mode, each entry in the tag file consists of
836 a separate line, each looking like this in the most general case:
837 tag_name<TAB>file_name<TAB>ex_cmd;"<TAB>extension_fields
839 The fields and separators of these lines are specified as follows:
841 1. tag name
843 2. single tab character
844 3. name of the file in which the object associated with the tag is
845 located
846 4. single tab character
847 5. EX command used to locate the tag within the file; generally a
848 search pattern (either /pattern/ or ?pattern?) or line number
849 (see --excmd). Tag file format 2 (see --format) extends this EX
850 command under certain circumstances to include a set of exten‐
851 sion fields (described below) embedded in an EX comment immedi‐
852 ately appended to the EX command, which leaves it backward-com‐
853 patible with original vi(1) implementations.
854 A few special tags are written into the tag file for internal purposes.
856 These tags are composed in such a way that they always sort to the top
857 of the file. Therefore, the first two characters of these tags are
858 used a magic number to detect a tag file for purposes of determining
859 whether a valid tag file is being overwritten rather than a source
860 file.
861 Note that the name of each source file will be recorded in the tag file
863 exactly as it appears on the command line. Therefore, if the path you
864 specified on the command line was relative to the current directory,
865 then it will be recorded in that same manner in the tag file. See, how‐
866 ever, the --tag-relative option for how this behavior can be modified.
867 Extension fields are tab-separated key-value pairs appended to the end
869 of the EX command as a comment, as described above. These key value
870 pairs appear in the general form "key:value". Their presence in the
871 lines of the tag file are controlled by the --fields option. The possi‐
872 ble keys and the meaning of their values are as follows:
873 access Indicates the visibility of this class member, where value
876 is specific to the language.
877 file Indicates that the tag has file-limited visibility. This
880 key has no corresponding value.
881 kind Indicates the type, or kind, of tag. Its value is either
884 one of the corresponding one-letter flags described under
885 the various --<LANG>-kinds options above, or a full name.
886 It is permitted (and is, in fact, the default) for the key
887 portion of this field to be omitted. The optional behaviors
888 are controlled with the --fields option.
889 implementation
892 When present, this indicates a limited implementation
893 (abstract vs. concrete) of a routine or class, where value
894 is specific to the language ("virtual" or "pure virtual"
895 for C++; "abstract" for Java).
896 inherits When present, value. is a comma-separated list of classes
899 from which this class is derived (i.e. inherits from).
900 signature When present, value is a language-dependent representation
903 of the signature of a routine. A routine signature in its
904 complete form specifies the return type of a routine and
905 its formal argument list. This extension field is presently
906 supported only for C-based languages and does not include
907 the return type.
908 In addition, information on the scope of the tag definition may be
911 available, with the key portion equal to some language-dependent con‐
912 struct name and its value the name declared for that construct in the
913 program. This scope entry indicates the scope in which the tag was
914 found. For example, a tag generated for a C structure member would have
915 a scope looking like "struct:myStruct".
916
920 Vi will, by default, expect a tag file by the name "tags" in the cur‐
921 rent directory. Once the tag file is built, the following commands
922 exercise the tag indexing feature:
923 vi -t tag Start vi and position the cursor at the file and line where
925 "tag" is defined.
926 :ta tag Find a tag.
928 Ctrl-] Find the tag under the cursor.
930 Ctrl-T Return to previous location before jump to tag (not widely
932 implemented).
933
937 Emacs will, by default, expect a tag file by the name "TAGS" in the
938 current directory. Once the tag file is built, the following commands
939 exercise the tag indexing feature:
940 M-x visit-tags-table <RET> FILE <RET>
942 Select the tag file, "FILE", to use.
943 M-. [TAG] <RET>
945 Find the first definition of TAG. The default tag is the
946 identifier under the cursor.
947 M-* Pop back to where you previously invoked "M-.".
949 C-u M-. Find the next definition for the last tag.
951 For more commands, see the Tags topic in the Emacs info document.
954
958 NEdit version 5.1 and later can handle the new extended tag file format
959 (see --format). To make NEdit use the tag file, select "File->Load Tags
960 File". To jump to the definition for a tag, highlight the word, the
961 press Ctrl-D. NEdit 5.1 can can read multiple tag files from different
962 directories. Setting the X resource nedit.tagFile to the name of a tag
963 file instructs NEdit to automatically load that tag file at startup
964 time.
965
969 Because ctags is neither a preprocessor nor a compiler, use of pre‐
970 processor macros can fool ctags into either missing tags or improperly
971 generating inappropriate tags. Although ctags has been designed to han‐
972 dle certain common cases, this is the single biggest cause of reported
973 problems. In particular, the use of preprocessor constructs which alter
974 the textual syntax of C can fool ctags. You can work around many such
975 problems by using the -I option.
