The Emacs Editor

Emacs is the advanced, extensible, customizable, self-documenting editor. This manual describes how to edit with Emacs and some of the ways to customize it; it corresponds to GNU Emacs version 29.1.90.

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This is the GNU Emacs Manual, updated for Emacs version 29.1.90.

Copyright © 1985–2024 Free Software Foundation, Inc.

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Table of Contents

Short Table of Contents


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You are reading about GNU Emacs, the GNU incarnation of the advanced, self-documenting, customizable, extensible editor Emacs. (The ‘G’ in GNU (GNU’s Not Unix) is not silent.)

We call Emacs advanced because it can do much more than simple insertion and deletion of text. It can control subprocesses, indent programs automatically, show multiple files at once, edit remote files like they were local files, and more. Emacs editing commands operate in terms of characters, words, lines, sentences, paragraphs, and pages, as well as expressions and comments in various programming languages.

Self-documenting means that at any time you can use special commands, known as help commands, to find out what your options are, or to find out what any command does, or to find all the commands that pertain to a given topic. See Help.

Customizable means that you can easily alter the behavior of Emacs commands in simple ways. For instance, if you use a programming language in which comments start with ‘<**’ and end with ‘**>’, you can tell the Emacs comment manipulation commands to use those strings (see Manipulating Comments). To take another example, you can rebind the basic cursor motion commands (up, down, left and right) to any keys on the keyboard that you find comfortable. See Customization.

Extensible means that you can go beyond simple customization and create entirely new commands. New commands are simply programs written in the Lisp language, which are run by Emacs’s own Lisp interpreter. Existing commands can even be redefined in the middle of an editing session, without having to restart Emacs. Most of the editing commands in Emacs are written in Lisp; the few exceptions could have been written in Lisp but use C instead for efficiency. Writing an extension is programming, but non-programmers can use it afterwards. See Preface in An Introduction to Programming in Emacs Lisp, if you want to learn Emacs Lisp programming.

1 The Organization of the Screen

On a graphical display, such as on GNU/Linux using the X Window System, Emacs occupies a graphical window. On a text terminal, Emacs occupies the entire terminal screen. We will use the term frame to mean a graphical window or terminal screen occupied by Emacs. Emacs behaves very similarly on both kinds of frames. It normally starts out with just one frame, but you can create additional frames if you wish (see Frames and Graphical Displays).

Each frame consists of several distinct regions. At the top of the frame is a menu bar, which allows you to access commands via a series of menus. On a graphical display, directly below the menu bar is a tool bar, a row of icons that perform editing commands when you click on them. At the very bottom of the frame is an echo area, where informative messages are displayed and where you enter information when Emacs asks for it.

The main area of the frame, below the tool bar (if one exists) and above the echo area, is called the window. Henceforth in this manual, we will use the word “window” in this sense. Graphical display systems commonly use the word “window” with a different meaning; but, as stated above, we refer to those graphical windows as “frames”.

An Emacs window is where the buffer—the text or other graphics you are editing or viewing—is displayed. On a graphical display, the window possesses a scroll bar on one side, which can be used to scroll through the buffer. The last line of the window is a mode line. This displays various information about what is going on in the buffer, such as whether there are unsaved changes, the editing modes that are in use, the current line number, and so forth.

When you start Emacs, there is normally only one window in the frame. However, you can subdivide this window horizontally or vertically to create multiple windows, each of which can independently display a buffer (see Multiple Windows).

At any time, one window is the selected window. On a graphical display, the selected window shows a more prominent cursor (usually solid and blinking); other windows show a less prominent cursor (usually a hollow box). On a text terminal, there is only one cursor, which is shown in the selected window. The buffer displayed in the selected window is called the current buffer, and it is where editing happens. Most Emacs commands implicitly apply to the current buffer; the text displayed in unselected windows is mostly visible for reference. If you use multiple frames on a graphical display, selecting a particular frame selects a window in that frame.

1.1 Point

The cursor in the selected window shows the location where most editing commands take effect, which is called point2. Many Emacs commands move point to different places in the buffer; for example, you can place point by clicking mouse button 1 (normally the left button) at the desired location.

By default, the cursor in the selected window is drawn as a solid block and appears to be on a character, but you should think of point as between two characters; it is situated before the character under the cursor. For example, if your text looks like ‘frob’ with the cursor over the ‘b’, then point is between the ‘o’ and the ‘b’. If you insert the character ‘!’ at that position, the result is ‘fro!b’, with point between the ‘!’ and the ‘b’. Thus, the cursor remains over the ‘b’, as before.

If you are editing several files in Emacs, each in its own buffer, each buffer has its own value of point. A buffer that is not currently displayed remembers its value of point if you later display it again. Furthermore, if a buffer is displayed in multiple windows, each of those windows has its own value of point.

See Displaying the Cursor, for options that control how Emacs displays the cursor.

1.2 The Echo Area

The line at the very bottom of the frame is the echo area. It is used to display small amounts of text for various purposes.

The echo area is so-named because one of the things it is used for is echoing, which means displaying the characters of a multi-character command as you type. Single-character commands are not echoed. Multi-character commands (see Keys) are echoed if you pause for more than a second in the middle of a command. Emacs then echoes all the characters of the command so far, to prompt you for the rest. Once echoing has started, the rest of the command echoes immediately as you type it. This behavior is designed to give confident users fast response, while giving hesitant users maximum feedback.

The echo area is also used to display an error message when a command cannot do its job. Error messages may be accompanied by beeping or by flashing the screen.

Some commands display informative messages in the echo area to tell you what the command has done, or to provide you with some specific information. These informative messages, unlike error messages, are not accompanied with a beep or flash. For example, C-x = (hold down Ctrl and type x, then let go of Ctrl and type =) displays a message describing the character at point, its position in the buffer, and its current column in the window. Commands that take a long time often display messages ending in ‘...’ while they are working (sometimes also indicating how much progress has been made, as a percentage), and add ‘done’ when they are finished.

Informative echo area messages are saved in a special buffer named *Messages*. (We have not explained buffers yet; see Using Multiple Buffers, for more information about them.) If you miss a message that appeared briefly on the screen, you can switch to the *Messages* buffer to see it again. The *Messages* buffer is limited to a certain number of lines, specified by the variable message-log-max. (We have not explained variables either; see Variables, for more information about them.) Beyond this limit, one line is deleted from the beginning whenever a new message line is added at the end.

See Customization of Display, for options that control how Emacs uses the echo area.

The echo area is also used to display the minibuffer, a special window where you can input arguments to commands, such as the name of a file to be edited. When the minibuffer is in use, the text displayed in the echo area begins with a prompt string, and the active cursor appears within the minibuffer, which is temporarily considered the selected window. You can always get out of the minibuffer by typing C-g. See The Minibuffer.

1.3 The Mode Line

At the bottom of each window is a mode line, which describes what is going on in the current buffer. When there is only one window, the mode line appears right above the echo area; it is the next-to-last line in the frame. On a graphical display, the mode line is drawn with a 3D box appearance. Emacs also usually draws the mode line of the selected window with a different color from that of unselected windows, in order to make it stand out.

The text displayed in the mode line has the following format:

 cs:ch-fr  buf      pos line   (major minor)

On a text terminal, this text is followed by a series of dashes extending to the right edge of the window. These dashes are omitted on a graphical display.

The cs string and the colon character after it describe the character set and newline convention used for the current buffer. Normally, Emacs automatically handles these settings for you, but it is sometimes useful to have this information.

cs describes the character set of the text in the buffer (see Coding Systems). If it is a dash (‘-’), that indicates no special character set handling (with the possible exception of end-of-line conventions, described in the next paragraph). ‘=’ means no conversion whatsoever, and is usually used for files containing non-textual data. Other characters represent various coding systems—for example, ‘1’ represents ISO Latin-1.

On a text terminal, cs is preceded by two additional characters that describe the coding systems for keyboard input and terminal output. Furthermore, if you are using an input method, cs is preceded by a string that identifies the input method (see Input Methods).

The character after cs is usually a colon. If a different string is displayed, that indicates a nontrivial end-of-line convention for encoding a file. Usually, lines of text are separated by newline characters in a file, but two other conventions are sometimes used. The MS-DOS convention uses a carriage return character followed by a linefeed character; when editing such files, the colon changes to either a backslash (‘\’) or ‘(DOS)’, depending on the operating system. Another convention, employed by older Macintosh systems, uses a carriage return character instead of a newline; when editing such files, the colon changes to either a forward slash (‘/’) or ‘(Mac)’. On some systems, Emacs displays ‘(Unix)’ instead of the colon for files that use newline as the line separator.

On frames created for emacsclient (see Invoking emacsclient), the next character is ‘@’. This indication is typical for frames of an Emacs process running as a daemon (see Using Emacs as a Server).

The next element on the mode line is the string indicated by ch. This shows two dashes (‘--’) if the buffer displayed in the window has the same contents as the corresponding file on the disk; i.e., if the buffer is unmodified. If the buffer is modified, it shows two stars (‘**’). For a read-only buffer, it shows ‘%*’ if the buffer is modified, and ‘%%’ otherwise.

The character after ch is normally a dash (‘-’). However, if default-directory (see File Names) for the current buffer is on a remote machine, ‘@’ is displayed instead.

fr gives the selected frame name (see Frames and Graphical Displays). It appears only on text terminals. The initial frame’s name is ‘F1’.

buf is the name of the buffer displayed in the window. Usually, this is the same as the name of a file you are editing. See Using Multiple Buffers.

pos tells you whether there is additional text above the top of the window, or below the bottom. If your buffer is small and all of it is visible in the window, pos is ‘All’. Otherwise, it is ‘Top’ if you are looking at the beginning of the buffer, ‘Bot’ if you are looking at the end of the buffer, or ‘nn%’, where nn is the percentage of the buffer above the top of the window. With Size Indication mode, you can display the size of the buffer as well. See Optional Mode Line Features.

line is the character ‘L’ followed by the line number at point. (You can display the current column number too, by turning on Column Number mode. See Optional Mode Line Features.)

major is the name of the major mode used in the buffer. A major mode is a principal editing mode for the buffer, such as Text mode, Lisp mode, C mode, and so forth. See Major Modes. Some major modes display additional information after the major mode name. For example, Compilation buffers and Shell buffers display the status of the subprocess.

minor is a list of some of the enabled minor modes, which are optional editing modes that provide additional features on top of the major mode. See Minor Modes.

Some features are listed together with the minor modes whenever they are turned on, even though they are not really minor modes. ‘Narrow’ means that the buffer being displayed has editing restricted to only a portion of its text (see Narrowing). ‘Def’ means that a keyboard macro is currently being defined (see Keyboard Macros).

In addition, if Emacs is inside a recursive editing level, square brackets (‘[…]’) appear around the parentheses that surround the modes. If Emacs is in one recursive editing level within another, double square brackets appear, and so on. Since recursive editing levels affect Emacs globally, such square brackets appear in the mode line of every window. See Recursive Editing Levels.

You can change the appearance of the mode line as well as the format of its contents. See Optional Mode Line Features. In addition, the mode line is mouse-sensitive; clicking on different parts of the mode line performs various commands. See Mode Line Mouse Commands. Also, hovering the mouse pointer above mouse-sensitive portions of the mode line shows tooltips (see Tooltips) with information about commands you can invoke by clicking on the mode line.

2 Kinds of User Input

GNU Emacs is primarily designed for use with the keyboard. While it is possible to use the mouse to issue editing commands through the menu bar and tool bar, that is usually not as efficient as using the keyboard.

Keyboard input into Emacs is based on a heavily-extended version of ASCII. Simple characters, like ‘a’, ‘B’, ‘3’, ‘=’, and the space character (denoted as SPC), are entered by typing the corresponding key. Control characters, such as RET, TAB, DEL, ESC, F1, Home, and LEFT, are also entered this way, as are certain characters found on non-English keyboards (see International Character Set Support).

Emacs also recognizes control characters that are entered using modifier keys. Two commonly-used modifier keys are Control (usually labeled Ctrl), and Meta (usually labeled Alt)3. For example, Control-a is entered by holding down the Ctrl key while pressing a; we will refer to this as C-a for short. Similarly, Meta-a, or M-a for short, is entered by holding down the Alt key and pressing a. Modifier keys can also be applied to non-alphanumerical characters, e.g., C-F1 or M-LEFT.

You can also type Meta characters using two-character sequences starting with ESC. Thus, you can enter M-a by typing ESC a. You can enter C-M-a (holding down both Ctrl and Alt, then pressing a) by typing ESC C-a. Unlike Meta, ESC is entered as a separate character. You don’t hold down ESC while typing the next character; instead, press ESC and release it, then enter the next character. This feature is useful on certain text terminals where the Meta key does not function reliably.

Emacs supports 3 additional modifier keys, see Modifier Keys.

Emacs has extensive support for using mouse buttons, mouse wheels and other pointing devices like touchpads and touch screens. See Mouse Input, for details.

On graphical displays, the window manager might block some keyboard inputs, including M-TAB, M-SPC, C-M-d and C-M-l. If you have this problem, you can either customize your window manager to not block those keys, or rebind the affected Emacs commands (see Customization).

Simple characters and control characters, as well as certain non-keyboard inputs such as mouse clicks, are collectively referred to as input events. For details about how Emacs internally handles input events, see Input Events in The Emacs Lisp Reference Manual.

3 Keys

Some Emacs commands are invoked by just one input event; for example, C-f moves forward one character in the buffer. Other commands take two or more input events to invoke, such as C-x C-f and C-x 4 C-f.

A key sequence, or key for short, is a sequence of one or more input events that is meaningful as a unit. If a key sequence invokes a command, we call it a complete key; for example, C-f, C-x C-f and C-x 4 C-f are all complete keys. If a key sequence isn’t long enough to invoke a command, we call it a prefix key; from the preceding example, we see that C-x and C-x 4 are prefix keys. Every key sequence is either a complete key or a prefix key.

A prefix key combines with the following input event to make a longer key sequence. For example, C-x is a prefix key, so typing C-x alone does not invoke a command; instead, Emacs waits for further input (if you pause for longer than a second, it echoes the C-x key to prompt for that input; see The Echo Area). C-x combines with the next input event to make a two-event key sequence, which could itself be a prefix key (such as C-x 4), or a complete key (such as C-x C-f). There is no limit to the length of key sequences, but in practice they are seldom longer than three or four input events.

You can’t add input events onto a complete key. For example, because C-f is a complete key, the two-event sequence C-f C-k is two key sequences, not one.

By default, the prefix keys in Emacs are C-c, C-h, C-x, C-x RET, C-x @, C-x a, C-x n, C-x r, C-x t, C-x v, C-x 4, C-x 5, C-x 6, ESC, and M-g. (F1 and F2 are aliases for C-h and C-x 6.) This list is not cast in stone; if you customize Emacs, you can make new prefix keys. You could even eliminate some of the standard ones, though this is not recommended for most users; for example, if you remove the prefix definition of C-x 4, then C-x 4 C-f becomes an invalid key sequence. See Customizing Key Bindings.

Typing the help character (C-h or F1) after a prefix key displays a list of the commands starting with that prefix. The sole exception to this rule is ESC: ESC C-h is equivalent to C-M-h, which does something else entirely. You can, however, use F1 to display a list of commands starting with ESC.

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4 Mouse Input

By default, Emacs supports all the normal mouse actions like setting the cursor by clicking on the left mouse button, and selecting an area by dragging the mouse pointer. All mouse actions can be used to bind commands in the same way you bind them to keyboard events (see Keys). This section provides a general overview of using the mouse in Emacs; see Mouse Commands for Editing, and the sections that follow it, for more details about mouse commands in Emacs.

When you click the left mouse button, Emacs receives a mouse-1 event. To see what command is bound to that event, you can type C-h c and then press the left mouse button. Similarly, the middle mouse button is mouse-2 and the right mouse button is mouse-3. If you have a mouse with a wheel, the wheel events are commonly bound to either wheel-down or wheel-up, or mouse-4 and mouse-5, but that depends on the operating system configuration.

In general, legacy X systems and terminals (see Using a Mouse in Text Terminals) will report mouse-4 and mouse-5, while all other systems will report wheel-down and wheel-up.

Some mice also have a horizontal scroll wheel, and touchpads usually support scrolling horizontally as well. These events are reported as wheel-left and wheel-right on all systems other than terminals and legacy X systems, where they are mouse-6 and mouse-7.

You can also combine keyboard modifiers with mouse events, so you can bind a special command that triggers when you, for instance, holds down the Meta key and then uses the middle mouse button. In that case, the event name will be M-mouse-2.

On some systems, you can also bind commands for handling touch screen events. In that case, the events are called touchscreen-update and touchscreen-end.

5 Keys and Commands

This manual is full of passages that tell you what particular keys do. But Emacs does not assign meanings to keys directly. Instead, Emacs assigns meanings to named commands, and then gives keys their meanings by binding them to commands.

Every command has a name chosen by a programmer. The name is usually made of a few English words separated by dashes; for example, next-line or forward-word. Internally, each command is a special type of Lisp function, and the actions associated with the command are performed by running the function. See What Is a Function in The Emacs Lisp Reference Manual.

The bindings between keys and commands are recorded in tables called keymaps. See Keymaps.

When we say that “C-n moves down vertically one line” we are glossing over a subtle distinction that is irrelevant in ordinary use, but vital for Emacs customization. The command next-line does a vertical move downward. C-n has this effect because it is bound to next-line. If you rebind C-n to the command forward-word, C-n will move forward one word instead.

In this manual, we will often speak of keys like C-n as commands, even though strictly speaking the key is bound to a command. Usually, we state the name of the command which really does the work in parentheses after mentioning the key that runs it. For example, we will say that “The command C-n (next-line) moves point vertically down”, meaning that the command next-line moves vertically down, and the key C-n is normally bound to it.

Since we are discussing customization, we should tell you about variables. Often the description of a command will say, “To change this, set the variable mumble-foo.” A variable is a name used to store a value. Most of the variables documented in this manual are meant for customization: some command or other part of Emacs examines the variable and behaves differently according to the value that you set. You can ignore the information about variables until you are interested in customizing them. Then read the basic information on variables (see Variables) and the information about specific variables will make sense.

6 Entering Emacs

The usual way to invoke Emacs is with the shell command emacs. From a terminal window running a Unix shell on a GUI terminal, you can run Emacs in the background with emacs &; this way, Emacs won’t tie up the terminal window, so you can use it to run other shell commands. (For comparable methods of starting Emacs on MS-Windows, see How to Start Emacs on MS-Windows.)

When Emacs starts up, the initial frame displays a special buffer named ‘*GNU Emacs*’. This startup screen contains information about Emacs and links to common tasks that are useful for beginning users. For instance, activating the ‘Emacs Tutorial’ link opens the Emacs tutorial; this does the same thing as the command C-h t (help-with-tutorial). To activate a link, either move point onto it and type RET, or click on it with mouse-1 (the left mouse button).

Using a command line argument, you can tell Emacs to visit one or more files as soon as it starts up. For example, emacs foo.txt starts Emacs with a buffer displaying the contents of the file ‘foo.txt’. This feature exists mainly for compatibility with other editors, which are designed to be launched from the shell for short editing sessions. If you call Emacs this way, the initial frame is split into two windows—one showing the specified file, and the other showing the startup screen. See Multiple Windows.

Generally, it is unnecessary and wasteful to start Emacs afresh each time you want to edit a file. The recommended way to use Emacs is to start it just once, just after you log in, and do all your editing in the same Emacs session. See File Handling, for information on visiting more than one file. If you use Emacs this way, the Emacs session accumulates valuable context, such as the kill ring, registers, undo history, and mark ring data, which together make editing more convenient. These features are described later in the manual.

To edit a file from another program while Emacs is running, you can use the emacsclient helper program to open a file in the existing Emacs session. See Using Emacs as a Server.

Emacs accepts other command line arguments that tell it to load certain Lisp files, where to put the initial frame, and so forth. See Command Line Arguments for Emacs Invocation.

If the variable inhibit-startup-screen is non-nil, Emacs does not display the startup screen. In that case, if one or more files were specified on the command line, Emacs simply displays those files; otherwise, it displays a buffer named *scratch*, which can be used to evaluate Emacs Lisp expressions interactively. See Lisp Interaction Buffers. You can set the variable inhibit-startup-screen using the Customize facility (see Easy Customization Interface), or by editing your initialization file (see The Emacs Initialization File).4

You can also force Emacs to display a file or directory at startup by setting the variable initial-buffer-choice to a string naming that file or directory. The value of initial-buffer-choice may also be a function (of no arguments) that should return a buffer which is then displayed. If initial-buffer-choice is non-nil, then if you specify any files on the command line, Emacs still visits them, but does not display them initially.

7 Exiting Emacs

C-x C-c

Kill Emacs (save-buffers-kill-terminal).


On a text terminal, suspend Emacs; on a graphical display, iconify (or “minimize”) the selected frame (suspend-frame).

Killing Emacs means terminating the Emacs program. To do this, type C-x C-c (save-buffers-kill-terminal). A two-character key sequence is used to make it harder to type by accident. If there are any modified file-visiting buffers when you type C-x C-c, Emacs first offers to save these buffers. If you do not save them all, it asks for confirmation again, since the unsaved changes will be lost. Emacs also asks for confirmation if any subprocesses are still running, since killing Emacs will also kill the subprocesses (see Running Shell Commands from Emacs).

C-x C-c behaves specially if you are using Emacs as a server. If you type it from a client frame, it closes the client connection. See Using Emacs as a Server.

Emacs can, optionally, record certain session information when you kill it, such as the files you were visiting at the time. This information is then available the next time you start Emacs. See Saving Emacs Sessions.

If the value of the variable confirm-kill-emacs is non-nil, C-x C-c assumes that its value is a predicate function, and calls that function. If the result of the function call is non-nil, the session is killed, otherwise Emacs continues to run. One convenient function to use as the value of confirm-kill-emacs is the function yes-or-no-p. The default value of confirm-kill-emacs is nil.

If the value of the variable confirm-kill-processes is nil, C-x C-c does not ask for confirmation before killing subprocesses started by Emacs. The value is t by default.

To further customize what happens when Emacs is exiting, see Killing Emacs in The GNU Emacs Lisp Reference Manual.

To kill Emacs without being prompted about saving, type M-x kill-emacs.

C-z runs the command suspend-frame. On a graphical display, this command minimizes (or iconifies) the selected Emacs frame, hiding it in a way that lets you bring it back later (exactly how this hiding occurs depends on the window system). On a text terminal, the C-z command suspends Emacs, stopping the program temporarily and returning control to the parent process (usually a shell); in most shells, you can resume Emacs after suspending it with the shell command %emacs.

Text terminals usually listen for certain special characters whose meaning is to kill or suspend the program you are running. This terminal feature is turned off while you are in Emacs. The meanings of C-z and C-x C-c as keys in Emacs were inspired by the use of C-z and C-c on several operating systems as the characters for stopping or killing a program, but that is their only relationship with the operating system. You can customize these keys to run any commands of your choice (see Keymaps).

8 Basic Editing Commands

Here we explain the basics of how to enter text, make corrections, and save the text in a file. If this material is new to you, we suggest you first run the Emacs learn-by-doing tutorial, by typing C-h t (help-with-tutorial).

8.1 Inserting Text

You can insert an ordinary graphic character (e.g., ‘a’, ‘B’, ‘3’, and ‘=’) by typing the associated key. This adds the character to the buffer at point. Insertion moves point forward, so that point remains just after the inserted text. See Point.

To end a line and start a new one, type RET (newline). (The RET key may be labeled Return, or Enter, or with a funny-looking left-pointing arrow on your keyboard, but we refer to it as RET in this manual.) This command inserts a newline character into the buffer, then indents (see Indentation) according to the major mode. If point is at the end of the line, the effect is to create a new blank line after it and indent the new line; if point is in the middle of a line, the line is split at that position. To turn off the auto-indentation, you can either disable Electric Indent mode (see Convenience Features for Indentation) or type C-j, which inserts just a newline, without any auto-indentation.

As we explain later in this manual, you can change the way Emacs handles text insertion by turning on minor modes. For instance, the minor mode called Auto Fill mode splits lines automatically when they get too long (see Filling Text). The minor mode called Overwrite mode causes inserted characters to replace (overwrite) existing text, instead of shoving it to the right. See Minor Modes.

Only graphic characters can be inserted by typing the associated key; other keys act as editing commands and do not insert themselves. For instance, DEL runs the command delete-backward-char by default (some modes bind it to a different command); it does not insert a literal ‘DEL’ character (ASCII character code 127).

To insert a non-graphic character, or a character that your keyboard does not support, first quote it by typing C-q (quoted-insert). There are two ways to use C-q:

  • C-q followed by any non-graphic character (even C-g) inserts that character. For instance, C-q DEL inserts a literal ‘DEL’ character.
  • C-q followed by a sequence of octal digits inserts the character with the specified octal character code. You can use any number of octal digits; any non-digit terminates the sequence. If the terminating character is RET, that RET serves only to terminate the sequence. Any other non-digit terminates the sequence and then acts as normal input—thus, C-q 1 0 1 B inserts ‘AB’.

    The use of octal sequences is disabled in ordinary non-binary Overwrite mode, to give you a convenient way to insert a digit instead of overwriting with it.

  • To use decimal or hexadecimal instead of octal, set the variable read-quoted-char-radix to 10 or 16. If the radix is 16, the letters a to f serve as part of a character code, just like digits. Case is ignored.

    A few common Unicode characters can be inserted via a command starting with C-x 8. For example, C-x 8 [ inserts which is Unicode code-point U+2018 LEFT SINGLE QUOTATION MARK, sometimes called a left single “curved quote” or “curly quote”. Similarly, C-x 8 ], C-x 8 { and C-x 8 } insert the curved quotes , and , respectively. Also, a working Alt key acts like C-x 8 (unless followed by RET); e.g., A-[ acts like C-x 8 [ and inserts . To see which characters have C-x 8 shorthands, type C-x 8 C-h.

    Alternatively, you can use the command C-x 8 RET (insert-char). This prompts for the Unicode name or code-point of a character, using the minibuffer. If you enter a name, the command provides completion (see Completion). If you enter a code-point, it should be as a hexadecimal number (the convention for Unicode), or a number with a specified radix, e.g., #o23072 (octal); See Integer Basics in The Emacs Lisp Reference Manual. The command then inserts the corresponding character into the buffer.

    For example, the following all insert the same character:

    C-x 8 RET left single quotation mark RET
    C-x 8 RET left sin TAB RET
    C-x 8 RET 2018 RET
    C-x 8 [
    A-[  (if the Alt key works)
    `    (in Electric Quote mode)

    A numeric argument to C-q or C-x 8 ... specifies how many copies of the character to insert (see Numeric Arguments).

    As an alternative to C-x 8, you can select the corresponding transient input method by typing C-u C-x \ iso-transl RET, then temporarily activating this transient input method by typing C-x \ [ will insert the same character (see transient input method).

    In addition, in some contexts, if you type a quotation using grave accent and apostrophe `like this', it is converted to a form ‘like this’ using single quotation marks, even without C-x 8 commands. Similarly, typing a quotation ``like this'' using double grave accent and apostrophe converts it to a form “like this” using double quotation marks. See Quotation Marks.

    8.2 Changing the Location of Point

    To do more than insert characters, you have to know how to move point (see Point). The keyboard commands C-f, C-b, C-n, and C-p move point to the right, left, down, and up, respectively. You can also move point using the arrow keys present on most keyboards: RIGHT, LEFT, DOWN, and UP; however, many Emacs users find that it is slower to use the arrow keys than the control keys, because you need to move your hand to the area of the keyboard where those keys are located.

    You can also click the left mouse button to move point to the position clicked. Emacs also provides a variety of additional keyboard commands that move point in more sophisticated ways.


    Move forward one character (forward-char).


    This command (right-char) behaves like C-f, except when point is in a right-to-left paragraph (see Bidirectional Editing).


    Move backward one character (backward-char).


    This command (left-char) behaves like C-b, except if the current paragraph is right-to-left (see Bidirectional Editing).


    Move down one screen line (next-line). This command attempts to keep the horizontal position unchanged, so if you start in the middle of one line, you move to the middle of the next.


    Move up one screen line (previous-line). This command preserves position within the line, like C-n.


    Move to the beginning of the line (move-beginning-of-line).


    Move to the end of the line (move-end-of-line).


    Move forward one word (forward-word). See Words.


    This command (right-word) behaves like M-f, except it moves backward by one word if the current paragraph is right-to-left. See Bidirectional Editing.


    Move backward one word (backward-word). See Words.


    This command (left-word) behaves like M-b, except it moves forward by one word if the current paragraph is right-to-left. See Bidirectional Editing.


    Without moving the text on the screen, reposition point on the left margin of the center-most text line of the window; on subsequent consecutive invocations, move point to the left margin of the top-most line, the bottom-most line, and so forth, in cyclic order (move-to-window-line-top-bottom).

    A numeric argument says which screen line to place point on, counting downward from the top of the window (zero means the top line). A negative argument counts lines up from the bottom (-1 means the bottom line). See Numeric Arguments, for more information on numeric arguments.


    Move to the top of the buffer (beginning-of-buffer). With numeric argument n, move to n/10 of the way from the top. On graphical displays, C-HOME does the same.


    Move to the end of the buffer (end-of-buffer). On graphical displays, C-END does the same.


    Scroll the display one screen forward, and move point onscreen if necessary (scroll-up-command). See Scrolling.


    Scroll one screen backward, and move point onscreen if necessary (scroll-down-command). See Scrolling.

    M-g c

    Read a number n and move point to buffer position n. Position 1 is the beginning of the buffer. If point is on or just after a number in the buffer, that is the default for n. Just type RET in the minibuffer to use it. You can also specify n by giving M-g c a numeric prefix argument.

    M-g M-g
    M-g g

    Read a number n and move point to the beginning of line number n (goto-line). Line 1 is the beginning of the buffer. If point is on or just after a number in the buffer, that is the default for n. Just type RET in the minibuffer to use it. You can also specify n by giving M-g M-g a numeric prefix argument. See Creating and Selecting Buffers, for the behavior of M-g M-g when you give it a plain prefix argument. Alternatively, you can use the command goto-line-relative to move point to the line relative to the accessible portion of the narrowed buffer.

    goto-line has its own history list (see Minibuffer History). You can have either a single list shared between all buffers (the default) or a separate list for each buffer, by customizing the user option goto-line-history-local.

    M-g TAB

    Read a number n and move to column n in the current line. Column 0 is the leftmost column. If called with a prefix argument, move to the column number specified by the argument’s numeric value.

    C-x C-n

    Use the current column of point as the semipermanent goal column (set-goal-column) in the current buffer. When a semipermanent goal column is in effect, C-n, C-p, <prior> and <next> always try to move to this column, or as close as possible to it, after moving vertically. The goal column remains in effect until canceled.

    C-u C-x C-n

    Cancel the goal column. Henceforth, C-n and C-p try to preserve the horizontal position, as usual.

    When a line of text in the buffer is longer than the width of the window, Emacs usually displays it on two or more screen lines, a.k.a. visual lines. For convenience, C-n and C-p move point by screen lines, as do the equivalent keys down and up. You can force these commands to move according to logical lines (i.e., according to the text lines in the buffer) by setting the variable line-move-visual to nil; if a logical line occupies multiple screen lines, the cursor then skips over the additional screen lines. For details, see Continuation Lines. See Variables, for how to set variables such as line-move-visual.

    Unlike C-n and C-p, most of the Emacs commands that work on lines work on logical lines. For instance, C-a (move-beginning-of-line) and C-e (move-end-of-line) respectively move to the beginning and end of the logical line. Whenever we encounter commands that work on screen lines, such as C-n and C-p, we will point these out.

    When line-move-visual is nil, you can also set the variable track-eol to a non-nil value. Then C-n and C-p, when starting at the end of the logical line, move to the end of the next logical line. Normally, track-eol is nil.

    C-n normally stops at the end of the buffer when you use it on the last line in the buffer. However, if you set the variable next-line-add-newlines to a non-nil value, C-n on the last line of a buffer creates an additional line at the end and moves down into it.

    8.3 Erasing Text


    Delete the character before point, or the region if it is active (delete-backward-char).


    Delete the character or grapheme cluster after point, or the region if it is active (delete-forward-char).


    Delete the character after point (delete-char).


    Kill to the end of the line (kill-line).


    Kill forward to the end of the next word (kill-word).


    Kill back to the beginning of the previous word (backward-kill-word).

    The DEL (delete-backward-char) command removes the character before point, moving the cursor and the characters after it backwards. If point was at the beginning of a line, this deletes the preceding newline, joining this line to the previous one.

    If, however, the region is active, DEL instead deletes the text in the region. See The Mark and the Region, for a description of the region.

    On most keyboards, DEL is labeled BACKSPACE, but we refer to it as DEL in this manual. (Do not confuse DEL with the Delete key; we will discuss Delete momentarily.) On some text terminals, Emacs may not recognize the DEL key properly. See If DEL Fails to Delete, if you encounter this problem.

    The Delete (delete-forward-char) command deletes in the opposite direction: it deletes the character after point, i.e., the character under the cursor. If point was at the end of a line, this joins the following line onto this one. Like DEL, it deletes the text in the region if the region is active (see The Mark and the Region). If the character after point is composed with following characters and displayed as a single display unit, a so-called grapheme cluster representing the entire sequence, Delete deletes the entire sequence in one go. This is in contrast to DEL which always deletes a single character, even if the character is composed.

    C-d (delete-char) deletes the character after point, similar to Delete, but regardless of whether the region is active.

    See Deletion, for more detailed information about the above deletion commands.

    C-k (kill-line) erases (kills) a line at a time. If you type C-k at the beginning or middle of a line, it kills all the text up to the end of the line. If you type C-k at the end of a line, it joins that line with the following line.

    See Killing and Moving Text, for more information about C-k and related commands.

    8.4 Undoing Changes

    C-x u

    Undo one entry of the undo records—usually, one command worth (undo). (The first key might be unavailable on text-mode displays.)

    Emacs records a list of changes made in the buffer text, so you can undo recent changes. This is done using the undo command, which is bound to C-/ (as well as C-x u and C-_). Normally, this command undoes the last change, moving point back to where it was before the change. The undo command applies only to changes in the buffer; you can’t use it to undo cursor motion.

    On a terminal that supports the Control modifier on all other keys, the easiest way to invoke undo is with C-/, since that doesn’t need the Shift modifier. On terminals which allow only the ASCII control characters, C-/ does not exist, but for many of them C-/ still works because it actually sends C-_ to Emacs, while many others allow you to omit the Shift modifier when you type C-_ (in effect pressing C--), making that the most convenient way to invoke undo.

    Although each editing command usually makes a separate entry in the undo records, very simple commands may be grouped together. Sometimes, an entry may cover just part of a complex command.

    If you repeat C-/ (or its aliases), each repetition undoes another, earlier change, back to the limit of the undo information available. If all recorded changes have already been undone, the undo command displays an error message and does nothing.

    To learn more about the undo command, see Undo.

    8.5 Files

    Text that you insert in an Emacs buffer lasts only as long as the Emacs session. To keep any text permanently, you must put it in a file.

    Suppose there is a file named test.emacs in your home directory. To begin editing this file in Emacs, type

    C-x C-f test.emacs RET

    Here the file name is given as an argument to the command C-x C-f (find-file). That command uses the minibuffer to read the argument, and you type RET to terminate the argument (see The Minibuffer).

    Emacs obeys this command by visiting the file: it creates a buffer, copies the contents of the file into the buffer, and then displays the buffer for editing. If you alter the text, you can save the new text in the file by typing C-x C-s (save-buffer). This copies the altered buffer contents back into the file test.emacs, making them permanent. Until you save, the changed text exists only inside Emacs, and the file test.emacs is unaltered.

    To create a file, just visit it with C-x C-f as if it already existed. This creates an empty buffer, in which you can insert the text you want to put in the file. Emacs actually creates the file the first time you save this buffer with C-x C-s.

    To learn more about using files in Emacs, see File Handling.

    Next: , Previous: , Up: Basic Editing Commands   [Contents][Index]

    8.6 Help

    If you forget what a key does, you can find out by typing C-h k (describe-key), followed by the key of interest; for example, C-h k C-n tells you what C-n does.

    The prefix key C-h stands for “help”. The key F1 serves as an alias for C-h. Apart from C-h k, there are many other help commands providing different kinds of help.

    See Help, for details.

    8.7 Blank Lines

    Here are special commands and techniques for inserting and deleting blank lines.


    Insert a blank line after the cursor (open-line).

    C-x C-o

    Delete all but one of many consecutive blank lines (delete-blank-lines).

    We have seen how RET (newline) starts a new line of text. However, it may be easier to see what you are doing if you first make a blank line and then insert the desired text into it. This is easy to do using the key C-o (open-line), which inserts a newline after point but leaves point in front of the newline. After C-o, type the text for the new line.

    You can make several blank lines by typing C-o several times, or by giving it a numeric argument specifying how many blank lines to make. See Numeric Arguments, for how. If you have a fill prefix, the C-o command inserts the fill prefix on the new line, if typed at the beginning of a line. See The Fill Prefix.

    The easy way to get rid of extra blank lines is with the command C-x C-o (delete-blank-lines). If point lies within a run of several blank lines, C-x C-o deletes all but one of them. If point is on a single blank line, C-x C-o deletes it. If point is on a nonblank line, C-x C-o deletes all following blank lines, if any exists.

    8.8 Continuation Lines

    Sometimes, a line of text in the buffer—a logical line—is too long to fit in the window, and Emacs displays it as two or more screen lines, or visual lines. This is called line wrapping or continuation, and the long logical line is called a continued line. On a graphical display, Emacs indicates line wrapping with small bent arrows in the left and right window fringes. On a text terminal, Emacs indicates line wrapping by displaying a ‘\’ character at the right margin.

    Most commands that act on lines act on logical lines, not screen lines. For instance, C-k kills a logical line. As described earlier, C-n (next-line) and C-p (previous-line) are special exceptions: they move point down and up, respectively, by one screen line (see Changing the Location of Point).

    Emacs can optionally truncate long logical lines instead of continuing them. This means that every logical line occupies a single screen line; if it is longer than the width of the window, the rest of the line is not displayed. On a graphical display, a truncated line is indicated by a small straight arrow in the right fringe; on a text terminal, it is indicated by a ‘$’ character in the right margin. See Line Truncation.

    By default, continued lines are wrapped at the right window edge. Since the wrapping may occur in the middle of a word, continued lines can be difficult to read. The usual solution is to break your lines before they get too long, by inserting newlines. If you prefer, you can make Emacs insert a newline automatically when a line gets too long, by using Auto Fill mode. See Filling Text.

    Sometimes, you may need to edit files containing many long logical lines, and it may not be practical to break them all up by adding newlines. In that case, you can use Visual Line mode, which enables word wrapping: instead of wrapping long lines exactly at the right window edge, Emacs wraps them at the word boundaries (i.e., space or tab characters) nearest to the right window edge. Visual Line mode also redefines editing commands such as C-a, C-n, and C-k to operate on screen lines rather than logical lines. See Visual Line Mode.

    8.9 Cursor Position Information

    Here are commands to get information about the size and position of parts of the buffer, and to count words and lines.

    M-x what-line

    Display the line number of point.

    M-x line-number-mode
    M-x column-number-mode

    Toggle automatic display of the current line number or column number. See Optional Mode Line Features. If you want to have a line number displayed before each line, see Customization of Display.


    Display the number of lines, sentences, words, and characters that are present in the region (count-words-region). See The Mark and the Region, for information about the region.

    M-x count-words

    Display the number of lines, sentences, words, and characters that are present in the buffer. If the region is active (see The Mark and the Region), display the numbers for the region instead.

    C-x =

    Display the character code of character after point, character position of point, and column of point (what-cursor-position).

    M-x hl-line-mode

    Enable or disable highlighting of the current line. See Displaying the Cursor.

    M-x size-indication-mode

    Toggle automatic display of the size of the buffer. See Optional Mode Line Features.

    M-x what-line displays the current line number in the echo area. This command is usually redundant because the current line number is shown in the mode line (see The Mode Line). However, if you narrow the buffer, the mode line shows the line number relative to the accessible portion (see Narrowing). By contrast, what-line displays both the line number relative to the narrowed region and the line number relative to the whole buffer.

    M-= (count-words-region) displays a message reporting the number of lines, sentences, words, and characters in the region (see The Mark and the Region, for an explanation of the region). With a prefix argument, C-u M-=, the command displays a count for the entire buffer.

    The command M-x count-words does the same job, but with a different calling convention. It displays a count for the region if the region is active, and for the buffer otherwise.

    The command C-x = (what-cursor-position) shows information about the current cursor position and the buffer contents at that position. It displays a line in the echo area that looks like this:

    Char: c (99, #o143, #x63) point=28062 of 36168 (78%) column=53

    After ‘Char:’, this shows the character in the buffer at point. The text inside the parenthesis shows the corresponding decimal, octal and hex character codes; for more information about how C-x = displays character information, see Introduction to International Character Sets. After ‘point=’ is the position of point as a character count (the first character in the buffer is position 1, the second character is position 2, and so on). The number after that is the total number of characters in the buffer, and the number in parenthesis expresses the position as a percentage of the total. After ‘column=’ is the horizontal position of point, in columns counting from the left edge of the window.

    If the user option what-cursor-show-names is non-nil, the name of the character, as defined by the Unicode Character Database, is shown as well. The part in parentheses would then become:

    (99, #o143, #x63, LATIN SMALL LETTER C)

    If the buffer has been narrowed, making some of the text at the beginning and the end temporarily inaccessible, C-x = displays additional text describing the currently accessible range. For example, it might display this:

    Char: C (67, #o103, #x43) point=252 of 889 (28%) <231-599> column=0

    where the two extra numbers give the smallest and largest character position that point is allowed to assume. The characters between those two positions are the accessible ones. See Narrowing.

    Related, but different feature is display-line-numbers-mode (see Customization of Display).

    8.10 Numeric Arguments

    In the terminology of mathematics and computing, argument means “data provided to a function or operation”. You can give any Emacs command a numeric argument (also called a prefix argument). Some commands interpret the argument as a repetition count. For example, giving C-f an argument of ten causes it to move point forward by ten characters instead of one. With these commands, no argument is equivalent to an argument of one, and negative arguments cause them to move or act in the opposite direction.

