crux

A Collection of Ridiculously Useful eXtensions for Emacs. crux bundles many useful interactive commands to enhance your overall Emacs experience.

Most of the crux commands are related to the editing experience, but there are also a bunch of utility commands that are just very useful to have (e.g. crux-open-with and crux-reopen-as-root).

Origins of crux

Many of the functions in crux started life as blog posts on Emacs Redux, then were included in Emacs Prelude, before finally being extracted to crux. You can see a full list of blog posts on functions in crux on the tags page.

Installation

Available on all major package.el community maintained repos - MELPA Stable and MELPA repos.

MELPA Stable is recommended as it has the latest stable version. MELPA has a development snapshot for users who don't mind breakage but don't want to run from a git checkout.

You can install crux using the following command:

M-x package-install [RET] crux [RET]

If the installation doesn't work try refreshing the package list:

M-x package-refresh-contents

Alternatively, you can add the following code to your Emacs config:

(unless (package-installed-p 'crux)
  (package-refresh-contents)
  (package-install 'crux))

Keybindings

crux doesn't setup any keybindings for its commands out-of-the-box. There are several reasons for this:

• Most users probably won't need all the commands, so it'd be an overkill to define a minor mode consuming a lot of valuable keybindings
• Many of the optimal keybindings are in the user space anyways (e.g. C-c some-letter)
• Everyone has their own preferences when it comes to keybindings

Here's the list of some suggested keybindings. Feel free to bind individual commands to whatever keybindings you prefer.

Command	Suggested Keybinding(s)	Description
crux-open-with	C-c o	Open the currently visited file with an external program.
crux-smart-kill-line	C-k or Super-k	First kill to end of line, then kill the whole line.
crux-smart-open-line-above	C-S-RET or Super-o	Insert an empty line above the current line and indent it properly.
crux-smart-open-line	S-RET or M-o	Insert an empty line and indent it properly (as in most IDEs).
crux-cleanup-buffer-or-region	C-c n	Fix indentation in buffer and strip whitespace.
crux-recentf-find-file	C-c f or Super-r	Open recently visited file.
crux-recentf-find-directory	C-c F	Open recently visited directory.
crux-view-url	C-c u	Open a new buffer containing the contents of URL.
crux-eval-and-replace	C-c e	Eval a bit of Emacs Lisp code and replace it with its result.
crux-transpose-windows	C-x 4 t	Transpose the buffers between two windows.
crux-delete-file-and-buffer	C-c D	Delete current file and buffer.
crux-copy-file-preserve-attributes	C-c c	Copy current file with file attributes preserved
crux-duplicate-current-line-or-region	C-c d	Duplicate the current line (or region).
crux-duplicate-and-comment-current-line-or-region	C-c M-d	Duplicate and comment the current line (or region).
crux-rename-file-and-buffer	C-c r	Rename the current buffer and its visiting file if any.
crux-visit-term-buffer	C-c t	Open a terminal emulator (ansi-term).
crux-visit-shell-buffer	C-c z	Open a shell buffer (eshell).
crux-kill-other-buffers	C-c k	Kill all open buffers except the one you're currently in.
crux-indent-defun	C-M z	Indent the definition at point.
crux-indent-rigidly-and-copy-to-clipboard	C-c TAB	Indent and copy region to clipboard
crux-sudo-edit	C-c s	Edit currently visited file as root.
crux-find-user-init-file	C-c I	Open user's init file.
crux-find-user-custom-file	C-c ,	Open user's custom file.
crux-find-shell-init-file	C-c S	Open shell's init file.
crux-find-current-directory-dir-locals-file	C-c l	Open current directory's .dir-locals.el file.
crux-top-join-line	Super-j or C-^	Join lines
crux-kill-whole-line	Super-k	Kill whole line
crux-kill-line-backwards	C-Backspace	Kill line backwards
crux-kill-and-join-forward	C-S-Backspace or C-k	If at end of line, join with following; otherwise kill line.
crux-kill-buffer-truename	C-c P	Kill absolute path of file visited in current buffer.
crux-ispell-word-then-abbrev	C-c i	Fix word using ispell and then save to abbrev.
crux-upcase-region	C-x C-u	upcase-region when transient-mark-mode is on and region is active.
crux-downcase-region	C-x C-l	downcase-region when transient-mark-mode is on and region is active.
crux-capitalize-region	C-x M-c	capitalize-region when transient-mark-mode is on and region is active.
crux-switch-to-previous-buffer	C-c b	Switch to previously open buffer. Repeated calls toggle between the two most recent buffers.
crux-other-window-or-switch-buffer	M-o	Select other window, or switch to most recent buffer if only one window.
crux-move-beginning-of-line	C-a	Move point to first non-whitespace character, or to the beginning of the line.
crux-insert-date	C-c d t	Insert a timestamp according to locale's date and time format.
crux-recompile-init		Byte-compile all your Emacs init files.
crux-create-scratch-buffer		Create a new scratch buffer.
crux-keyboard-quit-dwim	C-g	Do-What-I-Mean keyboard-quit. Closes the minibuffer or completions buffer even without focusing it.

Here's how you'd bind some of the commands to keycombos:

(global-set-key [remap move-beginning-of-line] #'crux-move-beginning-of-line)
(global-set-key (kbd "C-c o") #'crux-open-with)
(global-set-key [(shift return)] #'crux-smart-open-line)
(global-set-key (kbd "s-r") #'crux-recentf-find-file)
(global-set-key (kbd "C-<backspace>") #'crux-kill-line-backwards)
(global-set-key [remap kill-whole-line] #'crux-kill-whole-line)
(global-set-key [remap keyboard-quit] #'crux-keyboard-quit-dwim)

For crux-ispell-word-then-abbrev to be most effective you'll also need to add this to your config:

(setq save-abbrevs 'silently)
(setq-default abbrev-mode t)

Using the bundled advices

crux ships with some handy advice that can enhance the operation of existing commands.

(crux-with-region-or-buffer)

You can use crux-with-region-or-buffer to make a command acting normally on a region to operate on the entire buffer in the absence of a region. Here are a few examples you can stuff in your config:

(crux-with-region-or-buffer indent-region)
(crux-with-region-or-buffer untabify)

(crux-with-region-or-line)

Likewise, you can use crux-with-region-or-line to make a command alternately act on the current line if the mark is not active:

(crux-with-region-or-line comment-or-uncomment-region)

(crux-with-region-or-sexp-or-line)

Similarly, crux-with-region-or-sexp-or-line makes a command that acts on the active region, or else the current list (or string), or finally the current line:

(crux-with-region-or-sexp-or-line kill-region)

(crux-with-region-or-point-to-eol)

Sometimes you might want to act on the point until the end of the current line, rather than the whole line, in the absence of a region:

(crux-with-region-or-point-to-eol kill-ring-save)

Minor modes

(crux-reopen-as-root-mode)

Crux provides a crux-reopen-as-root command for reopening a file as root. This global minor mode changes find-file so all root files are automatically opened as root.

License

Copyright © 2015-2025 Bozhidar Batsov and contributors.

Distributed under the GNU General Public License; type C-h C-c to view it.