In this walk-through, I will describe each new function as we come to it, sometimes in detail and sometimes briefly. If you are interested, you can get the full documentation of any Emacs Lisp function at any time by typing C-h f and then the name of the function (and then RET). Similarly, you can get the full documentation for a variable by typing C-h v and then the name of the variable (and then RET).
describe-function will tell you the location of the
Put point into the name of the file that contains the function and
press the RET key. In this case, RET means
push-button rather than ‘return’ or ‘enter’. Emacs will take
you directly to the function definition.
More generally, if you want to see a function in its original source
file, you can use the
find-tag function to jump to it.
find-tag works with a wide variety of languages, not just
Lisp, and C, and it works with non-programming text as well. For
find-tag will jump to the various nodes in the
Texinfo source file of this document.
find-tag function depends on ‘tags tables’ that record
the locations of the functions, variables, and other items to which
To use the
find-tag command, type M-. (i.e., press the
period key while holding down the META key, or else type the
ESC key and then type the period key), and then, at the prompt,
type in the name of the function whose source code you want to see,
mark-whole-buffer, and then type RET. Emacs will
switch buffers and display the source code for the function on your
screen. To switch back to your current buffer, type C-x b
RET. (On some keyboards, the META key is labeled
Depending on how the initial default values of your copy of Emacs are
set, you may also need to specify the location of your ‘tags table’,
which is a file called TAGS. For example, if you are
interested in Emacs sources, the tags table you will most likely want,
if it has already been created for you, will be in a subdirectory of
the /usr/local/share/emacs/ directory; thus you would use the
M-x visit-tags-table command and specify a pathname such as
/usr/local/share/emacs/22.1.1/lisp/TAGS. If the tags table
has not already been created, you will have to create it yourself. It
will be in a file such as /usr/local/src/emacs/src/TAGS.
To create a TAGS file in a specific directory, switch to that
directory in Emacs using M-x cd command, or list 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
For more information, see Create Your Own TAGS File.
After you become more familiar with Emacs Lisp, you will find that you will
find-tag to navigate your way around source code;
and you will create your own TAGS tables.
Incidentally, the files that contain Lisp code are conventionally called libraries. The metaphor is derived from that of a specialized library, such as a law library or an engineering library, rather than a general library. Each library, or file, contains functions that relate to a particular topic or activity, such as abbrev.el for handling abbreviations and other typing shortcuts, and help.el for help. (Sometimes several libraries provide code for a single activity, as the various rmail… files provide code for reading electronic mail.) In The GNU Emacs Manual, you will see sentences such as “The C-h p command lets you search the standard Emacs Lisp libraries by topic keywords.”