    The easiest way to specify a numeric argument is to type a digit and/or a minus sign while holding down the Meta key. For example,

    M-5 C-n

    moves down five lines. The keys M-1, M-2, and so on, as well as M--, are bound to commands (digit-argument and negative-argument) that set up an argument for the next command. M-- without digits normally means -1.

    If you enter more than one digit, you need not hold down the Meta key for the second and subsequent digits. Thus, to move down fifty lines, type

    M-5 0 C-n

    Note that this does not insert five copies of ‘0’ and move down one line, as you might expect—the ‘0’ is treated as part of the prefix argument.

    (What if you do want to insert five copies of ‘0’? Type M-5 C-u 0. Here, C-u terminates the prefix argument, so that the next keystroke begins the command that you want to execute. Note that this meaning of C-u applies only to this case. For the usual role of C-u, see below.)

    Instead of typing M-1, M-2, and so on, another way to specify a numeric argument is to type C-u (universal-argument) followed by some digits, or (for a negative argument) a minus sign followed by digits. A minus sign without digits normally means -1.

    C-u alone has the special meaning of “four times”: it multiplies the argument for the next command by four. C-u C-u multiplies it by sixteen. Thus, C-u C-u C-f moves forward sixteen characters. Other useful combinations are C-u C-n, C-u C-u C-n (move down a good fraction of a screen), C-u C-u C-o (make sixteen blank lines), and C-u C-k (kill four lines).

    You can use a numeric argument before a self-inserting character to insert multiple copies of it. This is straightforward when the character is not a digit; for example, C-u 6 4 a inserts 64 copies of the character ‘a’. But this does not work for inserting digits; C-u 6 4 1 specifies an argument of 641. You can separate the argument from the digit to insert with another C-u; for example, C-u 6 4 C-u 1 does insert 64 copies of the character ‘1’.

    Some commands care whether there is an argument, but ignore its value. For example, the command M-q (fill-paragraph) fills text; with an argument, it justifies the text as well. (See Filling Text, for more information on M-q.) For these commands, it is enough to specify the argument with a single C-u.

    Some commands use the value of the argument as a repeat count but do something special when there is no argument. For example, the command C-k (kill-line) with argument n kills n lines, including their terminating newlines. But C-k with no argument is special: it kills the text up to the next newline, or, if point is right at the end of the line, it kills the newline itself. Thus, two C-k commands with no arguments can kill a nonblank line, just like C-k with an argument of one. (See Killing and Moving Text, for more information on C-k.)

    A few commands treat a plain C-u differently from an ordinary argument. A few others may treat an argument of just a minus sign differently from an argument of -1. These unusual cases are described when they come up; they exist to make an individual command more convenient, and they are documented in that command’s documentation string.

    We use the term prefix argument to emphasize that you type such arguments before the command, and to distinguish them from minibuffer arguments (see The Minibuffer), which are entered after invoking the command.

    On graphical displays, C-0, C-1, etc. act the same as M-0, M-1, etc.

    8.11 Repeating a Command

    Many simple commands, such as those invoked with a single key or with M-x command-name RET, can be repeated by invoking them with a numeric argument that serves as a repeat count (see Numeric Arguments). However, if the command you want to repeat prompts for input, or uses a numeric argument in another way, that method won’t work.

    The command C-x z (repeat) provides another way to repeat an Emacs command many times. This command repeats the previous Emacs command, whatever that was. Repeating a command uses the same arguments that were used before; it does not read new arguments each time.

    To repeat the command more than once, type additional z’s: each z repeats the command one more time. Repetition ends when you type a character other than z or press a mouse button.

    For example, suppose you type C-u 2 0 C-d to delete 20 characters. You can repeat that command (including its argument) three additional times, to delete a total of 80 characters, by typing C-x z z z. The first C-x z repeats the command once, and each subsequent z repeats it once again.

    You can also activate repeat-mode which allows repeating commands bound to sequences of two or more keys by typing a single character. For example, after typing C-x u (undo, see Undo) to undo the most recent edits, you can undo many more edits by typing u u u…. Similarly, type C-x o o o… instead of C-x o C-x o C-x o… to switch to the window several windows away. This works by entering a transient repeating mode after you type the full key sequence that invokes the command; the single-key shortcuts are shown in the echo area.

    Only some commands support repetition in repeat-mode; type M-x describe-repeat-maps RET to see which ones.

    The single-character shortcuts enabled by the transient repeating mode do not need to be identical: for example, after typing C-x {, either { or } or ^ or v, or any series that mixes these characters in any order, will resize the selected window in respective ways. Similarly, after M-g n or M-g p, typing any sequence of n and/or p in any mix will repeat next-error and previous-error to navigate in a *compilation* or *grep* buffer (see Compilation Mode).

    Typing any key other than those defined to repeat the previous command exits the transient repeating mode, and then the key you typed is executed normally. You can also define a key which will exit the transient repeating mode without executing the key which caused the exit. To this end, customize the user option repeat-exit-key to name a key; one natural value is RET. Finally, it’s possible to break the repetition chain automatically after some amount of idle time: customize the user option repeat-exit-timeout to specify the idle time in seconds after which this transient repetition mode will be turned off automatically.

    9 The Minibuffer

    The minibuffer is where Emacs commands read complicated arguments, such as file names, buffer names, Emacs command names, or Lisp expressions. We call it the “minibuffer” because it’s a special-purpose buffer with a small amount of screen space. You can use the usual Emacs editing commands in the minibuffer to edit the argument text.

    9.1 Using the Minibuffer

    When the minibuffer is in use, it appears in the echo area, with a cursor. The minibuffer starts with a prompt, usually ending with a colon. The prompt states what kind of input is expected, and how it will be used. The prompt is highlighted using the minibuffer-prompt face (see Text Faces).

    The simplest way to enter a minibuffer argument is to type the text, then RET to submit the argument and exit the minibuffer. Alternatively, you can type C-g to exit the minibuffer by canceling the command asking for the argument (see Quitting and Aborting).

    Sometimes, the prompt shows a default argument, inside parentheses before the colon. This default will be used as the argument if you just type RET. For example, commands that read buffer names usually show a buffer name as the default; you can type RET to operate on that default buffer. You can customize how the default argument is shown with the user option minibuffer-default-prompt-format.

    If you enable Minibuffer Electric Default mode, a global minor mode, Emacs hides the default argument as soon as you modify the contents of the minibuffer (since typing RET would no longer submit that default). If you ever bring back the original minibuffer text, the prompt again shows the default. To enable this minor mode, type M-x minibuffer-electric-default-mode.

    Since the minibuffer appears in the echo area, it can conflict with other uses of the echo area. If an error message or an informative message is emitted while the minibuffer is active, the message is displayed in brackets after the minibuffer text for a few seconds, or until you type something; then the message disappears. While the minibuffer is in use, Emacs does not echo keystrokes.

    While using the minibuffer, you can switch to a different frame, perhaps to note text you need to enter (see Frame Commands). By default, the active minibuffer moves to this new frame. If you set the user option minibuffer-follows-selected-frame to nil, then the minibuffer stays in the frame where you opened it, and you must switch back to that frame in order to complete (or abort) the current command. If you set that option to a value which is neither nil nor t, the minibuffer moves frame only after a recursive minibuffer has been opened in the current command (see (elisp)Recursive Mini). This option is mainly to retain (approximately) the behavior prior to Emacs 28.1. Note that the effect of the command, when you finally finish using the minibuffer, always takes place in the frame where you first opened it. The sole exception is that when that frame no longer exists, the action takes place in the currently selected frame.

    9.2 Minibuffers for File Names

    Commands such as C-x C-f (find-file) use the minibuffer to read a file name argument (see Files). When the minibuffer is used to read a file name, it typically starts out with some initial text ending in a slash. This is the default directory. For example, it may start out like this:

    Find file: /u2/emacs/src/

    Here, ‘Find file: ’ is the prompt and ‘/u2/emacs/src/’ is the default directory. If you now type buffer.c as input, that specifies the file /u2/emacs/src/buffer.c. See File Names, for information about the default directory.

    Alternative defaults for the file name you may want are available by typing M-n, see Minibuffer History.

    You can specify a file in the parent directory with ..: /a/b/../foo.el is equivalent to /a/foo.el. Alternatively, you can use M-DEL to kill directory names backwards (see Words).

    To specify a file in a completely different directory, you can kill the entire default with C-a C-k (see Editing in the Minibuffer). Alternatively, you can ignore the default, and enter an absolute file name starting with a slash or a tilde after the default directory. For example, you can specify /etc/termcap as follows:

    Find file: /u2/emacs/src//etc/termcap

    A double slash causes Emacs to ignore everything before the second slash in the pair. In the example above, /u2/emacs/src/ is ignored, so the argument you supplied is /etc/termcap. The ignored part of the file name is dimmed if the terminal allows it. (To disable this dimming, turn off File Name Shadow mode with the command M-x file-name-shadow-mode.)

    When completing remote file names (see Remote Files), a double slash behaves slightly differently: it causes Emacs to ignore only the file-name part, leaving the rest (method, host and username, etc.) intact. Typing three slashes in a row ignores everything in remote file names. See File name completion in The Tramp Manual.

    Emacs interprets ~/ as your home directory. Thus, ~/foo/bar.txt specifies a file named bar.txt, inside a directory named foo, which is in turn located in your home directory. In addition, ~user-id/ means the home directory of a user whose login name is user-id. Any leading directory name in front of the ~ is ignored: thus, /u2/emacs/~/foo/bar.txt is equivalent to ~/foo/bar.txt.

    On MS-Windows and MS-DOS systems, where a user doesn’t always have a home directory, Emacs uses several alternatives. For MS-Windows, see HOME and Startup Directories on MS-Windows; for MS-DOS, see File Names on MS-DOS. On these systems, the ~user-id/ construct is supported only for the current user, i.e., only if user-id is the current user’s login name.

    To prevent Emacs from inserting the default directory when reading file names, change the variable insert-default-directory to nil. In that case, the minibuffer starts out empty. Nonetheless, relative file name arguments are still interpreted based on the same default directory.

    You can also enter remote file names in the minibuffer. See Remote Files.

    9.3 Editing in the Minibuffer

    The minibuffer is an Emacs buffer, albeit a peculiar one, and the usual Emacs commands are available for editing the argument text. (The prompt, however, is read-only, and cannot be changed.)

    Since RET in the minibuffer submits the argument, you can’t use it to insert a newline. You can do that with C-q C-j, which inserts a C-j control character, which is formally equivalent to a newline character (see Inserting Text). Alternatively, you can use the C-o (open-line) command (see Blank Lines).

    Inside a minibuffer, the keys TAB, SPC, and ? are often bound to completion commands, which allow you to easily fill in the desired text without typing all of it. See Completion. As with RET, you can use C-q to insert a TAB, SPC, or ‘?’ character. If you want to make SPC and ? insert normally instead of starting completion, you can put the following in your init file:

    (keymap-unset minibuffer-local-completion-map "SPC")
    (keymap-unset minibuffer-local-completion-map "?")

    For convenience, C-a (move-beginning-of-line) in a minibuffer moves point to the beginning of the argument text, not the beginning of the prompt. For example, this allows you to erase the entire argument with C-a C-k.

    When the minibuffer is active, the echo area is treated much like an ordinary Emacs window. For instance, you can switch to another window (with C-x o), edit text there, then return to the minibuffer window to finish the argument. You can even kill text in another window, return to the minibuffer window, and yank the text into the argument. There are some restrictions on the minibuffer window, however: for instance, you cannot split it. See Multiple Windows.

    Normally, the minibuffer window occupies a single screen line. However, if you add two or more lines’ worth of text into the minibuffer, it expands automatically to accommodate the text. The variable resize-mini-windows controls the resizing of the minibuffer. The default value is grow-only, which means the behavior we have just described. If the value is t, the minibuffer window will also shrink automatically if you remove some lines of text from the minibuffer, down to a minimum of one screen line. If the value is nil, the minibuffer window never changes size automatically, but you can use the usual window-resizing commands on it (see Multiple Windows).

    The variable max-mini-window-height controls the maximum height for resizing the minibuffer window. A floating-point number specifies a fraction of the frame’s height; an integer specifies the maximum number of lines; nil means do not resize the minibuffer window automatically. The default value is 0.25.

    The C-M-v command in the minibuffer scrolls the help text from commands that display help text of any sort in another window. You can also scroll the help text with M-PageUp and M-PageDown (or, equivalently, M-prior and M-next). This is especially useful with long lists of possible completions. See Using Other Windows.

    Emacs normally disallows most commands that use the minibuffer while the minibuffer is active. To allow such commands in the minibuffer, set the variable enable-recursive-minibuffers to t. You might need also to enable minibuffer-depth-indicate-mode to show the current recursion depth in the minibuffer prompt on recursive use of the minibuffer.

    When active, the minibuffer is usually in minibuffer-mode. This is an internal Emacs mode without any special features.

    When not active, the minibuffer is in minibuffer-inactive-mode, and clicking mouse-1 there shows the *Messages* buffer. If you use a dedicated frame for minibuffers, Emacs also recognizes certain keys there, for example, n to make a new frame.

    9.4 Completion

    You can often use a feature called completion to help enter arguments. This means that after you type part of the argument, Emacs can fill in the rest, or some of it, based on what was typed so far.

    When completion is available, certain keys (usually TAB, RET, and SPC) are rebound in the minibuffer to special completion commands (see Completion Commands). These commands attempt to complete the text in the minibuffer, based on a set of completion alternatives provided by the command that requested the argument. You can usually type ? to see a list of completion alternatives.

    Although completion is usually done in the minibuffer, the feature is sometimes available in ordinary buffers too. See Completion for Symbol Names.

    9.4.1 Completion Example

    A simple example may help here. M-x uses the minibuffer to read the name of a command, so completion works by matching the minibuffer text against the names of existing Emacs commands. Suppose you wish to run the command auto-fill-mode. You can do that by typing M-x auto-fill-mode RET, but it is easier to use completion.

    If you type M-x a u TAB, the TAB looks for completion alternatives (in this case, command names) that start with ‘au’. There are several, including auto-fill-mode and autoconf-mode, but they all begin with auto, so the ‘au’ in the minibuffer completes to ‘auto’. (More commands may be defined in your Emacs session. For example, if a command called authorize-me was defined, Emacs could only complete as far as ‘aut’.)

    If you type TAB again immediately, it cannot determine the next character; it could be ‘-’, ‘a’, or ‘c’. So it does not add any characters; instead, TAB displays a list of all possible completions in another window.

    Next, type -f. The minibuffer now contains ‘auto-f’, and the only command name that starts with this is auto-fill-mode. If you now type TAB, completion fills in the rest of the argument ‘auto-fill-mode’ into the minibuffer.

    Hence, typing just a u TAB - f TAB allows you to enter ‘auto-fill-mode’.

    TAB also works while point is not at the end of the minibuffer. In that case, it will fill in text both at point and at the end of the minibuffer. If you type M-x autocm, then press C-b to move point before the ‘m’, you can type TAB to insert the text ‘onf-’ at point and ‘ode’ at the end of the minibuffer, so that the minibuffer contains ‘autoconf-mode’.

    9.4.2 Completion Commands

    Here is a list of the completion commands defined in the minibuffer when completion is allowed.


    Complete the text in the minibuffer as much as possible; if unable to complete, display a list of possible completions (minibuffer-complete).


    Complete up to one word from the minibuffer text before point (minibuffer-complete-word). This command is not available for arguments that often include spaces, such as file names.


    Submit the text in the minibuffer as the argument, possibly completing first (minibuffer-complete-and-exit). See Completion Exit.


    Display a list of completions (minibuffer-completion-help).

    TAB (minibuffer-complete) is the most fundamental completion command. It searches for all possible completions that match the existing minibuffer text, and attempts to complete as much as it can. See How Completion Alternatives Are Chosen, for how completion alternatives are chosen.

    SPC (minibuffer-complete-word) completes like TAB, but only up to the next hyphen or space. If you have ‘auto-f’ in the minibuffer and type SPC, it finds that the completion is ‘auto-fill-mode’, but it only inserts ‘ill-’, giving ‘auto-fill-’. Another SPC at this point completes all the way to ‘auto-fill-mode’.

    If TAB or SPC is unable to complete, it displays a list of matching completion alternatives (if there are any) in another window. You can display the same list with ? (minibuffer-completion-help). The following commands can be used with the completion list:


    While in the minibuffer, M-DOWN (minibuffer-next-completion and M-UP (minibuffer-previous-completion) navigate through the completions and displayed in the completions buffer. When minibuffer-completion-auto-choose is non-nil (which is the default), using these commands also inserts the current completion candidate into the minibuffer. If minibuffer-completion-auto-choose is nil, you can use the M-RET command (minibuffer-choose-completion) to insert the completion candidates into the minibuffer. By default, that exits the minibuffer, but with a prefix argument, C-u M-RET inserts the currently active candidate without exiting the minibuffer.


    Typing M-v, while in the minibuffer, selects the window showing the completion list (switch-to-completions). This paves the way for using the commands below. PageUp, prior and M-g M-c do the same. You can also select the window in other ways (see Multiple Windows).


    While in the completion list buffer, this chooses the completion at point (choose-completion). With a prefix argument, C-u RET inserts the completion at point into the minibuffer, but doesn’t exit the minibuffer—thus, you can change your mind and choose another candidate.


    While in the completion list buffer, these keys move point to the following completion alternative (next-completion).


    While in the completion list buffer, these keys move point to the previous completion alternative (previous-completion).


    While in the completion list buffer, this quits the window showing it and selects the window showing the minibuffer (quit-window).


    While in the completion list buffer, kill it and delete the window showing it (kill-current-buffer).

    9.4.3 Completion Exit

    When a command reads an argument using the minibuffer with completion, it also controls what happens when you type RET (minibuffer-complete-and-exit) to submit the argument. There are four types of behavior:

    • Strict completion accepts only exact completion matches. Typing RET exits the minibuffer only if the minibuffer text is an exact match, or completes to one. Otherwise, Emacs refuses to exit the minibuffer; instead it tries to complete, and if no completion can be done it momentarily displays ‘[No match]’ after the minibuffer text. (You can still leave the minibuffer by typing C-g to cancel the command.)

      An example of a command that uses this behavior is M-x, since it is meaningless for it to accept a non-existent command name.

    • Cautious completion is like strict completion, except RET exits only if the text is already an exact match. If the text completes to an exact match, RET performs that completion but does not exit yet; you must type a second RET to exit.

      Cautious completion is used for reading file names for files that must already exist, for example.

    • Permissive completion allows any input; the completion candidates are just suggestions. Typing RET does not complete, it just submits the argument as you have entered it.
    • Permissive completion with confirmation is like permissive completion, with an exception: if you typed TAB and this completed the text up to some intermediate state (i.e., one that is not yet an exact completion match), typing RET right afterward does not submit the argument. Instead, Emacs asks for confirmation by momentarily displaying ‘[Confirm]’ after the text; type RET again to confirm and submit the text. This catches a common mistake, in which one types RET before realizing that TAB did not complete as far as desired.

      You can tweak the confirmation behavior by customizing the variable confirm-nonexistent-file-or-buffer. The default value, after-completion, gives the behavior we have just described. If you change it to nil, Emacs does not ask for confirmation, falling back on permissive completion. If you change it to any other non-nil value, Emacs asks for confirmation whether or not the preceding command was TAB.

      This behavior is used by most commands that read file names, like C-x C-f, and commands that read buffer names, like C-x b.

    9.4.4 How Completion Alternatives Are Chosen

    Completion commands work by narrowing a large list of possible completion alternatives to a smaller subset that matches what you have typed in the minibuffer. In Completion Example, we gave a simple example of such matching. The procedure of determining what constitutes a match is quite intricate. Emacs attempts to offer plausible completions under most circumstances.

    Emacs performs completion using one or more completion styles—sets of criteria for matching minibuffer text to completion alternatives. During completion, Emacs tries each completion style in turn. If a style yields one or more matches, that is used as the list of completion alternatives. If a style produces no matches, Emacs falls back on the next style.

    The list variable completion-styles specifies the completion styles to use. Each list element is the name of a completion style (a Lisp symbol). The available style symbols are stored in the variable completion-styles-alist (see Completion Variables in The Emacs Lisp Reference Manual). The default completion styles are (in order):


    A matching completion alternative must have the same beginning as the text in the minibuffer before point. Furthermore, if there is any text in the minibuffer after point, the rest of the completion alternative must contain that text as a substring.


    This aggressive completion style divides the minibuffer text into words separated by hyphens or spaces, and completes each word separately. (For example, when completing command names, ‘em-l-m’ completes to ‘emacs-lisp-mode’.)

    Furthermore, a ‘*’ in the minibuffer text is treated as a wildcard—it matches any string of characters at the corresponding position in the completion alternative.


    This completion style is similar to basic, except that it ignores the text in the minibuffer after point. It is so-named because it corresponds to the completion behavior in Emacs 22.

    The following additional completion styles are also defined, and you can add them to completion-styles if you wish (see Customization):


    A matching completion alternative must contain the text in the minibuffer before point, and the text in the minibuffer after point, as substrings (in that same order).

    Thus, if the text in the minibuffer is ‘foobar’, with point between ‘foo’ and ‘bar’, that matches ‘afoobbarc’, where a, b, and c can be any string including the empty string.


    This aggressive completion style, also known as flx or fuzzy or scatter completion, attempts to complete using in-order substrings. For example, it can consider ‘foo’ to match ‘frodo’ or ‘fbarbazoo’.


    This very aggressive completion style attempts to complete acronyms and initialisms. For example, when completing command names, it matches ‘lch’ to ‘list-command-history’.

    There is also a very simple completion style called emacs21. In this style, if the text in the minibuffer is ‘foobar’, only matches starting with ‘foobar’ are considered.

    You can use different completion styles in different situations, by setting the variable completion-category-overrides. For example, the default setting says to use only basic and substring completion for buffer names.

    9.4.5 Completion Options

    Case is significant when completing case-sensitive arguments, such as command names. For example, when completing command names, ‘AU’ does not complete to ‘auto-fill-mode’. Case differences are ignored when completing arguments in which case does not matter.

    When completing file names, case differences are ignored if the variable read-file-name-completion-ignore-case is non-nil. The default value is nil on systems that have case-sensitive file-names, such as GNU/Linux; it is non-nil on systems that have case-insensitive file-names, such as Microsoft Windows. When completing buffer names, case differences are ignored if the variable read-buffer-completion-ignore-case is non-nil; the default is nil.

    When completing file names, Emacs usually omits certain alternatives that are considered unlikely to be chosen, as determined by the list variable completion-ignored-extensions. Each element in the list should be a string; any file name ending in such a string is ignored as a completion alternative. Any element ending in a slash (/) represents a subdirectory name. The standard value of completion-ignored-extensions has several elements including ".o", ".elc", and "~". For example, if a directory contains ‘foo.c’ and ‘foo.elc’, ‘foo’ completes to ‘foo.c’. However, if all possible completions end in otherwise-ignored strings, they are not ignored: in the previous example, ‘foo.e’ completes to ‘foo.elc’. Emacs disregards completion-ignored-extensions when showing completion alternatives in the completion list.

    Shell completion is an extended version of filename completion, see Shell Mode Options.

    If completion-auto-help is set to nil, the completion commands never display the completion list buffer; you must type ? to display the list. If the value is lazy, Emacs only shows the completion list buffer on the second attempt to complete. In other words, if there is nothing to complete, the first TAB echoes ‘Next char not unique’; the second TAB shows the completion list buffer. If the value is always, the completion list buffer is always shown when completion is attempted.

    The display of the completion list buffer after it is shown for the first time is also controlled by completion-auto-help. If the value is t or lazy, the window showing the completions pops down when Emacs is able to complete (and may pop up again if Emacs is again unable to complete after you type some more text); if the value is always, the window pops down only when you exit the completion. The value visible is a hybrid: it behaves like t when it decides whether to pop up the window showing the completion list buffer, and like always when it decides whether to pop it down.

    Emacs can optionally select the window showing the completions when it shows that window. To enable this behavior, customize the user option completion-auto-select to t, which changes the behavior of TAB when Emacs pops up the completions: pressing TAB will switch to the completion list buffer, and you can then move to a candidate by cursor motion commands and select it with RET. If the value of completion-auto-select is second-tab, then the first TAB will pop up the completions list buffer, and the second one will switch to it.

    If completion-cycle-threshold is non-nil, completion commands can cycle through completion alternatives. Normally, if there is more than one completion alternative for the text in the minibuffer, a completion command completes up to the longest common substring. If you change completion-cycle-threshold to t, the completion command instead completes to the first of those completion alternatives; each subsequent invocation of the completion command replaces that with the next completion alternative, in a cyclic manner. If you give completion-cycle-threshold a numeric value n, completion commands switch to this cycling behavior only when there are n or fewer alternatives.

    When displaying completions, Emacs will normally pop up a new buffer to display the completions. The completions will by default be sorted horizontally, using as many columns as will fit in the window-width, but this can be changed by customizing the completions-format user option. If its value is vertical, Emacs will sort the completions vertically instead, and if it’s one-column, Emacs will use just one column.

    The completions-sort user option controls the order in which the completions are sorted in the ‘*Completions*’ buffer. The default is alphabetical, which sorts in alphabetical order. The value nil disables sorting. The value can also be a function, which will be called with the list of completions, and should return the list in the desired order.

    When completions-max-height is non-nil, it limits the size of the completions window. It is specified in lines and include mode, header line and a bottom divider, if any. For a more complex control of the Completion window display properties, you can use display-buffer-alist (see Action Alists for Buffer Display in The Emacs Lisp Reference Manual).

    The variable completions-header-format is a format spec string to control the informative line shown before the completions list of candidates. If it contains a ‘%s’ construct, that get replaced by the number of completions shown in the completion list buffer. To suppress the display of the heading line, customize this variable to nil. The string that is the value of this variable can have text properties to change the visual appearance of the heading line; some useful properties face or cursor-intangible (see Properties with Special Meanings in The Emacs Lisp Reference Manual).

    When completions-highlight-face names a face, the current completion candidate, the one that will be selected by typing RET or clicking the mouse, will be highlighted using that face. The default value of this variable is completions-highlight; the value is nil disables this highlighting. This feature uses the special text property cursor-face.

    9.5 Minibuffer History

    Everything you type in the minibuffer is saved in a minibuffer history list so you can easily use it again later. This includes completion candidates (such as file names, buffer names, command names, etc.) and any other kind of minibuffer input. You can use the following commands to quickly fetch an earlier or alternative response into the minibuffer:


    Move to the previous item in the minibuffer history, an earlier argument (previous-history-element).


    Move to the next item in the minibuffer history (next-history-element).


    Like M-p and M-n, but move to the previous or next line of a multi-line item before going to the previous history item (previous-line-or-history-element and next-line-or-history-element) .

    M-r regexp RET

    Move to an earlier item in the minibuffer history that matches regexp (previous-matching-history-element).

    M-s regexp RET

    Move to a later item in the minibuffer history that matches regexp (next-matching-history-element).

    While in the minibuffer, M-p (previous-history-element) moves through the minibuffer history list, one item at a time. Each M-p fetches an earlier item from the history list into the minibuffer, replacing its existing contents. Typing M-n (next-history-element) moves through the minibuffer history list in the opposite direction, fetching later entries into the minibuffer.

    If you type M-n in the minibuffer when there are no later entries in the minibuffer history (e.g., if you haven’t previously typed M-p), Emacs tries fetching from a list of default arguments: values that you are likely to enter. You can think of this as moving through the “future history”.

    The “future history” for file names includes several possible alternatives you may find useful, such as the file name or the URL at point in the current buffer. The defaults put into the “future history” in this case are controlled by the functions mentioned in the value of the option file-name-at-point-functions. By default, its value invokes the ffap package (see Finding Files and URLs at Point), which tries to guess the default file or URL from the text around point. To disable this guessing, customize the option to a nil value, then the “future history” of file names will include only the file, if any, visited by the current buffer, and the default directory.

    The arrow keys UP and DOWN work like M-p and M-n, but if the current history item is longer than a single line, they allow you to move to the previous or next line of the current history item before going to the previous or next history item.

    If you edit the text inserted by the M-p or M-n minibuffer history commands, this does not change its entry in the history list. However, the edited argument does go at the end of the history list when you submit it.

    You can use M-r (previous-matching-history-element) to search through older elements in the history list, and M-s (next-matching-history-element) to search through newer entries. Each of these commands asks for a regular expression as an argument, and fetches the first matching entry into the minibuffer. See Syntax of Regular Expressions, for an explanation of regular expressions. A numeric prefix argument n means to fetch the nth matching entry. These commands are unusual, in that they use the minibuffer to read the regular expression argument, even though they are invoked from the minibuffer. An upper-case letter in the regular expression makes the search case-sensitive (see Lax Matching During Searching).

    You can also search through the history using an incremental search. See Searching the Minibuffer.

    Emacs keeps separate history lists for several different kinds of arguments. For example, there is a list for file names, used by all the commands that read file names. Other history lists include buffer names, command names (used by M-x), and command arguments (used by commands like query-replace).

    The variable history-length specifies the maximum length of a minibuffer history list; adding a new element deletes the oldest element if the list gets too long. If the value is t, there is no maximum length.

    The variable history-delete-duplicates specifies whether to delete duplicates in history. If it is non-nil, adding a new element deletes from the list all other elements that are equal to it. The default is nil.

    9.6 Repeating Minibuffer Commands

    Every command that uses the minibuffer once is recorded on a special history list, the command history, together with the values of its arguments, so that you can repeat the entire command. In particular, every use of M-x is recorded there, since M-x uses the minibuffer to read the command name.

    C-x ESC ESC

    Re-execute a recent minibuffer command from the command history (repeat-complex-command).

    M-x list-command-history

    Display the entire command history, showing all the commands C-x ESC ESC can repeat, most recent first.

    C-x ESC ESC re-executes a recent command that used the minibuffer. With no argument, it repeats the last such command. A numeric argument specifies which command to repeat; 1 means the last one, 2 the previous, and so on.

    C-x ESC ESC works by turning the previous command into a Lisp expression and then entering a minibuffer initialized with the text for that expression. Even if you don’t know Lisp, it will probably be obvious which command is displayed for repetition. If you type just RET, that repeats the command unchanged. You can also change the command by editing the Lisp expression before you execute it. The executed command is added to the front of the command history unless it is identical to the most recent item.

    Once inside the minibuffer for C-x ESC ESC, you can use the usual minibuffer history commands (see Minibuffer History) to move through the history list. After finding the desired previous command, you can edit its expression as usual and then execute it by typing RET.

    Incremental search does not, strictly speaking, use the minibuffer. Therefore, although it behaves like a complex command, it normally does not appear in the history list for C-x ESC ESC. You can make incremental search commands appear in the history by setting isearch-resume-in-command-history to a non-nil value. See Incremental Search.

    The list of previous minibuffer-using commands is stored as a Lisp list in the variable command-history. Each element is a Lisp expression that describes one command and its arguments. Lisp programs can re-execute a command by calling eval with the command-history element.

    9.7 Entering passwords

    Sometimes, you may need to enter a password into Emacs. For instance, when you tell Emacs to visit a file on another machine via a network protocol such as FTP, you often need to supply a password to gain access to the machine (see Remote Files).

    Entering a password is similar to using a minibuffer. Emacs displays a prompt in the echo area (such as ‘Password: ’); after you type the required password, press RET to submit it. To prevent others from seeing your password, every character you type is displayed as an asterisk (‘*’) instead of its usual form.

    Most of the features and commands associated with the minibuffer cannot be used when entering a password. There is no history or completion, and you cannot change windows or perform any other action with Emacs until you have submitted the password.

    While you are typing the password, you may press DEL to delete backwards, removing the last character entered. C-u deletes everything you have typed so far. C-g quits the password prompt (see Quitting and Aborting). C-y inserts the current kill into the password (see Killing and Moving Text). You may type either RET or ESC to submit the password. Any other self-inserting character key inserts the associated character into the password, and all other input is ignored.

    9.8 Yes or No Prompts

    An Emacs command may require you to answer a yes-or-no question during the course of its execution. Such queries come in two main varieties.

    For the first type of yes-or-no query, the prompt ends with ‘(y or n). You answer the query by typing a single key, either ‘y’ or ‘n’, which immediately exits the minibuffer and delivers the response. For example, if you type C-x C-w (write-file) to save a buffer, and enter the name of an existing file, Emacs issues a prompt like this:

    File ‘foo.el’ exists; overwrite? (y or n)

    The second type of yes-or-no query is typically employed if giving the wrong answer would have serious consequences; it thus features a longer prompt ending with ‘(yes or no)’. For example, if you invoke C-x k (kill-buffer) on a file-visiting buffer with unsaved changes, Emacs activates the minibuffer with a prompt like this:

    Buffer foo.el modified; kill anyway? (yes or no)

    To answer, you must type ‘yes’ or ‘no’ into the minibuffer, followed by RET.

    With both types of yes-or-no query the minibuffer behaves as described in the previous sections; you can recenter the selected window with C-l, scroll that window (C-v or PageDown scrolls forward, M-v or PageUp scrolls backward), switch to another window with C-x o, use the history commands M-p and M-n, etc. Type C-g to dismiss the query, and quit the minibuffer and the querying command (see Quitting and Aborting).

    Next: , Previous: , Up: The Emacs Editor   [Contents][Index]

    10 Running Commands by Name

    Every Emacs command has a name that you can use to run it. For convenience, many commands also have key bindings. You can run those commands by typing the keys, or run them by name. Most Emacs commands have no key bindings, so the only way to run them is by name. (See Customizing Key Bindings, for how to set up key bindings.)

    By convention, a command name consists of one or more words, separated by hyphens; for example, auto-fill-mode or manual-entry. Command names mostly use complete English words to make them easier to remember.

    To run a command by name, start with M-x, type the command name, then terminate it with RET. M-x uses the minibuffer to read the command name. The string ‘M-x’ appears at the beginning of the minibuffer as a prompt to remind you to enter a command name to be run. RET exits the minibuffer and runs the command. See The Minibuffer, for more information on the minibuffer.

    You can use completion to enter the command name. For example, to invoke the command forward-char, you can type

    M-x forward-char RET


    M-x forw TAB c RET

    Note that forward-char is the same command that you invoke with the key C-f. The existence of a key binding does not stop you from running the command by name.

    When M-x completes on commands, it ignores the commands that were declared obsolete in any previous major version of Emacs; for these, you will have to type their full name. Commands that were marked obsolete in the current version of Emacs are listed. (Obsolete commands are those for which newer, better alternatives exist, and which are slated for removal in some future Emacs release.)

    In addition, M-x completion can exclude commands that are not relevant to, and generally cannot work with, the current buffer’s major mode (see Major Modes) and minor modes (see Minor Modes). By default, no commands are excluded, but you can customize the option read-extended-command-predicate to exclude those irrelevant commands from completion results.

    Conversely, Emacs can exclude all commands except those that are particularly relevant to the current buffer. The M-S-x (that’s “meta shift x”) command works just like M-x, but instead of listing all (or most) of the commands Emacs knows about, it will only list the commands that have been marked as “belonging” to the current major mode, or any enabled minor modes.

    To cancel the M-x and not run a command, type C-g instead of entering the command name. This takes you back to command level.

    To pass a numeric argument to the command you are invoking with M-x, specify the numeric argument before M-x. The argument value appears in the prompt while the command name is being read, and finally M-x passes the argument to that command. For example, to pass the numeric argument of 42 to the command forward-char you can type C-u 42 M-x forward-char RET.

    When the command you run with M-x has a key binding, Emacs mentions this in the echo area after running the command. For example, if you type M-x forward-word, the message says that you can run the same command by typing M-f. You can turn off these messages by setting the variable suggest-key-bindings to nil. The value of suggest-key-bindings can also be a number, in which case Emacs will show the binding for that many seconds before removing it from display. The default behavior is to display the binding for 2 seconds.

    Additionally, when suggest-key-bindings is non-nil, the completion list of M-x shows equivalent key bindings for all commands that have them.

    Commands that don’t have key bindings, can still be invoked after typing less than their full name at the ‘M-x’ prompt. Emacs mentions such shorthands in the echo area if they are significantly shorter than the full command name, and extended-command-suggest-shorter is non-nil. The setting of suggest-key-bindings affects these hints as well.

    In this manual, when we speak of running a command by name, we often omit the RET that terminates the name. Thus we might say M-x auto-fill-mode rather than M-x auto-fill-mode RET. We mention the RET only for emphasis, such as when the command is followed by arguments.

    M-x works by running the command execute-extended-command, which is responsible for reading the name of another command and invoking it.

    11 Help

    Emacs provides a wide variety of help commands, all accessible through the prefix key C-h (or, equivalently, the function key F1). These help commands are described in the following sections. You can also type C-h C-h to view a list of help commands (help-for-help). You can scroll the list with SPC and DEL, then type the help command you want. To cancel, type C-g.

    Many help commands display their information in a special help buffer. In this buffer, you can type SPC and DEL to scroll and type RET to follow hyperlinks. See Help Mode Commands.

    By default, help commands display the help buffer in a separate window without selecting that window. The variable help-window-select controls this: its default value is nil; if it’s customized to the value t, the help window is unconditionally selected by help commands, and if its value is other, the help window is selected only if there are more than two windows on the selected frame.

    Conversely, many commands in the ‘*Help*’ buffer will pop up a new window to display the results. For instance, clicking on the link to show the source code, or using the i command to display the manual entry, will (by default) pop up a new window. If help-window-keep-selected is changed to non-nil, the window displaying the ‘*Help*’ buffer will be reused instead.

    If you are looking for a certain feature, but don’t know what it is called or where to look, we recommend three methods. First, try apropos commands, then try searching the manual index, then look in the FAQ and the package keywords, and finally try listing external packages.

    C-h a topics RET

    This searches for commands whose names match the argument topics. The argument can be a keyword, a list of keywords separated by whitespace, or a regular expression (see Syntax of Regular Expressions). See Apropos.

    C-h d topics RET

    Similar, but searches the text of the documentation strings rather than the names of commands and functions.

    C-h r i topic RET

    This searches for topic in the indices of the Emacs Info manual, displaying the first match found. Press , to see subsequent matches. You can use a regular expression as topic.

    C-h r s topic RET

    Similar, but searches the text of the manual rather than the indices.

    C-h C-f

    This displays the Emacs FAQ, using Info.

    C-h p

    This displays the available Emacs packages based on keywords. See Keyword Search for Packages.

    M-x list-packages

    This displays a list of external packages. See Emacs Lisp Packages.

    C-h or F1 mean “help” in various other contexts as well. For instance, you can type them after a prefix key to view a list of the keys that can follow the prefix key. (You can also use ? in this context. A few prefix keys don’t support C-h or ? in this way, because they define other meanings for those inputs, but they all support F1.)

    11.1 Help Summary

    Here is a summary of help commands for accessing the built-in documentation. Most of these are described in more detail in the following sections.

    C-h a topics RET

    Display a list of commands whose names match topics (apropos-command). See Apropos.

    C-h b

    Display all active key bindings; minor mode bindings first, then those of the major mode, then global bindings (describe-bindings). See Other Help Commands.

    C-h C-q

    Toggle display of a window showing popular commands and their key bindings. See Other Help Commands.

    C-h c key

    Show the name of the command that the key sequence key is bound to (describe-key-briefly). Here c stands for “character”. For more extensive information on key, use C-h k. See Documentation for a Key.

    C-h d topics RET

    Display the commands and variables whose documentation matches topics (apropos-documentation). See Apropos.

    C-h e

    Display the *Messages* buffer (view-echo-area-messages). See Other Help Commands.

    C-h f function RET

    Display documentation on the Lisp function named function (describe-function). Since commands are Lisp functions, this works for commands too, but you can also use C-h x. See Help by Command or Variable Name.

    C-h h

    Display the HELLO file, which shows examples of various character sets.

    C-h i

    Run Info, the GNU documentation browser (info). The Emacs manual is available in Info. See Other Help Commands.

    C-h k key

    Display the name and documentation of the command that key runs (describe-key). See Documentation for a Key.

    C-h l

    Display a description of your last 300 keystrokes (view-lossage). See Other Help Commands.

    C-h m

    Display documentation of the current major mode and minor modes (describe-mode). See Other Help Commands.

    C-h n

    Display news of recent Emacs changes (view-emacs-news). See Help Files.

    C-h o symbol

    Display documentation of the Lisp symbol named symbol (describe-symbol). This will show the documentation of all kinds of symbols: functions, variables, and faces. See Help by Command or Variable Name.

    C-h p

    Find packages by topic keyword (finder-by-keyword). See Keyword Search for Packages. This lists packages using a package menu buffer. See Emacs Lisp Packages.

    C-h P package RET

    Display documentation about the specified package (describe-package). See Keyword Search for Packages.

    C-h r

    Display the Emacs manual in Info (info-emacs-manual).

    C-h s

    Display the contents of the current syntax table (describe-syntax). See Other Help Commands. The syntax table says which characters are opening delimiters, which are parts of words, and so on. See Syntax Tables in The Emacs Lisp Reference Manual, for details.

    C-h t

    Enter the Emacs interactive tutorial (help-with-tutorial).

    C-h v var RET

    Display the documentation of the Lisp variable var (describe-variable). See Help by Command or Variable Name.

    C-h w command RET

    Show which keys run the command named command (where-is). See Documentation for a Key.

    C-h x command RET

    Display documentation on the named command (describe-command). See Help by Command or Variable Name.

    C-h C coding RET

    Describe the coding system coding (describe-coding-system). See Coding Systems.

    C-h C RET

    Describe the coding systems currently in use.

    C-h F command RET

    Enter Info and go to the node that documents the Emacs command command (Info-goto-emacs-command-node). See Help by Command or Variable Name.

    C-h I method RET

    Describe the input method method (describe-input-method). See Selecting an Input Method.

    C-h K key

    Enter Info and go to the node that documents the key sequence key (Info-goto-emacs-key-command-node). See Documentation for a Key.

    C-h L language-env RET

    Display information on the character sets, coding systems, and input methods used in language environment language-env (describe-language-environment). See Language Environments.

    C-h S symbol RET

    Display the Info documentation on symbol symbol according to the programming language you are editing (info-lookup-symbol). See Other Help Commands.

    C-h .

    Display the help message for a special text area, if point is in one (display-local-help). (These include, for example, links in *Help* buffers.) See Help on Active Text and Tooltips. If you invoke this command with a prefix argument, C-u C-h ., and point is on a button or a widget, this command will pop a new buffer that describes that button/widget.

