Emacs

emacs is a text editor for Linux and macOS.

Starting Emacs

To enter Emacs, just type its name:

$ emacs

`C-z`	Suspend Emacs
`C-x` `C-c`	Exit Emacs permanently

Global Description

`C-<key>`	Means hold the control, and press `<key>`
`M-<key>`	Means press the Esc once, and press `<key>`

NOTICE: This cheatsheet follows the above rules.

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

`C-@` `C-SPC`	Uet mark here
`C-x` `C-x`	Exchange point and mark
`M-@`	Set mark arg words away
`M-h`	Mark paragraph
`C-x` `C-p`	Mark page
`C-M-@`	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.

###

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.

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

Search

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

Incremental Search

`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.

`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