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 speci-
     fied 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, type-
     defs, defines, structs, enums and unions.

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

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

     -a      append to tags file.

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

     -f      Places the tag descriptions in a file called tagsfile.  The
             default behaviour 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 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 source files.  Files whose names
     end in `.l' are assumed to be lisp files if their first non-blank charac-
     ter is `;', `(', or `[', otherwise, they are treated as lex files.  Other

DIAGNOSTICS

     ctags exits with a value of 1 if an error occurred, 0 otherwise.  Dupli-
     cate objects are not considered errors.

SEE ALSO

     ex(1), vi(1)

BUGS

     Recognition of functions, subroutines and procedures for FORTRAN and Pas-
     cal is done is 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.  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, and any syntactical errors
     will completely confuse it.  It also finds some legal syntax confusing;
     for example, since 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 similarly be noted.

HISTORY

     The ctags command appeared in 3.0BSD.

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