    11.2 Documentation for a Key

    The help commands to get information about a key sequence are C-h c (describe-key-briefly) and C-h k (describe-key).

    C-h c key displays in the echo area the name of the command that key is bound to. For example, C-h c C-f displays ‘forward-char’.

    C-h k key is similar but gives more information: it displays a help buffer containing the command’s documentation string, which describes exactly what the command does.

    C-h K key displays the section of the Emacs manual that describes the command corresponding to key.

    C-h c, C-h k and C-h K work for any sort of key sequences, including function keys, menus, and mouse events (except that C-h c ignores mouse movement events). For instance, after C-h k you can select a menu item from the menu bar, to view the documentation string of the command it runs.

    C-h w command RET lists the keys that are bound to command. It displays the list in the echo area. If it says the command is not on any key, that means you must use M-x to run it. C-h w runs the command where-is.

    Some modes in Emacs use various buttons (see Buttons in The Emacs Lisp Reference Manual) and widgets (see Introduction in Emacs Widgets) that can be clicked to perform some action. To find out what function is ultimately invoked by these buttons, Emacs provides the button-describe and widget-describe commands, that should be run with point over the button.

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    11.3 Help by Command or Variable Name

    C-h x command RET (describe-command) displays the documentation of the named command, in a window. For example,

    C-h x auto-fill-mode RET

    displays the documentation of auto-fill-mode. This is how you would get the documentation of a command that is not bound to any key (one which you would normally run using M-x).

    C-h f function RET (describe-function) displays the documentation of Lisp function. This command is intended for Lisp functions that you use in a Lisp program. For example, if you have just written the expression (make-vector len) and want to check that you are using make-vector properly, type C-h f make-vector RET. Additionally, since all commands are Lisp functions, you can also use this command to view the documentation of any command.

    If you type C-h f RET, it describes the function called by the innermost Lisp expression in the buffer around point, provided that function name is a valid, defined Lisp function. (That name appears as the default while you enter the argument.) For example, if point is located following the text ‘(make-vector (car x)’, the innermost list containing point is the one that starts with ‘(make-vector’, so C-h f RET describes the function make-vector.

    C-h f is also useful just to verify that you spelled a function name correctly. If the minibuffer prompt for C-h f shows the function name from the buffer as the default, it means that name is defined as a Lisp function. Type C-g to cancel the C-h f command if you don’t really want to view the documentation.

    If you request help for an autoloaded function whose autoload form (see Autoload in The Emacs Lisp Reference Manual) doesn’t provide a doc string, the *Help* buffer won’t have any doc string to display. In that case, if help-enable-symbol-autoload is non-nil, Emacs will try to load the file in which the function is defined to see whether there’s a doc string there.

    You can get an overview of functions relevant for a particular topic by using the M-x shortdoc command. This will prompt you for an area of interest, e.g., string, and pop you to a buffer where many of the functions relevant for handling strings are listed.

    C-h v (describe-variable) is like C-h f but describes Lisp variables instead of Lisp functions. Its default is the Lisp symbol around or before point, if that is the name of a defined Lisp variable. See Variables.

    Help buffers that describe Emacs variables and functions normally have hyperlinks to the corresponding source code, if you have the source files installed (see Hyperlinking and Web Navigation Features).

    To find a command’s documentation in a manual, use C-h F (Info-goto-emacs-command-node). This knows about various manuals, not just the Emacs manual, and finds the right one.

    C-h o (describe-symbol) is like C-h f and C-h v, but it describes any symbol, be it a function, a variable, or a face. If the symbol has more than one definition, like it has both definition as a function and as a variable, this command will show the documentation of all of them, one after the other.

    If the completions-detailed user option is non-nil, some commands provide details about the possible values when displaying completions. For instance, C-h o TAB will then include the first line of the doc string, and will also say whether each symbol is a function or a variable (and so on). Which details are included varies depending on the command used.

    11.4 Apropos

    The apropos commands answer questions like, “What are the commands for working with files?” More precisely, you specify your query as an apropos pattern, which is either a word, a list of words separated by whitespace, or a regular expression.

    Each of the following apropos commands reads an apropos pattern in the minibuffer, searches for items that match the pattern, and displays the results in a different window.

    C-h a

    Search for commands (apropos-command). With a prefix argument, search for noninteractive functions too.

    M-x apropos

    Search for functions and variables. Both interactive functions (commands) and noninteractive functions can be found by this.

    M-x apropos-user-option

    Search for user-customizable variables. With a prefix argument, search for non-customizable variables too.

    M-x apropos-variable

    Search for variables. With a prefix argument, search for customizable variables only.

    M-x apropos-local-variable

    Search for buffer-local variables.

    M-x apropos-value

    Search for variables whose values match the specified pattern. With a prefix argument, search also for functions with definitions matching the pattern, and Lisp symbols with properties matching the pattern.

    M-x apropos-local-value

    Search for buffer-local variables whose values match the specified pattern.

    C-h d

    Search for functions and variables whose documentation strings match the specified pattern (apropos-documentation).

    The simplest kind of apropos pattern is one word. Anything containing that word matches the pattern. Thus, to find commands that work on files, type C-h a file RET. This displays a list of all command names that contain ‘file’, including copy-file, find-file, and so on. Each command name comes with a brief description and a list of keys you can currently invoke it with. In our example, it would say that you can invoke find-file by typing C-x C-f.

    By default, the window showing the apropos buffer with the results of the query is not selected, but you can cause it to be selected by customizing the variable help-window-select to any non-nil value.

    For more information about a function definition, variable or symbol property listed in an apropos buffer, you can click on it with mouse-1 or mouse-2, or move there and type RET.

    When you specify more than one word in the apropos pattern, a name must contain at least two of the words in order to match. Thus, if you are looking for commands to kill a chunk of text before point, you could try C-h a kill back backward behind before RET. The real command name kill-backward will match that; if there were a command kill-text-before, it would also match, since it contains two of the specified words.

    For even greater flexibility, you can specify a regular expression (see Syntax of Regular Expressions). An apropos pattern is interpreted as a regular expression if it contains any of the regular expression special characters, ‘^$*+?.\[’.

    Following the conventions for naming Emacs commands, here are some words that you’ll find useful in apropos patterns. By using them in C-h a, you will also get a feel for the naming conventions.

    char, line, word, sentence, paragraph, region, page, sexp, list, defun, rect, buffer, frame, window, face, file, dir, register, mode, beginning, end, forward, backward, next, previous, up, down, search, goto, kill, delete, mark, insert, yank, fill, indent, case, change, set, what, list, find, view, describe, default.

    If the variable apropos-do-all is non-nil, most apropos commands behave as if they had been given a prefix argument. There is one exception: apropos-variable without a prefix argument will always search for all variables, no matter what the value of apropos-do-all is.

    By default, all apropos commands except apropos-documentation list their results in alphabetical order. If the variable apropos-sort-by-scores is non-nil, these commands instead try to guess the relevance of each result, and display the most relevant ones first. The apropos-documentation command lists its results in order of relevance by default; to list them in alphabetical order, change the variable apropos-documentation-sort-by-scores to nil.

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    11.5 Help Mode Commands

    Help buffers have Help mode as their major mode. Help mode provides the same commands as View mode (see View Mode); for instance, SPC scrolls forward, and DEL or S-SPC scrolls backward. It also provides a few special commands:


    Follow a cross reference at point (help-follow).


    Move point forward to the next hyperlink (forward-button).


    Move point back to the previous hyperlink (backward-button).


    Follow a hyperlink that you click on.


    Move forward and back between pages in the Help buffer.

    C-c C-c

    Show all documentation about the symbol at point (help-follow-symbol).

    C-c C-f

    Go forward in history of help commands (help-go-forward).

    C-c C-b

    Go back in history of help commands (help-go-back).


    View the source of the current help topic (if any) (help-view-source).


    Look up the current topic in the manual(s) (help-goto-info).


    Look up the current topic in the Emacs Lisp manual (help-goto-lispref-info).


    Customize the variable or the face (help-customize).

    When a function name, variable name, or face name (see Text Faces) appears in the documentation in the help buffer, it is normally an underlined hyperlink. To view the associated documentation, move point there and type RET (help-follow), or click on the hyperlink with mouse-1 or mouse-2. Doing so replaces the contents of the help buffer; to retrace your steps, type C-c C-b or l (help-go-back). While retracing your steps, you can go forward by using C-c C-f or r (help-go-forward).

    To move between hyperlinks in a help buffer, use TAB (forward-button) to move forward to the next hyperlink and S-TAB (backward-button) to move back to the previous hyperlink. These commands act cyclically; for instance, typing TAB at the last hyperlink moves back to the first hyperlink.

    By default, many links in the help buffer are displayed surrounded by quote characters. If the help-clean-buttons user option is non-nil, these quote characters are removed from the buffer.

    Help buffers produced by some Help commands (like C-h b, which shows a long list of key bindings) are divided into pages by the ‘^L’ character. In such buffers, the n (help-goto-next-page) command will take you to the next start of page, and the p (help-goto-previous-page) command will take you to the previous start of page. This way you can quickly navigate between the different kinds of documentation in a help buffer.

    A help buffer can also contain hyperlinks to Info manuals, source code definitions, and URLs (web pages). The first two are opened in Emacs, and the third using a web browser via the browse-url command (see Following URLs).

    To view all documentation about any symbol in the text, move point to the symbol and type C-c C-c (help-follow-symbol). This shows the documentation for all the meanings of the symbol—as a variable, as a function, and/or as a face.

    11.6 Keyword Search for Packages

    Most optional features in Emacs are grouped into packages. Emacs contains several hundred built-in packages, and more can be installed over the network (see Emacs Lisp Packages).

    To make it easier to find packages related to a topic, most packages are associated with one or more keywords based on what they do. Type C-h p (finder-by-keyword) to bring up a list of package keywords, together with a description of what the keywords mean. To view a list of packages for a given keyword, type RET on that line; this displays the list of packages in a Package Menu buffer (see The Package Menu Buffer).

    C-h P (describe-package) prompts for the name of a package (see Emacs Lisp Packages), and displays a help buffer describing the attributes of the package and the features that it implements. The buffer lists the keywords that relate to the package in the form of buttons. Click on a button with mouse-1 or mouse-2 to see the list of other packages related to that keyword.

    11.7 Help for International Language Support

    For information on a specific language environment (see Language Environments), type C-h L (describe-language-environment). This displays a help buffer describing the languages supported by the language environment, and listing the associated character sets, coding systems, and input methods, as well as some sample text for that language environment.

    The command C-h h (view-hello-file) displays the file etc/HELLO, which demonstrates various character sets by showing how to say “hello” in many languages.

    The command C-h I (describe-input-method) describes an input method—either a specified input method, or by default the input method currently in use. See Input Methods.

    The command C-h C (describe-coding-system) describes coding systems—either a specified coding system, or the ones currently in use. See Coding Systems.

    11.8 Other Help Commands

    C-h i (info) runs the Info program, which browses structured documentation files. C-h 4 i (info-other-window) does the same, but shows the Info buffer in another window. The entire Emacs manual is available within Info, along with many other manuals for the GNU system. Type h after entering Info to run a tutorial on using Info.

    With a numeric argument n, C-h i selects the Info buffer ‘*info*<n>’. This is useful if you want to browse multiple Info manuals simultaneously. If you specify just C-u as the prefix argument, C-h i prompts for the name of a documentation file, so you can browse a file which doesn’t have an entry in the top-level Info menu.

    The help commands C-h F function RET and C-h K key, described above, enter Info and go straight to the documentation of function or key.

    When editing a program, if you have an Info version of the manual for the programming language, you can use C-h S (info-lookup-symbol) to find an entry for a symbol (keyword, function or variable) in the proper manual. The details of how this command works depend on the major mode.

    If something surprising happens, and you are not sure what you typed, use C-h l (view-lossage). C-h l displays your last input keystrokes and the commands they invoked. By default, Emacs stores the last 300 keystrokes; if you wish, you can change this number with the command lossage-size. If you see commands that you are not familiar with, you can use C-h k or C-h f to find out what they do.

    To review recent echo area messages, use C-h e (view-echo-area-messages). This displays the buffer *Messages*, where those messages are kept.

    Each Emacs major mode typically redefines a few keys and makes other changes in how editing works. C-h m (describe-mode) displays documentation on the current major mode, which normally describes the commands and features that are changed in this mode, and also its key bindings.

    C-h b (describe-bindings) and C-h s (describe-syntax) show other information about the current environment within Emacs. C-h b displays a list of all the key bindings now in effect: first the local bindings of the current minor modes, then the local bindings defined by the current major mode, and finally the global bindings (see Customizing Key Bindings). C-h s displays the contents of the syntax table, with explanations of each character’s syntax (see Syntax Tables in The Emacs Lisp Reference Manual).

    C-h C-q (help-quick-toggle) toggles on and off the display of a buffer showing the most popular Emacs commands and their respective key bindings (a.k.a. “cheat sheet”). The contents of that buffer are created by the command help-quick. Each key binding shown in this buffer is a button: click on it with mouse-1 or mouse-2 to show the documentation of the command bound to that key sequence.

    You can get a list of subcommands for a particular prefix key by typing C-h, ?, or F1 (describe-prefix-bindings) after the prefix key. (There are a few prefix keys for which not all of these keys work—those that provide their own bindings for that key. One of these prefix keys is ESC, because ESC C-h and ESC ? are actually C-M-h (mark-defun) and M-? (xref-find-references), respectively. However, ESC F1 works fine.)

    Finally, M-x describe-keymap prompts for the name of a keymap, with completion, and displays a listing of all key bindings in that keymap.

    11.9 Help Files

    Apart from the built-in documentation and manuals, Emacs contains several other files describing topics like copying conditions, release notes, instructions for debugging and reporting bugs, and so forth. You can use the following commands to view these files. Apart from C-h g, they all have the form C-h C-char.

    C-h C-c

    Display the rules under which you can copy and redistribute Emacs (describe-copying).

    C-h C-d

    Display help for debugging Emacs (view-emacs-debugging).

    C-h C-e

    Display information about where to get external packages (view-external-packages).

    C-h C-f

    Display the Emacs frequently-answered-questions list (view-emacs-FAQ).

    C-h g

    Visit the page with information about the GNU Project (describe-gnu-project).

    C-h C-m

    Display information about ordering printed copies of Emacs manuals (view-order-manuals).

    C-h C-n

    Display the news, which lists the new features in this version of Emacs (view-emacs-news).

    C-h C-o

    Display how to order or download the latest version of Emacs and other GNU software (describe-distribution).

    C-h C-p

    Display the list of known Emacs problems, sometimes with suggested workarounds (view-emacs-problems).

    C-h C-t

    Display the Emacs to-do list (view-emacs-todo).

    C-h C-w

    Display the full details on the complete absence of warranty for GNU Emacs (describe-no-warranty).

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    11.10 Help on Active Text and Tooltips

    In Emacs, stretches of active text (text that does something special in response to mouse clicks or RET) often have associated help text. This includes hyperlinks in Emacs buffers, as well as parts of the mode line. On graphical displays, as well as some text terminals which support mouse tracking, moving the mouse over the active text displays the help text as a tooltip. See Tooltips.

    On terminals that don’t support mouse-tracking, you can display the help text for active buffer text at point by typing C-h . (display-local-help). This shows the help text in the echo area. To display help text automatically whenever it is available at point, set the variable help-at-pt-display-when-idle to t.

    12 The Mark and the Region

    Emacs, like many other applications, lets you select some arbitrary part of the buffer text and invoke commands that operate on such selected text. In Emacs, we call the selected text the region; its handling is very similar to that of selected text in other programs, but there are also important differences.

    The region is the portion of the buffer between the mark and the current point. You define a region by setting the mark somewhere (with, for instance, the C-SPC command), and then moving point to where you want the region to end. (Or you can use the mouse to define a region.)

    The region always extends between point and the mark, no matter which of them comes earlier in the text; each time you move point, the region changes.

    Setting the mark at a position in the text activates it. When the mark is active, we say also that the region is active; Emacs indicates its extent by highlighting the text within it, using the region face (see Customizing Faces).

    After certain non-motion commands, including any command that changes the text in the buffer, Emacs automatically deactivates the mark; this turns off the highlighting. You can also explicitly deactivate the mark at any time, by typing C-g (see Quitting and Aborting).

    Many commands limit the text on which they operate to the active region. For instance, the M-% command (which replaces matching text) normally works on the entire accessible portion of the buffer, but if you have an active region, it’ll work only on that region instead.

    The mark is useful even if it is not active. For example, you can move to previous mark locations using the mark ring. See The Mark Ring. Additionally, some commands will have an effect even on an inactive region (for example upcase-region). You can also reactivate the region with commands like C-x C-x.

    The above behavior, which is the default in interactive sessions, is known as Transient Mark mode. Disabling Transient Mark mode switches Emacs to an alternative behavior, in which the region is usually not highlighted. See Disabling Transient Mark Mode.

    Setting the mark in one buffer has no effect on the marks in other buffers. When you return to a buffer with an active mark, the mark is at the same place as before. When multiple windows show the same buffer, they can have different values of point, and thus different regions, but they all share one common mark position. See Multiple Windows. Ordinarily, only the selected window highlights its region; however, if the variable highlight-nonselected-windows is non-nil, each window highlights its own region.

    There is another kind of region: the rectangular region. See Rectangles.

    12.1 Setting the Mark

    Here are some commands for setting the mark:


    Set the mark at point, and activate it (set-mark-command).


    The same.

    C-x C-x

    Set the mark at point, and activate it; then move point where the mark used to be (exchange-point-and-mark).


    Set point and the mark around the text you drag across.


    Set the mark at point, then move point to where you click (mouse-save-then-kill).

    Shifted cursor motion keys

    Set the mark at point if the mark is inactive, then move point. See Shift Selection.

    The most common way to set the mark is with C-SPC (set-mark-command)5. This sets the mark where point is, and activates it. You can then move point away, leaving the mark behind.

    For example, suppose you wish to convert part of the buffer to upper case. To accomplish this, go to one end of the desired text, type C-SPC, and move point until the desired portion of text is highlighted. Now type C-x C-u (upcase-region). This converts the text in the region to upper case, and then deactivates the mark.

    Whenever the mark is active, you can deactivate it by typing C-g (see Quitting and Aborting). Most commands that operate on the region also automatically deactivate the mark, like C-x C-u in the above example.

    Instead of setting the mark in order to operate on a region, you can also use it to remember a position in the buffer (by typing C-SPC C-SPC), and later jump back there (by typing C-u C-SPC). See The Mark Ring, for details.

    The command C-x C-x (exchange-point-and-mark) exchanges the positions of point and the mark. C-x C-x is useful when you are satisfied with the position of point but want to move the other end of the region (where the mark is). Using C-x C-x a second time, if necessary, puts the mark at the new position with point back at its original position. Normally, if the mark is inactive, this command first reactivates the mark wherever it was last set, to ensure that the region is left highlighted. However, if you call it with a prefix argument, it leaves the mark inactive and the region unhighlighted; you can use this to jump to the mark in a manner similar to C-u C-SPC.

    You can also set the mark with the mouse. If you press the left mouse button (down-mouse-1) and drag the mouse across a range of text, this sets the mark where you first pressed the mouse button and puts point where you release it. Alternatively, clicking the right mouse button (mouse-3) sets the mark at point and then moves point to where you clicked. See Mouse Commands for Editing, for a more detailed description of these mouse commands.

    Finally, you can set the mark by holding down the shift key while typing certain cursor motion commands (such as S-RIGHT, S-C-f, S-C-n, etc.). This is called shift-selection. It sets the mark at point before moving point, but only if there is no active mark set via a previous shift-selection or mouse commands. The mark set by mouse commands and by shift-selection behaves slightly differently from the usual mark: any subsequent unshifted cursor motion command deactivates it automatically. For details, see Shift Selection.

    Many commands that insert text, such as C-y (yank), set the mark at the other end of the inserted text, without activating it. This lets you easily return to that position (see The Mark Ring). You can tell that a command does this when it shows ‘Mark set’ in the echo area.

    Under X, every time the active region changes, Emacs saves the text in the region to the primary selection. This lets you insert that text into other X applications with mouse-2 clicks. See Cut and Paste with Other Window Applications.

    12.2 Commands to Mark Textual Objects

    Here are commands for placing point and the mark around a textual object such as a word, list, paragraph or page:


    Set mark at the end of the next word (mark-word). This does not move point.


    Set mark after end of following balanced expression (mark-sexp). This does not move point.


    Move point to the beginning of the current paragraph, and set mark at the end (mark-paragraph).


    Move point to the beginning of the current defun, and set mark at the end (mark-defun).

    C-x C-p

    Move point to the beginning of the current page, and set mark at the end (mark-page).

    C-x h

    Move point to the beginning of the buffer, and set mark at the end (mark-whole-buffer).

    M-@ (mark-word) sets the mark at the end of the next word (see Words, for information about words). Repeated invocations of this command extend the region by advancing the mark one word at a time. As an exception, if the mark is active and located before point, M-@ moves the mark backwards from its current position one word at a time.

    This command also accepts a numeric argument n, which tells it to advance the mark by n words. A negative argument -n moves the mark back by n words.

    Similarly, C-M-@ (mark-sexp) puts the mark at the end of the next balanced expression (see Expressions with Balanced Parentheses). Repeated invocations extend the region to subsequent expressions, while positive or negative numeric arguments move the mark forward or backward by the specified number of expressions.

    The other commands in the above list set both point and mark, so as to delimit an object in the buffer. M-h (mark-paragraph) marks paragraphs (see Paragraphs), C-M-h (mark-defun) marks top-level definitions (see Moving by Defuns), and C-x C-p (mark-page) marks pages (see Pages). Repeated invocations again play the same role, extending the region to consecutive objects; similarly, numeric arguments specify how many objects to move the mark by.

    C-x h (mark-whole-buffer) sets up the entire buffer as the region, by putting point at the beginning and the mark at the end.

    12.3 Operating on the Region

    Once you have a region, here are some of the ways you can operate on it:

    Some commands have a default behavior when the mark is inactive, but operate on the region if the mark is active. For example, M-$ (ispell-word) normally checks the spelling of the word at point, but it checks the text in the region if the mark is active (see Checking and Correcting Spelling). Normally, such commands use their default behavior if the region is empty (i.e., if mark and point are at the same position). If you want them to operate on the empty region, change the variable use-empty-active-region to t.

    As described in Erasing Text, the DEL (backward-delete-char) and Delete (delete-forward-char) commands also act this way. If the mark is active, they delete the text in the region. (As an exception, if you supply a numeric argument n, where n is not one, these commands delete n characters regardless of whether the mark is active). If you change the variable delete-active-region to nil, then these commands don’t act differently when the mark is active. If you change the value to kill, these commands kill the region instead of deleting it (see Killing and Moving Text).

    Other commands always operate on the region, and have no default behavior. Such commands usually have the word region in their names, like C-w (kill-region) and C-x C-u (upcase-region). If the mark is inactive, they operate on the inactive region—that is, on the text between point and the position at which the mark was last set (see The Mark Ring). To disable this behavior, change the variable mark-even-if-inactive to nil. Then these commands will instead signal an error if the mark is inactive.

    By default, text insertion occurs normally even if the mark is active—for example, typing a inserts the character ‘a’, then deactivates the mark. Delete Selection mode, a minor mode, modifies this behavior: if you enable that mode, then inserting text while the mark is active causes the text in the region to be deleted first. However, you can tune this behavior by customizing the delete-selection-temporary-region option. Its default value is nil, but you can set it to t, in which case only temporarily-active regions will be replaced: those which are set by dragging the mouse (see Setting the Mark) or by shift-selection (see Shift Selection), as well as by C-u C-x C-x when Transient Mark Mode is disabled. You can further tune the behavior by setting delete-selection-temporary-region to selection: then temporary regions by C-u C-x C-x won’t be replaced, only the ones activated by dragging the mouse or shift-selection. To toggle Delete Selection mode on or off, type M-x delete-selection-mode.

    12.4 The Mark Ring

    Each buffer remembers previous locations of the mark, in the mark ring. Commands that set the mark also push the old mark onto this ring. One of the uses of the mark ring is to remember spots that you may want to go back to.


    Set the mark, pushing it onto the mark ring, without activating it.

    C-u C-SPC

    Move point to where the mark was, and restore the mark from the ring of former marks.

    The command C-SPC C-SPC is handy when you want to use the mark to remember a position to which you may wish to return. It pushes the current point onto the mark ring, without activating the mark (which would cause Emacs to highlight the region). This is actually two consecutive invocations of C-SPC (set-mark-command); the first C-SPC sets the mark, and the second C-SPC deactivates it. (When Transient Mark mode is off, C-SPC C-SPC instead activates Transient Mark mode temporarily; see Disabling Transient Mark Mode.)

    To return to a marked position, use set-mark-command with a prefix argument: C-u C-SPC. This moves point to where the mark was, and deactivates the mark if it was active. Each subsequent C-u C-SPC jumps to a prior position stored in the mark ring. The positions you move through in this way are not lost; they go to the end of the ring.

    If you set set-mark-command-repeat-pop to non-nil, then immediately after you type C-u C-SPC, you can type C-SPC instead of C-u C-SPC to cycle through the mark ring. By default, set-mark-command-repeat-pop is nil.

    Each buffer has its own mark ring. All editing commands use the current buffer’s mark ring. In particular, C-u C-SPC always stays in the same buffer.

    The variable mark-ring-max specifies the maximum number of entries to keep in the mark ring. This defaults to 16 entries. If that many entries exist and another one is pushed, the earliest one in the list is discarded. Repeating C-u C-SPC cycles through the positions currently in the ring.

    If you want to move back to the same place over and over, the mark ring may not be convenient enough. If so, you can record the position in a register for later retrieval (see Saving Positions in Registers).

    12.5 The Global Mark Ring

    In addition to the ordinary mark ring that belongs to each buffer, Emacs has a single global mark ring. Each time you set a mark, this is recorded in the global mark ring in addition to the current buffer’s own mark ring, if you have switched buffers since the previous mark setting. Hence, the global mark ring records a sequence of buffers that you have been in, and, for each buffer, a place where you set the mark. The length of the global mark ring is controlled by global-mark-ring-max, and is 16 by default.

    The command C-x C-SPC (pop-global-mark) jumps to the buffer and position of the latest entry in the global ring. It also rotates the ring, so that successive uses of C-x C-SPC take you to earlier buffers and mark positions.

    12.6 Shift Selection

    If you hold down the shift key while typing a cursor motion command, this sets the mark before moving point, so that the region extends from the original position of point to its new position. This feature is referred to as shift-selection. It is similar to the way text is selected in other editors.

    The mark set via shift-selection behaves a little differently from what we have described above. Firstly, in addition to the usual ways of deactivating the mark (such as changing the buffer text or typing C-g), the mark is deactivated by any unshifted cursor motion command. Secondly, any subsequent shifted cursor motion command avoids setting the mark anew. Therefore, a series of shifted cursor motion commands will continuously adjust the region.

    Shift-selection only works if the shifted cursor motion key is not already bound to a separate command (see Customization). For example, if you bind S-C-f to another command, typing S-C-f runs that command instead of performing a shift-selected version of C-f (forward-char).

    A mark set via mouse commands behaves the same as a mark set via shift-selection (see Setting the Mark). For example, if you specify a region by dragging the mouse, you can continue to extend the region using shifted cursor motion commands. In either case, any unshifted cursor motion command deactivates the mark.

    To turn off shift-selection, set shift-select-mode to nil. Doing so does not disable setting the mark via mouse commands. If you set shift-select-mode to the value permanent, cursor motion keys that were not shift-translated will not deactivate the mark, so, for example, the region set by prior commands can be extended by shift-selection, and unshifted cursor motion keys will extend the region set by shift-selection.

    12.7 Disabling Transient Mark Mode

    The default behavior of the mark and region, in which setting the mark activates it and highlights the region, is called Transient Mark mode. This is a minor mode that is enabled by default in interactive sessions. It can be toggled with M-x transient-mark-mode, or with the ‘Highlight Active Region’ menu item in the ‘Options’ menu. Turning it off switches Emacs to an alternative mode of operation:

    • Setting the mark, with commands like C-SPC or C-x C-x, does not highlight the region. Therefore, you can’t tell by looking where the mark is located; you have to remember.

      The usual solution to this problem is to set the mark and then use it soon, before you forget where it is. You can also check where the mark is by using C-x C-x, which exchanges the positions of the point and the mark (see Setting the Mark).

    • Some commands, which ordinarily act on the region when the mark is active, no longer do so. For example, normally M-% (query-replace) performs replacements within the region, if the mark is active. When Transient Mark mode is off, it always operates from point to the end of the buffer. Commands that act this way are identified in their own documentation.

    While Transient Mark mode is off, you can activate it temporarily using C-SPC C-SPC or C-u C-x C-x.


    Set the mark at point (like plain C-SPC) and enable Transient Mark mode just once, until the mark is deactivated. (This is not really a separate command; you are using the C-SPC command twice.)

    C-u C-x C-x

    Exchange point and mark, activate the mark and enable Transient Mark mode temporarily, until the mark is next deactivated. (This is the C-x C-x command, exchange-point-and-mark, with a prefix argument.)

    These commands set or activate the mark, and enable Transient Mark mode only until the mark is deactivated. One reason you may want to use them is that some commands operate on the entire buffer instead of the region when Transient Mark mode is off. Enabling Transient Mark mode momentarily gives you a way to use these commands on the region.

    When you specify a region with the mouse (see Setting the Mark), or with shift-selection (see Shift Selection), this likewise activates Transient Mark mode temporarily and highlights the region.

    13 Killing and Moving Text

    In Emacs, killing means erasing text and copying it into the kill ring. Yanking means bringing text from the kill ring back into the buffer. (Some applications use the terms “cutting” and “pasting” for similar operations.) The kill ring is so-named because it can be visualized as a set of blocks of text arranged in a ring, which you can access in cyclic order. See The Kill Ring.

    Killing and yanking are the most common way to move or copy text within Emacs. It is very versatile, because there are commands for killing many different types of syntactic units.

    13.1 Deletion and Killing

    Most commands which erase text from the buffer save it in the kill ring (see The Kill Ring). These are known as kill commands, and their names normally contain the word ‘kill’ (e.g., kill-line). The kill ring stores several recent kills, not just the last one, so killing is a very safe operation: you don’t have to worry much about losing text that you previously killed. The kill ring is shared by all buffers, so text that is killed in one buffer can be yanked into another buffer.

    When you use C-/ (undo) to undo a kill command (see Undo), that brings the killed text back into the buffer, but does not remove it from the kill ring.

    On graphical displays, killing text also copies it to the system clipboard. See “Cut and Paste” Operations on Graphical Displays.

    Commands that erase text but do not save it in the kill ring are known as delete commands; their names usually contain the word ‘delete’. These include C-d (delete-char) and DEL (delete-backward-char), which delete only one character at a time, and those commands that delete only spaces or newlines. Commands that can erase significant amounts of nontrivial data generally do a kill operation instead.

    You can also use the mouse to kill and yank. See “Cut and Paste” Operations on Graphical Displays.

    13.1.1 Deletion

    Deletion means erasing text and not saving it in the kill ring. For the most part, the Emacs commands that delete text are those that erase just one character or only whitespace.


    Delete the previous character, or the text in the region if it is active (delete-backward-char).


    Delete the next character, or the text in the region if it is active (delete-forward-char).


    Delete the next character (delete-char).


    Delete spaces and tabs around point (delete-horizontal-space).

    M-x just-one-space

    Delete spaces and tabs around point, leaving one space.


    Delete spaces and tabs around point in flexible ways (cycle-spacing).

    C-x C-o

    Delete blank lines around the current line (delete-blank-lines).


    Join two lines by deleting the intervening newline, along with any indentation following it (delete-indentation).

    We have already described the basic deletion commands DEL (delete-backward-char), delete (delete-forward-char), and C-d (delete-char). See Erasing Text. With a numeric argument, they delete the specified number of characters. If the numeric argument is omitted or one, DEL and delete delete all the text in the region if it is active (see Operating on the Region).

    The other delete commands are those that delete only whitespace characters: spaces, tabs and newlines. M-\ (delete-horizontal-space) deletes all the spaces and tab characters before and after point. With a prefix argument, this only deletes spaces and tab characters before point.

    M-x just-one-space deletes tabs and spaces around point, but leaves a single space before point, regardless of the number of spaces that existed previously (even if there were none before). With a numeric argument n, it leaves n spaces before point if n is positive; if n is negative, it deletes newlines in addition to spaces and tabs, leaving -n spaces before point.

    The command cycle-spacing (M-SPC) acts like a more flexible version of just-one-space. It performs different space cleanup actions defined by cycle-spacing-actions, in a cyclic manner, if you call it repeatedly in succession. By default, the first invocation does the same as just-one-space, the second deletes all whitespace characters around point like delete-horizontal-space, and the third restores the original whitespace characters; then it cycles. If invoked with a prefix argument, each action is given that value of the argument. The user option cycle-spacing-actions can include other members; see the doc string of that option for the details.

    C-x C-o (delete-blank-lines) deletes all blank lines after the current line. If the current line is blank, it deletes all blank lines preceding the current line as well (leaving one blank line, the current line). On a solitary blank line, it deletes that line.

    M-^ (delete-indentation) joins the current line and the previous line, by deleting a newline and all surrounding spaces, usually leaving a single space. See M-^.

    The command delete-duplicate-lines searches the region for identical lines, and removes all but one copy of each. Normally it keeps the first instance of each repeated line, but with a C-u prefix argument it keeps the last. With a C-u C-u prefix argument, it only searches for adjacent identical lines. This is a more efficient mode of operation, useful when the lines have already been sorted. With a C-u C-u C-u prefix argument, it retains repeated blank lines.

    13.1.2 Killing by Lines


    Kill rest of line or one or more lines (kill-line).


    Kill an entire line at once (kill-whole-line)

    The simplest kill command is C-k (kill-line). If used at the end of a line, it kills the line-ending newline character, merging the next line into the current one (thus, a blank line is entirely removed). Otherwise, C-k kills all the text from point up to the end of the line; if point was originally at the beginning of the line, this leaves the line blank.

    Spaces and tabs at the end of the line are ignored when deciding which case applies. As long as point is after the last non-whitespace character in the line, you can be sure that C-k will kill the newline. To kill an entire non-blank line, go to the beginning and type C-k twice.

    In this context, “line” means a logical text line, not a screen line (see Continuation Lines).

    When C-k is given a positive argument n, it kills n lines and the newlines that follow them (text on the current line before point is not killed). With a negative argument -n, it kills n lines preceding the current line, together with the text on the current line before point. C-k with an argument of zero kills the text before point on the current line.

    If the variable kill-whole-line is non-nil, C-k at the very beginning of a line kills the entire line including the following newline. This variable is normally nil.

    C-S-backspace (kill-whole-line) kills a whole line including its newline, regardless of the position of point within the line. Note that many text terminals will prevent you from typing the key sequence C-S-backspace.

    13.1.3 Other Kill Commands


    Kill the region (kill-region).


    Copy the region into the kill ring (kill-ring-save).


    Kill the next word (kill-word). See Words.


    Kill one word backwards (backward-kill-word).

    C-x DEL

    Kill back to beginning of sentence (backward-kill-sentence). See Sentences.


    Kill to the end of the sentence (kill-sentence).


    Kill the following balanced expression (kill-sexp). See Expressions with Balanced Parentheses.

    M-z char

    Kill through the next occurrence of char (zap-to-char).

    M-x zap-up-to-char char

    Kill up to, but not including, the next occurrence of char.

    One of the commonly-used kill commands is C-w (kill-region), which kills the text in the region (see The Mark and the Region). Similarly, M-w (kill-ring-save) copies the text in the region into the kill ring without removing it from the buffer. If the mark is inactive when you type C-w or M-w, the command acts on the text between point and where you last set the mark (see Operating on the Region).

    Emacs also provides commands to kill specific syntactic units: words, with M-DEL and M-d (see Words); balanced expressions, with C-M-k (see Expressions with Balanced Parentheses); and sentences, with C-x DEL and M-k (see Sentences).

    The command M-z (zap-to-char) combines killing with searching: it reads a character and kills from point up to (and including) the next occurrence of that character in the buffer. A numeric argument acts as a repeat count; a negative argument means to search backward and kill text before point. A history of previously used characters is maintained and can be accessed via the M-p/M-n keystrokes. This is mainly useful if the character to be used has to be entered via a complicated input method. A similar command zap-up-to-char kills from point up to, but not including the next occurrence of a character, with numeric argument acting as a repeat count.

    13.1.4 Options for Killing

    Some specialized buffers contain read-only text, which cannot be modified and therefore cannot be killed. The kill commands work specially in a read-only buffer: they move over text and copy it to the kill ring, without actually deleting it from the buffer. Normally, they also beep and display an error message when this happens. But if you set the variable kill-read-only-ok to a non-nil value, they just print a message in the echo area to explain why the text has not been erased.

    Before saving the kill to the kill ring, you can transform the string using kill-transform-function. It’s called with the string to be killed, and it should return the string you want to be saved. It can also return nil, in which case the string won’t be saved to the kill ring. For instance, if you never want to save a pure white space string to the kill ring, you can say:

    (setq kill-transform-function
          (lambda (string)
            (and (not (string-blank-p string))

    If you change the variable kill-do-not-save-duplicates to a non-nil value, identical subsequent kills yield a single kill-ring entry, without duplication.

    13.2 Yanking

    Yanking means reinserting text previously killed. The usual way to move or copy text is to kill it and then yank it elsewhere.


    Yank the last kill into the buffer, at point (yank).


    Either replace the text just yanked with an earlier batch of killed text (yank-pop), or allow to select from the list of previously-killed batches of text. See Yanking Earlier Kills.


    Cause the following command, if it is a kill command, to append to the previous kill (append-next-kill). See Appending Kills.

    The basic yanking command is C-y (yank). It inserts the most recent kill, leaving the cursor at the end of the inserted text. It also sets the mark at the beginning of the inserted text, without activating the mark; this lets you jump easily to that position, if you wish, with C-u C-SPC (see The Mark Ring).

    With a plain prefix argument (C-u C-y), the command instead leaves the cursor in front of the inserted text, and sets the mark at the end. Using any other prefix argument specifies an earlier kill; e.g., C-u 4 C-y reinserts the fourth most recent kill. See Yanking Earlier Kills.

    On graphical displays and on capable text-mode displays, C-y first checks if another application has placed any text in the system clipboard more recently than the last Emacs kill. If so, it inserts the clipboard’s text instead. Thus, Emacs effectively treats “cut” or “copy” clipboard operations performed in other applications like Emacs kills, except that they are not recorded in the kill ring. See “Cut and Paste” Operations on Graphical Displays, for details.

    13.2.1 The Kill Ring

    The kill ring is a list of blocks of text that were previously killed. There is only one kill ring, shared by all buffers, so you can kill text in one buffer and yank it in another buffer. This is the usual way to move text from one buffer to another. (There are several other methods: for instance, you could store the text in a register; see Registers. See Accumulating Text, for some other ways to move text around.)

    The maximum number of entries in the kill ring is controlled by the variable kill-ring-max. The default is 120. If you make a new kill when this limit has been reached, Emacs makes room by deleting the oldest entry in the kill ring.

    The actual contents of the kill ring are stored in a variable named kill-ring; you can view the entire contents of the kill ring with C-h v kill-ring.

    Next: , Previous: , Up: Yanking   [Contents][Index]

    13.2.2 Yanking Earlier Kills

    As explained in Yanking, you can use a numeric argument to C-y to yank text that is no longer the most recent kill. This is useful if you remember which kill ring entry you want. If you don’t, you can use the M-y (yank-pop) command to cycle through the possibilities or to select one of the earlier kills.

    If the previous command was a yank command, M-y takes the text that was yanked and replaces it with the text from an earlier kill. So, to recover the text of the next-to-the-last kill, first use C-y to yank the last kill, and then use M-y to replace it with the previous kill. This works only after a C-y or another M-y. (If M-y is invoked after some other command, it works differently, see below.)

    You can understand this operation mode of M-y in terms of a last-yank pointer which points at an entry in the kill ring. Each time you kill, the last-yank pointer moves to the newly made entry at the front of the ring. C-y yanks the entry which the last-yank pointer points to. M-y after a C-y or another M-y moves the last-yank pointer to the previous entry, and the text in the buffer changes to match. Enough M-y commands one after another can move the pointer to any entry in the ring, so you can get any entry into the buffer. Eventually the pointer reaches the end of the ring; the next M-y loops back around to the first entry again.

    M-y moves the last-yank pointer around the ring, but it does not change the order of the entries in the ring, which always runs from the most recent kill at the front to the oldest one still remembered.

    When used after C-y or M-y, M-y can take a numeric argument, which tells it how many entries to advance the last-yank pointer by. A negative argument moves the pointer toward the front of the ring; from the front of the ring, it moves around to the last entry and continues forward from there.

    Once the text you are looking for is brought into the buffer, you can stop doing M-y commands and the last yanked text will stay there. It’s just a copy of the kill ring entry, so editing it in the buffer does not change what’s in the ring. As long as no new killing is done, the last-yank pointer remains at the same place in the kill ring, so repeating C-y will yank another copy of the same previous kill.

    When you call C-y with a numeric argument, that also sets the last-yank pointer to the entry that it yanks.

    You can also invoke M-y after a command that is not a yank command. In that case, M-y prompts you in the minibuffer for one of the previous kills. You can use the minibuffer history commands (see Minibuffer History) to navigate or search through the entries in the kill ring until you find the one you want to reinsert. Or you can use completion commands (see Completion Commands) to complete on an entry from the list of entries in the kill ring or pop up the *Completions* buffer with the candidate entries from which you can choose. After selecting the kill-ring entry, you can optionally edit it in the minibuffer. Finally, type RET to exit the minibuffer and insert the text of the selected kill-ring entry. Like in case of M-y after another yank command, the last-yank pointer is left pointing at the text you just yanked, whether it is one of the previous kills or an entry from the kill-ring that you edited before inserting it. (In the latter case, the edited entry is added to the front of the kill-ring.) So here, too, typing C-y will yank another copy of the text just inserted.

    When invoked with a plain prefix argument (C-u M-y) after a command that is not a yank command, M-y leaves the cursor in front of the inserted text, and sets the mark at the end, like C-y does.

