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Linux 2.6 - man page for ctags (linux section 1posix)

CTAGS(P)			    POSIX Programmer's Manual				 CTAGS(P)

       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 User Portability Utilities
       option, 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,  path-
       name,  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 IEEE Std 1003.1-2001,
       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

       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

       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

       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 IEEE Std 1003.1-2001, Section 8.2, Inter-
	      nationalization 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 interna-
	      tionalization variables.


	      Determine the order in which output is sorted for the -x option.	The POSIX  locale
	      determines the order in which the tagsfile is written.

	      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  argu-
	      ments  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

	      Determine the locale that should be used to affect the format and contents of diag-
	      nostic messages written to standard error.

	      Determine the location of message catalogs for the processing of LC_MESSAGES .


       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 decla-
       rations listed in the EXTENDED DESCRIPTION).

       An optional circumflex ( '^' ) can be added as a prefix to <pattern>, and an optional dol-
       lar 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 charac-
       ters 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 slashes in <pattern> shall not be  pre-
       ceded 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  <identi-
       fier> in <filename>.

       Neither	alternative  format  shall  be	produced by ctags when it is used as described by
       IEEE Std 1003.1-2001, 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

       The following exit values shall be returned:

	0     Successful completion.

       >0     An error occurred.


       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

       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.


       The  option  list  was  significantly reduced from that provided by historical implementa-
       tions. 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 recogni-
       tion 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 simi-
       lar locale concept. However, a general rule in this volume of IEEE Std 1003.1-2001 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 typi-
       cally 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 histori-
       cal 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 addi-
       tional 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

       The  following historical option was not specified, as vgrind is not included in this vol-
       ume of IEEE Std 1003.1-2001:

       -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.


       c99 , fort77 , vi

       Portions of this text are reprinted and	reproduced  in	electronic  form  from	IEEE  Std
       1003.1,	2003  Edition,	Standard  for Information Technology -- Portable Operating System
       Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003  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 orig-
       inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .

IEEE/The Open Group			       2003					 CTAGS(P)

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