1CTAGS(1P) POSIX Programmer's Manual CTAGS(1P)
2
6 This manual page is part of the POSIX Programmer's Manual. The Linux
7 implementation of this interface may differ (consult the corresponding
8 Linux manual page for details of Linux behavior), or the interface may
9 not be implemented on Linux.
10
12 ctags — create a tags file (DEVELOPMENT, FORTRAN)
13
15 ctags [-a] [-f tagsfile] pathname...
16 ctags -x pathname...
18
20 The ctags utility shall be provided on systems that support the the
21 Software Development Utilities option, and either or both of the C-Lan‐
22 guage Development Utilities option and FORTRAN Development Utilities
23 option. On other systems, it is optional.
24 The ctags utility shall write a tagsfile or an index of objects from C-
26 language or FORTRAN source files specified by the pathname operands.
27 The tagsfile shall list the locators of language-specific objects
28 within the source files. A locator consists of a name, pathname, and
29 either a search pattern or a line number that can be used in searching
30 for the object definition. The objects that shall be recognized are
31 specified in the EXTENDED DESCRIPTION section.
32
34 The ctags utility shall conform to the Base Definitions volume of
35 POSIX.1‐2017, Section 12.2, Utility Syntax Guidelines.
36 The following options shall be supported:
38 -a Append to tagsfile.
40 -f tagsfile
42 Write the object locator lists into tagsfile instead of the
43 default file named tags in the current directory.
44 -x Produce a list of object names, the line number, and filename
46 in which each is defined, as well as the text of that line,
47 and write this to the standard output. A tagsfile shall not
48 be created when -x is specified.
49
51 The following pathname operands are supported:
52 file.c Files with basenames ending with the .c suffix shall be
54 treated as C-language source code. Such files that are not
55 valid input to c99 produce unspecified results.
56 file.h Files with basenames ending with the .h suffix shall be
58 treated as C-language source code. Such files that are not
59 valid input to c99 produce unspecified results.
60 file.f Files with basenames ending with the .f suffix shall be
62 treated as FORTRAN-language source code. Such files that are
63 not valid input to fort77 produce unspecified results.
64 The handling of other files is implementation-defined.
66
68 See the INPUT FILES section.
69
71 The input files shall be text files containing source code in the lan‐
72 guage indicated by the operand filename suffixes.
73
75 The following environment variables shall affect the execution of
76 ctags:
77 LANG Provide a default value for the internationalization vari‐
79 ables that are unset or null. (See the Base Definitions vol‐
80 ume of POSIX.1‐2017, Section 8.2, Internationalization Vari‐
81 ables for the precedence of internationalization variables
82 used to determine the values of locale categories.)
83 LC_ALL If set to a non-empty string value, override the values of
85 all the other internationalization variables.
86 LC_COLLATE
88 Determine the order in which output is sorted for the -x
89 option. The POSIX locale determines the order in which the
90 tagsfile is written.
91 LC_CTYPE Determine the locale for the interpretation of sequences of
93 bytes of text data as characters (for example, single-byte as
94 opposed to multi-byte characters in arguments and input
95 files). When processing C-language source code, if the locale
96 is not compatible with the C locale described by the ISO C
97 standard, the results are unspecified.
98 LC_MESSAGES
100 Determine the locale that should be used to affect the format
101 and contents of diagnostic messages written to standard
102 error.
103 NLSPATH Determine the location of message catalogs for the processing
105 of LC_MESSAGES.
106
108 Default.
109
111 The list of object name information produced by the -x option shall be
112 written to standard output in the following format:
113 "%s %d %s %s", <object-name>, <line-number>, <filename>, <text>
116 where <text> is the text of line <line-number> of file <filename>.
118
120 The standard error shall be used only for diagnostic messages.
121
123 When the -x option is not specified, the format of the output file
124 shall be:
125 "%s\t%s\t/%s/\n", <identifier>, <filename>, <pattern>
128 where <pattern> is a search pattern that could be used by an editor to
130 find the defining instance of <identifier> in <filename> (where defin‐
131 ing instance is indicated by the declarations listed in the EXTENDED
132 DESCRIPTION).
133 An optional <circumflex> ('^') can be added as a prefix to <pattern>,
135 and an optional <dollar-sign> can be appended to <pattern> to indicate
136 that the pattern is anchored to the beginning (end) of a line of text.
137 Any <slash> or <backslash> characters in <pattern> shall be preceded by
138 a <backslash> character. The anchoring <circumflex>, <dollar-sign>, and
139 escaping <backslash> characters shall not be considered part of the
140 search pattern. All other characters in the search pattern shall be
141 considered literal characters.
142 An alternative format is:
144 "%s\t%s\t?%s?\n", <identifier>, <filename>, <pattern>
147 which is identical to the first format except that <slash> characters
149 in <pattern> shall not be preceded by escaping <backslash> characters,
150 and <question-mark> characters in <pattern> shall be preceded by <back‐
151 slash> characters.
152 A second alternative format is:
154 "%s\t%s\t%d\n", <identifier>, <filename>, <lineno>
157 where <lineno> is a decimal line number that could be used by an editor
159 to find <identifier> in <filename>.
160 Neither alternative format shall be produced by ctags when it is used
162 as described by POSIX.1‐2008, but the standard utilities that process
163 tags files shall be able to process those formats as well as the first
164 format.
165 In any of these formats, the file shall be sorted by identifier, based
167 on the collation sequence in the POSIX locale.