    13.2.3 Appending Kills

    Normally, each kill command pushes a new entry onto the kill ring. However, two or more kill commands in a row combine their text into a single entry, so that a single C-y yanks all the text as a unit, just as it was before it was killed.

    Thus, if you want to yank text as a unit, you need not kill all of it with one command; you can keep killing line after line, or word after word, until you have killed it all, and you can still get it all back at once.

    Commands that kill forward from point add onto the end of the previous killed text. Commands that kill backward from point add text onto the beginning. This way, any sequence of mixed forward and backward kill commands puts all the killed text into one entry without rearrangement. Numeric arguments do not break the sequence of appending kills. For example, suppose the buffer contains this text:

    This is a line ∗of sample text.

    with point shown by ∗. If you type M-d M-DEL M-d M-DEL, killing alternately forward and backward, you end up with ‘a line of sample’ as one entry in the kill ring, and ‘This is  text. in the buffer. (Note the double space between ‘is’ and ‘text’, which you can clean up with M-SPC or M-q.)

    Another way to kill the same text is to move back two words with M-b M-b, then kill all four words forward with C-u M-d. This produces exactly the same results in the buffer and in the kill ring. M-f M-f C-u M-DEL kills the same text, all going backward; once again, the result is the same. The text in the kill ring entry always has the same order that it had in the buffer before you killed it.

    If a kill command is separated from the last kill command by other commands (not just numeric arguments), it starts a new entry on the kill ring. But you can force it to combine with the last killed text, by typing C-M-w (append-next-kill) right beforehand. The C-M-w tells its following command, if it is a kill command, to treat the kill as part of the sequence of previous kills. As usual, the kill is appended to the previous killed text if the command kills forward, and prepended if the command kills backward. In this way, you can kill several separated pieces of text and accumulate them to be yanked back in one place.

    A kill command following M-w (kill-ring-save) does not append to the text that M-w copied into the kill ring.

    13.3 “Cut and Paste” Operations on Graphical Displays

    In most graphical desktop environments, you can transfer data (usually text) between different applications using a system facility called the clipboard. On X, two other similar facilities are available: the primary selection and the secondary selection. When Emacs is run on a graphical display, its kill and yank commands integrate with these facilities, so that you can easily transfer text between Emacs and other graphical applications.

    By default, Emacs uses UTF-8 as the coding system for inter-program text transfers. If you find that the pasted text is not what you expected, you can specify another coding system by typing C-x RET x or C-x RET X. You can also request a different data type by customizing x-select-request-type. See Coding Systems for Interprocess Communication.

    13.3.1 Using the Clipboard

    The clipboard is the facility that most graphical applications use for “cutting and pasting”. When the clipboard exists, the kill and yank commands in Emacs make use of it.

    When you kill some text with a command such as C-w (kill-region), or copy it to the kill ring with a command such as M-w (kill-ring-save), that text is also put in the clipboard.

    When an Emacs kill command puts text in the clipboard, the existing clipboard contents are normally lost. Optionally, Emacs can save the existing clipboard contents to the kill ring, preventing you from losing the old clipboard data. If save-interprogram-paste-before-kill has been set to a number, then the data is copied over if it’s smaller (in characters) than this number. If this variable is any other non-nil value, the data is always copied over—at the risk of high memory consumption if that data turns out to be large.

    Yank commands, such as C-y (yank), also use the clipboard. If another application “owns” the clipboard—i.e., if you cut or copied text there more recently than your last kill command in Emacs—then Emacs yanks from the clipboard instead of the kill ring.

    Normally, rotating the kill ring with M-y (yank-pop) does not alter the clipboard. However, if you change yank-pop-change-selection to t, then M-y saves the new yank to the clipboard.

    To prevent kill and yank commands from accessing the clipboard, change the variable select-enable-clipboard to nil.

    Programs can put other things than plain text on the clipboard. For instance, a web browser will usually let you choose “Copy Image” on images, and this image will be put on the clipboard. On capable platforms, Emacs can yank these objects with the yank-media command—but only in modes that have support for it (see Yanking Media in The Emacs Lisp Reference Manual).

    Many X desktop environments support a feature called the clipboard manager. If you exit Emacs while it is the current “owner” of the clipboard data, and there is a clipboard manager running, Emacs transfers the clipboard data to the clipboard manager so that it is not lost. In some circumstances, this may cause a delay when exiting Emacs; if you wish to prevent Emacs from transferring data to the clipboard manager, change the variable x-select-enable-clipboard-manager to nil.

    Since strings containing NUL bytes are usually truncated when passed through the clipboard, Emacs replaces such characters with “\0” before transferring them to the system’s clipboard.

    Prior to Emacs 24, the kill and yank commands used the primary selection (see Cut and Paste with Other Window Applications), not the clipboard. If you prefer this behavior, change select-enable-clipboard to nil, select-enable-primary to t, and mouse-drag-copy-region to t. In this case, you can use the following commands to act explicitly on the clipboard: clipboard-kill-region kills the region and saves it to the clipboard; clipboard-kill-ring-save copies the region to the kill ring and saves it to the clipboard; and clipboard-yank yanks the contents of the clipboard at point.

    13.3.2 Cut and Paste with Other Window Applications

    Under the X Window System, PGTK and Haiku, there exists a primary selection containing the last stretch of text selected in an X application (usually by dragging the mouse). Typically, this text can be inserted into other X applications by mouse-2 clicks. The primary selection is separate from the clipboard. Its contents are more fragile; they are overwritten each time you select text with the mouse, whereas the clipboard is only overwritten by explicit cut or copy commands.

    Under X, whenever the region is active (see The Mark and the Region), the text in the region is saved in the primary selection. This applies regardless of whether the region was made by dragging or clicking the mouse (see Mouse Commands for Editing), or by keyboard commands (e.g., by typing C-SPC and moving point; see Setting the Mark).

    If you change the variable select-active-regions to only, Emacs saves only temporarily active regions to the primary selection, i.e., those made with the mouse or with shift selection (see Shift Selection). If you change select-active-regions to nil, Emacs avoids saving active regions to the primary selection entirely.

    To insert the primary selection into an Emacs buffer, click mouse-2 (mouse-yank-primary) where you want to insert it. See Mouse Commands for Editing. You can also use the normal Emacs yank command (C-y) to insert this text if select-enable-primary is set (see Using the Clipboard).

    By default, Emacs keeps the region active even after text is selected in another program; this is contrary to typical X behavior. To make Emacs deactivate the region after another program places data in the primary selection, enable the global minor mode lost-selection-mode.

    MS-Windows provides no primary selection, but Emacs emulates it within a single Emacs session by storing the selected text internally. Therefore, all the features and commands related to the primary selection work on Windows as they do on X, for cutting and pasting within the same session, but not across Emacs sessions or with other applications.

    13.3.3 Secondary Selection

    In addition to the primary selection, the X Window System provides a second similar facility known as the secondary selection. Nowadays, few X applications make use of the secondary selection, but you can access it using the following Emacs commands:


    Set the secondary selection, with one end at the place where you press down the button, and the other end at the place where you release it (mouse-set-secondary). The selected text is highlighted, using the secondary-selection face, as you drag. The window scrolls automatically if you drag the mouse off the top or bottom of the window, just like mouse-set-region (see Mouse Commands for Editing).

    This command does not alter the kill ring.


    Set one endpoint for the secondary selection (mouse-start-secondary); use M-mouse-3 to set the other end and complete the selection. This command cancels any existing secondary selection, when it starts a new one.


    Set the secondary selection (mouse-secondary-save-then-kill), with one end at the position you click M-mouse-3, and the other at the position specified previously with M-mouse-1. This also puts the selected text in the kill ring. A second M-mouse-3 at the same place kills the text selected by the secondary selection just made.


    Insert the secondary selection where you click, placing point at the end of the yanked text (mouse-yank-secondary).

    Double or triple clicking of M-mouse-1 operates on words and lines, much like mouse-1.

    If mouse-yank-at-point is non-nil, M-mouse-2 yanks at point. Then it does not matter precisely where you click, or even which of the frame’s windows you click on. See Mouse Commands for Editing. This user option also effects interactive search: if it is non-nil, yanking with the mouse anywhere in the frame will add the text to the search string.

    13.4 Accumulating Text

    Usually we copy or move text by killing it and yanking it, but there are other convenient methods for copying one block of text in many places, or for copying many scattered blocks of text into one place. Here we describe the commands to accumulate scattered pieces of text into a buffer or into a file.

    M-x append-to-buffer

    Append region to the contents of a specified buffer.

    M-x prepend-to-buffer

    Prepend region to the contents of a specified buffer.

    M-x copy-to-buffer

    Copy region into a specified buffer, deleting that buffer’s old contents.

    M-x insert-buffer

    Insert the contents of a specified buffer into current buffer at point.

    M-x append-to-file

    Append region to the contents of a specified file, at the end.

    To accumulate text into a buffer, use M-x append-to-buffer. This reads a buffer name, then inserts a copy of the region into the buffer specified. If you specify a nonexistent buffer, append-to-buffer creates the buffer. The text is inserted wherever point is in that buffer. If you have been using the buffer for editing, the copied text goes into the middle of the text of the buffer, starting from wherever point happens to be at that moment.

    Point in that buffer is left at the end of the copied text, so successive uses of append-to-buffer accumulate the text in the specified buffer in the same order as they were copied. Strictly speaking, append-to-buffer does not always append to the text already in the buffer—it appends only if point in that buffer is at the end. However, if append-to-buffer is the only command you use to alter a buffer, then point is always at the end.

    M-x prepend-to-buffer is just like append-to-buffer except that point in the other buffer is left before the copied text, so successive uses of this command add text in reverse order. M-x copy-to-buffer is similar, except that any existing text in the other buffer is deleted, so the buffer is left containing just the text newly copied into it.

    The command C-x x i (insert-buffer) can be used to retrieve the accumulated text from another buffer. This prompts for the name of a buffer, and inserts a copy of all the text in that buffer into the current buffer at point, leaving point at the beginning of the inserted text. It also adds the position of the end of the inserted text to the mark ring, without activating the mark. See Using Multiple Buffers, for background information on buffers.

    Instead of accumulating text in a buffer, you can append text directly into a file with M-x append-to-file. This prompts for a filename, and adds the text of the region to the end of the specified file. The file is changed immediately on disk.

    You should use append-to-file only with files that are not being visited in Emacs. Using it on a file that you are editing in Emacs would change the file behind Emacs’s back, which can lead to losing some of your editing.

    Another way to move text around is to store it in a register. See Registers.

    13.5 Rectangles

    Rectangle commands operate on rectangular areas of the text: all the characters between a certain pair of columns, in a certain range of lines. Emacs has commands to kill rectangles, yank killed rectangles, clear them out, fill them with blanks or text, or delete them. Rectangle commands are useful with text in multicolumn formats, and for changing text into or out of such formats.

    To specify a rectangle for a command to work on, set the mark at one corner and point at the opposite corner. The rectangle thus specified is called the region-rectangle. If point and the mark are in the same column, the region-rectangle is empty. If they are in the same line, the region-rectangle is one line high.

    The region-rectangle is controlled in much the same way as the region is controlled. But remember that a given combination of point and mark values can be interpreted either as a region or as a rectangle, depending on the command that uses them.

    A rectangular region can also be marked using the mouse: click and drag C-M-mouse-1 from one corner of the rectangle to the opposite.

    C-x r k

    Kill the text of the region-rectangle, saving its contents as the last killed rectangle (kill-rectangle).

    C-x r M-w

    Save the text of the region-rectangle as the last killed rectangle (copy-rectangle-as-kill).

    C-x r d

    Delete the text of the region-rectangle (delete-rectangle).

    C-x r y

    Yank the last killed rectangle with its upper left corner at point (yank-rectangle).

    C-x r o

    Insert blank space to fill the space of the region-rectangle (open-rectangle). This pushes the previous contents of the region-rectangle to the right.

    C-x r N

    Insert line numbers along the left edge of the region-rectangle (rectangle-number-lines). This pushes the previous contents of the region-rectangle to the right.

    C-x r c

    Clear the region-rectangle by replacing all of its contents with spaces (clear-rectangle).

    M-x delete-whitespace-rectangle

    Delete whitespace in each of the lines on the specified rectangle, starting from the left edge column of the rectangle.

    C-x r t string RET

    Replace rectangle contents with string on each line (string-rectangle).

    M-x string-insert-rectangle RET string RET

    Insert string on each line of the rectangle.

    C-x SPC

    Toggle Rectangle Mark mode (rectangle-mark-mode). When this mode is active, the region-rectangle is highlighted and can be shrunk/grown, and the standard kill and yank commands operate on it.

    The rectangle operations fall into two classes: commands to erase or insert rectangles, and commands to make blank rectangles.

    There are two ways to erase the text in a rectangle: C-x r d (delete-rectangle) to delete the text outright, or C-x r k (kill-rectangle) to remove the text and save it as the last killed rectangle. In both cases, erasing the region-rectangle is like erasing the specified text on each line of the rectangle; if there is any following text on the line, it moves backwards to fill the gap.

    Killing a rectangle is not killing in the usual sense; the rectangle is not stored in the kill ring, but in a special place that only records the most recent rectangle killed. This is because yanking a rectangle is so different from yanking linear text that different yank commands have to be used. Yank-popping is not defined for rectangles.

    C-x r M-w (copy-rectangle-as-kill) is the equivalent of M-w for rectangles: it records the rectangle as the last killed rectangle, without deleting the text from the buffer.

    To yank the last killed rectangle, type C-x r y (yank-rectangle). The rectangle’s first line is inserted at point, the rectangle’s second line is inserted at the same horizontal position one line vertically below, and so on. The number of lines affected is determined by the height of the saved rectangle.

    For example, you can convert two single-column lists into a double-column list by killing one of the single-column lists as a rectangle, and then yanking it beside the other list.

    You can also copy rectangles into and out of registers with C-x r r r and C-x r i r. See Saving Rectangles in Registers.

    There are two commands you can use for making blank rectangles: C-x r c (clear-rectangle) blanks out existing text in the region-rectangle, and C-x r o (open-rectangle) inserts a blank rectangle.

    M-x delete-whitespace-rectangle deletes horizontal whitespace starting from a particular column. This applies to each of the lines in the rectangle, and the column is specified by the left edge of the rectangle. The right edge of the rectangle does not make any difference to this command.

    The command C-x r N (rectangle-number-lines) inserts line numbers along the left edge of the region-rectangle. Normally, the numbering begins from 1 (for the first line of the rectangle). With a prefix argument, the command prompts for a number to begin from, and for a format string with which to print the numbers (see Formatting Strings in The Emacs Lisp Reference Manual).

    The command C-x r t (string-rectangle) replaces the contents of a region-rectangle with a string on each line. The string’s width need not be the same as the width of the rectangle. If the string’s width is less, the text after the rectangle shifts left; if the string is wider than the rectangle, the text after the rectangle shifts right.

    The command M-x string-insert-rectangle is similar to string-rectangle, but inserts the string on each line, shifting the original text to the right.

    The command C-x SPC (rectangle-mark-mode) toggles whether the region-rectangle or the standard region is highlighted (first activating the region if necessary). When this mode is enabled, commands that resize the region (C-f, C-n etc.) do so in a rectangular fashion, and killing and yanking operate on the rectangle. See Killing and Moving Text. The mode persists only as long as the region is active.

    The region-rectangle works only when the mark is active. In particular, when Transient Mark mode is off (see Disabling Transient Mark Mode), in addition to typing C-x SPC you will need to activate the mark.

    Unlike the standard region, the region-rectangle can have its corners extended past the end of buffer, or inside stretches of white space that point normally cannot enter, like in the middle of a TAB character.

    When the region is active (see The Mark and the Region) and in rectangle-mark-mode, C-x C-x runs the command rectangle-exchange-point-and-mark, which cycles between the four corners of the region-rectangle. This comes in handy if you want to modify the dimensions of the region-rectangle before invoking an operation on the marked text.

    13.6 CUA Bindings

    The command M-x cua-mode sets up key bindings that are compatible with the Common User Access (CUA) system used in many other applications.

    When CUA mode is enabled, the keys C-x, C-c, C-v, and C-z invoke commands that cut (kill), copy, paste (yank), and undo respectively. The C-x and C-c keys perform cut and copy only if the region is active. Otherwise, they still act as prefix keys, so that standard Emacs commands like C-x C-c still work. Note that this means the variable mark-even-if-inactive has no effect for C-x and C-c (see Operating on the Region).

    To enter an Emacs command like C-x C-f while the mark is active, use one of the following methods: either hold Shift together with the prefix key, e.g., S-C-x C-f, or quickly type the prefix key twice, e.g., C-x C-x C-f.

    To disable the overriding of standard Emacs binding by CUA mode, while retaining the other features of CUA mode described below, set the variable cua-enable-cua-keys to nil.

    CUA mode by default activates Delete-Selection mode (see Mouse Commands for Editing) so that typed text replaces the active region. To use CUA without this behavior, set the variable cua-delete-selection to nil.

    CUA mode provides enhanced rectangle support with visible rectangle highlighting. Use C-RET to start a rectangle, extend it using the movement commands, and cut or copy it using C-x or C-c. RET moves the cursor to the next (clockwise) corner of the rectangle, so you can easily expand it in any direction. Normal text you type is inserted to the left or right of each line in the rectangle (on the same side as the cursor).

    You can use this rectangle support without activating CUA by calling the cua-rectangle-mark-mode command. There’s also the standard command rectangle-mark-mode, see Rectangles.

    With CUA you can easily copy text and rectangles into and out of registers by providing a one-digit numeric prefix to the kill, copy, and yank commands, e.g., C-1 C-c copies the region into register 1, and C-2 C-v yanks the contents of register 2.

    CUA mode also has a global mark feature which allows easy moving and copying of text between buffers. Use C-S-SPC to toggle the global mark on and off. When the global mark is on, all text that you kill or copy is automatically inserted at the global mark, and text you type is inserted at the global mark rather than at the current position.

    For example, to copy words from various buffers into a word list in a given buffer, set the global mark in the target buffer, then navigate to each of the words you want in the list, mark it (e.g., with S-M-f), copy it to the list with C-c or M-w, and insert a newline after the word in the target list by pressing RET.

    14 Registers

    Emacs registers are compartments where you can save text, rectangles, positions, and other things for later use. Once you save text or a rectangle in a register, you can copy it into the buffer once or many times; once you save a position in a register, you can jump back to that position once or many times.

    Each register has a name that consists of a single character, which we will denote by r; r can be a letter (such as ‘a’) or a number (such as ‘1’); case matters, so register ‘a’ is not the same as register ‘A’. You can also set a register in non-alphanumeric characters, for instance ‘*’ or ‘C-d’. Note, it’s not possible to set a register in ‘C-g’ or ‘ESC’, because these keys are reserved for quitting (see Quitting and Aborting).

    A register can store a position, a piece of text, a rectangle, a number, a window or frame configuration, a buffer name, or a file name, but only one thing at any given time. Whatever you store in a register remains there until you store something else in that register. To see what register r contains, use M-x view-register:

    M-x view-register RET r

    Display a description of what register r contains.

    All of the commands that prompt for a register will display a preview window that lists the existing registers (if there are any) after a short delay. To change the length of the delay, customize register-preview-delay. To prevent this display, set that option to nil. You can explicitly request a preview window by pressing C-h or F1.

    Bookmarks record files and positions in them, so you can return to those positions when you look at the file again. Bookmarks are similar in spirit to registers, so they are also documented in this chapter.

    14.1 Saving Positions in Registers

    C-x r SPC r

    Record the position of point and the current buffer in register r (point-to-register).

    C-x r j r

    Jump to the position and buffer saved in register r (jump-to-register).

    Typing C-x r SPC (point-to-register), followed by a character r, saves both the position of point and the current buffer in register r. The register retains this information until you store something else in it.

    The command C-x r j r switches to the buffer recorded in register r, pushes a mark, and moves point to the recorded position. (The mark is not pushed if point was already at the recorded position, or in successive calls to the command.) The contents of the register are not changed, so you can jump to the saved position any number of times.

    If you use C-x r j to go to a saved position, but the buffer it was saved from has been killed, C-x r j tries to create the buffer again by visiting the same file. Of course, this works only for buffers that were visiting files.

    14.2 Saving Text in Registers

    When you want to insert a copy of the same piece of text several times, it may be inconvenient to yank it from the kill ring, since each subsequent kill moves that entry further down the ring. An alternative is to store the text in a register and later retrieve it.

    C-x r s r

    Copy region into register r (copy-to-register).

    C-x r i r

    Insert text from register r (insert-register).

    M-x append-to-register RET r

    Append region to text in register r.

    When register r contains text, you can use C-x r + (increment-register) to append to that register. Note that command C-x r + behaves differently if r contains a number. See Keeping Numbers in Registers.

    M-x prepend-to-register RET r

    Prepend region to text in register r.

    C-x r s r stores a copy of the text of the region into the register named r. If the mark is inactive, Emacs first reactivates the mark where it was last set. The mark is deactivated at the end of this command. See The Mark and the Region. C-u C-x r s r, the same command with a prefix argument, copies the text into register r and deletes the text from the buffer as well; you can think of this as moving the region text into the register.

    M-x append-to-register RET r appends the copy of the text in the region to the text already stored in the register named r. If invoked with a prefix argument, it deletes the region after appending it to the register. The command prepend-to-register is similar, except that it prepends the region text to the text in the register instead of appending it.

    When you are collecting text using append-to-register and prepend-to-register, you may want to separate individual collected pieces using a separator. In that case, configure a register-separator and store the separator text in to that register. For example, to get double newlines as text separator during the collection process, you can use the following setting.

    (setq register-separator ?+)
    (set-register register-separator "\n\n")

    C-x r i r inserts in the buffer the text from register r. Normally it leaves point after the text and sets the mark before, without activating it. With a prefix argument, it instead puts point before the text and the mark after.

    14.3 Saving Rectangles in Registers

    A register can contain a rectangle instead of linear text. See Rectangles, for basic information on how to specify a rectangle in the buffer.

    C-x r r r

    Copy the region-rectangle into register r (copy-rectangle-to-register). With prefix argument, delete it as well.

    C-x r i r

    Insert the rectangle stored in register r (if it contains a rectangle) (insert-register).

    The C-x r i r (insert-register) command, previously documented in Saving Text in Registers, inserts a rectangle rather than a text string, if the register contains a rectangle.

    14.4 Saving Window and Frame Configurations in Registers

    You can save the window configuration of the selected frame in a register, or even the configuration of all windows in all frames, and restore the configuration later. See Convenience Features for Window Handling, for information about window configurations.

    C-x r w r

    Save the state of the selected frame’s windows in register r (window-configuration-to-register).

    C-x r f r

    Save the state of all frames, including all their windows (a.k.a. frameset), in register r (frameset-to-register).

    Use C-x r j r to restore a window or frame configuration. This is the same command used to restore a cursor position. When you restore a frame configuration, any existing frames not included in the configuration become invisible. If you wish to delete these frames instead, use C-u C-x r j r.

    14.5 Keeping Numbers in Registers

    There are commands to store a number in a register, to insert the number in the buffer in decimal, and to increment it. These commands can be useful in keyboard macros (see Keyboard Macros).

    C-u number C-x r n r

    Store number into register r (number-to-register).

    C-u number C-x r + r

    If r contains a number, increment the number in that register by number. Note that command C-x r + (increment-register) behaves differently if r contains text. See Saving Text in Registers.

    C-x r i r

    Insert the number from register r into the buffer.

    C-x r i is the same command used to insert any other sort of register contents into the buffer. C-x r + with no numeric argument increments the register value by 1; C-x r n with no numeric argument stores zero in the register.

    14.6 Keeping File and Buffer Names in Registers

    If you visit certain file names frequently, you can visit them more conveniently if you put their names in registers. Here’s the Lisp code used to put a file name into register r:

    (set-register r '(file . name))

    For example,

    (set-register ?z '(file . "/gd/gnu/emacs/19.0/src/ChangeLog"))

    puts the file name shown in register ‘z’.

    To visit the file whose name is in register r, type C-x r j r. (This is the same command used to jump to a position or restore a frame configuration.)

    Similarly, if there are certain buffers you visit frequently, you can put their names in registers. For instance, if you visit the ‘*Messages*’ buffer often, you can use the following snippet to put that buffer into the ‘m’ register:

    (set-register ?m '(buffer . "*Messages*"))

    To switch to the buffer whose name is in register r, type C-x r j r.

    14.7 Keyboard Macro Registers

    If you need to execute a keyboard macro (see Keyboard Macros) frequently, it is more convenient to put it in a register or save it (see Naming and Saving Keyboard Macros). C-x C-k x r (kmacro-to-register) stores the last keyboard macro in register r.

    To execute the keyboard macro in register r, type C-x r j r. (This is the same command used to jump to a position or restore a frameset.)


    Bookmarks are somewhat like registers in that they record positions you can jump to. Unlike registers, they have long names, and they persist automatically from one Emacs session to the next. The prototypical use of bookmarks is to record where you were reading in various files.

    C-x r m RET

    Set the bookmark for the visited file, at point.

    C-x r m bookmark RET

    Set the bookmark named bookmark at point (bookmark-set).

    C-x r M bookmark RET

    Like C-x r m, but don’t overwrite an existing bookmark.

    C-x r b bookmark RET

    Jump to the bookmark named bookmark (bookmark-jump).

    C-x r l

    List all bookmarks (list-bookmarks).

    M-x bookmark-save

    Save all the current bookmark values in the default bookmark file.

    To record the current position in the visited file, use the command C-x r m, which sets a bookmark using the visited file name as the default for the bookmark name. If you name each bookmark after the file it points to, then you can conveniently revisit any of those files with C-x r b (bookmark-jump), and move to the position of the bookmark at the same time.

    In addition to recording the current position, on graphical displays C-x r m places a special image on the left fringe (see Window Fringes) of the screen line corresponding to the recorded position, to indicate that there’s a bookmark there. This can be controlled by the user option bookmark-fringe-mark: customize it to nil to disable the fringe mark. The default value is bookmark-mark, which is the bitmap used for this purpose. When you later use C-x r b to jump back to the bookmark, the fringe mark will be again shown on the fringe.

    The command C-x r M (bookmark-set-no-overwrite) works like C-x r m, but it signals an error if the specified bookmark already exists, instead of overwriting it.

    To display a list of all your bookmarks in a separate buffer, type C-x r l (list-bookmarks). If you switch to that buffer, you can use it to edit your bookmark definitions or annotate the bookmarks. Type C-h m in the bookmark buffer for more information about its special editing commands.

    When you kill Emacs, Emacs saves your bookmarks, if you have changed any bookmark values. You can also save the bookmarks at any time with the M-x bookmark-save command. Bookmarks are saved to the file ~/.emacs.d/bookmarks (for compatibility with older versions of Emacs, if you have a file named ~/.emacs.bmk, that is used instead). The bookmark commands load your default bookmark file automatically. This saving and loading is how bookmarks persist from one Emacs session to the next.

    If you set the variable bookmark-save-flag to 1, each command that sets a bookmark will also save your bookmarks; this way, you don’t lose any bookmark values even if Emacs crashes. The value, if a number, says how many bookmark modifications should go by between saving. If you set this variable to nil, Emacs only saves bookmarks if you explicitly use M-x bookmark-save.

    The variable bookmark-default-file specifies the file in which to save bookmarks by default.

    If you set the variable bookmark-use-annotations to t, setting a bookmark will query for an annotation. If a bookmark has an annotation, it is automatically shown in a separate window when you jump to the bookmark.

    Bookmark position values are saved with surrounding context, so that bookmark-jump can find the proper position even if the file is modified slightly. The variable bookmark-search-size says how many characters of context to record on each side of the bookmark’s position. (In buffers that are visiting encrypted files, no context is saved in the bookmarks file no matter the value of this variable.)

    Here are some additional commands for working with bookmarks:

    M-x bookmark-load RET filename RET

    Load a file named filename that contains a list of bookmark values. You can use this command, as well as bookmark-write, to work with other files of bookmark values in addition to your default bookmark file.

    M-x bookmark-write RET filename RET

    Save all the current bookmark values in the file filename.

    M-x bookmark-delete RET bookmark RET

    Delete the bookmark named bookmark.

    M-x bookmark-insert-location RET bookmark RET

    Insert in the buffer the name of the file that bookmark bookmark points to.

    M-x bookmark-insert RET bookmark RET

    Insert in the buffer the contents of the file that bookmark bookmark points to.

    15 Controlling the Display

    Since only part of a large buffer fits in the window, Emacs has to show only a part of it. This chapter describes commands and variables that let you specify which part of the text you want to see, and how the text is displayed.

    15.1 Scrolling

    If a window is too small to display all the text in its buffer, it displays only a portion of it. Scrolling commands change which portion of the buffer is displayed.

    Scrolling forward or up advances the portion of the buffer displayed in the window; equivalently, it moves the buffer text upwards relative to the window. Scrolling backward or down displays an earlier portion of the buffer, and moves the text downwards relative to the window.

    In Emacs, scrolling up or down refers to the direction that the text moves in the window, not the direction that the window moves relative to the text. This terminology was adopted by Emacs before the modern meaning of “scrolling up” and “scrolling down” became widespread. Hence, the strange result that PageDown scrolls up in the Emacs sense.

    The portion of a buffer displayed in a window always contains point. If you move point past the bottom or top of the window, scrolling occurs automatically to bring it back onscreen (see Automatic Scrolling). You can also scroll explicitly with these commands:


    Scroll forward by nearly a full window (scroll-up-command).


    Scroll backward (scroll-down-command).

    C-v (scroll-up-command) scrolls forward by nearly the whole window height. The effect is to take the two lines at the bottom of the window and put them at the top, followed by lines that were not previously visible. If point was in the text that scrolled off the top, it ends up on the window’s new topmost line. The PageDown (or next) key is equivalent to C-v.

    M-v (scroll-down-command) scrolls backward in a similar way. The PageUp (or prior) key is equivalent to M-v.

    The number of lines of overlap left by these scroll commands is controlled by the variable next-screen-context-lines, whose default value is 2. You can supply the commands with a numeric prefix argument, n, to scroll by n lines; Emacs attempts to leave point unchanged, so that the text and point move up or down together. C-v with a negative argument is like M-v and vice versa.

    By default, these commands signal an error (by beeping or flashing the screen) if no more scrolling is possible, because the window has reached the beginning or end of the buffer. If you change the variable scroll-error-top-bottom to t, these commands move point to the farthest possible position. If point is already there, the commands signal an error.

    Some users like scroll commands to keep point at the same screen position, so that scrolling back to the same screen conveniently returns point to its original position. You can enable this behavior via the variable scroll-preserve-screen-position. If the value is t, Emacs adjusts point to keep the cursor at the same screen position whenever a scroll command moves it off-window, rather than moving it to the topmost or bottommost line. With any other non-nil value, Emacs adjusts point this way even if the scroll command leaves point in the window. This variable affects all the scroll commands documented in this section, as well as scrolling with the mouse wheel (see Mouse Commands for Editing); in general, it affects any command that has a non-nil scroll-command property. See Property Lists in The Emacs Lisp Reference Manual. The same property also causes Emacs not to exit incremental search when one of these commands is invoked and isearch-allow-scroll is non-nil (see Not Exiting Incremental Search).

    Sometimes, particularly when you hold down keys such as C-v and M-v, activating keyboard auto-repeat, Emacs fails to keep up with the rapid rate of scrolling requested; the display doesn’t update and Emacs can become unresponsive to input for quite a long time. You can counter this sluggishness by setting the variable fast-but-imprecise-scrolling to a non-nil value. This instructs the scrolling commands not to fontify (see Font Lock mode) any unfontified text they scroll over, instead to assume it has the default face. This can cause Emacs to scroll to somewhat wrong buffer positions when the faces in use are not all the same size, even with single (i.e., without auto-repeat) scrolling operations.

    As an alternative to setting fast-but-imprecise-scrolling you might prefer to enable jit-lock deferred fontification (see Font Lock mode). To do this, customize jit-lock-defer-time to a small positive number such as 0.25, or even 0.1 if you type quickly. This gives you less jerky scrolling when you hold down C-v, but the window contents after any action which scrolls into a fresh portion of the buffer will be momentarily unfontified.

    Finally, a third alternative to these variables is redisplay-skip-fontification-on-input. If this variable is non-nil, skip some fontifications if there’s input pending. This usually does not affect the display because redisplay is completely skipped anyway if input was pending, but it can make scrolling smoother by avoiding unnecessary fontification.

    The commands M-x scroll-up and M-x scroll-down behave similarly to scroll-up-command and scroll-down-command, except they do not obey scroll-error-top-bottom. Prior to Emacs 24, these were the default commands for scrolling up and down. The commands M-x scroll-up-line and M-x scroll-down-line scroll the current window by one line at a time. If you intend to use any of these commands, you might want to give them key bindings (see Rebinding Keys in Your Init File).

    On graphical displays, you can also scroll a window using the scroll bar; see Scroll Bars.

    15.2 Recentering


    Scroll the selected window so the current line is the center-most text line; on subsequent consecutive invocations, make the current line the top line, the bottom line, and so on in cyclic order. Possibly redisplay the screen too (recenter-top-bottom).


    Scroll the other window; this is equivalent to C-l acting on the other window.

    M-x recenter

    Scroll the selected window so the current line is the center-most text line. Possibly redisplay the screen too.


    Scroll heuristically to bring useful information onto the screen (reposition-window).

    The C-l (recenter-top-bottom) command recenters the selected window, scrolling it so that the current screen line is exactly in the center of the window, or as close to the center as possible.

    Typing C-l twice in a row (C-l C-l) scrolls the window so that point is on the topmost screen line. Typing a third C-l scrolls the window so that point is on the bottom-most screen line. Each successive C-l cycles through these three positions.

    You can change the cycling order by customizing the list variable recenter-positions. Each list element should be the symbol top, middle, or bottom, or a number; an integer means to move the line to the specified screen line, while a floating-point number between 0.0 and 1.0 specifies a percentage of the screen space from the top of the window. The default, (middle top bottom), is the cycling order described above. Furthermore, if you change the variable scroll-margin to a non-zero value n, C-l always leaves at least n screen lines between point and the top or bottom of the window (see Automatic Scrolling).

    You can also give C-l a prefix argument. A plain prefix argument, C-u C-l, simply recenters the line showing point. A positive argument n moves line showing point n lines down from the top of the window. An argument of zero moves point’s line to the top of the window. A negative argument -n moves point’s line n lines from the bottom of the window. When given an argument, C-l does not clear the screen or cycle through different screen positions.

    If the variable recenter-redisplay has a non-nil value, each invocation of C-l also clears and redisplays the screen; the special value tty (the default) says to do this on text-terminal frames only. Redisplaying is useful in case the screen becomes garbled for any reason (see Garbage on the Screen).

    The more primitive command M-x recenter behaves like recenter-top-bottom, but does not cycle among screen positions.

    C-M-l (reposition-window) scrolls the current window heuristically in a way designed to get useful information onto the screen. For example, in a Lisp file, this command tries to get the entire current defun onto the screen if possible.

    15.3 Automatic Scrolling

    Emacs performs automatic scrolling when point moves out of the visible portion of the text. Normally, automatic scrolling centers point vertically in the window, but there are several ways to alter this behavior.

    If you set scroll-conservatively to a small number n, then moving point just a little off the screen (no more than n lines) causes Emacs to scroll just enough to bring point back on screen; if doing so fails to make point visible, Emacs scrolls just far enough to center point in the window. If you set scroll-conservatively to a large number (larger than 100), automatic scrolling never centers point, no matter how far point moves; Emacs always scrolls text just enough to bring point into view, either at the top or bottom of the window depending on the scroll direction. By default, scroll-conservatively is 0, which means to always center point in the window. This said, in minibuffer windows, scrolling is always conservative by default because scroll-minibuffer-conservatively is non-nil, which takes precedence over scroll-conservatively.

    Another way to control automatic scrolling is to customize the variable scroll-step. Its value determines the number of lines by which to automatically scroll, when point moves off the screen. If scrolling by that number of lines fails to bring point back into view, point is centered instead. The default value is zero, which (by default) causes point to always be centered after scrolling.

    A third way to control automatic scrolling is to customize the variables scroll-up-aggressively and scroll-down-aggressively, which directly specify the vertical position of point after scrolling. The value of scroll-up-aggressively should be either nil (the default), or a floating point number f between 0 and 1. The latter means that when point goes below the bottom window edge (i.e., scrolling forward), Emacs scrolls the window so that point is f parts of the window height from the bottom window edge. Thus, larger f means more aggressive scrolling: more new text is brought into view. The default value, nil, is equivalent to 0.5.

    Likewise, scroll-down-aggressively is used when point goes above the top window edge (i.e., scrolling backward). The value specifies how far point should be from the top margin of the window after scrolling. Thus, as with scroll-up-aggressively, a larger value is more aggressive.

    Note that the variables scroll-conservatively, scroll-step, and scroll-up-aggressively / scroll-down-aggressively control automatic scrolling in contradictory ways. Therefore, you should pick no more than one of these methods to customize automatic scrolling. In case you customize multiple variables, the order of priority is: scroll-conservatively, then scroll-step, and finally scroll-up-aggressively / scroll-down-aggressively.

    The variable scroll-margin restricts how close point can come to the top or bottom of a window (even if aggressive scrolling specifies a fraction f that is larger than the window portion between the top and the bottom margins). Its value is a number of screen lines; if point comes within that many lines of the top or bottom of the window, Emacs performs automatic scrolling. By default, scroll-margin is 0. The effective margin size is limited to a quarter of the window height by default, but this limit can be increased up to half (or decreased down to zero) by customizing maximum-scroll-margin.

    15.4 Horizontal Scrolling

    Horizontal scrolling means shifting all the lines sideways within a window, so that some of the text near the left margin is not displayed. When the text in a window is scrolled horizontally, text lines are truncated rather than continued (see Line Truncation). If a window shows truncated lines, Emacs performs automatic horizontal scrolling whenever point moves off the left or right edge of the screen. By default, all the lines in the window are scrolled horizontally together, but if you set the variable auto-hscroll-mode to the special value of current-line, only the line showing the cursor will be scrolled. To disable automatic horizontal scrolling entirely, set the variable auto-hscroll-mode to nil. Note that when the automatic horizontal scrolling is turned off, if point moves off the edge of the screen, the cursor disappears to indicate that. (On text terminals, the cursor is left at the edge instead.)

    The variable hscroll-margin controls how close point can get to the window’s left and right edges before automatic scrolling occurs. It is measured in columns. For example, if the value is 5, then moving point within 5 columns of an edge causes horizontal scrolling away from that edge.

    The variable hscroll-step determines how many columns to scroll the window when point gets too close to the edge. Zero, the default value, means to center point horizontally within the window. A positive integer value specifies the number of columns to scroll by. A floating-point number (whose value should be between 0 and 1) specifies the fraction of the window’s width to scroll by.

    You can also perform explicit horizontal scrolling with the following commands:

    C-x <

    Scroll text in current window to the left (scroll-left).

    C-x >

    Scroll to the right (scroll-right).

    C-x < (scroll-left) scrolls text in the selected window to the left by the full width of the window, less two columns. (In other words, the text in the window moves left relative to the window.) With a numeric argument n, it scrolls by n columns.

    If the text is scrolled to the left, and point moves off the left edge of the window, the cursor will freeze at the left edge of the window, until point moves back to the displayed portion of the text. This is independent of the current setting of auto-hscroll-mode, which, for text scrolled to the left, only affects the behavior at the right edge of the window.

    C-x > (scroll-right) scrolls similarly to the right. The window cannot be scrolled any farther to the right once it is displayed normally, with each line starting at the window’s left margin; attempting to do so has no effect. This means that you don’t have to calculate the argument precisely for C-x >; any sufficiently large argument will restore the normal display.

    If you use those commands to scroll a window horizontally, that sets a lower bound for automatic horizontal scrolling. Automatic scrolling will continue to scroll the window, but never farther to the right than the amount you previously set by scroll-left. When auto-hscroll-mode is set to current-line, all the lines other than the one showing the cursor will be scrolled by that minimal amount.

    On graphical displays, you can scroll a window horizontally using the horizontal scroll bar, if you turn on the optional horizontal-scroll-bar-mode; see Scroll Bars.

    15.5 Narrowing

    Narrowing means focusing in on some portion of the buffer, making the rest temporarily inaccessible. The portion which you can still get to is called the accessible portion. Canceling the narrowing, which makes the entire buffer once again accessible, is called widening. The bounds of narrowing in effect in a buffer are called the buffer’s restriction.

    Narrowing can make it easier to concentrate on a single subroutine or paragraph by eliminating clutter. It can also be used to limit the range of operation of a replace command or repeating keyboard macro.

    C-x n n

    Narrow down to between point and mark (narrow-to-region).

    C-x n w

    Widen to make the entire buffer accessible again (widen).

    C-x n p

    Narrow down to the current page (narrow-to-page).

    C-x n d

    Narrow down to the current defun (narrow-to-defun).

    When you have narrowed down to a part of the buffer, that part appears to be all there is. You can’t see the rest, you can’t move into it (motion commands won’t go outside the accessible part), you can’t change it in any way. However, it is not gone, and if you save the file all the inaccessible text will be saved. The word ‘Narrow’ appears in the mode line whenever narrowing is in effect.

    The primary narrowing command is C-x n n (narrow-to-region). It sets the current buffer’s restrictions so that the text in the current region remains accessible, but all text before the region or after the region is inaccessible. Point and mark do not change.

    Alternatively, use C-x n p (narrow-to-page) to narrow down to the current page. See Pages, for the definition of a page. C-x n d (narrow-to-defun) narrows down to the defun containing point (see Top-Level Definitions, or Defuns).

    The way to cancel narrowing is to widen with C-x n w (widen). This makes all text in the buffer accessible again.

    You can get information on what part of the buffer you are narrowed down to using the C-x = command. See Cursor Position Information.

    Because narrowing can easily confuse users who do not understand it, narrow-to-region is normally a disabled command. Attempting to use this command asks for confirmation and gives you the option of enabling it; if you enable the command, confirmation will no longer be required for it. See Disabling Commands.

    15.6 View Mode

    View mode is a minor mode that lets you scan a buffer by sequential screenfuls. It provides commands for scrolling through the buffer conveniently but not for changing it. Apart from the usual Emacs cursor motion commands, you can type SPC to scroll forward one windowful, S-SPC or DEL to scroll backward, and s to start an incremental search.

