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PROLOG | NAME | SYNOPSIS | DESCRIPTION | OPTIONS | OPERANDS | STDIN | INPUT FILES | ENVIRONMENT VARIABLES | ASYNCHRONOUS EVENTS | STDOUT | STDERR | OUTPUT FILES | EXTENDED DESCRIPTION | EXIT STATUS | CONSEQUENCES OF ERRORS | APPLICATION USAGE | EXAMPLES | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT |
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CTAGS(1P) POSIX Programmer's Manual CTAGS(1P)
This manual page is part of the POSIX Programmer's Manual. The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
ctags — create a tags file (DEVELOPMENT, FORTRAN)
ctags [-a] [-f tagsfile] pathname...
ctags -x pathname...
The ctags utility shall be provided on systems that support the
the Software Development Utilities option, and either or both of
the C-Language Development Utilities option and FORTRAN
Development Utilities option. On other systems, it is optional.
The ctags utility shall write a tagsfile or an index of objects
from C-language or FORTRAN source files specified by the pathname
operands. The tagsfile shall list the locators of language-
specific objects within the source files. A locator consists of a
name, pathname, and either a search pattern or a line number that
can be used in searching for the object definition. The objects
that shall be recognized are specified in the EXTENDED
DESCRIPTION section.
The ctags utility shall conform to the Base Definitions volume of
POSIX.1‐2017, Section 12.2, Utility Syntax Guidelines.
The following options shall be supported:
-a Append to tagsfile.
-f tagsfile
Write the object locator lists into tagsfile instead of
the default file named tags in the current directory.
-x Produce a list of object names, the line number, and
filename in which each is defined, as well as the text
of that line, and write this to the standard output. A
tagsfile shall not be created when -x is specified.
The following pathname operands are supported:
file.c Files with basenames ending with the .c suffix shall be
treated as C-language source code. Such files that are
not valid input to c99 produce unspecified results.
file.h Files with basenames ending with the .h suffix shall be
treated as C-language source code. Such files that are
not valid input to c99 produce unspecified results.
file.f Files with basenames ending with the .f suffix shall be
treated as FORTRAN-language source code. Such files
that are not valid input to fort77 produce unspecified
results.
The handling of other files is implementation-defined.
See the INPUT FILES section.
The input files shall be text files containing source code in the
language indicated by the operand filename suffixes.
The following environment variables shall affect the execution of
ctags:
LANG Provide a default value for the internationalization
variables that are unset or null. (See the Base
Definitions volume of POSIX.1‐2017, Section 8.2,
Internationalization Variables for the precedence of
internationalization variables used to determine the
values of locale categories.)
LC_ALL If set to a non-empty string value, override the values
of all the other internationalization variables.
LC_COLLATE
Determine the order in which output is sorted for the
-x option. The POSIX locale determines the order in
which the tagsfile is written.
LC_CTYPE Determine the locale for the interpretation of
sequences of bytes of text data as characters (for
example, single-byte as opposed to multi-byte
characters in arguments and input files). When
processing C-language source code, if the locale is not
compatible with the C locale described by the ISO C
standard, the results are unspecified.
LC_MESSAGES
Determine the locale that should be used to affect the
format and contents of diagnostic messages written to
standard error.
NLSPATH Determine the location of message catalogs for the
processing of LC_MESSAGES.
Default.
The list of object name information produced by the -x option
shall be written to standard output in the following format:
"%s %d %s %s", <object-name>, <line-number>, <filename>, <text>
where <text> is the text of line <line-number> of file
<filename>.
The standard error shall be used only for diagnostic messages.
When the -x option is not specified, the format of the output
file shall be:
"%s\t%s\t/%s/\n", <identifier>, <filename>, <pattern>
where <pattern> is a search pattern that could be used by an
editor to find the defining instance of <identifier> in
<filename> (where defining instance is indicated by the
declarations listed in the EXTENDED DESCRIPTION).
An optional <circumflex> ('^') can be added as a prefix to
<pattern>, and an optional <dollar-sign> can be appended to
<pattern> to indicate that the pattern is anchored to the
beginning (end) of a line of text. Any <slash> or <backslash>
characters in <pattern> shall be preceded by a <backslash>
character. The anchoring <circumflex>, <dollar-sign>, and
escaping <backslash> characters shall not be considered part of
the search pattern. All other characters in the search pattern
shall be considered literal characters.
An alternative format is:
"%s\t%s\t?%s?\n", <identifier>, <filename>, <pattern>
which is identical to the first format except that <slash>
characters in <pattern> shall not be preceded by escaping
<backslash> characters, and <question-mark> characters in
<pattern> shall be preceded by <backslash> characters.
A second alternative format is:
"%s\t%s\t%d\n", <identifier>, <filename>, <lineno>
where <lineno> is a decimal line number that could be used by an
editor to find <identifier> in <filename>.
Neither alternative format shall be produced by ctags when it is
used as described by POSIX.1‐2008, but the standard utilities
that process tags files shall be able to process those formats as
well as the first format.
In any of these formats, the file shall be sorted by identifier,
based on the collation sequence in the POSIX locale.
