Getting Started with Emacs
Add-ons, called minor modes, supplement major modes. Most minor modes operate regardless of the major mode, so they can operate in different documents. For example, Show Paren mode matches parentheses for you. It is useful for the C programmer even in Text mode, and it's a godsend to the Lisp programmer.
Minor modes can be turned on and off as you wish. For example, when programming, Auto Fill mode (for filling, or line wrapping, paragraphs) is useful in comments, but a nuisance outside of them.
Some minor modes are global; they extend across all buffers when they are active. Others are local to a buffer. To activate a given mode, append -mode to its name and execute that command. So to activate Parentheses mode, press M-X then type show-paren-mode. To deactivate it, run the command again.
Several useful buffer-local minor modes are Abbrev mode (autocorrection on the fly), Auto Save mode, Font-Lock mode (color highlighting), Flyspell mode (spell checking on the fly) and Overwrite mode. Two useful minor modes that apply to all buffers are Line Number mode and Column Number mode. These print the current position of point in the mode line, usually over to the right.
Another useful mode is Ispell, which lets you spell check your buffer. It has special submodes for checking e-mail messages, programming language comments and strings, and other special uses.
Key to customizing Emacs is the initialization file, ~/.emacs. Administrators usually provide a global init file. If you don't like it you can tell Emacs to ignore it in your own init file. And, you can start Emacs with no init file with emacs -q, useful for debugging. The init file is nothing but some elisp used to set up Emacs the way you (or your administrator) like it (Figure 6).
You also can set variables in the init file. I customize HTML Helper mode by setting some mode variables:
(setq html-helper-do-write-file-hooks t) (setq html-helper-build-new-buffer t) (setq html-helper-address-string "<a href= \"mailto:firstname.lastname@example.org\">Charles Curley</a>")
Short useful functions, or macros, also go into .emacs. For example, the following function inserts today's date at point:
(defun insert-date () "Insert the current date according to the variable \"insert-date-format\"." (interactive "*") (insert (format-time-string insert-date-format (current-time))))Keystrokes and key sequences also can be bound to functions. This allows you to use the key sequence to activate the function. For example, having written the function insert-date, I can bind it to the F3 function key with this line:
(global-set-key [f3] 'insert-date)You also can use this capability to remap your keyboard. If you don't like some of the long key sequences in Emacs, you can rebind them.
The other way to customize Emacs is with the Customize menu, accessed with M-X customize or from the Options pull-down menu. This extensive menu system allows users to change variables and store the changes in your init file.
A number of programs, such as crontab and mutt, invoke an external program as their editor. To let them run Emacs, set Emacs up to run as a server by putting this line into your .emacs file:
Next, set the environment variable EDITOR or VISUAL to emacsclient. In Bash, add this to your /etc/bashrc or your ~/x.bash_profile:
export VISUAL=emacsclientNow, when you execute crontab -e or edit a message in mutt, you edit in your existing Emacs session instead of waiting for a new Emacs to start up. To finish editing and make emacslient exit, end your session in that buffer with Ctrl-C # instead of Ctrl-X K.
For emacsclient to work, Emacs must be running when the external program invokes it. This is consistent with the preferred way of using Emacs, which is to start Emacs when you log in and leave it running until you log out. One result of using emacsclient is you only have one instance of Emacs running at any one time. While memory is cheap today, it wasn't always so. And even today, if you want to run Linux on your laptop or elderly computers, conserving memory is always a good idea.
You might want to have Emacs edit your mail in Mail mode. If you use mutt, add this to your .emacs file:
;; Automatically go into mail-mode if filename starts with /tmp/mutt (setq auto-mode-alist (append (list (cons "^\/tmp\/mutt" 'mail-mode)) auto-mode-alist))
Of course, to comply with the RFCs on netiquette, you will want Auto Fill mode active when you edit mail. Most major modes have a hook they execute on entering the mode and another they execute on leaving. Here is how to get Mail mode to invoke Auto Fill mode:
(defun my-mail-mode-hook () (auto-fill-mode 1) ) (add-hook 'mail-mode-hook 'my-mail-mode-hook)When you are done writing your e-mail, if you want to annoy the NSA, use Spook. To protest the Communications Decency Act (a decent thing to do) and annoy a lot of American politicians, see Bruce.
Finally, before we take our leave of this wild and woolly editor, let me bring the etc directory (in the Emacs directory tree) to your attention. It contains a number of useful documents, such as an Emacs English language reference card, in source (refcard.tex) and postscript (refcard.ps) form. Translations of the reference card into other languages are available. There is also some background material on Emacs and the GNU Project and a copy of the GPL.
Something you rarely find in proprietary software (at least, not deliberately) is present in Emacs: humor. Check out the bug report from the year 2199, the word list for Spook mode, some explanations of what Emacs stands for and more. And if you really want to exercise your font server, visit the file “HELLO”.