    Typing q (View-quit) disables View mode, and switches back to the buffer and position before View mode was enabled. Typing e (View-exit) disables View mode, keeping the current buffer and position.

    M-x view-buffer prompts for an existing Emacs buffer, switches to it, and enables View mode. M-x view-file prompts for a file and visits it with View mode enabled.

    15.7 Follow Mode

    Follow mode is a minor mode that makes two windows, both showing the same buffer, scroll as a single tall virtual window. To use Follow mode, go to a frame with just one window, split it into two side-by-side windows using C-x 3, and then type M-x follow-mode. From then on, you can edit the buffer in either of the two windows, or scroll either one; the other window follows it.

    In Follow mode, if you move point outside the portion visible in one window and into the portion visible in the other window, that selects the other window—again, treating the two as if they were parts of one large window.

    To turn off Follow mode, type M-x follow-mode a second time.

    15.8 Text Faces

    Emacs can display text in several different styles, called faces. Each face can specify various face attributes, such as the font, height, weight, slant, foreground and background color, and underlining or overlining. Most major modes assign faces to the text automatically, via Font Lock mode. See Font Lock mode, for more information about how these faces are assigned.

    To see what faces are currently defined, and what they look like, type M-x list-faces-display. With a prefix argument, this prompts for a regular expression, and displays only faces with names matching that regular expression (see Syntax of Regular Expressions).

    It’s possible for a given face to look different in different frames. For instance, some text terminals do not support all face attributes, particularly font, height, and width, and some support a limited range of colors. In addition, most Emacs faces are defined so that their attributes are different on light and dark frame backgrounds, for reasons of legibility. By default, Emacs automatically chooses which set of face attributes to display on each frame, based on the frame’s current background color. However, you can override this by giving the variable frame-background-mode a non-nil value. A value of dark makes Emacs treat all frames as if they have a dark background, whereas a value of light makes it treat all frames as if they have a light background.

    You can customize a face to alter its attributes, and save those customizations for future Emacs sessions. See Customizing Faces, for details.

    The default face is the default for displaying text, and all of its attributes are specified. Its background color is also used as the frame’s background color. See Colors for Faces.

    Another special face is the cursor face. On graphical displays, the background color of this face is used to draw the text cursor. None of the other attributes of this face have any effect; the foreground color for text under the cursor is taken from the background color of the underlying text. On text terminals, the appearance of the text cursor is determined by the terminal, not by the cursor face.

    You can also use X resources to specify attributes of any particular face. See X Resources.

    Emacs can display variable-width fonts, but some Emacs commands, particularly indentation commands, do not account for variable character display widths. Therefore, we recommend not using variable-width fonts for most faces, particularly those assigned by Font Lock mode.

    15.9 Colors for Faces

    Faces can have various foreground and background colors. When you specify a color for a face—for instance, when customizing the face (see Customizing Faces)—you can use either a color name or an RGB triplet.

    15.9.1 Color Names

    A color name is a pre-defined name, such as ‘dark orange’ or ‘medium sea green’. To view a list of color names, type M-x list-colors-display. To control the order in which colors are shown, customize list-colors-sort. If you run this command on a graphical display, it shows the full range of color names known to Emacs (these are the standard X11 color names, defined in X’s rgb.txt file). If you run the command on a text terminal, it shows only a small subset of colors that can be safely displayed on such terminals. However, Emacs understands X11 color names even on text terminals; if a face is given a color specified by an X11 color name, it is displayed using the closest-matching terminal color.

    15.9.2 RGB Triplets

    An RGB triplet is a string of the form ‘#RRGGBB’. Each of the primary color components is represented by a hexadecimal number between ‘00’ (intensity 0) and ‘FF’ (the maximum intensity). It is also possible to use one, three, or four hex digits for each component, so ‘red’ can be represented as ‘#F00’, ‘#fff000000’, or ‘#ffff00000000’. The components must have the same number of digits. For hexadecimal values A to F, either upper or lower case are acceptable.

    The M-x list-colors-display command also shows the equivalent RGB triplet for each named color. For instance, ‘medium sea green’ is equivalent to ‘#3CB371’.

    You can change the foreground and background colors of a face with M-x set-face-foreground and M-x set-face-background. These commands prompt in the minibuffer for a face name and a color, with completion, and then set that face to use the specified color. They affect the face colors on all frames, but their effects do not persist for future Emacs sessions, unlike using the customization buffer or X resources. You can also use frame parameters to set foreground and background colors for a specific frame; See Frame Parameters.

    15.10 Standard Faces

    Here are the standard faces for specifying text appearance. You can apply them to specific text when you want the effects they produce.


    This face is used for ordinary text that doesn’t specify any face. Its background color is used as the frame’s background color.


    This face uses a bold variant of the default font.


    This face uses an italic variant of the default font.


    This face uses a bold italic variant of the default font.


    This face underlines text.


    This face forces use of a fixed-width font. It’s reasonable to customize this face to use a different fixed-width font, if you like, but you should not make it a variable-width font.


    This face is like fixed-pitch, except the font has serifs and looks more like traditional typewriting.


    This face forces use of a variable-width (i.e., proportional) font. The font size picked for this face matches the font picked for the default (usually fixed-width) font.


    This is like the variable-pitch face (from which it inherits), but is slightly larger. A proportional font of the same height as a monospace font usually appears visually smaller, and can therefore be harder to read. When displaying longer texts, this face can be a good choice over the (slightly smaller) variable-pitch face.


    This face is used for making the text less noticeable than the surrounding ordinary text. Usually this can be achieved by using shades of gray in contrast with either black or white default foreground color.

    Here’s an incomplete list of faces used to highlight parts of the text temporarily for specific purposes. (Many other modes define their own faces for this purpose.)


    This face is used for text highlighting in various contexts, such as when the mouse cursor is moved over a hyperlink.


    This face is used to highlight the current Isearch match (see Incremental Search).


    This face is used to highlight the current Query Replace match (see Replacement Commands).


    This face is used to highlight lazy matches for Isearch and Query Replace (matches other than the current one).


    This face is used for displaying an active region (see The Mark and the Region). When Emacs is built with GTK+ support, its colors are taken from the current GTK+ theme.


    This face is used for displaying a secondary X selection (see Secondary Selection).


    The face for highlighting excess spaces and tabs at the end of a line when show-trailing-whitespace is non-nil (see Useless Whitespace).


    The face for displaying control characters and escape sequences (see How Text Is Displayed).


    The face for displaying lookalike characters, i.e., characters that look like but are not the characters being represented (see How Text Is Displayed).


    The face for displaying no-break space characters (see How Text Is Displayed).


    The face for displaying no-break hyphen characters (see How Text Is Displayed).

    The following faces control the appearance of parts of the Emacs frame:


    This is the base face used for the mode lines, as well as header lines and for menu bars when toolkit menus are not used. By default, it’s drawn with shadows for a raised effect on graphical displays, and drawn as the inverse of the default face on text terminals.

    The mode-line-active and mode-line-inactive faces (which are the ones used on the mode lines) inherit from this face.


    Like mode-line, but used for the mode line of the currently selected window. This face inherits from mode-line, so changes in that face affect mode lines in all windows.


    Like mode-line, but used for mode lines of the windows other than the selected one (if mode-line-in-non-selected-windows is non-nil). This face inherits from mode-line, so changes in that face affect mode lines in all windows.


    Like highlight, but used for mouse-sensitive portions of text on mode lines. Such portions of text typically pop up tooltips (see Tooltips) when the mouse pointer hovers above them.


    This face is used for buffer identification parts in the mode line.


    Similar to mode-line for a window’s header line, which appears at the top of a window just as the mode line appears at the bottom. Most windows do not have a header line—only some special modes, such Info mode, create one.


    Similar to highlight and mode-line-highlight, but used for mouse-sensitive portions of text on header lines. This is a separate face because the header-line face might be customized in a way that does not interact well with highlight.


    Similar to mode-line for a window’s tab line, which appears at the top of a window with tabs representing window buffers. See Window Tab Line.


    This face is used for the vertical divider between windows on text terminals.


    This face is used for the prompt strings displayed in the minibuffer. By default, Emacs automatically adds this face to the value of minibuffer-prompt-properties, which is a list of text properties (see Text Properties in the Emacs Lisp Reference Manual) used to display the prompt text. (This variable takes effect when you enter the minibuffer.)


    The face for the fringes to the left and right of windows on graphic displays. (The fringes are the narrow portions of the Emacs frame between the text area and the window’s right and left borders.) See Window Fringes.


    The :background attribute of this face specifies the color of the text cursor. See Displaying the Cursor.


    This face is used for tooltip text. By default, if Emacs is built with GTK+ support, tooltips are drawn via GTK+ and this face has no effect. See Tooltips.


    This face determines the color of the mouse pointer.

    The following faces likewise control the appearance of parts of the Emacs frame, but only on text terminals, or when Emacs is built on X with no toolkit support. (For all other cases, the appearance of the respective frame elements is determined by system-wide settings.)


    This face determines the visual appearance of the scroll bar. See Scroll Bars.


    This face determines the color of tool bar icons. See Tool Bars.


    This face determines the color of tab bar icons. See Tab Bars.


    This face determines the colors and font of Emacs’s menus. See Menu Bars.


    This face is used to display enabled menu items on text-mode terminals.


    This face is used to display disabled menu items on text-mode terminals.


    This face is used to display on text-mode terminals the menu item that would be selected if you click a mouse or press RET.

    15.11 Icons

    Emacs sometimes displays clickable buttons (or other informative icons), and you can customize how these look on display.

    The main customization point here is the icon-preference user option. By using this, you can tell Emacs your overall preferences for icons. This is a list of icon types, and the first icon type that’s supported will be used. The supported types are:


    Use an image for the icon.


    Use a colorful emoji for the icon.


    Use a monochrome symbol for the icon.


    Use a simple text for the icon.

    In addition, each individual icon can be customized with M-x customize-icon, and themes can further alter the looks of the icons.

    To get a quick description of an icon, use the M-x describe-icon command.

    15.12 Text Scale

    To increase the font size of the default face in the current buffer, type C-x C-+ or C-x C-=. To decrease it, type C-x C--. To restore the default (global) font size, type C-x C-0. These keys are all bound to the same command, text-scale-adjust, which looks at the last key typed to determine which action to take and adjusts the font size accordingly by changing the height of the default face.

    Most faces don’t have an explicit setting of the :height attribute, and thus inherit the height from the default face. Those faces are also scaled by the above commands.

    Faces other than default that have an explicit setting of the :height attribute are not affected by these font size changes. The header-line face is an exception: it will be scaled even if it has an explicit setting of the :height attribute.

    Similarly, scrolling the mouse wheel with the Ctrl modifier pressed, when the mouse pointer is above buffer text, will increase or decrease the font size of the affected faces, depending on the direction of the scrolling.

    The final key of these commands may be repeated without the leading C-x and without the modifiers. For instance, C-x C-= C-= C-= and C-x C-= = = increase the face height by three steps. Each step scales the text height by a factor of 1.2; to change this factor, customize the variable text-scale-mode-step. A numeric argument of 0 to the text-scale-adjust command restores the default height, the same as typing C-x C-0.

    Similarly, to change the sizes of the fonts globally, type C-x C-M-+, C-x C-M-=, C-x C-M-- or C-x C-M-0, or scroll the mouse wheel with both the Ctrl and Meta modifiers pressed. To enable frame resizing when the font size is changed globally, customize the variable global-text-scale-adjust-resizes-frames (see Easy Customization Interface).

    The commands text-scale-increase and text-scale-decrease increase or decrease the size of the font in the current buffer, just like C-x C-+ and C-x C-- respectively. You may find it convenient to bind to these commands, rather than text-scale-adjust.

    The command text-scale-set scales the size of the font in the current buffer to an absolute level specified by its prefix argument.

    The above commands automatically enable the minor mode text-scale-mode if the current font scaling is other than 1, and disable it otherwise.

    The command text-scale-pinch increases or decreases the text scale based on the distance between fingers on a touchpad when a pinch gesture is performed by placing two fingers on a touchpad and moving them towards or apart from each other. This is only available on some systems with supported hardware.

    The command mouse-wheel-text-scale also changes the text scale. Normally, it is run when you press Ctrl while moving the mouse wheel. The text scale is increased when the wheel is moved downwards, and it is decreased when the wheel is moved upwards.

    15.13 Font Lock mode

    Font Lock mode is a minor mode, always local to a particular buffer, which assigns faces to (or fontifies) the text in the buffer. Each buffer’s major mode tells Font Lock mode which text to fontify; for instance, programming language modes fontify syntactically relevant constructs like comments, strings, and function names.

    Font Lock mode is enabled by default in major modes that support it. To toggle it in the current buffer, type M-x font-lock-mode. A positive numeric argument unconditionally enables Font Lock mode, and a negative or zero argument disables it.

    Type M-x global-font-lock-mode to toggle Font Lock mode in all buffers. To impose this setting for future Emacs sessions, customize the variable global-font-lock-mode (see Easy Customization Interface), or add the following line to your init file:

    (global-font-lock-mode 0)

    If you have disabled Global Font Lock mode, you can still enable Font Lock for specific major modes by adding the function font-lock-mode to the mode hooks (see Hooks). For example, to enable Font Lock mode for editing C files, you can do this:

    (add-hook 'c-mode-hook 'font-lock-mode)

    Font Lock mode uses several specifically named faces to do its job, including font-lock-string-face, font-lock-comment-face, and others. The easiest way to find them all is to use M-x customize-group RET font-lock-faces RET. You can then use that customization buffer to customize the appearance of these faces. See Customizing Faces.

    Fontifying very large buffers can take a long time. To avoid large delays when a file is visited, Emacs initially fontifies only the visible portion of a buffer. As you scroll through the buffer, each portion that becomes visible is fontified as soon as it is displayed; this type of Font Lock is called Just-In-Time (or JIT) Lock. You can control how JIT Lock behaves, including telling it to perform fontification while idle, by customizing variables in the customization group ‘jit-lock’. See Customizing Specific Items.

    The information that major modes use for determining which parts of buffer text to fontify and what faces to use can be based on several different ways of analyzing the text:

    • Search for keywords and other textual patterns based on regular expressions (see Regular Expression Search).
    • Find syntactically distinct parts of text based on built-in syntax tables (see Syntax Tables in The Emacs Lisp Reference Manual).
    • Use syntax tree produced by a full-blown parser, via a special-purpose library, such as the tree-sitter library (see Parsing Program Source in The Emacs Lisp Reference Manual), or an external program.

    15.13.1 Traditional Font Lock

    “Traditional” methods of providing font-lock information are based on regular-expression search and on syntactic analysis using syntax tables built into Emacs. This subsection describes the use and customization of font-lock for major modes which use these traditional methods.

    You can control the amount of fontification applied by Font Lock mode by customizing the variable font-lock-maximum-decoration, for major modes that support this feature. The value of this variable should be a number (with 1 representing a minimal amount of fontification; some modes support levels as high as 3); or t, meaning “as high as possible” (the default). To be effective for a given file buffer, the customization of font-lock-maximum-decoration should be done before the file is visited; if you already have the file visited in a buffer when you customize this variable, kill the buffer and visit the file again after the customization.

    You can also specify different numbers for particular major modes; for example, to use level 1 for C/C++ modes, and the default level otherwise, use the value

    '((c-mode . 1) (c++-mode . 1)))

    Comment and string fontification (or “syntactic” fontification) relies on analysis of the syntactic structure of the buffer text. For the sake of speed, some modes, including Lisp mode, rely on a special convention: an open-parenthesis or open-brace in the leftmost column always defines the beginning of a defun, and is thus always outside any string or comment. Therefore, you should avoid placing an open-parenthesis or open-brace in the leftmost column, if it is inside a string or comment. See Left Margin Convention, for details.

    Font Lock highlighting patterns already exist for most modes, but you may want to fontify additional patterns. You can use the function font-lock-add-keywords, to add your own highlighting patterns for a particular mode. For example, to highlight ‘FIXME:’ words in C comments, use this:

    (add-hook 'c-mode-hook
              (lambda ()
               (font-lock-add-keywords nil
                '(("\\<\\(FIXME\\):" 1
                   font-lock-warning-face t)))))

    To remove keywords from the font-lock highlighting patterns, use the function font-lock-remove-keywords. See Search-based Fontification in The Emacs Lisp Reference Manual. Alternatively, you can selectively disable highlighting due to some keywords by customizing the font-lock-ignore option, see Customizing Keywords in The Emacs Lisp Reference Manual.

    15.13.2 Parser-based Font Lock

    If your Emacs was built with the tree-sitter library, it can use the results of parsing the buffer text by that library for the purposes of fontification. This is usually faster and more accurate than the “traditional” methods described in the previous subsection, since the tree-sitter library provides full-blown parsers for programming languages and other kinds of formatted text which it supports. Major modes which utilize the tree-sitter library are named foo-ts-mode, with the ‘-ts-’ part indicating the use of the library. This subsection documents the Font Lock support based on the tree-sitter library.

    You can control the amount of fontification applied by Font Lock mode of major modes based on tree-sitter by customizing the variable treesit-font-lock-level. Its value is a number between 1 and 4:

    Level 1

    This level usually fontifies only comments and function names in function definitions.

    Level 2

    This level adds fontification of keywords, strings, and data types.

    Level 3

    This is the default level; it adds fontification of assignments, numbers, etc.

    Level 4

    This level adds everything else that can be fontified: operators, delimiters, brackets, other punctuation, function names in function calls, property look ups, variables, etc.

    What exactly constitutes each of the syntactical categories mentioned above depends on the major mode and the parser grammar used by tree-sitter for the major-mode’s language. However, in general the categories follow the conventions of the programming language or the file format supported by the major mode. The buffer-local value of the variable treesit-font-lock-feature-list holds the fontification features supported by a tree-sitter based major mode, where each sub-list shows the features provided by the corresponding fontification level.

    Once you change the value of treesit-font-lock-level via M-x customize-variable (see Customizing Specific Items), it takes effect immediately in all the existing buffers and for files you visit in the future in the same session.

    15.14 Interactive Highlighting

    Highlight Changes mode is a minor mode that highlights the parts of the buffer that were changed most recently, by giving that text a different face. To enable or disable Highlight Changes mode, use M-x highlight-changes-mode.

    Hi Lock mode is a minor mode that highlights text that matches regular expressions you specify. For example, you can use it to highlight all the references to a certain variable in a program source file, highlight certain parts in a voluminous output of some program, or highlight certain names in an article. To enable or disable Hi Lock mode, use the command M-x hi-lock-mode. To enable Hi Lock mode for all buffers, use M-x global-hi-lock-mode or place (global-hi-lock-mode 1) in your .emacs file.

    Hi Lock mode works like Font Lock mode (see Font Lock mode), except that you specify explicitly the regular expressions to highlight. You can control them with the following commands. (The key bindings below that begin with C-x w are deprecated in favor of the global M-s h bindings, and will be removed in some future Emacs version.)

    M-s h r regexp RET face RET
    C-x w h regexp RET face RET

    Highlight text that matches regexp using face face (highlight-regexp). The highlighting will remain as long as the buffer is loaded. For example, to highlight all occurrences of the word “whim” using the default face (a yellow background), type M-s h r whim RET RET. Any face can be used for highlighting, Hi Lock provides several of its own and these are pre-loaded into a list of default values. While being prompted for a face use M-n and M-p to cycle through them. A prefix numeric argument limits the highlighting to the corresponding subexpression.

    Setting the option hi-lock-auto-select-face to a non-nil value causes this command (and other Hi Lock commands that read faces) to automatically choose the next face from the default list without prompting.

    You can use this command multiple times, specifying various regular expressions to highlight in different ways.

    M-s h u regexp RET
    C-x w r regexp RET

    Unhighlight regexp (unhighlight-regexp). If you invoke this from the menu, you select the expression to unhighlight from a list. If you invoke this from the keyboard, you use the minibuffer. It will show the most recently added regular expression; use M-n to show the next older expression and M-p to select the next newer expression. (You can also type the expression by hand, with completion.) When the expression you want to unhighlight appears in the minibuffer, press RET to exit the minibuffer and unhighlight it.

    M-s h l regexp RET face RET
    C-x w l regexp RET face RET

    Highlight entire lines containing a match for regexp, using face face (highlight-lines-matching-regexp).

    M-s h p phrase RET face RET
    C-x w p phrase RET face RET

    Highlight matches of phrase, using face face (highlight-phrase). phrase can be any regexp, but spaces will be replaced by matches to whitespace and initial lower-case letters will become case insensitive.

    M-s h .
    C-x w .

    Highlight the symbol found near point, using the next available face (highlight-symbol-at-point).

    M-s h w
    C-x w b

    Insert all the current highlighting regexp/face pairs into the buffer at point, with comment delimiters to prevent them from changing your program. (This key binding runs the hi-lock-write-interactive-patterns command.)

    These patterns are extracted from the comments, if appropriate, if you invoke M-x hi-lock-find-patterns, or if you visit the file while Hi Lock mode is enabled (since that runs hi-lock-find-patterns).

    M-s h f
    C-x w i

    Extract regexp/face pairs from comments in the current buffer (hi-lock-find-patterns). Thus, you can enter patterns interactively with highlight-regexp, store them into the file with hi-lock-write-interactive-patterns, edit them (perhaps including different faces for different parenthesized parts of the match), and finally use this command (hi-lock-find-patterns) to have Hi Lock highlight the edited patterns.

    The variable hi-lock-file-patterns-policy controls whether Hi Lock mode should automatically extract and highlight patterns found in a file when it is visited. Its value can be nil (never highlight), ask (query the user), or a function. If it is a function, hi-lock-find-patterns calls it with the patterns as argument; if the function returns non-nil, the patterns are used. The default is ask. Note that patterns are always highlighted if you call hi-lock-find-patterns directly, regardless of the value of this variable.

    Also, hi-lock-find-patterns does nothing if the current major mode’s symbol is a member of the list hi-lock-exclude-modes.

    15.15 Window Fringes

    On graphical displays, each Emacs window normally has narrow fringes on the left and right edges. The fringes are used to display symbols that provide information about the text in the window. You can type M-x fringe-mode to toggle display of the fringes or to modify their width. This command affects fringes in all frames; to modify fringes on the selected frame only, use M-x set-fringe-style. You can make your changes to the fringes permanent by customizing the variable fringe-mode.

    The most common use of the fringes is to indicate a continuation line (see Continuation Lines). When one line of text is split into multiple screen lines, the left fringe shows a curving arrow for each screen line except the first, indicating that this is not the real beginning. The right fringe shows a curving arrow for each screen line except the last, indicating that this is not the real end. If the line’s direction is right-to-left (see Bidirectional Editing), the meanings of the curving arrows in the fringes are swapped.

    The fringes indicate line truncation (see Line Truncation) with short horizontal arrows meaning there’s more text on this line which is scrolled horizontally out of view. Clicking the mouse on one of the arrows scrolls the display horizontally in the direction of the arrow.

    The fringes can also indicate other things, such as buffer boundaries (see Displaying Boundaries), unused lines near the end of the window (see indicate-empty-lines), and where a program you are debugging is executing (see Running Debuggers Under Emacs).

    The fringe is also used for drawing the cursor, if the current line is exactly as wide as the window and point is at the end of the line. To disable this, change the variable overflow-newline-into-fringe to nil; this causes Emacs to continue or truncate lines that are exactly as wide as the window.

    If you customize fringe-mode to remove the fringes on one or both sides of the window display, the features that display on the fringe are not available. Indicators of line continuation and truncation are an exception: when fringes are not available, Emacs uses the leftmost and rightmost character cells to indicate continuation and truncation with special ASCII characters, see Continuation Lines, and Line Truncation. This reduces the width available for displaying text on each line, because the character cells used for truncation and continuation indicators are reserved for that purpose. Since buffer text can include bidirectional text, and thus both left-to-right and right-to-left paragraphs (see Bidirectional Editing), removing only one of the fringes still reserves two character cells, one on each side of the window, for truncation and continuation indicators, because these indicators are displayed on opposite sides of the window in right-to-left paragraphs.

    15.16 Displaying Boundaries

    Emacs can display an indication of the fill-column position (see Explicit Fill Commands). The fill-column indicator is a useful functionality especially in prog-mode and its descendants (see Major Modes) to indicate the position of a specific column that has some special meaning for formatting the source code of a program. This assumes the buffer uses a fixed-pitch font, where all the characters (with the possible exception of double-width characters) have the same width on display. If the buffer uses variable-pitch fonts, the fill-column indicators on different lines might appear unaligned.

    To activate the fill-column indication display, use the minor modes display-fill-column-indicator-mode and global-display-fill-column-indicator-mode, which enable the indicator locally or globally, respectively.

    Alternatively, you can set the two buffer-local variables display-fill-column-indicator and display-fill-column-indicator-character to activate the indicator and control the character used for the indication. Note that both variables must be non-nil for the indication to be displayed. (Turning on the minor mode sets both these variables.)

    There are 2 buffer local variables and a face to customize this mode:


    Specifies the column number where the indicator should be set. It can take positive numerical values for the column, or the special value t, which means that the value of the variable fill-column will be used.

    Any other value disables the indicator. The default value is t.


    Specifies the character used for the indicator. This character can be any valid character including Unicode ones if the font supports them. The value nil disables the indicator. When the mode is enabled through the functions display-fill-column-indicator-mode or global-display-fill-column-indicator-mode, they will use the character specified by this variable, if it is non-nil; otherwise Emacs will use the character U+2502 BOX DRAWINGS LIGHT VERTICAL, falling back to ‘|’ if U+2502 cannot be displayed.


    Specifies the face used to display the indicator. It inherits its default values from the face shadow, but without background color. To change the indicator color, you need only set the foreground color of this face.

    On graphical displays, Emacs can indicate the buffer boundaries in the fringes. If you enable this feature, the first line and the last line are marked with angle images in the fringes. This can be combined with up and down arrow images which say whether it is possible to scroll the window.

    The buffer-local variable indicate-buffer-boundaries controls how the buffer boundaries and window scrolling is indicated in the fringes. If the value is left or right, both angle and arrow bitmaps are displayed in the left or right fringe, respectively.

    If value is an alist (see Association Lists in the Emacs Lisp Reference Manual), each element (indicator . position) specifies the position of one of the indicators. The indicator must be one of top, bottom, up, down, or t which specifies the default position for the indicators not present in the alist. The position is one of left, right, or nil which specifies not to show this indicator.

    For example, ((top . left) (t . right)) places the top angle bitmap in left fringe, the bottom angle bitmap in right fringe, and both arrow bitmaps in right fringe. To show just the angle bitmaps in the left fringe, but no arrow bitmaps, use ((top . left) (bottom . left)).

    15.17 Useless Whitespace

    It is easy to leave unnecessary spaces at the end of a line, or empty lines at the end of a buffer, without realizing it. In most cases, this trailing whitespace has no effect, but sometimes it can be a nuisance.

    You can make trailing whitespace at the end of a line visible by setting the buffer-local variable show-trailing-whitespace to t. Then Emacs displays trailing whitespace, using the face trailing-whitespace.

    This feature does not apply when point is at the end of the line containing the whitespace. Strictly speaking, that is trailing whitespace nonetheless, but displaying it specially in that case looks ugly while you are typing in new text. In this special case, the location of point is enough to show you that the spaces are present.

    Type M-x delete-trailing-whitespace to delete all trailing whitespace. This command deletes all extra spaces at the end of each line in the buffer, and all empty lines at the end of the buffer; to ignore the latter, change the variable delete-trailing-lines to nil. If the region is active, the command instead deletes extra spaces at the end of each line in the region.

    On graphical displays, Emacs can indicate unused lines at the end of the window with a small image in the left fringe (see Window Fringes). The image appears for screen lines that do not correspond to any buffer text, so blank lines at the end of the buffer stand out because they lack this image. To enable this feature, set the buffer-local variable indicate-empty-lines to a non-nil value. You can enable or disable this feature for all new buffers by setting the default value of this variable, e.g., (setq-default indicate-empty-lines t).

    Whitespace mode is a buffer-local minor mode that lets you visualize many kinds of whitespace in the buffer, by either drawing the whitespace characters with a special face or displaying them as special glyphs. To toggle this mode, type M-x whitespace-mode. The kinds of whitespace visualized are determined by the list variable whitespace-style. Individual elements in that list can be toggled on or off in the current buffer by typing M-x whitespace-toggle-options. Here is a partial list of possible elements (see the variable’s documentation for the full list):


    Enable all visualizations which use special faces. This element has a special meaning: if it is absent from the list, none of the other visualizations take effect except space-mark, tab-mark, and newline-mark.


    Highlight trailing whitespace.


    Highlight tab characters.


    Highlight space and non-breaking space characters.


    Highlight lines longer than 80 columns. To change the column limit, customize the variable whitespace-line-column.


    Highlight newlines.


    Highlight the final character if the buffer doesn’t end with a newline character.


    Highlight empty lines at the beginning and/or end of the buffer.


    Highlight too-deep indentation. By default any sequence of at least 4 consecutive tab characters or 32 consecutive space characters is highlighted. To change that, customize the regular expression whitespace-big-indent-regexp.


    Draw space and non-breaking characters with a special glyph.


    Draw tab characters with a special glyph.


    Draw newline characters with a special glyph.

    Global Whitespace mode is a global minor mode that lets you visualize whitespace in all buffers. To toggle individual features, use M-x global-whitespace-toggle-options.

    15.18 Selective Display

    Emacs has the ability to hide lines indented more than a given number of columns. You can use this to get an overview of a part of a program.

    To hide lines in the current buffer, type C-x $ (set-selective-display) with a numeric argument n. Then lines with at least n columns of indentation disappear from the screen. The only indication of their presence is that three dots (‘’) appear at the end of each visible line that is followed by one or more hidden ones.

    The commands C-n and C-p move across the hidden lines as if they were not there.

    The hidden lines are still present in the buffer, and most editing commands see them as usual, so you may find point in the middle of the hidden text. When this happens, the cursor appears at the end of the previous line, after the three dots. If point is at the end of the visible line, before the newline that ends it, the cursor appears before the three dots.

    To make all lines visible again, type C-x $ with no argument.

    If you set the variable selective-display-ellipses to nil, the three dots do not appear at the end of a line that precedes hidden lines. Then there is no visible indication of the hidden lines. This variable becomes local automatically when set.

    See also Outline Mode for another way to hide part of the text in a buffer.

    15.19 Optional Mode Line Features

    The buffer percentage pos indicates the percentage of the buffer above the top of the window. You can additionally display the size of the buffer by typing M-x size-indication-mode to turn on Size Indication mode. The size will be displayed immediately following the buffer percentage like this:

    pos of size

    Here size is the human readable representation of the number of characters in the buffer, which means that ‘k’ for 10^3, ‘M’ for 10^6, ‘G’ for 10^9, etc., are used to abbreviate.

    The current line number of point appears in the mode line when Line Number mode is enabled. Use the command M-x line-number-mode to turn this mode on and off; normally it is on. The line number appears after the buffer percentage pos, with the letter ‘L’ to indicate what it is.

    Similarly, you can display the current column number by turning on Column Number mode with M-x column-number-mode. The column number is indicated by the letter ‘C’. However, when both of these modes are enabled, the line and column numbers are displayed in parentheses, the line number first, rather than with ‘L’ and ‘C’. For example: ‘(561,2)’. See Minor Modes, for more information about minor modes and about how to use these commands.

    In Column Number mode, the displayed column number counts from zero starting at the left margin of the window. If you would prefer for the displayed column number to count from one, you may set column-number-indicator-zero-based to nil.

    If you have narrowed the buffer (see Narrowing), the displayed line number is relative to the accessible portion of the buffer. Thus, it isn’t suitable as an argument to goto-line. (The command what-line shows the line number relative to the whole file.) You can use goto-line-relative command to move point to the line relative to the accessible portion of the narrowed buffer.

    If the buffer is very large (larger than the value of line-number-display-limit), Emacs won’t compute the line number, because that would be too slow; therefore, the line number won’t appear on the mode-line. To remove this limit, set line-number-display-limit to nil.

    Line-number computation can also be slow if the lines in the buffer are too long. For this reason, Emacs doesn’t display line numbers if the average width, in characters, of lines near point is larger than the value of line-number-display-limit-width. The default value is 200 characters.

    Emacs can optionally display the time and system load in all mode lines. To enable this feature, type M-x display-time or customize the option display-time-mode. The information added to the mode line looks like this:

    hh:mmPM l.ll

    Here hh and mm are the hour and minute, followed always by ‘AM’ or ‘PM’. l.ll is the average number, collected for the last few minutes, of processes in the whole system that were either running or ready to run (i.e., were waiting for an available processor). (Some fields may be missing if your operating system cannot support them.) If you prefer time display in 24-hour format, set the variable display-time-24hr-format to t.

    The word ‘Mail’ appears after the load level if there is mail for you that you have not read yet. On graphical displays, you can use an icon instead of ‘Mail’ by customizing display-time-use-mail-icon; this may save some space on the mode line. You can customize display-time-mail-face to make the mail indicator prominent. Use display-time-mail-file to specify the mail file to check, or set display-time-mail-directory to specify the directory to check for incoming mail (any nonempty regular file in the directory is considered to be newly arrived mail).

    When running Emacs on a laptop computer, you can display the battery charge on the mode-line, by using the command display-battery-mode or customizing the variable display-battery-mode. The variable battery-mode-line-format determines the way the battery charge is displayed; the exact mode-line message depends on the operating system, and it usually shows the current battery charge as a percentage of the total charge. The functions in battery-update-functions are run after updating the mode line, and can be used to trigger actions based on the battery status.

    On graphical displays, the mode line is drawn as a 3D box. If you don’t like this effect, you can disable it by customizing the mode-line face and setting its box attribute to nil. See Customizing Faces.

    By default, the mode line of nonselected windows is displayed in a different face, called mode-line-inactive. Only the selected window is displayed in the mode-line face. This helps show which window is selected. When the minibuffer is selected, since it has no mode line, the window from which you activated the minibuffer has its mode line displayed using mode-line; as a result, ordinary entry to the minibuffer does not change any mode lines.

    You can disable use of mode-line-inactive by setting variable mode-line-in-non-selected-windows to nil; then all mode lines are displayed in the mode-line face.

    You can customize the mode line display for each of the end-of-line formats by setting each of the variables eol-mnemonic-unix, eol-mnemonic-dos, eol-mnemonic-mac, and eol-mnemonic-undecided to the strings you prefer.

    15.20 How Text Is Displayed

    Most characters are printing characters: when they appear in a buffer, they are displayed literally on the screen. Printing characters include ASCII numbers, letters, and punctuation characters, as well as many non-ASCII characters.

    The ASCII character set contains non-printing control characters. Two of these are displayed specially: the newline character (Unicode code point U+000A) is displayed by starting a new line, while the tab character (U+0009) is displayed as a space that extends to the next tab stop column (normally every 8 columns). The number of spaces per tab is controlled by the buffer-local variable tab-width, which must have an integer value between 1 and 1000, inclusive. Note that the way the tab character in the buffer is displayed has nothing to do with the definition of TAB as a command.

    Other ASCII control characters, whose codes are below U+0020 (octal 40, decimal 32), are displayed as a caret (‘^’) followed by the non-control version of the character, with the escape-glyph face. For instance, the ‘control-A’ character, U+0001, is displayed as ‘^A’.

    The raw bytes with codes U+0080 (octal 200) through U+009F (octal 237) are displayed as octal escape sequences, with the escape-glyph face. For instance, character code U+0098 (octal 230) is displayed as ‘\230’. If you change the buffer-local variable ctl-arrow to nil, the ASCII control characters are also displayed as octal escape sequences instead of caret escape sequences. (You can also request that raw bytes be shown in hex, see display-raw-bytes-as-hex.)

    Some non-ASCII characters have the same appearance as an ASCII space or hyphen (minus) character. Such characters can cause problems if they are entered into a buffer without your realization, e.g., by yanking; for instance, source code compilers typically do not treat non-ASCII spaces as whitespace characters. To deal with this problem, Emacs displays such characters specially: it displays U+00A0 NO-BREAK SPACE and other characters from the Unicode horizontal space class with the nobreak-space face, and it displays U+00AD SOFT HYPHEN, U+2010 HYPHEN, and U+2011 NON-BREAKING HYPHEN with the nobreak-hyphen face. To disable this, change the variable nobreak-char-display to nil. If you give this variable a non-nil and non-t value, Emacs instead displays such characters as a highlighted backslash followed by a space or hyphen.

    You can customize the way any particular character code is displayed by means of a display table. See Display Tables in The Emacs Lisp Reference Manual.

    On graphical displays, some characters may have no glyphs in any of the fonts available to Emacs. These glyphless characters are normally displayed as boxes containing the hexadecimal character code. Similarly, on text terminals, characters that cannot be displayed using the terminal encoding (see Coding Systems for Terminal I/O) are normally displayed as question signs. You can control the display method by customizing the variable glyphless-char-display-control. You can also customize the glyphless-char face to make these characters more prominent on display. See Glyphless Character Display in The Emacs Lisp Reference Manual, for details.

    The glyphless-display-mode minor mode can be used to toggle the display of glyphless characters in the current buffer. The glyphless characters will be displayed as boxes with acronyms of their names inside.

    Emacs tries to determine if the curved quotes and can be displayed on the current display. By default, if this seems to be so, then Emacs will translate the ASCII quotes (‘`’ and ‘'’), when they appear in messages and help texts, to these curved quotes. You can influence or inhibit this translation by customizing the user option text-quoting-style (see Keys in Documentation in The Emacs Lisp Reference Manual).

    If the curved quotes , , , and are known to look just like ASCII characters, they are shown with the homoglyph face. Curved quotes that are known not to be displayable are shown as their ASCII approximations ‘`’, ‘'’, and ‘"’ with the homoglyph face.

    15.21 Displaying the Cursor

    On a text terminal, the cursor’s appearance is controlled by the terminal, largely out of the control of Emacs. Some terminals offer two different cursors: a visible static cursor, and a very visible blinking cursor. By default, Emacs uses the very visible cursor, and switches to it when you start or resume Emacs. If the variable visible-cursor is nil when Emacs starts or resumes, it uses the normal cursor.

    On a graphical display, many more properties of the text cursor can be altered. To customize its color, change the :background attribute of the face named cursor (see Customizing Faces). (The other attributes of this face have no effect; the text shown under the cursor is drawn using the frame’s background color.) To change its shape, customize the buffer-local variable cursor-type; possible values are box (the default), (box . size) (box cursor becoming a hollow box under masked images larger than size pixels in either dimension), hollow (a hollow box), bar (a vertical bar), (bar . n) (a vertical bar n pixels wide), hbar (a horizontal bar), (hbar . n) (a horizontal bar n pixels tall), or nil (no cursor at all).

    By default, the cursor stops blinking after 10 blinks, if Emacs does not get any input during that time; any input event restarts the count. You can customize the variable blink-cursor-blinks to control that: its value says how many times to blink without input before stopping. Setting that variable to a zero or negative value will make the cursor blink forever. To disable cursor blinking altogether, change the variable blink-cursor-mode to nil (see Easy Customization Interface), or add the line

      (blink-cursor-mode 0)

    to your init file. Alternatively, you can change how the cursor looks when it blinks off by customizing the list variable blink-cursor-alist. Each element in the list should have the form (on-type . off-type); this means that if the cursor is displayed as on-type when it blinks on (where on-type is one of the cursor types described above), then it is displayed as off-type when it blinks off.

    Some characters, such as tab characters, are extra wide. When the cursor is positioned over such a character, it is normally drawn with the default character width. You can make the cursor stretch to cover wide characters, by changing the variable x-stretch-cursor to a non-nil value.

    The cursor normally appears in non-selected windows as a non-blinking hollow box. (For a bar cursor, it instead appears as a thinner bar.) To turn off cursors in non-selected windows, change the variable cursor-in-non-selected-windows to nil.

    To make the cursor even more visible, you can use HL Line mode, a minor mode that highlights the line containing point. Use M-x hl-line-mode to enable or disable it in the current buffer. M-x global-hl-line-mode enables or disables the same mode globally.

    15.22 Line Truncation

    As an alternative to continuation (see Continuation Lines), Emacs can display long lines by truncation. This means that all the characters that do not fit in the width of the screen or window do not appear at all. On graphical displays, a small straight arrow in the fringe indicates truncation at either end of the line. On text terminals, this is indicated with ‘$’ signs in the rightmost and/or leftmost columns.

    Horizontal scrolling automatically causes line truncation (see Horizontal Scrolling). You can explicitly enable line truncation for a particular buffer with the command C-x x t (toggle-truncate-lines). This works by locally changing the variable truncate-lines. If that variable is non-nil, long lines are truncated; if it is nil, they are continued onto multiple screen lines. Setting the variable truncate-lines in any way makes it local to the current buffer; until that time, the default value, which is normally nil, is in effect.

    Since line truncation and word wrap (described in the next section) are contradictory, toggle-truncate-lines disables word wrap when it turns on line truncation.

    If a split window becomes too narrow, Emacs may automatically enable line truncation. See Splitting Windows, for the variable truncate-partial-width-windows which controls this.

    15.23 Visual Line Mode

    Another alternative to ordinary line continuation (see Continuation Lines) is to use word wrap. Here, each long logical line is divided into two or more screen lines, or “visual lines”, like in ordinary line continuation. However, Emacs attempts to wrap the line at word boundaries near the right window edge. (If the line’s direction is right-to-left, it is wrapped at the left window edge instead.) This makes the text easier to read, as wrapping does not occur in the middle of words.

    Word wrap is enabled by Visual Line mode, an optional minor mode. To turn on Visual Line mode in the current buffer, type M-x visual-line-mode; repeating this command turns it off. You can also turn on Visual Line mode using the menu bar: in the Options menu, select the ‘Line Wrapping in this Buffer’ submenu, followed by the ‘Word Wrap (Visual Line mode)’ menu item. While Visual Line mode is enabled, the mode line shows the string ‘wrap’ in the mode display. The command M-x global-visual-line-mode toggles Visual Line mode in all buffers.

    Since word wrap and line truncation (described in the previous section) are contradictory, turning on visual-line-mode disables line truncation.

    In Visual Line mode, some editing commands work on screen lines instead of logical lines: C-a (beginning-of-visual-line) moves to the beginning of the screen line, C-e (end-of-visual-line) moves to the end of the screen line, and C-k (kill-visual-line) kills text to the end of the screen line.