If the operand identifies C-language source, the ctags utility
shall attempt to produce an output line for each of the following
objects:
* Function definitions
* Type definitions
* Macros with arguments
It may also produce output for any of the following objects:
* Function prototypes
* Structures
* Unions
* Global variable definitions
* Enumeration types
* Macros without arguments
* #define statements
* #line statements
Any #if and #ifdef statements shall produce no output. The tag
main is treated specially in C programs. The tag formed shall be
created by prefixing M to the name of the file, with the trailing
.c, and leading pathname components (if any) removed.
On systems that do not support the C-Language Development
Utilities option, ctags produces unspecified results for C-
language source code files. It should write to standard error a
message identifying this condition and cause a non-zero exit
status to be produced.
If the operand identifies FORTRAN source, the ctags utility shall
produce an output line for each function definition. It may also
produce output for any of the following objects:
* Subroutine definitions
* COMMON statements
* PARAMETER statements
* DATA and BLOCK DATA statements
* Statement numbers
On systems that do not support the FORTRAN Development Utilities
option, ctags produces unspecified results for FORTRAN source
code files. It should write to standard error a message
identifying this condition and cause a non-zero exit status to be
produced.
It is implementation-defined what other objects (including
duplicate identifiers) produce output.
The following exit values shall be returned:
0 Successful completion.
>0 An error occurred.
Default.
The following sections are informative.
The output with -x is meant to be a simple index that can be
written out as an off-line readable function index. If the input
files to ctags (such as .c files) were not created using the same
locale as that in effect when ctags -x is run, results might not
be as expected.
The description of C-language processing says ``attempts to''
because the C language can be greatly confused, especially
through the use of #defines, and this utility would be of no use
if the real C preprocessor were run to identify them. The output
from ctags may be fooled and incorrect for various constructs.
None.
The option list was significantly reduced from that provided by
historical implementations. The -F option was omitted as
redundant, since it is the default. The -B option was omitted as
being of very limited usefulness. The -t option was omitted since
the recognition of typedefs is now required for C source files.
The -u option was omitted because the update function was judged
to be not only inefficient, but also rarely needed.
An early proposal included a -w option to suppress warning
diagnostics. Since the types of such diagnostics could not be
described, the option was omitted as being not useful.
The text for LC_CTYPE about compatibility with the C locale
acknowledges that the ISO C standard imposes requirements on the
locale used to process C source. This could easily be a superset
of that known as ``the C locale'' by way of implementation
extensions, or one of a few alternative locales for systems
supporting different codesets. No statement is made for FORTRAN
because the ANSI X3.9‐1978 standard (FORTRAN 77) does not (yet)
define a similar locale concept. However, a general rule in this
volume of POSIX.1‐2017 is that any time that locales do not match
(preparing a file for one locale and processing it in another),
the results are suspect.
The collation sequence of the tags file is not affected by
LC_COLLATE because it is typically not used by human readers, but
only by programs such as vi to locate the tag within the source
files. Using the POSIX locale eliminates some of the problems of
coordinating locales between the ctags file creator and the vi
file reader.
Historically, the tags file has been used only by ex and vi.
However, the format of the tags file has been published to
encourage other programs to use the tags in new ways. The format
allows either patterns or line numbers to find the identifiers
because the historical vi recognizes either. The ctags utility
does not produce the format using line numbers because it is not
useful following any source file changes that add or delete
lines. The documented search patterns match historical practice.
It should be noted that literal leading <circumflex> or trailing
<dollar-sign> characters in the search pattern will only behave
correctly if anchored to the beginning of the line or end of the
line by an additional <circumflex> or <dollar-sign> character.
Historical implementations also understand the objects used by
the languages Pascal and sometimes LISP, and they understand the
C source output by lex and yacc. The ctags utility is not
required to accommodate these languages, although implementors
are encouraged to do so.
The following historical option was not specified, as vgrind is
not included in this volume of POSIX.1‐2017:
-v If the -v flag is given, an index of the form expected
by vgrind is produced on the standard output. This
listing contains the function name, filename, and page
number (assuming 64-line pages). Since the output is
sorted into lexicographic order, it may be desired to
run the output through sort -f. Sample use:
ctags -v files | sort -f > index vgrind -x index
The special treatment of the tag main makes the use of ctags
practical in directories with more than one program.
None.
c99(1p), fort77(1p), vi(1p)
The Base Definitions volume of POSIX.1‐2017, Chapter 8,
Environment Variables, Section 12.2, Utility Syntax Guidelines
Portions of this text are reprinted and reproduced in electronic
form from IEEE Std 1003.1-2017, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The
Open Group Base Specifications Issue 7, 2018 Edition, Copyright
(C) 2018 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any
discrepancy between this version and the original IEEE and The
Open Group Standard, the original IEEE and The Open Group
Standard is the referee document. The original Standard can be
obtained online at http://www.opengroup.org/unix/online.html .
Any typographical or formatting errors that appear in this page
are most likely to have been introduced during the conversion of
the source files to man page format. To report such errors, see
https://www.kernel.org/doc/man-pages/reporting_bugs.html .
IEEE/The Open Group 2017 CTAGS(1P)
Pages that refer to this page: ex(1p), more(1p)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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