168
170 If the operand identifies C-language source, the ctags utility shall
171 attempt to produce an output line for each of the following objects:
172 * Function definitions
174 * Type definitions
176 * Macros with arguments
178 It may also produce output for any of the following objects:
180 * Function prototypes
182 * Structures
184 * Unions
186 * Global variable definitions
188 * Enumeration types
190 * Macros without arguments
192 * #define statements
194 * #line statements
196 Any #if and #ifdef statements shall produce no output. The tag main is
198 treated specially in C programs. The tag formed shall be created by
199 prefixing M to the name of the file, with the trailing .c, and leading
200 pathname components (if any) removed.
201 On systems that do not support the C-Language Development Utilities
203 option, ctags produces unspecified results for C-language source code
204 files. It should write to standard error a message identifying this
205 condition and cause a non-zero exit status to be produced.
206 If the operand identifies FORTRAN source, the ctags utility shall pro‐
208 duce an output line for each function definition. It may also produce
209 output for any of the following objects:
210 * Subroutine definitions
212 * COMMON statements
214 * PARAMETER statements
216 * DATA and BLOCK DATA statements
218 * Statement numbers
220 On systems that do not support the FORTRAN Development Utilities
222 option, ctags produces unspecified results for FORTRAN source code
223 files. It should write to standard error a message identifying this
224 condition and cause a non-zero exit status to be produced.
225 It is implementation-defined what other objects (including duplicate
227 identifiers) produce output.
228
230 The following exit values shall be returned:
231 0 Successful completion.
233 >0 An error occurred.
235
237 Default.
238 The following sections are informative.
240
242 The output with -x is meant to be a simple index that can be written
243 out as an off-line readable function index. If the input files to ctags
244 (such as .c files) were not created using the same locale as that in
245 effect when ctags -x is run, results might not be as expected.
246 The description of C-language processing says ``attempts to'' because
248 the C language can be greatly confused, especially through the use of
249 #defines, and this utility would be of no use if the real C preproces‐
250 sor were run to identify them. The output from ctags may be fooled and
251 incorrect for various constructs.
252
254 None.
255
257 The option list was significantly reduced from that provided by histor‐
258 ical implementations. The -F option was omitted as redundant, since it
259 is the default. The -B option was omitted as being of very limited use‐
260 fulness. The -t option was omitted since the recognition of typedefs is
261 now required for C source files. The -u option was omitted because the
262 update function was judged to be not only inefficient, but also rarely
263 needed.
264 An early proposal included a -w option to suppress warning diagnostics.
266 Since the types of such diagnostics could not be described, the option
267 was omitted as being not useful.
268 The text for LC_CTYPE about compatibility with the C locale acknowl‐
270 edges that the ISO C standard imposes requirements on the locale used
271 to process C source. This could easily be a superset of that known as
272 ``the C locale'' by way of implementation extensions, or one of a few
273 alternative locales for systems supporting different codesets. No
274 statement is made for FORTRAN because the ANSI X3.9‐1978 standard (FOR‐
275 TRAN 77) does not (yet) define a similar locale concept. However, a
276 general rule in this volume of POSIX.1‐2017 is that any time that
277 locales do not match (preparing a file for one locale and processing it
278 in another), the results are suspect.
279 The collation sequence of the tags file is not affected by LC_COLLATE
281 because it is typically not used by human readers, but only by programs
282 such as vi to locate the tag within the source files. Using the POSIX
283 locale eliminates some of the problems of coordinating locales between
284 the ctags file creator and the vi file reader.
285 Historically, the tags file has been used only by ex and vi. However,
287 the format of the tags file has been published to encourage other pro‐
288 grams to use the tags in new ways. The format allows either patterns or
289 line numbers to find the identifiers because the historical vi recog‐
290 nizes either. The ctags utility does not produce the format using line
291 numbers because it is not useful following any source file changes that
292 add or delete lines. The documented search patterns match historical
293 practice. It should be noted that literal leading <circumflex> or
294 trailing <dollar-sign> characters in the search pattern will only
295 behave correctly if anchored to the beginning of the line or end of the
296 line by an additional <circumflex> or <dollar-sign> character.
297 Historical implementations also understand the objects used by the lan‐
299 guages Pascal and sometimes LISP, and they understand the C source out‐
300 put by lex and yacc. The ctags utility is not required to accommodate
301 these languages, although implementors are encouraged to do so.
302 The following historical option was not specified, as vgrind is not
304 included in this volume of POSIX.1‐2017:
305 -v If the -v flag is given, an index of the form expected by
307 vgrind is produced on the standard output. This listing con‐
308 tains the function name, filename, and page number (assuming
309 64-line pages). Since the output is sorted into lexicographic
310 order, it may be desired to run the output through sort -f.
311 Sample use:
312 ctags -v files | sort -f > index vgrind -x index
315 The special treatment of the tag main makes the use of ctags practical
317 in directories with more than one program.
318
320 None.
321
323 c99, fort77, vi
324 The Base Definitions volume of POSIX.1‐2017, Chapter 8, Environment
326 Variables, Section 12.2, Utility Syntax Guidelines
327
329 Portions of this text are reprinted and reproduced in electronic form
330 from IEEE Std 1003.1-2017, Standard for Information Technology -- Por‐
331 table Operating System Interface (POSIX), The Open Group Base Specifi‐
332 cations Issue 7, 2018 Edition, Copyright (C) 2018 by the Institute of
333 Electrical and Electronics Engineers, Inc and The Open Group. In the
334 event of any discrepancy between this version and the original IEEE and
335 The Open Group Standard, the original IEEE and The Open Group Standard
336 is the referee document. The original Standard can be obtained online
337 at http://www.opengroup.org/unix/online.html .
338 Any typographical or formatting errors that appear in this page are
340 most likely to have been introduced during the conversion of the source
341 files to man page format. To report such errors, see https://www.ker‐
342 nel.org/doc/man-pages/reporting_bugs.html .
343IEEE/The Open Group 2017 CTAGS(1P)