976 Note that since ctags generates patterns for locating tags (see the
978 --excmd option), it is entirely possible that the wrong line may be
979 found by your editor if there exists another source line which is iden‐
980 tical to the line containing the tag. The following example demon‐
981 strates this condition:
982 int variable;
984 /* ... */
986 void foo(variable)
987 int variable;
988 {
989 /* ... */
990 }
991 Depending upon which editor you use and where in the code you happen to
993 be, it is possible that the search pattern may locate the local parame‐
994 ter declaration in foo() before it finds the actual global variable
995 definition, since the lines (and therefore their search patterns are
996 identical). This can be avoided by use of the --excmd=n option.
997
1001 Ctags has more options than ls(1).
1002 When parsing a C++ member function definition (e.g. "className::func‐
1004 tion"), ctags cannot determine whether the scope specifier is a class
1005 name or a namespace specifier and always lists it as a class name in
1006 the scope portion of the extension fields. Also, if a C++ function is
1007 defined outside of the class declaration (the usual case), the access
1008 specification (i.e. public, protected, or private) and implementation
1009 information (e.g. virtual, pure virtual) contained in the function dec‐
1010 laration are not known when the tag is generated for the function defi‐
1011 nition. It will, however be available for prototypes (e.g
1012 --c++-kinds=+p).
1013 No qualified tags are generated for language objects inherited into a
1015 class.
1016
1020 CTAGS If this environment variable exists, it will be expected to
1021 contain a set of default options which are read when ctags
1022 starts, after the configuration files listed in FILES, below,
1023 are read, but before any command line options are read. Options
1024 appearing on the command line will override options specified
1025 in this variable. Only options will be read from this variable.
1026 Note that all white space in this variable is considered a sep‐
1027 arator, making it impossible to pass an option parameter con‐
1028 taining an embedded space. If this is a problem, use a configu‐
1029 ration file instead.
1030 ETAGS Similar to the CTAGS variable above, this variable, if found,
1033 will be read when etags starts. If this variable is not found,
1034 etags will try to use CTAGS instead.
1035 TMPDIR On Unix-like hosts where mkstemp() is available, the value of
1038 this variable specifies the directory in which to place tempo‐
1039 rary files. This can be useful if the size of a temporary file
1040 becomes too large to fit on the partition holding the default
1041 temporary directory defined at compilation time. ctags creates
1042 temporary files only if either (1) an emacs-style tag file is
1043 being generated, (2) the tag file is being sent to standard
1044 output, or (3) the program was compiled to use an internal sort
1045 algorithm to sort the tag files instead of the the sort utility
1046 of the operating system. If the sort utility of the operating
1047 system is being used, it will generally observe this variable
1048 also. Note that if ctags is setuid, the value of TMPDIR will be
1049 ignored.
1050
1054 /ctags.cnf (on MSDOS, MSWindows only)
1055 /etc/ctags.conf
1056 /usr/local/etc/ctags.conf
1057 $HOME/.ctags
1058 $HOME/ctags.cnf (on MSDOS, MSWindows only)
1059 .ctags
1060 ctags.cnf (on MSDOS, MSWindows only)
1061 If any of these configuration files exist, each will be expected
1062 to contain a set of default options which are read in the order
1063 listed when ctags starts, but before the CTAGS environment vari‐
1064 able is read or any command line options are read. This makes it
1065 possible to set up site-wide, personal or project-level
1066 defaults. It is possible to compile ctags to read an additional
1067 configuration file before any of those shown above, which will
1068 be indicated if the output produced by the --version option
1069 lists the "custom-conf" feature. Options appearing in the CTAGS
1070 environment variable or on the command line will override
1071 options specified in these files. Only options will be read from
1072 these files. Note that the option files are read in line-ori‐
1073 ented mode in which spaces are significant (since shell quoting
1074 is not possible). Each line of the file is read as one command
1075 line parameter (as if it were quoted with single quotes). There‐
1076 fore, use new lines to indicate separate command-line arguments.
1077 tags The default tag file created by ctags.
1080 TAGS The default tag file created by etags.
1082
1085 The official Exuberant Ctags web site at:
1086 http://ctags.sourceforge.net
1088 Also ex(1), vi(1), elvis, or, better yet, vim, the official editor of
1090 ctags. For more information on vim, see the VIM Pages web site at:
1091 http://www.vim.org/
1093
1097 Darren Hiebert <dhiebert at users.sourceforge.net>
1098 http://DarrenHiebert.com/
1099
1103 "Think ye at all times of rendering some service to every member of the
1104 human race."
1105 "All effort and exertion put forth by man from the fullness of his
1107 heart is worship, if it is prompted by the highest motives and the will
1108 to do service to humanity."
1109 -- From the Baha'i Writings
1111
1115 This version of ctags was originally derived from and inspired by the
1116 ctags program by Steve Kirkendall <kirkenda@cs.pdx.edu> that comes with
1117 the Elvis vi clone (though virtually none of the original code
1118 remains).
1119 Credit is also due Bram Moolenaar <Bram@vim.org>, the author of vim,
1121 who has devoted so much of his time and energy both to developing the
1122 editor as a service to others, and to helping the orphans of Uganda.
1123 The section entitled "HOW TO USE WITH GNU EMACS" was shamelessly stolen
1125 from the info page for GNU etags.
1126Darren Hiebert Version 5.8 CTAGS(1)