Here are some examples of doing certain commonly desired things with Lisp expressions:
(add-to-list 'load-path '/path/to/lisp/libraries')
(setq c-tab-always-indent nil)
Here we have a variable whose value is normally t for “true”
and the alternative is
nil for “false”.
(setq-default case-fold-search nil)
This sets the default value, which is effective in all buffers that do
not have local values for the variable (see Locals). Setting
setq affects only the current
buffer’s local value, which is probably not what you want to do in an
(setq user-mail-address 'email@example.com')
Various Emacs packages, such as Message mode, consult user-mail-address when they need to know your email address. See Mail Headers.
(setq-default major-mode 'text-mode)
text-mode is used because it is the command for
entering Text mode. The single-quote before it makes the symbol a
text-mode would be treated as a variable
(add-hook 'text-mode-hook 'auto-fill-mode)
When the argument to
load is a relative file name, not starting
with ‘/’ or ‘~’,
load searches the directories in
load-path (see Lisp Libraries).
Here a full file name is used, so no searching is done.
myfunctionby loading a Lisp library named mypackage (i.e., a file mypackage.elc or mypackage.el):
(autoload 'myfunction 'mypackage' 'Do what I say.' t)
Here the string
'Do what I say.' is the function’s
documentation string. You specify it in the
definition so it will be available for help commands even when the
package is not loaded. The last argument, t, indicates that
this function is interactive; that is, it can be invoked interactively
by typing M-x myfunction RET or by binding it to a key.
If the function is not interactive, omit the t or use
make-symbolic-link(see Init Rebinding).
(global-set-key '\C-xl' 'make-symbolic-link)
(define-key global-map '\C-xl' 'make-symbolic-link)
Note once again the single-quote used to refer to the symbol
make-symbolic-link instead of its value as a variable.
(define-key lisp-mode-map '\C-xl' 'make-symbolic-link)
next-linein Fundamental mode so that they run
(substitute-key-definition 'next-line 'forward-line global-map)
One reason to undefine a key is so that you can make it a prefix. Simply defining C-x C-v anything will make C-x C-v a prefix, but C-x C-v must first be freed of its usual non-prefix definition.
(modify-syntax-entry ?\$ '.' text-mode-syntax-table)
(put 'narrow-to-region 'disabled nil)
Users typically want Emacs to behave the same on all systems, so the same init file is right for all platforms. However, sometimes it happens that a function you use for customizing Emacs is not available on some platforms or in older Emacs versions. To deal with that situation, put the customization inside a conditional that tests whether the function or facility is available, like this:
(if (fboundp 'blink-cursor-mode) (blink-cursor-mode 0)) (if (boundp 'coding-category-utf-8) (set-coding-priority '(coding-category-utf-8)))
You can also simply disregard the errors that occur if the function is not defined.
(ignore-errors (set-face-background 'region 'grey75'))
setq on a variable which does not exist is generally
harmless, so those do not need a conditional.