QuickRef.ME

Emacs

Emacs is the extensible, customizable, self-documenting real time display text editor. This reference was made for Emacs 27.

#Getting started

#Starting Emacs

To enter GNU Emacs 27, just type its name:

$ emacs

- -
C-z Suspend Emacs
(or iconify it under X)
C-x C-c Exit Emacs permanently

#Motion

Backward Forward Entity to move over
C-b C-f Haracter
M-b M-f Word
C-p C-n Line
C-a C-e Line beginning
(or end)
M-a M-e Sentence
M-{ M-} Paragraph
C-x [ C-x ] Page
C-M-b C-M-f Sexp
C-M-a C-M-e Function
M-< M-> Buffer beginning
(or end)

#Case Change

- -
M-u Uppercase word
M-l Lowercase word
M-c Capitalize word
C-x C-u Uppercase region
C-x C-l Lowercase region

#Files

- -
C-x C-f Read a file into Emacs
C-x C-s Save a file back to disk
C-x s Save all files
C-x i Insert contents of another file into this buffer
C-x C-v Replace this file with your file
C-x C-w Write buffer to a specified file
C-x C-q Toggle read-only status of buffer

#Error Recovery

- -
C-g Abort partially typed or executing command
M-x recover-session Recover files lost by a system crash
C-x u
C-_
C-/
Undo an unwanted change
M-x revert-buffer Restore a buffer to its original contents
C-l Redraw garbaged screen

#Transposing

- -
C-t Transpose characters
M-t Transpose words
C-x C-t Transpose lines
C-M-t Transpose sexps

#Scroll

- -
C-v Scroll to next screen
M-v Scroll to previous screen
C-x < Scroll left
C-x > Scroll right
C-l Scroll current line to
center, top, bottom

#Goto

- -
M-g g Goto line
M-g c Goto char
M-m Back to indentation

#Marking

- -
[email protected]
C-SPC
Uet mark here
C-x C-x Exchange point and mark
[email protected] Set mark arg words away
M-h Mark paragraph
C-x C-p Mark page
[email protected] Mark sexp
C-M-h Mark function
C-x h Mark entire buffer

#Killing and Deleting

Backward Forward Entity to kill
DEL C-d Character
(delete)
M-DEL M-d Word
M-0 C-k C-k Line
(to end of)
C-x DEL M-k Sentence
M-- C-M-k C-M-k Sexp

#Killing

- -
C-W Kill region C-w
M-w Copy region to kill ring
M-z char Kill through next occurrence of char
C-y Yank back last thing killed
M-y Replace last yank with previous kill

#Getting Help

- -
C-x 1 Remove help window
C-M-v Scroll help window
C-h a Apropos: show commands matching a string
C-h k Describe the function a key runs
C-h f Describe a function
C-h m Get mode-specific information

The help system is simple. Type C-h (or F1) and follow the directions. If you are a first-time user, type C-h t for a tutorial.

#Multiple Windows

When two commands are shown, the second is a similar command for a frame instead of a window.

- - -
C-x 5 1 C-x 1 Delete all other windows
C-x 5 2 C-x 2 Split window, above and below
C-x 5 0 C-x 0 Delete this window
C-x 3 Split window, side by side
C-M-v Scroll other window
C-x 5 o C-x o Switch cursor to another window
C-x 5 b C-x 4 b Select buffer in other window
C-x 5 C-o C-x 4 C-o Display buffer in other window
C-x 5 f C-x 4 f Find file in other window
C-x 5 r C-x 4 r Find file read-only in other window
C-x 5 d C-x 4 d Run Dired in other window
C-x 5 . C-x 4 . Find tag in other window
C-x ^ Grow window taller
C-x { Shrink window narrower
C-x } Grow window wider

#Formatting

- -
TAB Indent current line (mode-dependent)
C-M-\ Indent region (mode-dependent)
C-M-q Indent sexp (mode-dependent)
C-x TAB Indent region rigidly arg columns
M-; Indent for comment
C-o Insert newline after point
C-M-o Move rest of line vertically down
C-x C-o Delete blank lines around point
M-^ Join line with previous (with arg, next)
M-\ Delete all white space around point
M-SPC Put exactly one space at point
M-q Fill paragraph
C-x f Set fill column to arg
C-x . Set prefix each line starts with
M-o Set face

#Info

- -
C-h i Enter the Info documentation reader
C-h S Find specified function or variable in Info

#Moving within a node

- -
SPC Scroll forward
DEL Scroll reverse
b Beginning of node

#Moving between nodes

- -
n Next node
p Previous node
u Move up
m Select menu item by name
n Select nth menu item by number (1–9)
f Follow cross reference (return with l)
l Return to last node you saw
d Return to directory node
t Go to top node of Info file
g Go to any node by name

#Other

- -
h Run Info tutorial
i Look up a subject in the indices
s Search nodes for regexp
q Quit Info

#Minibuffer

The following keys are defined in the minibuffer.