    To move by logical lines, use the commands M-x next-logical-line and M-x previous-logical-line. These move point to the next logical line and the previous logical line respectively, regardless of whether Visual Line mode is enabled. If you use these commands frequently, it may be convenient to assign key bindings to them. See Rebinding Keys in Your Init File.

    By default, word-wrapped lines do not display fringe indicators. Visual Line mode is often used to edit files that contain many long logical lines, so having a fringe indicator for each wrapped line would be visually distracting. You can change this by customizing the variable visual-line-fringe-indicators.

    By default, Emacs only breaks lines after whitespace characters like SPC and TAB, but does not break after whitespace characters like EN QUAD. Emacs provides a minor mode called word-wrap-whitespace-mode that switches on word wrapping in the current mode, and sets up which characters to wrap lines on based on the word-wrap-whitespace-characters user option. There’s also a globalized version of that mode called global-word-wrap-whitespace-mode.

    Only breaking after whitespace character produces incorrect results when CJK and Latin text are mixed together (because CJK characters don’t use whitespace to separate words). You can customize the option word-wrap-by-category to allow Emacs to break lines after any character with ‘|’ category (see Categories in the Emacs Lisp Reference Manual), which provides better support for CJK characters. Also, if this variable is set using Customize, Emacs automatically loads kinsoku.el. When kinsoku.el is loaded, Emacs respects kinsoku rules when breaking lines. That means characters with the ‘>’ category don’t appear at the beginning of a line (e.g., U+FF0C FULLWIDTH COMMA), and characters with the ‘<’ category don’t appear at the end of a line (e.g., U+300A LEFT DOUBLE ANGLE BRACKET). You can view the category set of a character using the commands char-category-set and category-set-mnemonics, or by typing C-u C-x = with point on the character and looking at the “category” section in the report. You can add categories to a character using the command modify-category-entry.

    15.24 Customization of Display

    This section describes variables that control miscellaneous aspects of the appearance of the Emacs screen. Beginning users can skip it.

    If you want to have Emacs display line numbers for every line in the buffer, customize the buffer-local variable display-line-numbers; it is nil by default. This variable can have several different values to support various modes of line-number display:


    Display (an absolute) line number before each non-continuation screen line that displays buffer text. If the line is a continuation line, or if the entire screen line displays a display or an overlay string, that line will not be numbered.


    Display relative line numbers before non-continuation lines which show buffer text. The line numbers are relative to the line showing point, so the numbers grow both up and down as lines become farther from the current line.


    This value causes Emacs to count lines visually: only lines actually shown on the display will be counted (disregarding any lines in invisible parts of text), and lines which wrap to consume more than one screen line will be numbered that many times. The displayed numbers are relative, as with relative value above. This is handy in modes that fold text, such as Outline mode (see Outline Mode), and when you need to move by exact number of screen lines.

    anything else

    Any other non-nil value is treated as t.

    The command M-x display-line-numbers-mode provides a convenient way to turn on display of line numbers. This mode has a globalized variant, global-display-line-numbers-mode. The user option display-line-numbers-type controls which sub-mode of line-number display, described above, these modes will activate.

    Note that line numbers are not displayed in the minibuffer and in the tooltips, even if you turn on display-line-numbers-mode globally.

    When Emacs displays relative line numbers, you can control the number displayed before the current line, the line showing point. By default, Emacs displays the absolute number of the current line there, even though all the other line numbers are relative. If you customize the variable display-line-numbers-current-absolute to a nil value, the number displayed for the current line will be zero. This is handy if you don’t care about the number of the current line, and want to leave more horizontal space for text in large buffers.

    In a narrowed buffer (see Narrowing) lines are normally numbered starting at the beginning of the narrowing. However, if you customize the variable display-line-numbers-widen to a non-nil value, line numbers will disregard any narrowing and will start at the first character of the buffer.

    If the value of display-line-numbers-offset is non-zero, it is added to each absolute line number, and lines are counted from the beginning of the buffer, as if display-line-numbers-widen were non-nil. It has no effect when set to zero, or when line numbers are not absolute.

    In selective display mode (see Selective Display), and other modes that hide many lines from display (such as Outline and Org modes), you may wish to customize the variables display-line-numbers-width-start and display-line-numbers-grow-only, or set display-line-numbers-width to a large enough value, to avoid occasional miscalculations of space reserved for the line numbers.

    The line numbers are displayed in a special face line-number. The current line number is displayed in a different face, line-number-current-line, so you can make the current line’s number have a distinct appearance, which will help locating the line showing point. Additional faces line-number-major-tick and line-number-minor-tick can be used to highlight the line numbers of lines which are a multiple of certain numbers. Customize display-line-numbers-major-tick and display-line-numbers-minor-tick respectively to set those numbers.

    If the variable visible-bell is non-nil, Emacs attempts to make the whole screen blink when it would normally make an audible bell sound. This variable has no effect if your terminal does not have a way to make the screen blink.

    The variable echo-keystrokes controls the echoing of multi-character keys; its value is the number of seconds of pause required to cause echoing to start, or zero, meaning don’t echo at all. The value takes effect when there is something to echo. See The Echo Area.

    On graphical displays, Emacs displays the mouse pointer as an hourglass if Emacs is busy. To disable this feature, set the variable display-hourglass to nil. The variable hourglass-delay determines the number of seconds of busy time before the hourglass is shown; the default is 1.

    If the mouse pointer lies inside an Emacs frame, Emacs makes it invisible each time you type a character to insert text, to prevent it from obscuring the text. (To be precise, the hiding occurs when you type a self-inserting character. See Inserting Text.) Moving the mouse pointer makes it visible again. To disable this feature, set the variable make-pointer-invisible to nil.

    On graphical displays, the variable underline-minimum-offset determines the minimum distance between the baseline and underline, in pixels, for underlined text. By default, the value is 1; increasing it may improve the legibility of underlined text for certain fonts. (However, Emacs will never draw the underline below the current line area.) The variable x-underline-at-descent-line determines how to draw underlined text. The default is nil, which means to draw it at the baseline level of the font; if you change it to t, Emacs draws the underline at the same height as the font’s descent line. (If non-default line spacing was specified for the underlined text, see Line Height in The Emacs Lisp Reference Manual, Emacs draws the underline below the additional spacing.)

    The variable overline-margin specifies the vertical position of an overline above the text, including the height of the overline itself, in pixels; the default is 2.

    On some text terminals, bold face and inverse video together result in text that is hard to read. Call the function tty-suppress-bold-inverse-default-colors with a non-nil argument to suppress the effect of bold-face in this case.

    Raw bytes are displayed in octal format by default, for example a byte with a decimal value of 128 is displayed as \200. To change display to the hexadecimal format of \x80, set the variable display-raw-bytes-as-hex to t. Care may be needed when interpreting a raw byte when copying text from a terminal containing an Emacs session, or when a terminal’s escape-glyph face looks like the default face. For example, by default Emacs displays the four characters ‘\’, ‘2’, ‘0’, ‘0’ with the same characters it displays a byte with decimal value 128. The problem can be worse with hex displays, where the raw byte 128 followed by the character ‘7’ is displayed as \x807, which Emacs Lisp reads as the single character U+0807 SAMARITAN LETTER IT; this confusion does not occur with the corresponding octal display \2007 because octal escapes contain at most three digits.

    17 Commands for Fixing Typos

    In this chapter we describe commands that are useful when you catch a mistake while editing. The most fundamental of these commands is the undo command C-/ (also bound to C-x u and C-_). This undoes a single command, or a part of a command (as in the case of query-replace), or several consecutive character insertions. Consecutive repetitions of C-/ undo earlier and earlier changes, back to the limit of the undo information available.

    Aside from the commands described here, you can erase text using deletion commands such as DEL (delete-backward-char). These were described earlier in this manual. See Erasing Text.

    17.1 Undo

    The undo command reverses recent changes in the buffer’s text. Each buffer records changes individually, and the undo command always applies to the current buffer. You can undo all the changes in a buffer for as far back as the buffer’s records go. Usually, each editing command makes a separate entry in the undo records, but some commands such as query-replace divide their changes into multiple entries for flexibility in undoing. Consecutive character insertion commands are usually grouped together into a single undo record, to make undoing less tedious.

    C-x u

    Undo one entry in the current buffer’s undo records (undo).

    To begin to undo, type C-/ (or its aliases, C-_ or C-x u)6. This undoes the most recent change in the buffer, and moves point back to where it was before that change. Consecutive repetitions of C-/ (or its aliases) undo earlier and earlier changes in the current buffer. If all the recorded changes have already been undone, the undo command signals an error.

    Any command other than an undo command breaks the sequence of undo commands. Starting from that moment, the entire sequence of undo commands that you have just performed are themselves placed into the undo record. Therefore, to re-apply changes you have undone, type C-f or any other command that harmlessly breaks the sequence of undoing; then type C-/ one or more times to undo some of the undo commands.

    Alternatively, if you want to resume undoing, without redoing previous undo commands, use M-x undo-only. This is like undo, but will not redo changes you have just undone. To complement it, M-x undo-redo will undo previous undo commands (and will not record itself as an undoable command).

    If you notice that a buffer has been modified accidentally, the easiest way to recover is to type C-/ repeatedly until the stars disappear from the front of the mode line (see The Mode Line). Whenever an undo command makes the stars disappear from the mode line, it means that the buffer contents are the same as they were when the file was last read in or saved. If you do not remember whether you changed the buffer deliberately, type C-/ once. When you see the last change you made undone, you will see whether it was an intentional change. If it was an accident, leave it undone. If it was deliberate, redo the change as described above.

    Alternatively, you can discard all the changes since the buffer was last visited or saved with M-x revert-buffer (see Reverting a Buffer).

    When there is an active region, any use of undo performs selective undo: it undoes the most recent change within the region, instead of the entire buffer. However, when Transient Mark mode is off (see Disabling Transient Mark Mode), C-/ always operates on the entire buffer, ignoring the region. In this case, you can perform selective undo by supplying a prefix argument to the undo command: C-u C-/. To undo further changes in the same region, repeat the undo command (no prefix argument is needed).

    Some specialized buffers do not make undo records. Buffers whose names start with spaces never do; these buffers are used internally by Emacs to hold text that users don’t normally look at or edit.

    When the undo information for a buffer becomes too large, Emacs discards the oldest records from time to time (during garbage collection). You can specify how much undo information to keep by setting the variables undo-limit, undo-strong-limit, and undo-outer-limit. Their values are expressed in bytes.

    The variable undo-limit sets a soft limit: Emacs keeps undo data for enough commands to reach this size, and perhaps exceed it, but does not keep data for any earlier commands beyond that. Its default value is 160000. The variable undo-strong-limit sets a stricter limit: any previous command (though not the most recent one) that pushes the size past this amount is forgotten. The default value of undo-strong-limit is 240000.

    Regardless of the values of those variables, the most recent change is never discarded unless it gets bigger than undo-outer-limit (normally 24,000,000). At that point, Emacs discards the undo data and warns you about it. This is the only situation in which you cannot undo the last command. If this happens, you can increase the value of undo-outer-limit to make it even less likely to happen in the future. But if you didn’t expect the command to create such large undo data, then it is probably a bug and you should report it. See Reporting Bugs.

    17.2 Transposing Text


    Transpose two characters (transpose-chars).


    Transpose two words (transpose-words).


    Transpose two balanced expressions (transpose-sexps).

    C-x C-t

    Transpose two lines (transpose-lines).

    M-x transpose-sentences

    Transpose two sentences (transpose-sentences).

    M-x transpose-paragraphs

    Transpose two paragraphs (transpose-paragraphs).

    M-x transpose-regions

    Transpose two regions.

    The common error of transposing two characters can be fixed, when they are adjacent, with the C-t command (transpose-chars). Normally, C-t transposes the two characters on either side of point. When given at the end of a line, rather than transposing the last character of the line with the newline, which would be useless, C-t transposes the last two characters on the line. So, if you catch your transposition error right away, you can fix it with just a C-t. If you don’t catch it so fast, you must move the cursor back between the two transposed characters before you type C-t. If you transposed a space with the last character of the word before it, the word motion commands (M-f, M-b, etc.) are a good way of getting there. Otherwise, a reverse search (C-r) is often the best way. See Searching and Replacement.

    M-t transposes the word before point with the word after point (transpose-words). It moves point forward over a word, dragging the word preceding or containing point forward as well. The punctuation characters between the words do not move. For example, ‘FOO, BAR transposes into ‘BAR, FOO rather than ‘BAR FOO,. When point is at the end of the line, it will transpose the word before point with the first word on the next line.

    C-M-t (transpose-sexps) is a similar command for transposing two expressions (see Expressions with Balanced Parentheses), and C-x C-t (transpose-lines) exchanges lines. M-x transpose-sentences and M-x transpose-paragraphs transpose sentences and paragraphs, respectively. These commands work like M-t except as regards the units of text they transpose.

    A numeric argument to a transpose command serves as a repeat count: it tells the transpose command to move the character (or word or expression or line) before or containing point across several other characters (or words or expressions or lines). For example, C-u 3 C-t moves the character before point forward across three other characters. It would change ‘f∗oobar’ into ‘oobf∗ar’. This is equivalent to repeating C-t three times. C-u - 4 M-t moves the word before point backward across four words. C-u - C-M-t would cancel the effect of plain C-M-t.

    A numeric argument of zero is assigned a special meaning (because otherwise a command with a repeat count of zero would do nothing): to transpose the character (or word or expression or line) ending after point with the one ending after the mark.

    M-x transpose-regions transposes the text between point and mark with the text between the last two marks pushed to the mark ring (see Setting the Mark). With a numeric prefix argument, it transposes the text between point and mark with the text between two successive marks that many entries back in the mark ring. This command is best used for transposing multiple characters (or words or sentences or paragraphs) in one go.

    17.3 Case Conversion

    M-- M-l

    Convert last word to lower case. Note Meta-- is Meta-minus.

    M-- M-u

    Convert last word to all upper case.

    M-- M-c

    Convert last word to lower case with capital initial.

    A very common error is to type words in the wrong case. Because of this, the word case-conversion commands M-l, M-u, and M-c have a special feature when used with a negative argument: they do not move the cursor. As soon as you see you have mistyped the last word, you can simply case-convert it and go on typing. See Case Conversion Commands.

    17.4 Checking and Correcting Spelling

    This section describes the commands to check the spelling of a single word or of a portion of a buffer. These commands only work if a spelling checker program, one of Hunspell, Aspell, Ispell or Enchant, is installed. These programs are not part of Emacs, but one of them is usually installed on GNU/Linux and other free operating systems. See Aspell in The Aspell Manual.

    If you have only one of the spelling checker programs installed, Emacs will find it when you invoke for the first time one of the commands described here. If you have more than one of them installed, you can control which one is used by customizing the variable ispell-program-name.


    Check and correct spelling of the word at point (ispell-word). If the region is active, do it for all words in the region instead.

    C-u M-$

    If a previous spelling operation was interrupted, continue that operation (ispell-continue).

    M-x ispell

    Check and correct spelling of all words in the buffer. If the region is active, do it for all words in the region instead.

    M-x ispell-buffer

    Check and correct spelling in the buffer.

    M-x ispell-region

    Check and correct spelling in the region.

    M-x ispell-message

    Check and correct spelling in a draft mail message, excluding cited material.

    M-x ispell-comments-and-strings

    Check and correct spelling of comments and strings in the buffer or region.

    M-x ispell-comment-or-string-at-point

    Check the comment or string at point.

    M-x ispell-change-dictionary RET dict RET

    Restart the spell-checker process, using dict as the dictionary.

    M-x ispell-kill-ispell

    Kill the spell-checker subprocess.


    Complete the word before point based on the spelling dictionary (ispell-complete-word).

    M-x flyspell-mode

    Enable Flyspell mode, which highlights all misspelled words.

    M-x flyspell-prog-mode

    Enable Flyspell mode for comments and strings only.

    To check the spelling of the word around or before point, and optionally correct it as well, type M-$ (ispell-word). If a region is active, M-$ checks the spelling of all words within the region. See The Mark and the Region. (When Transient Mark mode is off, M-$ always acts on the word around or before point, ignoring the region; see Disabling Transient Mark Mode.) When invoked with a prefix argument, C-u M-$, this calls ispell-continue, which continues the spelling operation, if any, which was interrupted with X or C-g.

    Similarly, the command M-x ispell performs spell-checking in the region if one is active, or in the entire buffer otherwise. The commands M-x ispell-buffer and M-x ispell-region explicitly perform spell-checking on the entire buffer or the region respectively. To check spelling in an email message you are writing, use M-x ispell-message; that command checks the whole buffer, except for material that is indented or appears to be cited from other messages. See Sending Mail. When dealing with source code, you can use M-x ispell-comments-and-strings or M-x ispell-comment-or-string-at-point to check only comments or string literals.

    When one of these commands encounters what appears to be an incorrect word, it asks you what to do. It usually displays a list of numbered near-misses—words that are close to the incorrect word. Then you must type a single-character response. Here are the valid responses:


    Replace the word, just this time, with one of the displayed near-misses. Each near-miss is listed with a digit; type that digit to select it.


    Skip this word—continue to consider it incorrect, but don’t change it here.

    r new RET

    Replace the word, just this time, with new. (The replacement string will be rescanned for more spelling errors.)

    R new RET

    Replace the word with new, and do a query-replace so you can replace it elsewhere in the buffer if you wish. (The replacements will be rescanned for more spelling errors.)


    Accept the incorrect word—treat it as correct, but only in this editing session.


    Accept the incorrect word—treat it as correct, but only in this editing session and for this buffer.


    Insert this word in your private dictionary file so that it will be considered correct from now on, even in future sessions.


    Like i, but you can also specify dictionary completion information.


    Insert the lower-case version of this word in your private dictionary file.

    l word RET

    Look in the dictionary for words that match word. These words become the new list of near-misses; you can select one of them as the replacement by typing a digit. You can use ‘*’ in word as a wildcard.


    Interrupt the interactive spell-checking, leaving point at the word that was being checked. You can restart checking again afterward with C-u M-$.


    Quit interactive spell-checking and move point back to where it was when you started spell-checking.


    Quit interactive spell-checking and kill the spell-checker subprocess.


    Enter recursive-edit (see Recursive Editing Levels). When you exit recursive-edit with C-M-c, the interactive spell-checking will resume. This allows you to consult the buffer text without interrupting the spell-checking. Do not modify the buffer in the recursive editing, and especially don’t modify the misspelled word, as the edits will be undone when you exit recursive-edit. If you need to edit the misspelled word, use r or R instead, or use X, edit the buffer, then resume with C-u M-$.


    Suspend Emacs or iconify the selected frame.


    Show the list of options.

    In Text mode and related modes, M-TAB (ispell-complete-word) performs in-buffer completion based on spelling correction. Insert the beginning of a word, and then type M-TAB; this shows a list of completions. (If your window manager intercepts M-TAB, type ESC TAB or C-M-i.) Each completion is listed with a digit or character; type that digit or character to choose it.

    Once started, the spell-checker subprocess continues to run, waiting for something to do, so that subsequent spell-checking commands complete more quickly. If you want to get rid of the process, use M-x ispell-kill-ispell. This is not usually necessary, since the process uses no processor time except when you do spelling correction.

    Spell-checkers look up spelling in two dictionaries: the standard dictionary and your personal dictionary. The standard dictionary is specified by the variable ispell-local-dictionary or, if that is nil, by the variable ispell-dictionary. If both are nil, the spelling program’s default dictionary is used. The command M-x ispell-change-dictionary sets the standard dictionary for the buffer and then restarts the subprocess, so that it will use a different standard dictionary. Your personal dictionary is specified by the variable ispell-personal-dictionary. If that is nil, the spelling program looks for a personal dictionary in a default location, which is specific to each spell-checker.

    A separate dictionary is used for word completion. The variable ispell-complete-word-dict specifies the file name of this dictionary. The completion dictionary must be different because it cannot use the information about roots and affixes of the words, which spell-checking uses to detect variations of words. For some languages, there is a spell-checking dictionary but no word completion dictionary.

    Flyspell mode is a minor mode that performs automatic spell-checking of the text you type as you type it. When it finds a word that it does not recognize, it highlights that word. Type M-x flyspell-mode to toggle Flyspell mode in the current buffer. To enable Flyspell mode in all text mode buffers, add flyspell-mode to text-mode-hook. See Hooks. Note that, as Flyspell mode needs to check each word across which you move, it will slow down cursor motion and scrolling commands. It also doesn’t automatically check the text you didn’t type or move across; use flyspell-region or flyspell-buffer for that.

    When Flyspell mode highlights a word as misspelled, you can click on it with mouse-2 (flyspell-correct-word) to display a menu of possible corrections and actions. If you want this menu on mouse-3 instead, enable context-menu-mode. In addition, C-. or ESC TAB (flyspell-auto-correct-word) will propose various successive corrections for the word at point, and C-c $ (flyspell-correct-word-before-point) will pop up a menu of possible corrections. Of course, you can always correct the misspelled word by editing it manually in any way you like.

    Flyspell Prog mode works just like ordinary Flyspell mode, except that it only checks words in comments and string constants. This feature is useful for editing programs. Type M-x flyspell-prog-mode to enable or disable this mode in the current buffer. To enable this mode in all programming mode buffers, add flyspell-prog-mode to prog-mode-hook (see Hooks).

    18 Keyboard Macros

    In this chapter we describe how to record a sequence of editing commands so you can repeat it conveniently later.

    A keyboard macro is a command defined by an Emacs user to stand for another sequence of keys. For example, if you discover that you are about to type C-n M-d C-d forty times, you can speed your work by defining a keyboard macro to do C-n M-d C-d, and then executing it 39 more times.

    You define a keyboard macro by executing and recording the commands which are its definition. Put differently, as you define a keyboard macro, the definition is being executed for the first time. This way, you can see the effects of your commands, so that you don’t have to figure them out in your head. When you close the definition, the keyboard macro is defined and also has been, in effect, executed once. You can then do the whole thing over again by invoking the macro.

    Keyboard macros differ from ordinary Emacs commands in that they are written in the Emacs command language rather than in Lisp. This makes it easier for the novice to write them, and makes them more convenient as temporary hacks. However, the Emacs command language is not powerful enough as a programming language to be useful for writing anything intelligent or general. For such things, Lisp must be used.

    18.1 Basic Use


    Start defining a keyboard macro (kmacro-start-macro-or-insert-counter).


    If a keyboard macro is being defined, end the definition; otherwise, execute the most recent keyboard macro (kmacro-end-or-call-macro).

    C-u F3

    Re-execute last keyboard macro, then append keys to its definition.

    C-u C-u F3

    Append keys to the last keyboard macro without re-executing it.

    C-x C-k r

    Run the last keyboard macro on each line that begins in the region (apply-macro-to-region-lines).

    C-x (

    Start defining a keyboard macro (old style) (kmacro-start-macro); with a prefix argument, append keys to the last macro.

    C-x )

    End a macro definition (old style) (kmacro-end-macro); prefix argument serves as the repeat count for executing the macro.

    C-x e

    Execute the most recently defined keyboard macro (kmacro-end-and-call-macro); prefix argument serves as repeat count.

    To start defining a keyboard macro, type F3. From then on, your keys continue to be executed, but also become part of the definition of the macro. ‘Def’ appears in the mode line to remind you of what is going on. When you are finished, type F4 (kmacro-end-or-call-macro) to terminate the definition. For example,

    F3 M-f foo F4

    defines a macro to move forward a word and then insert ‘foo’. Note that F3 and F4 do not become part of the macro.

    After defining the macro, you can call it with F4. For the above example, this has the same effect as typing M-f foo again. (Note the two roles of the F4 command: it ends the macro if you are in the process of defining one, or calls the last macro otherwise.) You can also supply F4 with a numeric prefix argument ‘n’, which means to invoke the macro ‘n’ times. An argument of zero repeats the macro indefinitely, until it gets an error or you type C-g (or, on MS-DOS, C-Break).

    The above example demonstrates a handy trick that you can employ with keyboard macros: if you wish to repeat an operation at regularly spaced places in the text, include a motion command as part of the macro. In this case, repeating the macro inserts the string ‘foo’ after each successive word.

    After terminating the definition of a keyboard macro, you can append more keystrokes to its definition by typing C-u F3. This is equivalent to plain F3 followed by retyping the whole definition so far. As a consequence, it re-executes the macro as previously defined. If you change the variable kmacro-execute-before-append to nil, the existing macro will not be re-executed before appending to it (the default is t). You can also add to the end of the definition of the last keyboard macro without re-executing it by typing C-u C-u F3.

    When a command reads an argument with the minibuffer, your minibuffer input becomes part of the macro along with the command. So when you replay the macro, the command gets the same argument as when you entered the macro. For example,

    F3 C-a C-k C-x b foo RET C-y C-x b RET F4

    defines a macro that kills the current line, yanks it into the buffer ‘foo’, then returns to the original buffer.

    Most keyboard commands work as usual in a keyboard macro definition, with some exceptions. Typing C-g (keyboard-quit) quits the keyboard macro definition. Typing C-M-c (exit-recursive-edit) can be unreliable: it works as you’d expect if exiting a recursive edit that started within the macro, but if it exits a recursive edit that started before you invoked the keyboard macro, it also necessarily exits the keyboard macro too. Mouse events are also unreliable, even though you can use them in a keyboard macro: when the macro replays the mouse event, it uses the original mouse position of that event, the position that the mouse had while you were defining the macro. The effect of this may be hard to predict.

    The command C-x C-k r (apply-macro-to-region-lines) repeats the last defined keyboard macro on each line that begins in the region. It does this line by line, by moving point to the beginning of the line and then executing the macro.

    In addition to the F3 and F4 commands described above, Emacs also supports an older set of key bindings for defining and executing keyboard macros. To begin a macro definition, type C-x ( (kmacro-start-macro); as with F3, a prefix argument appends this definition to the last keyboard macro. To end a macro definition, type C-x ) (kmacro-end-macro). To execute the most recent macro, type C-x e (kmacro-end-and-call-macro). If you enter C-x e while defining a macro, the macro is terminated and executed immediately. Immediately after typing C-x e, you can type e repeatedly to immediately repeat the macro one or more times. You can also give C-x e a repeat argument, just like F4 (when it is used to execute a macro).

    C-x ) can be given a repeat count as an argument. This means to repeat the macro right after defining it. The macro definition itself counts as the first repetition, since it is executed as you define it, so C-u 4 C-x ) executes the macro immediately 3 additional times.

    While executing a long-running keyboard macro, it can sometimes be useful to trigger a redisplay (to show how far we’ve gotten). The C-x C-k d command can be used for this. As a not very useful example, C-x ( M-f C-x C-k d C-x ) will create a macro that will redisplay once per iteration when saying C-u 42 C-x e.

    18.2 The Keyboard Macro Ring

    All defined keyboard macros are recorded in the keyboard macro ring. There is only one keyboard macro ring, shared by all buffers.

    C-x C-k C-k

    Execute the keyboard macro at the head of the ring (kmacro-end-or-call-macro-repeat).

    C-x C-k C-n

    Rotate the keyboard macro ring to the next macro (defined earlier) (kmacro-cycle-ring-next).

    C-x C-k C-p

    Rotate the keyboard macro ring to the previous macro (defined later) (kmacro-cycle-ring-previous).

    All commands which operate on the keyboard macro ring use the same C-x C-k prefix. Most of these commands can be executed and repeated immediately after each other without repeating the C-x C-k prefix. For example,

    C-x C-k C-p C-p C-k C-k C-k C-n C-n C-k C-p C-k C-d

    will rotate the keyboard macro ring to the second-previous macro, execute the resulting head macro three times, rotate back to the original head macro, execute that once, rotate to the previous macro, execute that, and finally delete it from the macro ring.

    The command C-x C-k C-k (kmacro-end-or-call-macro-repeat) executes the keyboard macro at the head of the macro ring. You can repeat the macro immediately by typing another C-k, or you can rotate the macro ring immediately by typing C-n or C-p.

    When a keyboard macro is being defined, C-x C-k C-k behaves like F4 except that, immediately afterward, you can use most key bindings of this section without the C-x C-k prefix. For instance, another C-k will re-execute the macro.

    The commands C-x C-k C-n (kmacro-cycle-ring-next) and C-x C-k C-p (kmacro-cycle-ring-previous) rotate the macro ring, bringing the next or previous keyboard macro to the head of the macro ring. The definition of the new head macro is displayed in the echo area. You can continue to rotate the macro ring immediately by repeating just C-n and C-p until the desired macro is at the head of the ring. To execute the new macro ring head immediately, just type C-k.

    Note that Emacs treats the head of the macro ring as the last defined keyboard macro. For instance, F4 will execute that macro, and C-x C-k n will give it a name.

    The maximum number of macros stored in the keyboard macro ring is determined by the customizable variable kmacro-ring-max.

    18.3 The Keyboard Macro Counter

    Each keyboard macro has an associated counter, which is initialized to 0 when you start defining the macro. This current counter allows you to insert a number into the buffer that depends on the number of times the macro has been called. The counter is normally incremented each time its value is inserted into the buffer.

    In addition to the current counter, keyboard macros also maintain the previous counter, which records the value the current counter had last time it was incremented or set. Note that incrementing the current counter by zero, e.g., with C-u 0 C-x C-k C-i, also records the value of the current counter as the previous counter value.


    In a keyboard macro definition, insert the keyboard macro counter value in the buffer (kmacro-start-macro-or-insert-counter).

    C-x C-k C-i

    Insert the keyboard macro counter value in the buffer (kmacro-insert-counter).

    C-x C-k C-c

    Set the keyboard macro counter (kmacro-set-counter).

    C-x C-k C-a

    Add the prefix arg to the keyboard macro counter (kmacro-add-counter).

    C-x C-k C-f

    Specify the format for inserting the keyboard macro counter (kmacro-set-format).

    When you are defining a keyboard macro, the command F3 (kmacro-start-macro-or-insert-counter) inserts the current value of the keyboard macro’s counter into the buffer, and increments the counter by 1. (If you are not defining a macro, F3 begins a macro definition instead. See Basic Use.) You can use a numeric prefix argument to specify a different increment. If you just specify a C-u prefix, that inserts the previous counter value, and doesn’t change the current value.

    As an example, let us show how the keyboard macro counter can be used to build a numbered list. Consider the following key sequence:

    F3 C-a F3 . SPC F4

    As part of this keyboard macro definition, the string ‘0. ’ was inserted into the beginning of the current line. If you now move somewhere else in the buffer and type F4 to invoke the macro, the string ‘1. ’ is inserted at the beginning of that line. Subsequent invocations insert ‘2. ’, ‘3. ’, and so forth.

    The command C-x C-k C-i (kmacro-insert-counter) does the same thing as F3, but it can be used outside a keyboard macro definition. When no keyboard macro is being defined or executed, it inserts and increments the counter of the macro at the head of the keyboard macro ring.

    The command C-x C-k C-c (kmacro-set-counter) sets the current macro counter to the value of the numeric argument. If you use it inside the macro, it operates on each repetition of the macro. If you specify just C-u as the prefix, while executing the macro, that resets the counter to the value it had at the beginning of the current repetition of the macro (undoing any increments so far in this repetition).

    The command C-x C-k C-a (kmacro-add-counter) adds the prefix argument to the current macro counter. With just C-u as argument, it resets the counter to the last value inserted by any keyboard macro. (Normally, when you use this, the last insertion will be in the same macro and it will be the same counter.)

    The command C-x C-k C-f (kmacro-set-format) prompts for the format to use when inserting the macro counter. The default format is ‘%d’, which means to insert the number in decimal without any padding. You can exit with empty minibuffer to reset the format to this default. You can specify any format string that the format function accepts and that makes sense with a single integer extra argument (see Formatting Strings in The Emacs Lisp Reference Manual). Do not put the format string inside double quotes when you insert it in the minibuffer.

    If you use this command while no keyboard macro is being defined or executed, the new format affects all subsequent macro definitions. Existing macros continue to use the format in effect when they were defined. If you set the format while defining a keyboard macro, this affects the macro being defined from that point on, but it does not affect subsequent macros. Execution of the macro will, at each step, use the format in effect at that step during its definition. Changes to the macro format during execution of a macro, like the corresponding changes during its definition, have no effect on subsequent macros.

    The format set by C-x C-k C-f does not affect insertion of numbers stored in registers.

    If you use a register as a counter, incrementing it on each repetition of the macro, that accomplishes the same thing as a keyboard macro counter. See Keeping Numbers in Registers. For most purposes, it is simpler to use a keyboard macro counter.

    18.4 Executing Macros with Variations

    In a keyboard macro, you can create an effect similar to that of query-replace, in that the macro asks you each time around whether to make a change.

    C-x q

    When this point is reached during macro execution, ask for confirmation (kbd-macro-query).

    While defining the macro, type C-x q at the point where you want the query to occur. During macro definition, the C-x q does nothing, but when you run the macro later, C-x q asks you interactively whether to continue.

    The valid responses when C-x q asks are:

    SPC (or y)

    Continue executing the keyboard macro.

    DEL (or n)

    Skip the remainder of this repetition of the macro, and start right away with the next repetition.

    RET (or q)

    Skip the remainder of this repetition and cancel further repetitions.


    Enter a recursive editing level, in which you can perform editing which is not part of the macro. When you exit the recursive edit using C-M-c, you are asked again how to continue with the keyboard macro. If you type a SPC at this time, the rest of the macro definition is executed. It is up to you to leave point and the text in a state such that the rest of the macro will do what you want.

    C-u C-x q, which is C-x q with a prefix argument, performs a completely different function. It enters a recursive edit reading input from the keyboard, both when you type it during the definition of the macro, and when it is executed from the macro. During definition, the editing you do inside the recursive edit does not become part of the macro. During macro execution, the recursive edit gives you a chance to do some particularized editing on each repetition. See Recursive Editing Levels.

    18.5 Naming and Saving Keyboard Macros

    C-x C-k n

    Give a command name (for the duration of the Emacs session) to the most recently defined keyboard macro (kmacro-name-last-macro).

    C-x C-k b

    Bind the most recently defined keyboard macro to a key sequence (for the duration of the session) (kmacro-bind-to-key).

    M-x insert-kbd-macro

    Insert in the buffer a keyboard macro’s definition, as Lisp code.

    If you wish to save a keyboard macro for later use, you can give it a name using C-x C-k n (kmacro-name-last-macro). This reads a name as an argument using the minibuffer and defines that name to execute the last keyboard macro, in its current form. (If you later add to the definition of this macro, that does not alter the name’s definition as a macro.) The macro name is a Lisp symbol, and defining it in this way makes it a valid command name for calling with M-x or for binding a key to with keymap-global-set (see Keymaps). If you specify a name that has a prior definition other than a keyboard macro, an error message is shown and nothing is changed.

    You can also bind the last keyboard macro (in its current form) to a key, using C-x C-k b (kmacro-bind-to-key) followed by the key sequence you want to bind. You can bind to any key sequence in the global keymap, but since most key sequences already have other bindings, you should select the key sequence carefully. If you try to bind to a key sequence with an existing binding (in any keymap), this command asks you for confirmation before replacing the existing binding.

    To avoid problems caused by overriding existing bindings, the key sequences C-x C-k 0 through C-x C-k 9 and C-x C-k A through C-x C-k Z are reserved for your own keyboard macro bindings. In fact, to bind to one of these key sequences, you only need to type the digit or letter rather than the whole key sequences. For example,

    C-x C-k b 4

    will bind the last keyboard macro to the key sequence C-x C-k 4.

    Once a macro has a command name, you can save its definition in a file. Then it can be used in another editing session. First, visit the file you want to save the definition in. Then use this command:

    M-x insert-kbd-macro RET macroname RET

    This inserts some Lisp code that, when executed later, will define the same macro with the same definition it has now. (You don’t need to understand Lisp code to do this, because insert-kbd-macro writes the Lisp code for you.) Then save the file. You can load the file later with load-file (see Libraries of Lisp Code for Emacs). If the file you save in is your init file ~/.emacs (see The Emacs Initialization File) then the macro will be defined each time you run Emacs.

    If you give insert-kbd-macro a prefix argument, it makes additional Lisp code to record the keys (if any) that you have bound to macroname, so that the macro will be reassigned the same keys when you load the file.

    18.6 Editing a Keyboard Macro

    C-x C-k C-e

    Edit the last defined keyboard macro (kmacro-edit-macro).

    C-x C-k e name RET

    Edit a previously defined keyboard macro name (edit-kbd-macro).

    C-x C-k l

    Edit the last 300 keystrokes as a keyboard macro (kmacro-edit-lossage).

    You can edit the last keyboard macro by typing C-x C-k C-e or C-x C-k RET (kmacro-edit-macro). This formats the macro definition in a buffer and enters a specialized major mode for editing it. Type C-h m once in that buffer to display details of how to edit the macro. When you are finished editing, type C-c C-c.

    You can edit a named keyboard macro or a macro bound to a key by typing C-x C-k e (edit-kbd-macro). Follow that with the keyboard input that you would use to invoke the macro—C-x e or M-x name or some other key sequence.

    You can edit the last 300 keystrokes as a macro by typing C-x C-k l (kmacro-edit-lossage).

    18.7 Stepwise Editing a Keyboard Macro

    You can interactively replay and edit the last keyboard macro, one command at a time, by typing C-x C-k SPC (kmacro-step-edit-macro). Unless you quit the macro using q or C-g, the edited macro replaces the last macro on the macro ring.

    This macro editing feature shows the last macro in the minibuffer together with the first (or next) command to be executed, and prompts you for an action. You can enter ? to get a summary of your options. These actions are available:

    • SPC and y execute the current command, and advance to the next command in the keyboard macro.
    • n, d, and DEL skip and delete the current command.
    • f skips the current command in this execution of the keyboard macro, but doesn’t delete it from the macro.
    • TAB executes the current command, as well as all similar commands immediately following the current command; for example, TAB may be used to insert a sequence of characters (corresponding to a sequence of self-insert-command commands).
    • c continues execution (without further editing) until the end of the keyboard macro. If execution terminates normally, the edited macro replaces the original keyboard macro.
    • C-k skips and deletes the rest of the keyboard macro, terminates step-editing, and replaces the original keyboard macro with the edited macro.
    • q and C-g cancels the step-editing of the keyboard macro; discarding any changes made to the keyboard macro.
    • i key… C-j reads and executes a series of key sequences (not including the final C-j), and inserts them before the current command in the keyboard macro, without advancing over the current command.
    • I key reads one key sequence, executes it, and inserts it before the current command in the keyboard macro, without advancing over the current command.
    • r key… C-j reads and executes a series of key sequences (not including the final C-j), and replaces the current command in the keyboard macro with them, advancing over the inserted key sequences.
    • R key reads one key sequence, executes it, and replaces the current command in the keyboard macro with that key sequence, advancing over the inserted key sequence.
    • a key… C-j executes the current command, then reads and executes a series of key sequences (not including the final C-j), and inserts them after the current command in the keyboard macro; it then advances over the current command and the inserted key sequences.
    • A key… C-j executes the rest of the commands in the keyboard macro, then reads and executes a series of key sequences (not including the final C-j), and appends them at the end of the keyboard macro; it then terminates the step-editing and replaces the original keyboard macro with the edited macro.

    19 File Handling

    The operating system stores data permanently in named files, so most of the text you edit with Emacs comes from a file and is ultimately stored in a file.

    To edit a file, you must tell Emacs to read the file and prepare a buffer containing a copy of the file’s text. This is called visiting the file. Editing commands apply directly to text in the buffer; that is, to the copy inside Emacs. Your changes appear in the file itself only when you save the buffer back into the file.

    In addition to visiting and saving files, Emacs can delete, copy, rename, and append to files, keep multiple versions of them, and operate on file directories.

    19.1 File Names

    Many Emacs commands that operate on a file require you to specify the file name, using the minibuffer (see Minibuffers for File Names).

    While in the minibuffer, you can use the usual completion and history commands (see The Minibuffer). Note that file name completion ignores file names whose extensions appear in the variable completion-ignored-extensions (see Completion Options). Note also that most commands use permissive completion with confirmation for reading file names: you are allowed to submit a nonexistent file name, but if you type RET immediately after completing up to a nonexistent file name, Emacs prints ‘[Confirm]’ and you must type a second RET to confirm. See Completion Exit, for details.

    Minibuffer history commands offer some special features for reading file names, see Minibuffer History.

    Each buffer has a default directory, stored in the buffer-local variable default-directory. Whenever Emacs reads a file name using the minibuffer, it usually inserts the default directory into the minibuffer as the initial contents. You can inhibit this insertion by changing the variable insert-default-directory to nil (see Minibuffers for File Names). Regardless, Emacs always assumes that any relative file name is relative to the default directory, e.g., entering a file name without a directory specifies a file in the default directory.

    When you visit a file, Emacs sets default-directory in the visiting buffer to the directory of its file. When you create a new buffer that is not visiting a file, via a command like C-x b, its default directory is usually copied from the buffer that was current at the time (see Creating and Selecting Buffers). You can use the command M-x pwd to see the value of default-directory in the current buffer. The command M-x cd prompts for a directory’s name, and sets the buffer’s default-directory to that directory (doing this does not change the buffer’s file name, if any).

    As an example, when you visit the file /u/rms/gnu/gnu.tasks, the default directory is set to /u/rms/gnu/. If you invoke a command that reads a file name, entering just ‘foo’ in the minibuffer, with a directory omitted, specifies the file /u/rms/gnu/foo; entering ‘../.login’ specifies /u/rms/.login; and entering ‘new/foo’ specifies /u/rms/gnu/new/foo.

    When typing a file name into the minibuffer, you can make use of a couple of shortcuts: a double slash ignores everything before the second slash in the pair, and ‘~/’ is your home directory. See Minibuffers for File Names.

    The character ‘$’ is used to substitute an environment variable into a file name. The name of the environment variable consists of all the alphanumeric characters after the ‘$’; alternatively, it can be enclosed in braces after the ‘$’. For example, if you have used the shell command export FOO=rms/hacks to set up an environment variable named FOO, then both /u/$FOO/test.c and /u/${FOO}/test.c are abbreviations for /u/rms/hacks/test.c. If the environment variable is not defined, no substitution occurs, so that the character ‘$’ stands for itself. Note that environment variables set outside Emacs affect Emacs only if they are applied before Emacs is started.

    To access a file with ‘$’ in its name, if the ‘$’ causes expansion, type ‘$$’. This pair is converted to a single ‘$’ at the same time that variable substitution is performed for a single ‘$’. Alternatively, quote the whole file name with ‘/:’ (see Quoted File Names). File names which begin with a literal ‘~’ should also be quoted with ‘/:’.

