NAME
ctags - create a tags file

SYNOPSIS
ctags [ -BFadtuwvx ] [ -f tagsfile ] 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 on the options provided to
ctags, objects will consist of subroutines, typedefs, defines,
structs, enums and unions.

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 second section of the lex file.

If the -x flag is given, 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.

If the -v flag is given, 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 -f. Sample
use:
ctags -v files | sort -f > index
vgrind -x index

Normally ctags places the tag descriptions in a file called tags;
this may be overridden with the -f option.

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, and, if
not, are searched for C style definitions.

Other options are:

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

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

-a append to tags file.

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

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

-w suppress warning diagnostics.

-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.)

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.

FILES
tags default output tags file

DIAGNOSTICS
Ctags exits with a value of 1 if an error occurred, where duplicate
objects are not considered errors, 0 otherwise.

SEE ALSO
ex(1), vi(1)

AUTHOR
Ken Arnold; FORTRAN added by Jim Kleckner; Bill Joy added Pascal
and -x, replacing cxref; C typedefs added by Ed Pelegri-Llopart.

BUGS
Recognition of functions, subroutines and procedures for FORTRAN
and Pascal 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, as 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.

__________
* Not currently supported under MachTen