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(emacs-lisp-intro.info)etags

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Create Your Own `TAGS' File
===========================

   The `M-.' (`find-tag') command takes you directly to the source for
a function, variable, node, or other source.  The function depends on
tags tables to tell it where to go.

   You often need to build and install tags tables yourself.  They are
not built automatically.  A tags table is called a `TAGS' file; the
name is in upper case letters.

   You can create a `TAGS' file by calling the `etags' program that
comes as a part of the Emacs distribution.  Usually, `etags' is
compiled and installed when Emacs is built.  (`etags' is not an Emacs
Lisp function or a part of Emacs; it is a C program.)

   To create a `TAGS' file, first switch to the directory in which you
want to create the file.  In Emacs you can do this with the `M-x cd'
command, or by visiting a file in the directory, or by listing the
directory with `C-x d' (`dired').  Then run the compile command, with
`etags *.el' as the command to execute

     M-x compile RET etags *.el RET

to create a `TAGS' file.

   For example, if you have a large number of files in your `~/emacs'
directory, as I do--I have 137 `.el' files in it, of which I load
12--you can create a `TAGS' file for the Emacs Lisp files in that
directory.

   The `etags' program takes all the usual shell `wildcards'.  For
example, if you have two directories for which you want a single `TAGS
file', type `etags *.el ../elisp/*.el', where `../elisp/' is the second
directory:

     M-x compile RET etags *.el ../elisp/*.el RET

   Type

     M-x compile RET etags --help RET

to see a list of the options accepted by `etags' as well as a list of
supported languages.

   The `etags' program handles more than 20 languages, including Emacs
Lisp, Common Lisp, Scheme, C, C++, Ada, Fortran, Java, LaTeX, Pascal,
Perl, Python, Texinfo, makefiles, and most assemblers.  The program has
no switches for specifying the language; it recognizes the language in
an input file according to its file name and contents.

   `etags' is very helpful when you are writing code yourself and want
to refer back to functions you have already written.  Just run `etags'
again at intervals as you write new functions, so they become part of
the `TAGS' file.

   If you think an appropriate `TAGS' file already exists for what you
want, but do not know where it is, you can use the `locate' program to
attempt to find it.

   Type `M-x locate RET TAGS RET' and Emacs will list for you the full
path names of all your `TAGS' files.  On my system, this command lists
34 `TAGS' files.  On the other hand, a `plain vanilla' system I
recently installed did not contain any `TAGS' files.

   If the tags table you want has been created, you can use the `M-x
visit-tags-table' command to specify it.  Otherwise, you will need to
create the tag table yourself and then use `M-x visit-tags-table'.

Building Tags in the Emacs sources
..................................

   The GNU Emacs sources come with a `Makefile' that contains a
sophisticated `etags' command that creates, collects, and merges tags
tables from all over the Emacs sources and puts the information into
one `TAGS' file in the `src/' directory below the top level of your
Emacs source directory.

   To build this `TAGS' file, go to the top level of your Emacs source
directory and run the compile command `make tags':

     M-x compile RET make tags RET

(The `make tags' command works well with the GNU Emacs sources, as well
as with some other source packages.)

   For more information, see Note: Tag Tables.