    You can include non-ASCII characters in file names. See Coding Systems for File Names.

    Next: , Previous: , Up: File Handling   [Contents][Index]

    19.2 Visiting Files

    C-x C-f

    Visit a file (find-file).

    C-x C-r

    Visit a file for viewing, without allowing changes to it (find-file-read-only).

    C-x C-v

    Visit a different file instead of the one visited last (find-alternate-file).

    C-x 4 f

    Visit a file, in another window (find-file-other-window). Don’t alter what is displayed in the selected window.

    C-x 5 f

    Visit a file, in a new frame (find-file-other-frame). Don’t alter what is displayed in the selected frame.

    M-x find-file-literally

    Visit a file with no conversion of the contents.

    Visiting a file means reading its contents into an Emacs buffer so you can edit them. Emacs makes a new buffer for each file that you visit.

    To visit a file, type C-x C-f (find-file) and use the minibuffer to enter the name of the desired file. While in the minibuffer, you can abort the command by typing C-g. See File Names, for details about entering file names into minibuffers.

    If the specified file exists but the system does not allow you to read it, an error message is displayed in the echo area (on GNU and Unix systems you might be able to visit such a file using the ‘su’ or ‘sudo’ methods; see Remote Files). Otherwise, you can tell that C-x C-f has completed successfully by the appearance of new text on the screen, and by the buffer name shown in the mode line (see The Mode Line). Emacs normally constructs the buffer name from the file name, omitting the directory name. For example, a file named /usr/rms/emacs.tex is visited in a buffer named ‘emacs.tex’. If there is already a buffer with that name, Emacs constructs a unique name; the normal method is to add a suffix based on the directory name (e.g., ‘<rms>’, ‘<tmp>’, and so on), but you can select other methods. See Making Buffer Names Unique.

    To create a new file, just visit it using the same command, C-x C-f. Emacs displays ‘(New file)’ in the echo area, but in other respects behaves as if you had visited an existing empty file.

    After visiting a file, the changes you make with editing commands are made in the Emacs buffer. They do not take effect in the visited file, until you save the buffer (see Saving Files). If a buffer contains changes that have not been saved, we say the buffer is modified. This implies that some changes will be lost if the buffer is not saved. The mode line displays two stars near the left margin to indicate that the buffer is modified.

    If you visit a file that is already in Emacs, C-x C-f switches to the existing buffer instead of making another copy. Before doing so, it checks whether the file has changed since you last visited or saved it. If the file has changed, Emacs offers to reread it.

    If you try to visit a file larger than large-file-warning-threshold (the default is 10000000, which is about 10 megabytes), Emacs asks you for confirmation first. You can answer y to proceed with visiting the file or l to visit the file literally (see below). Visiting large files literally speeds up navigation and editing of such files, because various potentially-expensive features are turned off. Note, however, that Emacs cannot visit files that are larger than the maximum Emacs buffer size, which is limited by the amount of memory Emacs can allocate and by the integers that Emacs can represent (see Using Multiple Buffers). If you try, Emacs displays an error message saying that the maximum buffer size has been exceeded.

    If you try to visit a file whose major mode (see Major Modes) uses the tree-sitter parsing library, Emacs will display a warning if the file’s size in bytes is larger than the value of the variable treesit-max-buffer-size. The default value is 40 megabytes for 64-bit Emacs and 15 megabytes for 32-bit Emacs. This avoids the danger of having Emacs run out of memory by preventing the activation of major modes based on tree-sitter in such large buffers, because a typical tree-sitter parser needs about 10 times as much memory as the text it parses.

    If the file name you specify contains shell-style wildcard characters, Emacs visits all the files that match it. (On case-insensitive filesystems, Emacs matches the wildcards disregarding the letter case.) Wildcards include ‘?’, ‘*’, and ‘[…]’ sequences. To enter the wild card ‘?’ in a file name in the minibuffer, you need to type C-q ?. See Quoted File Names, for information on how to visit a file whose name actually contains wildcard characters. You can disable the wildcard feature by customizing find-file-wildcards.

    If you’re asking to visit a file that’s already visited in a buffer, but the file has changed externally, Emacs normally asks you whether you want to re-read the file from disk. But if you set query-about-changed-file to nil, Emacs won’t query you, but will instead just display the buffer’s contents before the changes, and show an echo-area message telling you how to revert the buffer from the file.

    If you visit the wrong file unintentionally by typing its name incorrectly, type C-x C-v (find-alternate-file) to visit the file you really wanted. C-x C-v is similar to C-x C-f, but it kills the current buffer (after first offering to save it if it is modified). When C-x C-v reads the file name to visit, it inserts the entire default file name in the buffer, with point just after the directory part; this is convenient if you made a slight error in typing the name.

    If you visit a file that is actually a directory, Emacs invokes Dired, the Emacs directory browser. See Dired, the Directory Editor. You can disable this behavior by setting the variable find-file-run-dired to nil; in that case, it is an error to try to visit a directory.

    Files which are actually collections of other files, or file archives, are visited in special modes which invoke a Dired-like environment to allow operations on archive members. See File Archives, for more about these features.

    If you visit a file that the operating system won’t let you modify, or that is marked read-only, Emacs makes the buffer read-only too, so that you won’t go ahead and make changes that you’ll have trouble saving afterward. You can make the buffer writable with C-x C-q (read-only-mode). See Miscellaneous Buffer Operations.

    If you want to visit a file as read-only in order to protect yourself from entering changes accidentally, visit it with the command C-x C-r (find-file-read-only) instead of C-x C-f.

    C-x 4 f (find-file-other-window) is like C-x C-f except that the buffer containing the specified file is selected in another window. The window that was selected before C-x 4 f continues to show the same buffer it was already showing. If this command is used when only one window is being displayed, that window is split in two, with one window showing the same buffer as before, and the other one showing the newly requested file. See Multiple Windows.

    C-x 5 f (find-file-other-frame) is similar, but opens a new frame, or selects any existing frame showing the specified file. See Frames and Graphical Displays.

    On graphical displays, there are two additional methods for visiting files. Firstly, when Emacs is built with a suitable GUI toolkit, commands invoked with the mouse (by clicking on the menu bar or tool bar) use the toolkit’s standard file selection dialog instead of prompting for the file name in the minibuffer. On GNU/Linux and Unix platforms, Emacs does this when built with GTK+, LessTif, and Motif toolkits; on MS-Windows and Mac, the GUI version does that by default. For information on how to customize this, see Using Dialog Boxes.

    Secondly, Emacs supports drag and drop: dropping a file into an ordinary Emacs window visits the file using that window. As an exception, dropping a file into a window displaying a Dired buffer moves or copies the file into the displayed directory. For details, see Drag and Drop, and Other Dired Features.

    On text-mode terminals and on graphical displays when Emacs was built without a GUI toolkit, you can visit files via the menu-bar ‘File’ menu, which has the ‘Visit New File’ and the ‘Open File’ items.

    Each time you visit a file, Emacs automatically scans its contents to detect what character encoding and end-of-line convention it uses, and converts these to Emacs’s internal encoding and end-of-line convention within the buffer. When you save the buffer, Emacs performs the inverse conversion, writing the file to disk with its original encoding and end-of-line convention. See Coding Systems.

    If you wish to edit a file as a sequence of ASCII characters with no special encoding or conversion, use the M-x find-file-literally command. This visits a file, like C-x C-f, but does not do format conversion (see Format Conversion in the Emacs Lisp Reference Manual), character code conversion (see Coding Systems), or automatic uncompression (see Accessing Compressed Files), and does not add a final newline because of require-final-newline (see Customizing Saving of Files). If you have already visited the same file in the usual (non-literal) manner, this command asks you whether to visit it literally instead.

    Files are sometimes (loosely) tied to other files, and you could call these files sibling files. For instance, when editing C files, if you have a file called ‘"foo.c"’, you often also have a file called ‘"foo.h"’, and that could be its sibling file. Or you may have different versions of a file, for instance ‘"src/emacs/emacs-27/lisp/allout.el"’ and ‘"src/emacs/emacs-28/lisp/allout.el"’ might be considered siblings. Emacs provides the find-sibling-file command to jump between sibling files, but it’s impossible to guess at which files a user might want to be considered siblings, so Emacs lets you configure this freely by altering the find-sibling-rules user option. This is a list of match/expansion elements.

    For instance, to do the ‘".c"’ to ‘".h"’ mapping, you could say:

    (setq find-sibling-rules
          '(("\\([^/]+\\)\\.c\\'" "\\1.h")))

    (ff-find-related-file offers similar functionality especially geared towards C files, see Other Commands for C Mode.)

    Or, if you want to consider all files under ‘"src/emacs/DIR/file-name"’ to be siblings of other dirs, you could say:

    (setq find-sibling-rules
          '(("src/emacs/[^/]+/\\(.*\\)\\'" "src/emacs/.*/\\1")))

    As you can see, this is a list of elements of the form (MATCH expansion…). The match is a regular expression that matches the visited file name, and each expansion may refer to match groups by using ‘\\1’ and so on. The resulting expansion string is then applied to the file system to see if any files match this expansion (interpreted as a regexp).

    Two special hook variables allow extensions to modify the operation of visiting files. Visiting a file that does not exist runs the functions in find-file-not-found-functions; this variable holds a list of functions, which are called one by one (with no arguments) until one of them returns non-nil. This is not a normal hook, and the name ends in ‘-functions’ rather than ‘-hook’ to indicate that fact.

    Successful visiting of any file, whether existing or not, calls the functions in find-file-hook, with no arguments. This variable is a normal hook. In the case of a nonexistent file, the find-file-not-found-functions are run first. See Hooks.

    There are several ways to specify automatically the major mode for editing the file (see Choosing File Modes), and to specify local variables defined for that file (see Local Variables in Files).

    19.3 Saving Files

    Saving a buffer in Emacs means writing its contents back into the file that was visited in the buffer.

    19.3.1 Commands for Saving Files

    These are the commands that relate to saving and writing files.

    C-x C-s

    Save the current buffer to its file (save-buffer).

    C-x s

    Save any or all buffers to their files (save-some-buffers).


    Forget that the current buffer has been changed (not-modified). With prefix argument (C-u), mark the current buffer as changed.

    C-x C-w

    Save the current buffer with a specified file name (write-file).

    M-x set-visited-file-name

    Change the file name under which the current buffer will be saved.

    M-x rename-visited-file

    The same as M-x set-visited-file-name, but also rename the file the buffer is visiting (if any).

    When you wish to save the file and make your changes permanent, type C-x C-s (save-buffer). After saving is finished, C-x C-s displays a message like this:

    Wrote /u/rms/gnu/gnu.tasks

    If the current buffer is not modified (no changes have been made in it since the buffer was created or last saved), saving is not really done, because it would have no effect. Instead, C-x C-s displays a message like this in the echo area:

    (No changes need to be saved)

    With a prefix argument, C-u C-x C-s, Emacs also marks the buffer to be backed up when the next save is done. See Backup Files.

    The command C-x s (save-some-buffers) offers to save any or all modified buffers. It asks you what to do with each buffer. The possible responses are analogous to those of query-replace:


    Save this buffer and ask about the rest of the buffers.


    Don’t save this buffer, but ask about the rest of the buffers.


    Save this buffer and all the rest with no more questions.


    Terminate save-some-buffers without any more saving.


    Save this buffer, then exit save-some-buffers without even asking about other buffers.


    View the buffer that you are currently being asked about. When you exit View mode, you get back to save-some-buffers, which asks the question again.


    Exit save-some-buffers and visit the buffer that you are currently being asked about.


    Diff the buffer against its corresponding file, so you can see what changes you would be saving. This calls the command diff-buffer-with-file (see Comparing Files).


    Display a help message about these options.

    You can customize the value of save-some-buffers-default-predicate to control which buffers Emacs will ask about.

    C-x C-c, the key sequence to exit Emacs, invokes save-some-buffers and therefore asks the same questions.

    If you have changed a buffer but do not wish to save the changes, you should take some action to prevent it. Otherwise, each time you use C-x s or C-x C-c, you are liable to save this buffer by mistake. One thing you can do is type M-~ (not-modified), which clears out the indication that the buffer is modified. If you do this, none of the save commands will believe that the buffer needs to be saved. (‘~’ is often used as a mathematical symbol for “not”; thus M-~ is “not”, metafied.) Alternatively, you can cancel all the changes made since the file was visited or saved, by reading the text from the file again. This is called reverting. See Reverting a Buffer. (You could also undo all the changes by repeating the undo command C-x u until you have undone all the changes; but reverting is easier.)

    M-x set-visited-file-name alters the name of the file that the current buffer is visiting. It reads the new file name using the minibuffer. Then it marks the buffer as visiting that file name, and changes the buffer name correspondingly. set-visited-file-name does not save the buffer in the newly visited file; it just alters the records inside Emacs in case you do save later. It also marks the buffer as modified so that C-x C-s in that buffer will save.

    If you wish to mark the buffer as visiting a different file and save it right away, use C-x C-w (write-file). This is equivalent to set-visited-file-name followed by C-x C-s, except that C-x C-w asks for confirmation if the file exists. C-x C-s used on a buffer that is not visiting a file has the same effect as C-x C-w; that is, it reads a file name, marks the buffer as visiting that file, and saves it there. The default file name in a buffer that is not visiting a file is made by combining the buffer name with the buffer’s default directory (see File Names).

    If the new file name implies a major mode, then C-x C-w switches to that major mode, in most cases. The command set-visited-file-name also does this. See Choosing File Modes.

    If you wish to save the current buffer to a different file without visiting that file, use mark-whole-buffer (C-x h), then M-x write-region (see Miscellaneous File Operations).

    If Emacs is about to save a file and sees that the date of the latest version on disk does not match what Emacs last read or wrote, Emacs notifies you of this fact, because it probably indicates a problem caused by simultaneous editing and requires your immediate attention. See Simultaneous Editing.

    19.3.2 Backup Files

    On most operating systems, rewriting a file automatically destroys all record of what the file used to contain. Thus, saving a file from Emacs throws away the old contents of the file—or it would, except that Emacs carefully copies the old contents to another file, called the backup file, before actually saving.

    Emacs makes a backup for a file only the first time the file is saved from the buffer that visits it. No matter how many times you subsequently save the file, its backup remains unchanged. However, if you kill the buffer and then visit the file again, a new backup file will be made.

    For most files, the variable make-backup-files determines whether to make backup files. On most operating systems, its default value is t, so that Emacs does write backup files.

    For files managed by a version control system (see Version Control), the variable vc-make-backup-files determines whether to make backup files. By default it is nil, since backup files are redundant when you store all the previous versions in a version control system. See General Options.

    At your option, Emacs can keep either a single backup for each file, or make a series of numbered backup files for each file that you edit. See Single or Numbered Backups.

    The default value of the backup-enable-predicate variable prevents backup files being written for files in the directories used for temporary files, specified by temporary-file-directory or small-temporary-file-directory.

    You can explicitly tell Emacs to make another backup file from a buffer, even though that buffer has been saved before. If you save the buffer with C-u C-x C-s, the version thus saved will be made into a backup file if you save the buffer again. C-u C-u C-x C-s saves the buffer, but first makes the previous file contents into a new backup file. C-u C-u C-u C-x C-s does both things: it makes a backup from the previous contents, and arranges to make another from the newly saved contents if you save again.

    You can customize the variable backup-directory-alist to specify that files matching certain patterns should be backed up in specific directories. A typical use is to add an element ("." . dir) to make all backups in the directory with absolute name dir. Emacs modifies the backup file names to avoid clashes between files with the same names originating in different directories. Alternatively, adding, ("." . ".~") would make backups in the invisible subdirectory .~ of the original file’s directory. Emacs creates the directory, if necessary, to make the backup. Single or Numbered Backups

    When Emacs makes a backup file, its name is normally constructed by appending ‘~’ to the file name being edited; thus, the backup file for eval.c would be eval.c~.

    If access control stops Emacs from writing backup files under the usual names, it writes the backup file as ~/.emacs.d/%backup%~. Only one such file can exist, so only the most recently made such backup is available.

    Emacs can also make numbered backup files. Numbered backup file names contain ‘.~’, the number, and another ‘~’ after the original file name. Thus, the backup files of eval.c would be called eval.c.~1~, eval.c.~2~, and so on, all the way through names like eval.c.~259~ and beyond.

    The variable version-control determines whether to make single backup files or multiple numbered backup files. Its possible values are:


    Make numbered backups for files that have numbered backups already. Otherwise, make single backups. This is the default.


    Make numbered backups.


    Never make numbered backups; always make single backups.

    The usual way to set this variable is globally, through your init file or the customization buffer. However, you can set version-control locally in an individual buffer to control the making of backups for that buffer’s file (see Local Variables). Some modes, such as Rmail mode, set this variable. You can also have Emacs set version-control locally whenever you visit a given file (see Local Variables in Files).

    If you set the environment variable VERSION_CONTROL, to tell various GNU utilities what to do with backup files, Emacs also obeys the environment variable by setting the Lisp variable version-control accordingly at startup. If the environment variable’s value is ‘t’ or ‘numbered’, then version-control becomes t; if the value is ‘nil’ or ‘existing’, then version-control becomes nil; if it is ‘never’ or ‘simple’, then version-control becomes never.

    If you set the variable make-backup-file-name-function to a suitable Lisp function, you can override the usual way Emacs constructs backup file names. Automatic Deletion of Backups

    To prevent excessive consumption of disk space, Emacs can delete numbered backup versions automatically. Generally Emacs keeps the first few backups and the latest few backups, deleting any in between. This happens every time a new backup is made.

    The two variables kept-old-versions and kept-new-versions control this deletion. Their values are, respectively, the number of oldest (lowest-numbered) backups to keep and the number of newest (highest-numbered) ones to keep, each time a new backup is made. The backups in the middle (excluding those oldest and newest) are the excess middle versions—those backups are deleted. These variables’ values are used when it is time to delete excess versions, just after a new backup version is made; the newly made backup is included in the count in kept-new-versions. By default, both variables are 2.

    If delete-old-versions is t, Emacs deletes the excess backup files silently. If it is nil, the default, Emacs asks you whether it should delete the excess backup versions. If it has any other value, then Emacs never automatically deletes backups.

    Dired’s . (Period) command can also be used to delete old versions. See Flagging Many Files at Once. Copying vs. Renaming

    Backup files can be made by copying the old file or by renaming it. This makes a difference when the old file has multiple names (hard links). If the old file is renamed into the backup file, then the alternate names become names for the backup file. If the old file is copied instead, then the alternate names remain names for the file that you are editing, and the contents accessed by those names will be the new contents.

    The method of making a backup file may also affect the file’s owner and group. If copying is used, these do not change. If renaming is used, you become the file’s owner, and the file’s group becomes the default (different operating systems have different defaults for the group).

    The choice of renaming or copying is made as follows:

    • If the variable backup-by-copying is non-nil (the default is nil), use copying.
    • Otherwise, if the variable backup-by-copying-when-linked is non-nil (the default is nil), and the file has multiple names, use copying.
    • Otherwise, if the variable backup-by-copying-when-mismatch is non-nil (the default is t), and renaming would change the file’s owner or group, use copying.

      If you change backup-by-copying-when-mismatch to nil, Emacs checks the numeric user-id of the file’s owner and the numeric group-id of the file’s group. If either is no greater than backup-by-copying-when-privileged-mismatch, then it behaves as though backup-by-copying-when-mismatch is non-nil anyway.

    • Otherwise, renaming is the default choice.

    When a file is managed with a version control system (see Version Control), Emacs does not normally make backups in the usual way for that file. But committing (a.k.a. checking in, see Concepts of Version Control) new versions of files is similar in some ways to making backups. One unfortunate similarity is that these operations typically break hard links, disconnecting the file name you visited from any alternate names for the same file. This has nothing to do with Emacs—the version control system does it.

    Some file storage services support file versioning: they record history of previous versions of files, and allow reverting to those previous versions. If you want to be able to do that with files hosted by those services when editing them with Emacs, customize backup-by-copying to a non-nil value.

    Copying the old file for backup is also useful when editing precious files, because it makes sure the old file keeps its name if something fails between the backup and the saving of your edits. Alternatively, you can customize file-precious-flag to a non-nil value, which implies backups by copying and also protects against I/O errors while saving your edits.

    19.3.3 Customizing Saving of Files

    If the value of the variable require-final-newline is t, saving or writing a file silently puts a newline at the end if there isn’t already one there. If the value is visit, Emacs adds a newline at the end of any file that doesn’t have one, just after it visits the file. (This marks the buffer as modified, and you can undo it.) If the value is visit-save, Emacs adds such newlines both on visiting and on saving. If the value is nil, Emacs leaves the end of the file unchanged; any other non-nil value means Emacs asks you whether to add a newline. The default is nil.

    Some major modes are designed for specific kinds of files that are always supposed to end in newlines. Such major modes set the variable require-final-newline to the value of mode-require-final-newline, which defaults to t. By setting the latter variable, you can control how these modes handle final newlines.

    If this option is non-nil and you’re visiting a file via a symbolic link, Emacs will break the symbolic link upon saving the buffer, and will write the buffer to a file with the same name as the symbolic link, if the value of file-precious-flag is non-nil (see file-precious-flag in The Emacs Lisp Reference Manual). If you want Emacs to save the buffer to the file the symbolic link points to (thereby preserving the link) in these cases, customize the variable file-preserve-symlinks-on-save to t.

    Normally, when a program writes a file, the operating system briefly caches the file’s data in main memory before committing the data to disk. This can greatly improve performance; for example, when running on laptops, it can avoid a disk spin-up each time a file is written. However, it risks data loss if the operating system crashes before committing the cache to disk.

    To lessen this risk, Emacs can invoke the fsync system call after saving a file. Using fsync does not eliminate the risk of data loss, partly because many systems do not implement fsync properly, and partly because Emacs’s file-saving procedure typically relies also on directory updates that might not survive a crash even if fsync works properly.

    The write-region-inhibit-fsync variable controls whether Emacs invokes fsync after saving a file. The variable’s default value is nil when Emacs is interactive, and t when Emacs runs in batch mode (see Batch Mode).

    Emacs never uses fsync when writing auto-save files, as these files might lose data anyway.

    19.3.4 Protection against Simultaneous Editing

    Simultaneous editing occurs when two users visit the same file, both make changes, and then both save them. If nobody is informed that this is happening, whichever user saves first would later find that their changes were lost.

    On some systems, Emacs notices immediately when the second user starts to change the file, and issues an immediate warning. On all systems, Emacs checks when you save the file, and warns if you are about to overwrite another user’s changes. You can prevent loss of the other user’s work by taking the proper corrective action instead of saving the file.

    When you make the first modification in an Emacs buffer that is visiting a file, Emacs records that the file is locked by you. (It does this by creating a specially-named symbolic link7 with special contents in the same directory. See (elisp)File Locks, for more details.) Emacs removes the lock when you save the changes. The idea is that the file is locked whenever an Emacs buffer visiting it has unsaved changes.

    You can prevent the creation of lock files by setting the variable create-lockfiles to nil. Caution: by doing so you will lose the benefits that this feature provides. You can also control where lock files are written by using the lock-file-name-transforms variable.

    If you begin to modify the buffer while the visited file is locked by someone else, this constitutes a collision. When Emacs detects a collision, it asks you what to do, by calling the Lisp function ask-user-about-lock. You can redefine this function for the sake of customization. The standard definition of this function asks you a question and accepts three possible answers:


    Steal the lock. Whoever was already changing the file loses the lock, and you gain the lock.


    Proceed. Go ahead and edit the file despite its being locked by someone else.


    Quit. This causes an error (file-locked), and the buffer contents remain unchanged—the modification you were trying to make does not actually take place.

    If Emacs or the operating system crashes, this may leave behind lock files which are stale, so you may occasionally get warnings about spurious collisions. When you determine that the collision is spurious, just use p to tell Emacs to go ahead anyway.

    Note that locking works on the basis of a file name; if a file has multiple names, Emacs does not prevent two users from editing it simultaneously under different names.

    A lock file cannot be written in some circumstances, e.g., if Emacs lacks the system permissions or cannot create lock files for some other reason. In these cases, Emacs can still detect the collision when you try to save a file, by checking the file’s last-modification date. If the file has changed since the last time Emacs visited or saved it, that implies that changes have been made in some other way, and will be lost if Emacs proceeds with saving. Emacs then displays a warning message and asks for confirmation before saving; answer yes to save, and no or C-g cancel the save.

    If you are notified that simultaneous editing has already taken place, one way to compare the buffer to its file is the M-x diff-buffer-with-file command. See Comparing Files.

    You can prevent the creation of remote lock files by setting the variable remote-file-name-inhibit-locks to t.

    The minor mode lock-file-mode, called interactively, toggles the local value of create-lockfiles in the current buffer.

    19.3.5 Shadowing Files

    You can arrange to keep identical shadow copies of certain files in more than one place—possibly on different machines. To do this, first you must set up a shadow file group, which is a set of identically-named files shared between a list of sites. The file group is permanent and applies to further Emacs sessions as well as the current one. Once the group is set up, every time you exit Emacs, it will copy the file you edited to the other files in its group. You can also do the copying without exiting Emacs, by typing M-x shadow-copy-files.

    A shadow cluster is a group of hosts that share directories, so that copying to or from one of them is sufficient to update the file on all of them. Each shadow cluster has a name, and specifies the network address of a primary host (the one we copy files to), and a regular expression that matches the host names of all the other hosts in the cluster. You can define a shadow cluster with M-x shadow-define-cluster.

    M-x shadow-initialize

    Set up file shadowing.

    M-x shadow-define-literal-group

    Declare a single file to be shared between sites.

    M-x shadow-define-regexp-group

    Make all files that match each of a group of files be shared between hosts.

    M-x shadow-define-cluster RET name RET

    Define a shadow file cluster name.

    M-x shadow-copy-files

    Copy all pending shadow files.

    M-x shadow-cancel

    Cancel the instruction to shadow some files.

    To set up a shadow file group, use M-x shadow-define-literal-group or M-x shadow-define-regexp-group. See their documentation strings for further information.

    Before copying a file to its shadows, Emacs asks for confirmation. You can answer “no” to bypass copying of this file, this time. If you want to cancel the shadowing permanently for a certain file, use M-x shadow-cancel to eliminate or change the shadow file group.

    File Shadowing is not available on MS Windows.

    19.3.6 Updating Time Stamps Automatically

    You can arrange to put a time stamp in a file, so that it is updated automatically each time you edit and save the file. The time stamp must be in the first eight lines of the file, and you should insert it like this:

    Time-stamp: <>

    or like this:

    Time-stamp: " "

    Then add the function time-stamp to the hook before-save-hook (see Hooks). When you save the file, this function then automatically updates the time stamp with the current date and time. You can also use the command M-x time-stamp to update the time stamp manually. By default the time stamp is formatted according to your locale setting (see Environment Variables) and time zone (see Time of Day in The Emacs Lisp Reference Manual). For customizations, see the Custom group time-stamp.

    19.4 Reverting a Buffer

    If you have made extensive changes to a file-visiting buffer and then change your mind, you can revert the changes and go back to the saved version of the file. To do this, type C-x x g. Since reverting unintentionally could lose a lot of work, Emacs asks for confirmation first if the buffer is modified.

    The revert-buffer command tries to position point in such a way that, if the file was edited only slightly, you will be at approximately the same part of the text as before. But if you have made major changes, point may end up in a totally different location.

    Reverting marks the buffer as not modified. However, it adds the reverted changes as a single modification to the buffer’s undo history (see Undo). Thus, after reverting, you can type C-/ or its aliases to bring the reverted changes back, if you happen to change your mind.

    To revert a buffer more conservatively, you can use the command revert-buffer-with-fine-grain. This command acts like revert-buffer, but it tries to be as non-destructive as possible, making an effort to preserve all markers, properties and overlays in the buffer. Since reverting this way can be very slow when you have made a large number of changes, you can modify the variable revert-buffer-with-fine-grain-max-seconds to specify a maximum amount of seconds that replacing the buffer contents this way should take. Note that it is not ensured that the whole execution of revert-buffer-with-fine-grain won’t take longer than this.

    Some kinds of buffers that are not associated with files, such as Dired buffers, can also be reverted. For them, reverting means recalculating their contents. Buffers created explicitly with C-x b cannot be reverted; revert-buffer reports an error if you try.

    When you edit a file that changes automatically and frequently—for example, a log of output from a process that continues to run—it may be useful for Emacs to revert the file without querying you. To request this behavior, set the variable revert-without-query to a list of regular expressions. When a file name matches one of these regular expressions, find-file and revert-buffer will revert it automatically if it has changed—provided the buffer itself is not modified. (If you have edited the text, it would be wrong to discard your changes.)

    The C-x x g keystroke is bound to the revert-buffer-quick command. This is like the revert-buffer command, but prompts less. Unlike revert-buffer, it will not prompt if the current buffer visits a file, and the buffer is not modified. It also respects the revert-buffer-quick-short-answers user option. If this option is non-nil, use a shorter y/n query instead of a longer yes/no query.

    You can also tell Emacs to revert buffers automatically when their visited files change on disk; see Auto Revert: Keeping buffers automatically up-to-date.

    19.5 Auto Revert: Keeping buffers automatically up-to-date

    A buffer can get out of sync with respect to its visited file on disk if that file is changed by another program. To keep it up to date, you can enable Auto Revert mode by typing M-x auto-revert-mode. This automatically reverts the buffer when its visited file changes on disk. To do the same for all file buffers, type M-x global-auto-revert-mode to enable Global Auto Revert mode.

    Auto Revert will not revert a buffer if it has unsaved changes, or if its file on disk is deleted or renamed.

    One use of Auto Revert mode is to “tail” a file such as a system log, so that changes made to that file by other programs are continuously displayed. To do this, just move the point to the end of the buffer, and it will stay there as the file contents change. However, if you are sure that the file will only change by growing at the end, use Auto Revert Tail mode instead (auto-revert-tail-mode). It is more efficient for this. Auto Revert Tail mode also works for remote files.

    When a buffer is auto-reverted, a message is generated. This can be suppressed by setting auto-revert-verbose to nil.

    The Auto Revert modes do not check or revert remote files, because that is usually too slow. This behavior can be changed by setting the variable auto-revert-remote-files to non-nil.

    By default, Auto Revert mode works using file notifications, whereby changes in the filesystem are reported to Emacs by the OS. You can disable use of file notifications by customizing the variable auto-revert-use-notify to a nil value, then Emacs will check for file changes by polling every five seconds. You can change the polling interval through the variable auto-revert-interval.

    Not all systems support file notifications; where they are not supported, auto-revert-use-notify will be nil by default.

    By default, Auto Revert mode will poll files for changes periodically even when file notifications are used. Polling is unnecessary in many cases, and turning it off may save power by relying on notifications only. To do so, set the variable auto-revert-avoid-polling to non-nil. However, notification is ineffective on certain file systems; mainly network file system on Unix-like machines, where files can be altered from other machines. For such file systems, polling may be necessary. To force polling when auto-revert-avoid-polling is non-nil, set auto-revert-notify-exclude-dir-regexp to match files that should be excluded from using notification.

    In Dired buffers (see Dired, the Directory Editor), Auto Revert mode refreshes the buffer when a file is created or deleted in the buffer’s directory.

    See Undoing Version Control Actions, for commands to revert to earlier versions of files under version control. See Version Control and the Mode Line, for Auto Revert peculiarities when visiting files under version control.

    19.5.1 Auto Reverting Non-File Buffers

    Global Auto Revert Mode normally only reverts file buffers. There are two ways to auto-revert certain non-file buffers: by enabling Auto Revert Mode in those buffers (using M-x auto-revert-mode); and by setting global-auto-revert-non-file-buffers to a non-nil value. The latter enables Auto Reverting for all types of buffers for which it is implemented (listed in the menu below).

    Like file buffers, non-file buffers should normally not revert while you are working on them, or while they contain information that might get lost after reverting. Therefore, they do not revert if they are modified. This can get tricky, because deciding when a non-file buffer should be marked modified is usually more difficult than for file buffers.

    Another tricky detail is that, for efficiency reasons, Auto Revert often does not try to detect all possible changes in the buffer, only changes that are major or easy to detect. Hence, enabling auto-reverting for a non-file buffer does not always guarantee that all information in the buffer is up-to-date, and does not necessarily make manual reverts useless.

    At the other extreme, certain buffers automatically revert every auto-revert-interval seconds. (This currently only applies to the Buffer Menu.) In this case, Auto Revert does not print any messages while reverting, even when auto-revert-verbose is non-nil.

    Some non-file buffers can be updated reliably by file notification on their default directory; Dired buffers is an example. The major mode can indicate this by setting buffer-auto-revert-by-notification to a non-nil value in that buffer, allowing Auto Revert to avoid periodic polling. Such notification does not include changes to files in that directory, only to the directory itself.

    The details depend on the particular types of buffers and are explained in the corresponding sections. Auto Reverting the Buffer Menu

    If auto-reverting of non-file buffers is enabled, the Buffer Menu (see Operating on Several Buffers) automatically reverts every auto-revert-interval seconds, whether there is a need for it or not. (It would probably take longer to check whether there is a need than to actually revert.)

    If the Buffer Menu inappropriately gets marked modified, just revert it manually using g and auto-reverting will resume. However, if you marked certain buffers to get deleted or to be displayed, you have to be careful, because reverting erases all marks. The fact that adding marks sets the buffer’s modified flag prevents Auto Revert from automatically erasing the marks. Auto Reverting Dired buffers

    Dired buffers only auto-revert when the file list of the buffer’s main directory changes (e.g., when a new file is added or deleted). They do not auto-revert when information about a particular file changes (e.g., when the size changes) or when inserted subdirectories change. To be sure that all listed information is up to date, you have to manually revert using g, even if auto-reverting is enabled in the Dired buffer. Sometimes, you might get the impression that modifying or saving files listed in the main directory actually does cause auto-reverting. This is because making changes to a file, or saving it, very often causes changes in the directory itself; for instance, through backup files or auto-save files. However, this is not guaranteed.

    If the Dired buffer is marked modified and there are no changes you want to protect, then most of the time you can make auto-reverting resume by manually reverting the buffer using g. There is one exception. If you flag or mark files, you can safely revert the buffer. This will not erase the flags or marks (unless the marked file has been deleted, of course). However, the buffer will stay modified, even after reverting, and auto-reverting will not resume. This is because, if you flag or mark files, you may be working on the buffer and you might not want the buffer to change without warning. If you want auto-reverting to resume in the presence of marks and flags, mark the buffer non-modified using M-~. However, adding, deleting or changing marks or flags will mark it modified again.

    Remote Dired buffers are currently not auto-reverted. Neither are Dired buffers for which you used shell wildcards or file arguments to list only some of the files. *Find* and *Locate* buffers do not auto-revert either.

    Note that auto-reverting Dired buffers may not work satisfactorily on some systems.

    19.6 Auto-Saving: Protection Against Disasters

    From time to time, Emacs automatically saves each visited file in a separate file, without altering the file you actually use. This is called auto-saving. It prevents you from losing more than a limited amount of work if the system crashes.

    When Emacs determines that it is time for auto-saving, it considers each buffer, and each is auto-saved if auto-saving is enabled for it and it has been changed since the last time it was auto-saved. When the auto-save-no-message variable is set to nil (the default), the message ‘Auto-saving...’ is displayed in the echo area during auto-saving, if any files are actually auto-saved; to disable these messages, customize the variable to a non-nil value. Errors occurring during auto-saving are caught so that they do not interfere with the execution of commands you have been typing.

    19.6.1 Auto-Save Files

    Auto-saving does not normally save in the files that you visited, because it can be very undesirable to save a change that you did not want to make permanent. Instead, auto-saving is done in a different file called the auto-save file, and the visited file is changed only when you request saving explicitly (such as with C-x C-s).

    Normally, the auto-save file name is made by appending ‘#’ to the front and rear of the visited file name. Thus, a buffer visiting file foo.c is auto-saved in a file #foo.c#. Most buffers that are not visiting files are auto-saved only if you request it explicitly; when they are auto-saved, the auto-save file name is made by appending ‘#’ to the front and rear of buffer name, then adding digits and letters at the end for uniqueness. For example, the *mail* buffer in which you compose messages to be sent might be auto-saved in a file named #*mail*#704juu. Auto-save file names are made this way unless you reprogram parts of Emacs to do something different (the functions make-auto-save-file-name and auto-save-file-name-p). The file name to be used for auto-saving in a buffer is calculated when auto-saving is turned on in that buffer.

    The variable auto-save-file-name-transforms allows a degree of control over the auto-save file name. It lets you specify a series of regular expressions and replacements to transform the auto save file name. The default value puts the auto-save files for remote files (see Remote Files) into the temporary file directory on the local machine.

    When you delete a substantial part of the text in a large buffer, auto save turns off temporarily in that buffer. This is because if you deleted the text unintentionally, you might find the auto-save file more useful if it contains the deleted text. To reenable auto-saving after this happens, save the buffer with C-x C-s, or use C-u 1 M-x auto-save-mode.

    If you want auto-saving to be done in the visited file rather than in a separate auto-save file, enable the global minor mode auto-save-visited-mode. In this mode, auto-saving is identical to explicit saving. Note that this mode is orthogonal to the auto-save mode described above; you can enable both at the same time. However, if auto-save mode is active in some buffer and the obsolete auto-save-visited-file-name variable is set to a non-nil value, that buffer won’t be affected by auto-save-visited-mode.

    You can use the variable auto-save-visited-interval to customize the interval between auto-save operations in auto-save-visited-mode; by default it’s five seconds. auto-save-interval and auto-save-timeout have no effect on auto-save-visited-mode. See Controlling Auto-Saving, for details on these variables.

    A buffer’s auto-save file is deleted when you save the buffer in its visited file. (You can inhibit this by setting the variable delete-auto-save-files to nil.) Changing the visited file name with C-x C-w or set-visited-file-name renames any auto-save file to go with the new visited name.

    Killing a buffer, by default, doesn’t remove the buffer’s auto-save file. If kill-buffer-delete-auto-save-files is non-nil, killing a buffer that has an auto-save file will make Emacs prompt the user for whether the auto-save file should be deleted. (This is inhibited if delete-auto-save-files is nil.)

    19.6.2 Controlling Auto-Saving

    Each time you visit a file, auto-saving is turned on for that file’s buffer if the variable auto-save-default is non-nil (but not in batch mode; see Initial Options). The default for this variable is t, so auto-saving is the usual practice for file-visiting buffers. To toggle auto-saving in the current buffer, type M-x auto-save-mode. Auto Save mode acts as a buffer-local minor mode (see Minor Modes).

    Emacs auto-saves periodically based on how many characters you have typed since the last auto-save. The variable auto-save-interval specifies how many characters there are between auto-saves. By default, it is 300. Emacs doesn’t accept values that are too small: if you customize auto-save-interval to a value less than 20, Emacs will behave as if the value is 20.

    Auto-saving also takes place when you stop typing for a while. By default, it does this after 30 seconds of idleness (at this time, Emacs may also perform garbage collection; see Garbage Collection in The Emacs Lisp Reference Manual). To change this interval, customize the variable auto-save-timeout. The actual time period is longer if the current buffer is long; this is a heuristic which aims to keep out of your way when you are editing long buffers, in which auto-save takes an appreciable amount of time. Auto-saving during idle periods accomplishes two things: first, it makes sure all your work is saved if you go away from the terminal for a while; second, it may avoid some auto-saving while you are actually typing.

    When auto-save-visited-mode is enabled, Emacs will auto-save file-visiting buffers after five seconds of idle time. You can customize the variable auto-save-visited-interval to change the idle time interval.

    Emacs also does auto-saving whenever it gets a fatal error. This includes killing the Emacs job with a shell command such as ‘kill %emacs’, or disconnecting a phone line or network connection.

    You can perform an auto-save explicitly with the command M-x do-auto-save.

    19.6.3 Recovering Data from Auto-Saves

    You can use the contents of an auto-save file to recover from a loss of data with the command M-x recover-file RET file RET. This visits file and then (after your confirmation) restores the contents from its auto-save file #file#. You can then save with C-x C-s to put the recovered text into file itself. For example, to recover file foo.c from its auto-save file #foo.c#, do:

    M-x recover-file RET foo.c RET
    yes RET
    C-x C-s

    Before asking for confirmation, M-x recover-file displays a directory listing describing the specified file and the auto-save file, so you can compare their sizes and dates. If the auto-save file is older, M-x recover-file does not offer to read it.

    If Emacs or the computer crashes, you can recover all the files you were editing from their auto save files with the command M-x recover-session. This first shows you a list of recorded interrupted sessions. Move point to the one you choose, and type C-c C-c.

    Then recover-session asks about each of the files that were being edited during that session, asking whether to recover that file. If you answer y, it calls recover-file, which works in its normal fashion. It shows the dates of the original file and its auto-save file, and asks once again whether to recover that file.

    When recover-session is done, the files you’ve chosen to recover are present in Emacs buffers. You should then save them. Only this—saving them—updates the files themselves.

    Emacs records information about interrupted sessions in files named .saves-pid-hostname~ in the directory ~/.emacs.d/auto-save-list/. This directory is determined by the variable auto-save-list-file-prefix. If you set auto-save-list-file-prefix to nil, sessions are not recorded for recovery.

    19.7 File Name Aliases

    Symbolic links and hard links both make it possible for several file names to refer to the same file. Hard links are alternate names that refer directly to the file; all the names are equally valid, and no one of them is preferred. By contrast, a symbolic link is a kind of defined alias: when foo is a symbolic link to bar, you can use either name to refer to the file, but bar is the real name, while foo is just an alias. More complex cases occur when symbolic links point to directories.

    Normally, if you visit a file which Emacs is already visiting under a different name, Emacs displays a message in the echo area and uses the existing buffer visiting that file. This can happen on systems that support hard or symbolic links, or if you use a long file name on a system that truncates long file names, or on a case-insensitive file system. You can suppress the message by setting the variable find-file-suppress-same-file-warnings to a non-nil value. You can disable this feature entirely by setting the variable find-file-existing-other-name to nil: then if you visit the same file under two different names, you get a separate buffer for each file name.

    If the variable find-file-visit-truename is non-nil, then the file name recorded for a buffer is the file’s truename (made by replacing all symbolic links with their target names), rather than the name you specify. Setting find-file-visit-truename also implies the effect of find-file-existing-other-name.