- -
TAB Complete as much as possible
SPC Complete up to one word
RET Complete and execute
? Show possible completions
M-p Fetch previous minibuffer input
M-n Fetch later minibuffer input or default
M-r Regexp search backward through history
M-s Regexp search forward through history
C-g Abort command

Type C-x ESC ESC to edit and repeat the last command that used the minibuffer. Type F10 to activate menu bar items on text terminals.

#Tags

- -
M-. Find a tag (a definition)
C-u M-. Find next occurrence of tag
M-x visit-tags-table Specify a new tags file
M-x tags-search Regexp search on all files in tags table
M-x tags-query-replace Run query-replace on all the files
M-, Continue last tags search or query-replace

#Rectangles

- -
C-x r r Copy rectangle to register
C-x r k Kill rectangle
C-x r y Yank rectangle
C-x r o Open rectangle, shifting text right
C-x r c Blank out rectangle
C-x r t Prefix each line with a string

#Keyboard Macros

- -
C-x ( Start defining a keyboard macro
C-x ) End keyboard macro definition
C-x e Execute last-defined keyboard macro
C-u C-x ( Append to last keyboard macro
M-x name-last-kbd-macro Name last keyboard macro
M-x insert-kbd-macro Insert Lisp definition in buffer

#Buffers

- -
C-x b Select another buffer
C-x C-b List all buffers
C-x k Kill a buffer

#Regex (common)

- -
. (dot) Any single character except a newline
* Zero or more repeats
+ One or more repeats
? Zero or one repeat
\ Quote special characters
\c Quote regular expression special character c
\| Alternative (“or”)
\(...\) Grouping
\(:?...\) Shy grouping
\(:NUM...\) Explicit numbered grouping
\n Same text as nth group
\b At word break
\B Not at word break

#Regex (entry)

Start End Entity
^ $ Line
\< \> Word
\_< \_> Symbol
\‘ \’ Buffer

#Regex (conflict)

These Others class
[...] [^...] Explicit set
\w \W Word-syntax character
\sc \Sc Character with syntax c
\cc \Cc Character with category c
- -
C-s Search forward
C-r Search backward
C-M-s Regular expression search
C-M-r Reverse regular expression search
M-p Select previous search string
M-n Select next later search string
RET Exit incremental search
DEL Undo effect of last character
C-g Abort current search

Use C-s or C-r again to repeat the search in either direction. If Emacs is still searching, C-g cancels only the part not matched.

#Query Replace

- -
M-% Interactively replace a text string
M-x regexp Using regular expressions
SPC / y Replace this one, go on to next
, Replace this one, don’t move
DEL / n Skip to next without replacing
! Replace all remaining matches
^ Back up to the previous match
RET Exit query-replace
C-r Enter recursive edit (C-M-c to exit)

#Misc

#Shells

- -
M-! Execute a shell command
M-& Execute a shell command asynchronously
M- Run a shell command on the region
C-u M- Filter region through a shell command
M-x shell Start a shell in window shell

#International Character Sets

- -
C-x RET l specify principal language
M-x list-input-methods show all input methods
C-\ enable or disable input method
C-x RET c set coding system for next command
M-x list-coding-systems show all coding systems
M-x prefer-coding-system choose preferred coding system

#Registers

- -
C-x r s Save region in register
C-x r i Insert register contents into buffer
C-x r SPC Save value of point in register
C-x r j Jump to point saved in register

#Miscellaneous

- -
C-u num Numeric argument
M-- Negative argument
C-q char Quoted insert

#Commands Dealing with Emacs Lisp

- -
C-x C-e Eval sexp before point
C-M-x Eval current defun
M-x eval-region Eval region
M-: Read and eval minibuffer
M-x load-library Load a Lisp library from load-path

#Simple Customization

- -
M-x customize customize variables and faces

Making global key bindings in Emacs Lisp:

(global-set-key (kbd "C-c g") ’search-forward)
(global-set-key (kbd "M-#") ’query-replace-regexp)

#Abbrevs

- -
C-x a g Add global abbrev
C-x a l Add mode-local abbrev
C-x a i g Add global expansion for this abbrev
C-x a i l Add mode-local expansion for this abbrev
C-x a e Explicitly expand abbrev
M-/ Expand previous word dynamically

#Spelling Check

- -
M-$ Check spelling of current word
M-x ispell-region Check spelling of all words in region
M-x ispell-buffer Check spelling of entire buffer
M-x flyspell-mode Toggle on-the-fly spell checking

#Writing Commands

#Syntax

(defun command-name (args)
"documentation" (interactive "template")
body)

#Example

(defun this-line-to-top-of-window (line)
    "Reposition current line to top of window.
With prefix argument LINE, put point on LINE."
    (interactive "P")
    (recenter (if (null line)
                  0
              (prefix-numeric-value line))))

The interactive spec says how to read arguments interactively. Type C-h f interactive RET for more details.