How to Install Emacs Packages

Xah Lee, 2008-07-30, …, 2012-10-03

This page is a tutorial on the general mechanism of how emacs packages are installed. Useful when you want to manually install packages downloaded from the web.

If you are using emacs 24, you should use its package system. See: A Guide on Emacs Package System.

There are hundreds of useful emacs packages on the web that are not bundled with emacs. Often, there is no install instruction included, and you may notice that each's installation methods seem to differ wildly. The following gives a overview on how emacs package are installed.

Loading the File

Load the File Manually

Suppose you downloaded a simple emacs package on the web named “xyz.el”. To use the package, all you have to do is to make emacs load the file.

• Call load-file (type 【Alt+x】) then give the file path.
• Now, emacs is aware of the package. To activate, call the command in the package. For example, if the file name is 〔xyz.el〕, then the command to activate it is typically “xyz” or “xyz-mode”.

Load File at Startup

If you want emacs to load the file when it starts, put the file in the dir 〔~/.emacs.d/〕, then put the following in your emacs init file:

;; Tell emacs where is your personal elisp lib dir
;; this is default dir for extra packages
(add-to-list 'load-path "~/.emacs.d/")

;; load the packaged named xyz.
(load "xyz") ;; best not to include the ending “.el” or “.elc”

What is the Purpose of 〔~/.emacs.d/〕 Path?

By convention, the 〔~/.emacs.d/〕 is a dir for all your personal packages. It is the default value of the variable user-emacs-directory. On Windows, the path is 〔%HOMEPATH%/.emacs.d/〕. 〔☛ Windows Environment Variables Basic Tutorial〕 Emacs 23 should have created this dir for you. If it's not there, you can just create it yourself.

Byte Compile

Elisp source code can be byte compiled. When a file is byte compiled, it loads faster, and the functions will run faster too (about 6 times faster). For simple packages, the difference in speed is not noticeable.

To compile your code, call byte-compile-file. Once you compiled the code, you'll get a file with suffix “.elc”.

You can byte-compile multiple files. In dired, press m to mark them (press u to unmark), then press B (diredp-byte-compile-this-file). 〔☛ File Management with Emacs (dired tutorial)〕

(info "(elisp) Byte Compilation")

Auto-Activation of Mode When Opening File

This is usually setup by the package, but not always. Here's the basics:

;; setup files ending in “.js” to open in js2-mode
(add-to-list 'auto-mode-alist '("\\.js\\'" . js2-mode))

For detail, see: Emacs: How to Associate a File with a Major Mode?.

Mode Documentation

Emacs mode usually comes with inline documentation. To view it, first activate the mode (【Alt+x ‹mode name›】). Once in the mode, call describe-mode 【F1 m 】. Emacs will show its inline documentation. (Emacs will first list a bunch of minor modes that's on.)

Robust modes usually have graphical menus too. So, activate the mode, then you can check what menu commands it has in the menu bar.

Sometimes, a mode comes with complete documentation in info format (file with suffix “.info”). To read the info, type 【Ctrl+u Alt+x info】 then type the info file's name.

What's the difference between {load-file, load, autoload, require}?

See: Emacs Lisp's Library System.