A smart M-x enhancement for Emacs.
Emacs Lisp
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Smex is a M-x enhancement for Emacs. Built on top of Ido, it provides a convenient interface to your recently and most frequently used commands. And to all the other commands, too.

Get started

  • Download Smex.

  • Make sure Emacs knows where to find smex.el. (Find out more.)

  • To auto-start Smex every time you open Emacs add these lines to your .emacs file: (require 'smex) Put this line at the very end of your .emacs file: (It should be run after all your other Emacs packages have been loaded.) (smex-initialize) Starter Kit users do the following: (eval-after-load "init.el" '(smex-initialize)) Bind some keys: (global-set-key (kbd "M-x") 'smex) (global-set-key (kbd "M-X") 'smex-major-mode-commands) (global-set-key (kbd "C-c M-x") 'smex-update-and-run) ;; This is your old M-x. (global-set-key (kbd "C-c C-c M-x") 'execute-extended-command)

  • Run Smex. (Type M-x, if that's your key binding).

The commands are displayed in an Ido completion buffer, ordered by relevance. The 7 most recently executed commands come first, the rest is sorted by frequency of use and in alphabetical order. (When you run Smex for the first time, all you see is the alphabetical order.)

Ido completion in 10 seconds: Typing selects matching commands: e.g. 'lnmd' matches 'line-number-mode'. C-s/C-r switches to the next/previous match. Enter executes the selected command.

Learn more

Show only major mode commands

smex-major-mode-commands runs Smex, limited only to commands that are relevant to the active major mode. Try it with Dired or Magit.

Command help

C-h f, while Smex is active, runs describe-function on the currently selected command.

Show unbound commands

smex-show-unbound-commands shows frequently used commands that have no key bindings.


Smex keeps a file to save its state betweens Emacs sessions. The default path is '~/smex.save'; you can change it by setting the variable smex-save-file.

Cache maintenance

To guarantee snappiness, Smex maintains command caches - which, unfortunately, can not be automatically refreshed when new commands are defined (or unloaded).

Run smex-update-and-run to update and invoke Smex, e.g. to access commands of a library you have just loaded.

Additionally, you can teach Smex to update its caches after Emacs has been idle for 60 seconds: (smex-auto-update). (Provide an integer argument for a custom time period in seconds.)


Set smex-history-length to change the number of recent commands that Smex keeps track of.


Smex is my first venture into Elisp. I'd be glad to receive patches, comments and your considered criticism.

Have fun with Smex!