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

NAME

     ctags -- create a tags file

SYNOPSIS

     ctags [-BFadtuwvx] [-f tags_file] name ...

DESCRIPTION

     ctags makes a tags file for ex(1) from the specified C, Pascal, Fortran, YACC, lex, 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.

     -a      append to tags file.

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

     -d      create tags for #defines that don't take arguments; #defines that take arguments are tagged automatically.

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

     -f      Places the tag descriptions in a file called tags_file.  The default behavior is to place them in a file called tags.

     -t      create tags for typedefs, structs, unions, and enums.

     -u      update the specified files in the tags file, that is, all references 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).  Because the output will be sorted into lexicographic order, it may be desirable 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 function index which can be printed out for reading off-line.

     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 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 files.  Other files are first examined to see if they contain any
     Pascal or Fortran routine definitions; if not, they 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.

     Yacc and lex files each have a special tag.  Yyparse is the start of the second section of the yacc file, and yylex is the start of the sec-
     ond section of the lex file.

FILES

     tags     default output tags file

DIAGNOSTICS

     ctags exits with a value of 1 if an error occurred, 0 otherwise.  Duplicate objects are not considered to be errors.

SEE ALSO

     cc(1), ex(1), lex(1), sort(1), vgrind(1), vi(1), yacc(1)

BUGS

     Recognition of functions, subroutines, and procedures for FORTRAN and Pascal is done in a very simple-minded way.	No attempt is made to deal
     with block structure; if you have Pascal procedures with the same name in different blocks, you lose.  ctags doesn't understand about Pascal
     types.

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

     ctags relies on the input being well formed, so any syntactical errors will completely confuse it.  It also finds some legal syntax to be
     confusing; for example, because it doesn't understand #ifdef's (incidentally, that's a feature, not a bug), any code with unbalanced braces
     inside #ifdef's will cause it to become somewhat disoriented.  In a similar fashion, multiple line changes within a definition will cause it
     to enter the last line of the object, rather than the first, as the searching pattern.  The last line of multiple line typedef's will simi-
     larly be noted.

HISTORY

     The ctags command appeared in 3.0BSD.

4th Berkeley Distribution					   June 6, 1993 					 4th Berkeley Distribution