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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

  • Get Smex

  • To auto-start Smex every time you open Emacs add these lines to your .emacs file:

    (require 'smex) ; Not needed if you use package.el
    (smex-initialize) ; Can be omitted. This might cause a (minimal) delay
                      ; when Smex is auto-initialized on its first run.
  • Bind some keys:

    (global-set-key (kbd "M-x") 'smex)
    (global-set-key (kbd "M-X") 'smex-major-mode-commands)
    ;; 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 are sorted by frequency of use, command length and in 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 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.

M-. jumps to the definition of the selected command.

C-h w shows the key bindings for the selected command. (Via where-is.)

Accessing new commands

Before accepting user input, Smex checks for new command definitions and updates its caches accordingly. You can disable auto-updating and gain some slight speed improvements on older systems by setting smex-auto-update to nil.

To manually update Smex, call it a second time while it is already running.

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

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-items"; you can change it by setting the variable smex-save-file.


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


Set smex-prompt-string for a custom prompt.

Ignore menu bar bindings

Enable smex-key-advice-ignore-menu-bar to ignore clues to menu bar bindings.



  • Remove smex-detect-legacy-save-file. Only relevant (but a breaking change) when you rely on a long deprecated default value of smex-save-file.
  • Ignore smex-save-file when it's empty instead of raising an error. Warn on invalid data in smex-save-file. Fixes issue #23.


  • Allow running where-is on the selected command.
  • Fix compatibility with ido-ubiquitous.


  • Add auto-initialization.
  • Minor fixes.


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

Have fun with Smex!

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