CTAGS(1)		  BSD General Commands Manual		      CTAGS(1)

NAME
     ctags — create a tags file

SYNOPSIS
     ctags [-BFTaduwvx] [-f tagsfile] file ...

DESCRIPTION
     The ctags utility makes a tags file for ex(1) from the specified C, Pas‐
     cal, Fortran, yacc(1), lex(1), and Lisp sources.  A tags file gives the
     locations of specified objects in a group of files.  Each line of the
     tags file contains the object name, the file in which it is defined, and
     a search pattern for the object definition, separated by white-space.
     Using the tags file, ex(1) can quickly locate these object definitions.
     Depending upon the options provided to ctags, objects will consist of
     subroutines, typedefs, defines, structs, enums and unions.

     The following options are available:

     -B	     Use backward searching patterns (?...?).

     -F	     Use forward searching patterns (/.../) (the default).

     -T	     Do not create tags for typedefs, structs, unions, and enums.

     -a	     Append to tags file.

     -d	     Create tags for #defines that do not take arguments; #defines
	     that take arguments are tagged automatically.

     -f	     Place the tag descriptions in a file called tagsfile.  The
	     default behaviour is to place them in a file called tags.

     -u	     Update the specified files in the tags file, that is, all refer‐
	     ences to them are deleted, and the new values are appended to the
	     file.  (Beware: this option is implemented in a way which is
	     rather slow; it is usually faster to simply rebuild the tags
	     file.)

     -v	     An index of the form expected by vgrind(1) is produced on the
	     standard output.  This listing contains the object name, file
	     name, and page number (assuming 64 line pages).  Since the output
	     will be sorted into lexicographic order, it may be desired to run
	     the output through sort(1).  Sample use:

		   ctags -v files | sort -f > index
		   vgrind -x index

     -w	     Suppress warning diagnostics.

     -x	     ctags produces a list of object names, the line number and file
	     name on which each is defined, as well as the text of that line
	     and prints this on the standard output.  This is a simple index
	     which can be printed out as an off-line readable function index.

     Files whose names end in .c or .h are assumed to be C source files and
     are searched for C style routine and macro definitions.  Files whose
     names end in .y are assumed to be yacc(1) source files.  Files whose
     names end in .l are assumed to be Lisp files if their first non-blank
     character is ‘;’, ‘(’, or ‘[’, otherwise, they are treated as lex(1)
     files.  Other files are first examined to see if they contain any Pascal
     or Fortran routine definitions, and, if not, are searched for C style
     definitions.

     The tag “main” is treated specially in C programs.	 The tag formed is
     created by prepending ‘M’ to the name of the file, with the trailing .c
     and any leading pathname components removed.  This makes use of ctags
     practical in directories with more than one program.

     The yacc(1) and lex(1) files each have a special tag.  “yyparse” is the
     start of the second section of the yacc(1) file, and “yylex” is the start
     of the second section of the lex(1) file.

FILES
     tags  default output tags file

EXIT STATUS
     The ctags utility exits with a value of 1 if an error occurred, 0 other‐
     wise.  Duplicate objects are not considered errors.

COMPATIBILITY
     The -t option is a no-op for compatibility with previous versions of
     ctags that did not create tags for typedefs, enums, structs and unions by
     default.

SEE ALSO
     ex(1), vi(1)

STANDARDS
     The ctags utility conforms to IEEE Std 1003.1-2001 (“POSIX.1”).

HISTORY
     The ctags utility appeared in 3.0BSD.

BUGS
     Recognition of functions, subroutines and procedures for Fortran and Pas‐
     cal is done in a very simpleminded way.  No attempt is made to deal with
     block structure; if you have two Pascal procedures in different blocks
     with the same name you lose.  The ctags utility does not understand about
     Pascal types.

     The method of deciding whether to look for C, Pascal or Fortran functions
     is a hack.

     The ctags utility relies on the input being well formed, and any syntac‐
     tical errors will completely confuse it.  It also finds some legal syntax
     confusing; for example, since it does not understand #ifdef's (inciden‐
     tally, that is a feature, not a bug), any code with unbalanced braces
     inside #ifdef's will cause it to become somewhat disoriented.  In a simi‐
     lar fashion, multiple line changes within a definition will cause it to
     enter the last line of the object, rather than the first, as the search‐
     ing pattern.  The last line of multiple line typedef's will similarly be
     noted.

BSD				 June 6, 1993				   BSD

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