    Sometimes, a directory is ordinarily accessed through a symbolic link, and you may want Emacs to preferentially show its linked name. To do this, customize directory-abbrev-alist. Each element in this list should have the form (from . to), which means to replace from with to whenever from appears in a directory name. The from string is a regular expression (see Syntax of Regular Expressions). It is matched against directory names anchored at the first character, and should start with ‘\`’ (to support directory names with embedded newlines, which would defeat ‘^’). The to string should be an ordinary absolute directory name pointing to the same directory. Do not use ‘~’ to stand for a home directory in the to string; Emacs performs these substitutions separately. Here’s an example, from a system on which /home/fsf is normally accessed through a symbolic link named /fsf:

    (("\\`/home/fsf" . "/fsf"))

    19.8 File Directories

    The file system groups files into directories. A directory listing is a list of all the files in a directory. Emacs provides commands to create and delete directories, and to make directory listings in brief format (file names only) and verbose format (sizes, dates, and other attributes included). Emacs also includes a directory browser feature called Dired, which you can invoke with C-x d; see Dired, the Directory Editor.

    C-x C-d dir-or-pattern RET

    Display a brief directory listing (list-directory).

    C-u C-x C-d dir-or-pattern RET

    Display a verbose directory listing.

    M-x make-directory RET dirname RET

    Create a new directory named dirname.

    M-x delete-directory RET dirname RET

    Delete the directory named dirname. If it isn’t empty, you will be asked whether you want to delete it recursively.

    The command to display a directory listing is C-x C-d (list-directory). It reads using the minibuffer a file name which is either a directory to be listed or a wildcard-containing pattern for the files to be listed. For example,

    C-x C-d /u2/emacs/etc RET

    lists all the files in directory /u2/emacs/etc. Here is an example of specifying a file name pattern:

    C-x C-d /u2/emacs/src/*.c RET

    Normally, C-x C-d displays a brief directory listing containing just file names. A numeric argument (regardless of value) tells it to make a verbose listing including sizes, dates, and owners (like ‘ls -l’).

    The text of a directory listing is mostly obtained by running ls in an inferior process. Two Emacs variables control the switches passed to ls: list-directory-brief-switches is a string giving the switches to use in brief listings ("-CF" by default), and list-directory-verbose-switches is a string giving the switches to use in a verbose listing ("-l" by default).

    In verbose directory listings, Emacs adds information about the amount of free space on the disk that contains the directory.

    The command M-x delete-directory prompts for a directory’s name using the minibuffer, and deletes the directory if it is empty. If the directory is not empty, you will be asked whether you want to delete it recursively. On systems that have a “Trash” (or “Recycle Bin”) feature, you can make this command move the specified directory to the Trash instead of deleting it outright, by changing the variable delete-by-moving-to-trash to t. See Miscellaneous File Operations, for more information about using the Trash.

    Next: , Previous: , Up: File Handling   [Contents][Index]

    19.9 Comparing Files

    The command M-x diff prompts for two file names, using the minibuffer, and displays the differences between the two files in a buffer named *diff*. This works by running the diff program, using options taken from the variable diff-switches. The value of diff-switches should be a string; the default is "-u" to specify a unified context diff. See Diff in Comparing and Merging Files, for more information about the diff program.

    The output of the diff command is shown using a major mode called Diff mode. See Diff Mode.

    A (much more sophisticated) alternative is M-x ediff (see Ediff in The Ediff Manual).

    The command M-x diff-backup compares a specified file with its most recent backup. If you specify the name of a backup file, diff-backup compares it with the source file that it is a backup of. In all other respects, this behaves like M-x diff.

    The command M-x diff-buffer-with-file compares a specified buffer with its corresponding file. This shows you what changes you would make to the file if you save the buffer.

    The command M-x diff-buffers compares the contents of two specified buffers.

    The command M-x compare-windows compares the text in the current window with that in the window that was the selected window before you selected the current one. (For more information about windows in Emacs, see Multiple Windows.) Comparison starts at point in each window, after pushing each initial point value on the mark ring (see The Mark Ring) in its respective buffer. Then it moves point forward in each window, one character at a time, until it reaches characters that don’t match. Then the command exits.

    If point in the two windows is followed by non-matching text when the command starts, M-x compare-windows tries heuristically to advance up to matching text in the two windows, and then exits. So if you use M-x compare-windows repeatedly (see Repeating a Command), each time it either skips one matching range or finds the start of another.

    With a numeric argument, compare-windows ignores changes in whitespace. If the variable compare-ignore-case is non-nil, the comparison ignores differences in case as well. If the variable compare-ignore-whitespace is non-nil, compare-windows by default ignores changes in whitespace, but a prefix argument turns that off for that single invocation of the command.

    You can use M-x smerge-mode to turn on Smerge mode, a minor mode for editing output from the diff3 program. This is typically the result of a failed merge from a version control system update outside VC, due to conflicting changes to a file. Smerge mode provides commands to resolve conflicts by selecting specific changes.

    See Merging Files with Emerge, for the Emerge facility, which provides a powerful interface for merging files.

    19.10 Diff Mode

    Diff mode is a major mode used for the output of M-x diff and other similar commands. This kind of output is called a patch, because it can be passed to the patch command to automatically apply the specified changes. To select Diff mode manually, type M-x diff-mode.

    The changes specified in a patch are grouped into hunks, which are contiguous chunks of text that contain one or more changed lines. Hunks usually also include unchanged lines to provide context for the changes. Each hunk is preceded by a hunk header, which specifies the old and new line numbers where the hunk’s changes occur. Diff mode highlights each hunk header, to distinguish it from the actual contents of the hunk.

    The first hunk in a patch is preceded by a file header, which shows the names of the new and the old versions of the file, and their time stamps. If a patch shows changes for more than one file, each file has such a header before the first hunk of that file’s changes.

    You can edit a Diff mode buffer like any other buffer. (If it is read-only, you need to make it writable first; see Miscellaneous Buffer Operations.) Whenever you edit a hunk, Diff mode attempts to automatically correct the line numbers in the hunk headers, to ensure that the patch remains correct, and could still be applied by patch. To disable automatic line number correction, change the variable diff-update-on-the-fly to nil.

    Diff mode arranges for hunks to be treated as compiler error messages by M-g M-n and other commands that handle error messages (see Compilation Mode). Thus, you can use the compilation-mode commands to visit the corresponding source locations.

    In addition, Diff mode provides the following commands to navigate, manipulate and apply parts of patches:


    Move to the next hunk-start (diff-hunk-next). With prefix argument n, move forward to the nth next hunk.

    By default, Diff mode refines hunks as Emacs displays them, highlighting their changes with better granularity. Alternatively, if you set diff-refine to the symbol navigation, Diff mode only refines the hunk you move to with this command or with diff-hunk-prev.


    Move to the previous hunk-start (diff-hunk-prev). With prefix argument n, move back to the nth previous hunk. Like M-n, this command refines the hunk you move to if you set diff-refine to the symbol navigation.


    Move to the next file-start, in a multi-file patch (diff-file-next). With prefix argument n, move forward to the start of the nth next file.


    Move to the previous file-start, in a multi-file patch (diff-file-prev). With prefix argument n, move back to the start of the nth previous file.


    Kill the hunk at point (diff-hunk-kill).


    In a multi-file patch, kill the current file part. (diff-file-kill).

    C-c C-a

    Apply this hunk to its target file (diff-apply-hunk). With a prefix argument of C-u, revert this hunk, i.e. apply the reverse of the hunk, which changes the “new” version into the “old” version. If diff-jump-to-old-file is non-nil, apply the hunk to the “old” version of the file instead.

    C-c C-b

    Highlight the changes of the hunk at point with a finer granularity (diff-refine-hunk). This allows you to see exactly which parts of each changed line were actually changed.

    By default, Diff mode refines hunks as Emacs displays them, so you may find this command useful if you customize diff-refine to a non-default value.

    C-c C-c

    Go to the source file and line corresponding to this hunk (diff-goto-source). By default, this jumps to the “new” version of the file, the one shown first on the file header. With a prefix argument, jump to the “old” version instead. If diff-jump-to-old-file is non-nil, this command by default jumps to the “old” file, and the meaning of the prefix argument is reversed. If the prefix argument is a number greater than 8 (e.g., if you type C-u C-u C-c C-c), then this command also sets diff-jump-to-old-file for the next invocation. If the source file is under version control (see Version Control), this jumps to the work file by default. With a prefix argument, jump to the “old” revision of the file (see Examining And Comparing Old Revisions), when point is on the old line, or otherwise jump to the “new” revision.

    C-c C-e

    Start an Ediff session with the patch (diff-ediff-patch). See Ediff in The Ediff Manual.

    C-c C-n

    Restrict the view to the current hunk (diff-restrict-view). See Narrowing. With a prefix argument, restrict the view to the current file of a multiple-file patch. To widen again, use C-x n w (widen).

    C-c C-r

    Reverse the direction of comparison for the entire buffer (diff-reverse-direction). With a prefix argument, reverse the direction only inside the current region (see The Mark and the Region). Reversing the direction means changing the hunks and the file-start headers to produce a patch that would change the “new” version into the “old” one.

    C-c C-s

    Split the hunk at point (diff-split-hunk) into two separate hunks. This inserts a hunk header and modifies the header of the current hunk. This command is useful for manually editing patches, and only works with the unified diff format produced by the -u or --unified options to the diff program. If you need to split a hunk in the context diff format produced by the -c or --context options to diff, first convert the buffer to the unified diff format with C-c C-u.

    C-c C-d

    Convert the entire buffer to the context diff format (diff-unified->context). With a prefix argument, convert only the hunks within the region.

    C-c C-u

    Convert the entire buffer to unified diff format (diff-context->unified). With a prefix argument, convert unified format to context format. When the mark is active, convert only the hunks within the region.

    C-c C-l

    Re-generate the current hunk (diff-refresh-hunk).

    C-c C-w

    Re-generate the current hunk, disregarding changes in whitespace (diff-ignore-whitespace-hunk).

    C-x 4 A

    Generate a ChangeLog entry, like C-x 4 a does (see Change Logs), for each one of the hunks (diff-add-change-log-entries-other-window). This creates a skeleton of the log of changes that you can later fill with the actual descriptions of the changes. C-x 4 a itself in Diff mode operates on behalf of the current hunk’s file, but gets the function name from the patch itself. This is useful for making log entries for functions that are deleted by the patch.

    Patches sometimes include trailing whitespace on modified lines, as an unintentional and undesired change. There are two ways to deal with this problem. Firstly, if you enable Whitespace mode in a Diff buffer (see Useless Whitespace), it automatically highlights trailing whitespace in modified lines. Secondly, you can use the command M-x diff-delete-trailing-whitespace, which searches for trailing whitespace in the lines modified by the patch, and removes that whitespace in both the patch and the patched source file(s). This command does not save the modifications that it makes, so you can decide whether to save the changes (the list of modified files is displayed in the echo area). With a prefix argument, it tries to modify the original (“old”) source files rather than the patched (“new”) source files.

    If diff-font-lock-syntax is non-nil, fragments of source in hunks are highlighted according to the appropriate major mode.

    19.11 Copying, Naming and Renaming Files

    Emacs has several commands for copying, naming, and renaming files. All of them read two file names, old (or target) and new, using the minibuffer, and then copy or adjust a file’s name accordingly; they do not accept wildcard file names.

    In all these commands, if the argument new is just a directory name (see Directory Names in the Emacs Lisp Reference Manual), the real new name is in that directory, with the same non-directory component as old. For example, the command M-x rename-file RET ~/foo RET /tmp/ RET renames ~/foo to /tmp/foo. On GNU and other POSIX-like systems, directory names end in ‘/’.

    All these commands ask for confirmation when the new file name already exists.

    M-x copy-file copies the contents of the file old to the file new.

    M-x copy-directory copies directories, similar to the cp -r shell command. If new is a directory name, it creates a copy of the old directory and puts it in new. Otherwise it copies all the contents of old into a new directory named new. If copy-directory-create-symlink is non-nil and old is a symbolic link, this command will copy the symbolic link. If nil, this command will follow the link and copy the contents instead. (This is the default.)

    M-x rename-file renames file old as new. If the file name new already exists, you must confirm with yes or renaming is not done; this is because renaming causes the old meaning of the name new to be lost. If old and new are on different file systems, the file old is copied and deleted.

    If a file is under version control (see Version Control), you should rename it using M-x vc-rename-file instead of M-x rename-file. See Deleting and Renaming Version-Controlled Files.

    M-x add-name-to-file adds an additional name to an existing file without removing the old name. The new name is created as a hard link to the existing file. The new name must belong on the same file system that the file is on. On MS-Windows, this command works only if the file resides in an NTFS file system. On MS-DOS, and some remote system types, it works by copying the file.

    M-x make-symbolic-link creates a symbolic link named new, which points at target. The effect is that future attempts to open file new will refer to whatever file is named target at the time the opening is done, or will get an error if the name target is nonexistent at that time. This command does not expand the argument target, so that it allows you to specify a relative name as the target of the link. However, this command does expand leading ‘~’ in target so that you can easily specify home directories, and strips leading ‘/:’ so that you can specify relative names beginning with literal ‘~’ or ‘/:’. See Quoted File Names. On MS-Windows, this command works only on MS Windows Vista and later. When new is remote, it works depending on the system type.

    19.12 Miscellaneous File Operations

    Emacs has commands for performing many other operations on files. All operate on one file; they do not accept wildcard file names.

    M-x delete-file prompts for a file and deletes it. If you are deleting many files in one directory, it may be more convenient to use Dired rather than delete-file. See Deleting Files with Dired.

    M-x move-file-to-trash moves a file into the system Trash (or Recycle Bin). This is a facility available on most operating systems; files that are moved into the Trash can be brought back later if you change your mind. (The way to restore trashed files is system-dependent.)

    By default, Emacs deletion commands do not use the Trash. To use the Trash (when it is available) for common deletion commands, change the variable delete-by-moving-to-trash to t. This affects the commands M-x delete-file and M-x delete-directory (see File Directories), as well as the deletion commands in Dired (see Deleting Files with Dired). Supplying a prefix argument to M-x delete-file or M-x delete-directory makes them delete outright, instead of using the Trash, regardless of delete-by-moving-to-trash.

    If you have delete-by-moving-to-trash set, and you want to delete files manually in Emacs from the Trash directory, using commands like D (dired-do-delete) doesn’t work well in the Trash directory (it’ll just give the file a new name, but won’t delete anything). If you want to be able to do this, you should create a .dir-locals.el file containing something like the following in the Trash directory:

    ((dired-mode . ((delete-by-moving-to-trash . nil))))

    Note, however, if you use the system “empty trash” command, it’s liable to also delete this .dir-locals.el file, so this should only be done if you delete files from the Trash directory manually.

    If a file is under version control (see Version Control), you should delete it using M-x vc-delete-file instead of M-x delete-file. See Deleting and Renaming Version-Controlled Files.

    M-x insert-file (also C-x i) inserts a copy of the contents of the specified file into the current buffer at point, leaving point unchanged before the contents. The position after the inserted contents is added to the mark ring, without activating the mark (see The Mark Ring).

    M-x insert-file-literally is like M-x insert-file, except the file is inserted literally: it is treated as a sequence of ASCII characters with no special encoding or conversion, similar to the M-x find-file-literally command (see Visiting Files).

    M-x write-region is the inverse of M-x insert-file; it copies the contents of the region into the specified file. M-x append-to-file adds the text of the region to the end of the specified file. See Accumulating Text. The variable write-region-inhibit-fsync applies to these commands, as well as saving files; see Customizing Saving of Files.

    M-x set-file-modes reads a file name followed by a file mode, and applies that file mode to the specified file. File modes, also called file permissions, determine whether a file can be read, written to, or executed, and by whom. This command reads file modes using the same symbolic or octal format accepted by the chmod command; for instance, ‘u+x’ means to add execution permission for the user who owns the file. It has no effect on operating systems that do not support file modes. chmod is a convenience alias for this function.

    19.13 Accessing Compressed Files

    Emacs automatically uncompresses compressed files when you visit them, and automatically recompresses them if you alter them and save them. Emacs recognizes compressed files by their file names. File names ending in ‘.gz’ indicate a file compressed with gzip. Other endings indicate other compression programs.

    Automatic uncompression and compression apply to all the operations in which Emacs uses the contents of a file. This includes visiting it, saving it, inserting its contents into a buffer, loading it, and byte compiling it.

    To disable this feature, type the command M-x auto-compression-mode. You can disable it permanently by customizing the variable auto-compression-mode.

    19.14 File Archives

    A file whose name ends in ‘.tar’ is normally an archive made by the tar program. Emacs views these files in a special mode called Tar mode which provides a Dired-like list of the contents (see Dired, the Directory Editor). You can move around through the list just as you would in Dired, and visit the subfiles contained in the archive. However, not all Dired commands are available in Tar mode.

    If Auto Compression mode is enabled (see Accessing Compressed Files), then Tar mode is used also for compressed archives—files with extensions ‘.tgz’, .tar.Z and .tar.gz.

    The keys e, f and RET all extract a component file into its own buffer. You can edit it there, and if you save the buffer, the edited version will replace the version in the Tar buffer. Clicking with the mouse on the file name in the Tar buffer does likewise. v extracts a file into a buffer in View mode (see View Mode). o extracts the file and displays it in another window, so you could edit the file and operate on the archive simultaneously.

    The I key adds a new (regular) file to the archive. The file is initially empty, but can readily be edited using the commands above. The command inserts the new file before the current one, so that using it on the topmost line of the Tar buffer makes the new file the first one in the archive, and using it at the end of the buffer makes it the last one.

    d marks a file for deletion when you later use x, and u unmarks a file, as in Dired. C copies a file from the archive to disk and R renames a file within the archive. g reverts the buffer from the archive on disk. The keys M, G, and O change the file’s permission bits, group, and owner, respectively.

    Saving the Tar buffer writes a new version of the archive to disk with the changes you made to the components.

    You don’t need the tar program to use Tar mode—Emacs reads the archives directly. However, accessing compressed archives requires the appropriate uncompression program.

    A separate but similar Archive mode is used for arc, jar, lzh, zip, rar, 7z, and zoo archives, as well as exe files that are self-extracting executables.

    The key bindings of Archive mode are similar to those in Tar mode, with the addition of the m key which marks a file for subsequent operations, and M-DEL which unmarks all the marked files. Also, the a key toggles the display of detailed file information, for those archive types where it won’t fit in a single line. Operations such as renaming a subfile, or changing its mode or owner, are supported only for some of the archive formats.

    Unlike Tar mode, Archive mode runs the archiving programs to unpack and repack archives. However, you don’t need these programs to look at the archive table of contents, only to extract or manipulate the subfiles in the archive. Details of the program names and their options can be set in the ‘Archive’ Customize group (see Customization Groups).

    19.15 Remote Files

    You can refer to files on other machines using a special file name syntax:


    To carry out this request, Emacs uses a remote-login program such as ssh. You must always specify in the file name which method to use—for example, /ssh:user@host:filename uses ssh. When you specify the pseudo method ‘-’ in the file name, Emacs chooses the method as follows:

    1. If the host name starts with ‘ftp.’ (with dot), Emacs uses FTP.
    2. If the user name is ‘ftp’ or ‘anonymous’, Emacs uses FTP.
    3. If the variable tramp-default-method is set to ‘ftp’, Emacs uses FTP.
    4. If ssh-agent is running, Emacs uses scp.
    5. Otherwise, Emacs uses ssh.

    You can entirely turn off the remote file name feature by setting the variable tramp-mode to nil. You can turn off the feature in individual cases by quoting the file name with ‘/:’ (see Quoted File Names).

    Remote file access through FTP is handled by the Ange-FTP package, which is documented in the following. Remote file access through the other methods is handled by the Tramp package, which has its own manual. See The Tramp Manual in The Tramp Manual.

    When the Ange-FTP package is used, Emacs logs in through FTP using the name user, if that is specified in the remote file name. If user is unspecified, Emacs logs in using your user name on the local system; but if you set the variable ange-ftp-default-user to a string, that string is used instead. When logging in, Emacs may also ask for a password.

    For performance reasons, Emacs does not make backup files for files accessed via FTP by default. To make it do so, change the variable ange-ftp-make-backup-files to a non-nil value.

    By default, auto-save files for remote files are made in the temporary file directory on the local machine, as specified by the variable auto-save-file-name-transforms. See Auto-Save Files.

    To visit files accessible by anonymous FTP, you use special user names ‘anonymous’ or ‘ftp’. Passwords for these user names are handled specially. The variable ange-ftp-generate-anonymous-password controls what happens: if the value of this variable is a string, then that string is used as the password; if non-nil (the default), then the value of user-mail-address is used; if nil, then Emacs prompts you for a password as usual (see Entering passwords).

    Sometimes you may be unable to access files on a remote machine because a firewall in between blocks the connection for security reasons. If you can log in on a gateway machine from which the target files are accessible, and whose FTP server supports gatewaying features, you can still use remote file names; all you have to do is specify the name of the gateway machine by setting the variable ange-ftp-gateway-host, and set ange-ftp-smart-gateway to t. Otherwise you may be able to make remote file names work, but the procedure is complex. You can read the instructions by typing M-x finder-commentary RET ange-ftp RET.

    19.16 Quoted File Names

    You can quote an absolute file name to prevent special characters and syntax in it from having their special effects. The way to do this is to add ‘/:’ at the beginning.

    For example, you can quote a local file name which appears remote, to prevent it from being treated as a remote file name. Thus, if you have a directory named /foo: and a file named bar in it, you can refer to that file in Emacs as ‘/:/foo:/bar’.

    If you want to quote only special characters in the local part of a remote file name, you can quote just the local part. ‘/ssh:baz:/:/foo:/bar’ refers to the file bar of directory /foo: on the host baz.

    /:’ can also prevent ‘~’ from being treated as a special character for a user’s home directory. For example, /:/tmp/~hack refers to a file whose name is ~hack in directory /tmp.

    Quoting with ‘/:’ is also a way to enter in the minibuffer a file name that contains ‘$’. In order for this to work, the ‘/:’ must be at the beginning of the minibuffer contents. (You can also double each ‘$’; see File Names with $.)

    You can also quote wildcard characters with ‘/:’, for visiting. For example, /:/tmp/foo*bar visits the file /tmp/foo*bar.

    Another method of getting the same result is to enter /tmp/foo[*]bar, which is a wildcard specification that matches only /tmp/foo*bar. However, in many cases there is no need to quote the wildcard characters because even unquoted they give the right result. For example, if the only file name in /tmp that starts with ‘foo’ and ends with ‘bar’ is foo*bar, then specifying /tmp/foo*bar will visit only /tmp/foo*bar.

    19.17 File Name Cache

    You can use the file name cache to make it easy to locate a file by name, without having to remember exactly where it is located. When typing a file name in the minibuffer, C-TAB (file-cache-minibuffer-complete) completes it using the file name cache. If you repeat C-TAB, that cycles through the possible completions of what you had originally typed. (However, note that the C-TAB character cannot be typed on most text terminals.)

    The file name cache does not fill up automatically. Instead, you load file names into the cache using these commands:

    M-x file-cache-add-directory RET directory RET

    Add each file name in directory to the file name cache.

    M-x file-cache-add-directory-using-find RET directory RET

    Add each file name in directory and all of its nested subdirectories to the file name cache.

    M-x file-cache-add-directory-using-locate RET directory RET

    Add each file name in directory and all of its nested subdirectories to the file name cache, using locate to find them all.

    M-x file-cache-add-directory-list RET variable RET

    Add each file name in each directory listed in variable to the file name cache. variable should be a Lisp variable whose value is a list of directories, like load-path.

    M-x file-cache-clear-cache RET

    Clear the cache; that is, remove all file names from it.

    The file name cache is not persistent: it is kept and maintained only for the duration of the Emacs session. You can view the contents of the cache with the file-cache-display command.

    19.18 Convenience Features for Finding Files

    In this section, we introduce some convenient facilities for finding recently-opened files, reading file names from a buffer.

    If you enable Recentf mode, with M-x recentf-mode, Emacs maintains a list of recently opened files. To open a file from this list, use the M-x recentf-open command. When this mode is enabled, the ‘File’ menu will include a submenu that you can use to visit one of these files. M-x recentf-save-list saves the current recentf-list to a file, and M-x recentf-edit-list edits it.

    The M-x ffap command generalizes find-file with more powerful heuristic defaults (see Finding Files and URLs at Point), often based on the text at point. Partial Completion mode offers other features extending find-file, which can be used with ffap. See Completion Options.

    19.19 Viewing Image Files

    Visiting image files automatically selects Image mode. In this major mode, you can type C-c C-c (image-toggle-display) to toggle between displaying the file as an image in the Emacs buffer, and displaying its underlying text (or raw byte) representation. Additionally you can type C-c C-x (image-toggle-hex-display) to toggle between displaying the file as an image in the Emacs buffer, and displaying it in hex representation. Displaying the file as an image works only if Emacs is compiled with support for displaying such images.

    If the displayed image is wider or taller than the window in which it is displayed, the usual point motion keys (C-f, C-p, and so forth) cause different parts of the image to be displayed. However, by default images are resized automatically to fit the window, so this is only necessary if you customize the default behavior by using the options image-auto-resize and image-auto-resize-on-window-resize.

    To resize the image manually you can use the command image-transform-fit-to-window bound to s w that fits the image to both the window height and width. To scale the image to a percentage of its original size, use the command image-transform-set-percent bound to s p. To scale the image specifying a scale factor, use the command image-transform-set-scale bound to s s. To reset all transformations to the initial state, use image-transform-reset-to-initial bound to s 0, or image-transform-reset-to-original bound to s o.

    You can press n (image-next-file) and p (image-previous-file) to visit the next image file and the previous image file in the same directory, respectively. These commands will consult the “parent” dired buffer to determine what the next/previous image file is. These commands also work when opening a file from archive files (like zip or tar files), and will then instead consult the archive mode buffer. If neither an archive nor a dired “parent” buffer can be found, a dired buffer is opened.

    When looking through images, it’s sometimes convenient to be able to mark the files for later processing (for instance, if you want to select a group of images to copy somewhere else). The m (image-mode-mark-file) command will mark the current file in any Dired buffer(s) that display the current file’s directory. If no such buffer is open, the directory is opened in a new buffer. To unmark files, use the u (image-mode-mark-file) command. Finally, if you just want to copy the current buffers file name to the kill ring, you can use the w (image-mode-copy-file-name-as-kill) command.

    If the image can be animated, the command RET (image-toggle-animation) starts or stops the animation. Animation plays once, unless the option image-animate-loop is non-nil. With f (image-next-frame) and b (image-previous-frame) you can step through the individual frames. Both commands accept a numeric prefix to step through several frames at once. You can go to a specific frame with F (image-goto-frame). Frames are indexed from 1. Typing a + (image-increase-speed) increases the speed of the animation, a - (image-decrease-speed) decreases it, and a r (image-reverse-speed) reverses it. The command a 0 (image-reset-speed) resets the speed to the original value.

    In addition to the above key bindings, which are specific to Image mode, images shown in any Emacs buffer have special key bindings when point is at or inside the image:

    i +

    Increase the image size (image-increase-size) by 20%. Prefix numeric argument controls the increment; the value of n means to multiply the size by the factor of 1 + n / 10, so C-u 5 i + means to increase the size by 50%.

    i -

    Decrease the image size (image-decrease-size) by 20%. Prefix numeric argument controls the decrement; the value of n means to multiply the size by the factor of - n / 10, so C-u 3 i - means to decrease the size by 30%.

    i r

    Rotate the image by 90 degrees clockwise (image-rotate). With the prefix argument, rotate by 90 degrees counter-clockwise instead. Note that this command is not available for sliced images.

    i h

    Flip the image horizontally (image-flip-horizontally). This presents the image as if reflected in a vertical mirror. Note that this command is not available for sliced images.

    i v

    Flip the image vertically (image-flip-vertically). This presents the image as if reflected in a horizontal mirror. Note that this command is not available for sliced images.

    i o

    Save the image to a file (image-save). This command prompts you for the name of the file to save the image.

    i c

    Crop the image (image-crop). This command is available only if your system has an external program installed that can be used for cropping and cutting of images; the user option image-crop-crop-command determines what program to use, and defaults to the ImageMagick’s convert program. The command displays the image with a rectangular frame superimposed on it, and lets you use the mouse to move and resize the frame. Type m to cause mouse movements to move the frame instead of resizing it; type s to move a square frame instead. When you are satisfied with the position and size of the cropping frame, type RET to actually crop the part under the frame; or type q to exit without cropping. You can then save the cropped image using i o or M-x image-save.

    i x

    Cut a rectangle from the image (image-cut). This works the same as image-crop (and also requires an external program, defined by the variable image-crop-cut-command, to perform the image cut), but instead of cropping the image, it removes the part inside the frame and fills that part with the color specified by image-cut-color. With prefix argument, the command prompts for the color to use.

    The size and rotation commands are “repeating”, which means that you can continue adjusting the image without using the i prefix.

    If Emacs was compiled with support for the ImageMagick library, it can use ImageMagick to render a wide variety of images. The variable imagemagick-enabled-types lists the image types that Emacs may render using ImageMagick; each element in the list should be an internal ImageMagick name for an image type, as a symbol or an equivalent string (e.g., BMP for .bmp images). To enable ImageMagick for all possible image types, change imagemagick-enabled-types to t. The variable imagemagick-types-inhibit lists the image types which should never be rendered using ImageMagick, regardless of the value of imagemagick-enabled-types (the default list includes types like C and HTML, which ImageMagick can render as an image but Emacs should not). To disable ImageMagick entirely, change imagemagick-types-inhibit to t.

    If Emacs doesn’t have native support for the image format in question, and image-use-external-converter is non-nil, Emacs will try to determine whether there are external utilities that can be used to transform the image in question to PNG before displaying. GraphicsMagick, ImageMagick and ffmpeg are currently supported for image conversions.

    In addition, you may wish to add special handlers for certain image formats. These can be added with the image-converter-add-handler function. For instance, to allow viewing Krita files as simple images, you could say something like:

     (lambda (file data-p)
       (if data-p
           (error "Can't decode non-files")
         (call-process "unzip" nil t nil
                       "-qq" "-c" "-x" file "mergedimage.png"))))

    The function takes two parameters, where the first is a file name suffix, and the second is a function to do the “conversion”. This function takes two parameters, where the first is the file name or a string with the data, and the second says whether the first parameter is data or not, and should output an image in image-convert-to-format format in the current buffer.

    The Image-Dired package can also be used to view images as thumbnails. See Viewing Image Thumbnails in Dired.

    19.20 Filesets

    If you regularly edit a certain group of files, you can define them as a fileset. This lets you perform certain operations, such as visiting, query-replace, and shell commands on all the files at once. To make use of filesets, you must first add the expression (filesets-init) to your init file (see The Emacs Initialization File). This adds a ‘Filesets’ sub-menu to the menu bar’s ‘File’ menu.

    The simplest way to define a fileset is by adding files to it one at a time. To add a file to fileset name, visit the file and type M-x filesets-add-buffer RET name RET. If there is no fileset name, this creates a new one, which initially contains only the current file. The command M-x filesets-remove-buffer removes the current file from a fileset.

    You can also edit the list of filesets directly, with M-x filesets-edit (or by choosing ‘Edit Filesets’ from the ‘Filesets’ menu). The editing is performed in a Customize buffer (see Easy Customization Interface). Normally, a fileset is a simple list of files, but you can also define a fileset as a regular expression matching file names. Some examples of these more complicated filesets are shown in the Customize buffer. Remember to select ‘Save for future sessions’ if you want to use the same filesets in future Emacs sessions.

    You can use the command M-x filesets-open to visit all the files in a fileset, and M-x filesets-close to close them. Use M-x filesets-run-cmd to run a shell command on all the files in a fileset. These commands are also available from the ‘Filesets’ menu, where each existing fileset is represented by a submenu.

    See Version Control, for a different concept of filesets: groups of files bundled together for version control operations. Filesets of that type are unnamed, and do not persist across Emacs sessions.

    20 Using Multiple Buffers

    The text you are editing in Emacs resides in an object called a buffer. Each time you visit a file, a buffer is used to hold the file’s text. Each time you invoke Dired, a buffer is used to hold the directory listing. If you send a message with C-x m, a buffer is used to hold the text of the message. When you ask for a command’s documentation, that appears in a buffer named *Help*.

    Buffers exist as long as they are in use, and are deleted (“killed”) when no longer needed, either by you (see Killing Buffers) or by Emacs (e.g., when you exit Emacs, see Exiting Emacs).

    Each buffer has a unique name, which can be of any length. When a buffer is displayed in a window, its name is shown in the mode line (see The Mode Line). The distinction between upper and lower case matters in buffer names. Most buffers are made by visiting files, and their names are derived from the files’ names; however, you can also create an empty buffer with any name you want. A newly started Emacs has several buffers, including one named *scratch*, which can be used for evaluating Lisp expressions and is not associated with any file (see Lisp Interaction Buffers).

    At any time, one and only one buffer is selected; we call it the current buffer. We sometimes say that a command operates on “the buffer”; this really means that it operates on the current buffer. When there is only one Emacs window, the buffer displayed in that window is current. When there are multiple windows, the buffer displayed in the selected window is current. See Multiple Windows.

    A buffer’s contents consist of a series of characters, each of which optionally carries a set of text properties (see Text properties) that can specify more information about that character.

    Aside from its textual contents, each buffer records several pieces of information, such as what file it is visiting (if any), whether it is modified, and what major mode and minor modes are in effect (see Major and Minor Modes). These are stored in buffer-local variables—variables that can have a different value in each buffer. See Local Variables.

    A buffer’s size cannot be larger than some maximum, which is defined by the largest buffer position representable by Emacs integers. This is because Emacs tracks buffer positions using that data type. For typical 64-bit machines, this maximum buffer size is 2^{61} - 2 bytes, or about 2 EiB. For typical 32-bit machines, the maximum is usually 2^{29} - 2 bytes, or about 512 MiB. Buffer sizes are also limited by the amount of memory in the system.

    20.1 Creating and Selecting Buffers

    C-x b buffer RET

    Select or create a buffer named buffer (switch-to-buffer).

    C-x 4 b buffer RET

    Similar, but select buffer in another window (switch-to-buffer-other-window).

    C-x 5 b buffer RET

    Similar, but select buffer in a separate frame (switch-to-buffer-other-frame).

    C-x LEFT

    Select the previous buffer in the buffer list (previous-buffer).

    C-x RIGHT

    Select the next buffer in the buffer list (next-buffer).

    C-u M-g M-g
    C-u M-g g

    Read a number n and move to line n in the most recently selected buffer other than the current buffer, in another window.

    The C-x b (switch-to-buffer) command reads a buffer name using the minibuffer. Then it makes that buffer current, and displays it in the currently-selected window. An empty input specifies the buffer that was current most recently among those not now displayed in any window.

    While entering the buffer name, you can use the usual completion and history commands (see The Minibuffer). Note that C-x b, and related commands, use permissive completion with confirmation for minibuffer completion: if you type RET when the minibuffer text names a nonexistent buffer, Emacs prints ‘[Confirm]’ and you must type a second RET to submit that buffer name. See Completion Exit, for details. For other completion options and features, see Completion Options.

    If you specify a buffer that does not exist, C-x b creates a new, empty buffer that is not visiting any file, and selects it for editing. The default value of the variable major-mode determines the new buffer’s major mode; the default value is Fundamental mode. See Major Modes. One reason to create a new buffer is to use it for making temporary notes. If you try to save it, Emacs asks for the file name to use, and the buffer’s major mode is re-established taking that file name into account (see Choosing File Modes).

    For conveniently switching between a few buffers, use the commands C-x LEFT and C-x RIGHT. C-x LEFT (previous-buffer) selects the previous buffer (following the order of most recent selection in the current frame), while C-x RIGHT (next-buffer) moves through buffers in the reverse direction. Both commands support a numeric prefix argument that serves as a repeat count.

    To select a buffer in a window other than the current one (see Multiple Windows), type C-x 4 b (switch-to-buffer-other-window). This prompts for a buffer name using the minibuffer, displays that buffer in another window, and selects that window.

    Similarly, C-x 5 b (switch-to-buffer-other-frame) prompts for a buffer name, displays that buffer in another frame (see Frames and Graphical Displays), and selects that frame. If the buffer is already being shown in a window on another frame, Emacs selects that window and frame instead of creating a new frame.

    See Displaying a Buffer in a Window, for how the C-x 4 b and C-x 5 b commands get the window and/or frame to display in.

    In addition, C-x C-f, and any other command for visiting a file, can also be used to switch to an existing file-visiting buffer. See Visiting Files.

    C-u M-g M-g, that is goto-line with a plain prefix argument, reads a number n using the minibuffer, selects the most recently selected buffer other than the current buffer in another window, and then moves point to the beginning of line number n in that buffer. This is mainly useful in a buffer that refers to line numbers in another buffer: if point is on or just after a number, goto-line uses that number as the default for n. Note that prefix arguments other than just C-u behave differently. C-u 4 M-g M-g goes to line 4 in the current buffer, without reading a number from the minibuffer. (Remember that M-g M-g without prefix argument reads a number n and then moves to line number n in the current buffer. See Changing the Location of Point.)

    Emacs uses buffer names that start with a space for internal purposes. It treats these buffers specially in minor ways—for example, by default they do not record undo information. It is best to avoid using such buffer names yourself.

    20.2 Listing Existing Buffers

    C-x C-b

    List the existing buffers (list-buffers).

    To display a list of existing buffers, type C-x C-b. This pops up a buffer menu in a buffer named *Buffer List*. Each line in the list shows one buffer’s name, size, major mode and visited file. The buffers are listed in the order that they were current; the buffers that were current most recently come first. This section describes how the list of buffers is displayed and how to interpret the various indications in the list; see Operating on Several Buffers, for description of the special mode in the *Buffer List* buffer and the commands available there.

    .’ in the first field of a line indicates that the buffer is current. ‘%’ indicates a read-only buffer. ‘*’ indicates that the buffer is modified. If several buffers are modified, it may be time to save some with C-x s (see Commands for Saving Files). Here is an example of a buffer list:

    CRM Buffer                Size  Mode              File
    . * .emacs                3294  Emacs-Lisp        ~/.emacs
     %  *Help*                 101  Help
        search.c             86055  C                 ~/cvs/emacs/src/search.c
     %  src                  20959  Dired by name     ~/cvs/emacs/src/
      * *mail*                  42  Mail
     %  HELLO                 1607  Fundamental       ~/cvs/emacs/etc/HELLO
     %  NEWS                481184  Outline           ~/cvs/emacs/etc/NEWS
        *scratch*              191  Lisp Interaction
      * *Messages*            1554  Messages

    The buffer *Help* was made by a help request (see Help); it is not visiting any file. The buffer src was made by Dired on the directory ~/cvs/emacs/src/. You can list only buffers that are visiting files by giving the command a prefix argument, as in C-u C-x C-b.

    list-buffers omits buffers whose names begin with a space, unless they visit files: such buffers are used internally by Emacs.

    20.3 Miscellaneous Buffer Operations

    C-x C-q

    Toggle read-only status of buffer (read-only-mode).

    C-x x r RET buffer RET

    Change the name of the current buffer.

    C-x x u

    Rename the current buffer by adding ‘<number>’ to the end.

    M-x view-buffer RET buffer RET

    Scroll through buffer buffer. See View Mode.

    A buffer can be read-only, which means that commands to insert or delete its text are not allowed. (However, other commands, like C-x RET f, can still mark it as modified, see Specifying a Coding System for File Text). The mode line indicates read-only buffers with ‘%%’ or ‘%*’ near the left margin. See The Mode Line. Read-only buffers are usually made by subsystems such as Dired and Rmail that have special commands to operate on the text. Visiting a file whose access control says you cannot write it also makes the buffer read-only.

    The command C-x C-q (read-only-mode) makes a read-only buffer writable, and makes a writable buffer read-only. This works by setting the variable buffer-read-only, which has a local value in each buffer and makes the buffer read-only if its value is non-nil. If you change the option view-read-only to a non-nil value, making the buffer read-only with C-x C-q also enables View mode in the buffer (see View Mode).

    C-x x r (rename-buffer changes the name of the current buffer. You specify the new name as a minibuffer argument; there is no default. If you specify a name that is in use for some other buffer, an error happens and no renaming is done.

    C-x x u (rename-uniquely) renames the current buffer to a similar name with a numeric suffix added to make it both different and unique. This command does not need an argument. It is useful for creating multiple shell buffers: if you rename the *shell* buffer, then do M-x shell again, it makes a new shell buffer named *shell*; meanwhile, the old shell buffer continues to exist under its new name. This method is also good for mail buffers, compilation buffers, and most Emacs features that create special buffers with particular names. (With some of these features, such as M-x compile, M-x grep, you need to switch to some other buffer before using the command again, otherwise it will reuse the current buffer despite the name change.)

    The commands M-x append-to-buffer and C-x x i (insert-buffer) can also be used to copy text from one buffer to another. See Accumulating Text.

    20.4 Killing Buffers

    If you continue an Emacs session for a while, you may accumulate a large number of buffers. You may then find it convenient to kill the buffers you no longer need. (Some other editors call this operation close, and talk about “closing the buffer” or “closing the file” visited in the buffer.) On most operating systems, killing a buffer releases the memory Emacs used for the buffer back to the operating system so that other programs can use it. Here are some commands for killing buffers:

    C-x k buffer RET

    Kill buffer buffer (kill-buffer).

    M-x kill-some-buffers

    Offer to kill each buffer, one by one.

    M-x kill-matching-buffers

    Offer to kill all buffers matching a regular expression.

    C-x k (kill-buffer) kills one buffer, whose name you specify in the minibuffer. The default, used if you type just RET in the minibuffer, is to kill the current buffer. If you kill the current buffer, another buffer becomes current: one that was current in the recent past but is not displayed in any window now. If you ask to kill a file-visiting buffer that is modified, then you must confirm with yes before the buffer is killed.

    The command M-x kill-some-buffers asks about each buffer, one by one. An answer of yes means to kill the buffer, just like kill-buffer. This command ignores buffers whose names begin with a space, which are used internally by Emacs.

    The command M-x kill-matching-buffers prompts for a regular expression and kills all buffers whose names match that expression. See Syntax of Regular Expressions. Like kill-some-buffers, it asks for confirmation before each kill. This command normally ignores buffers whose names begin with a space, which are used internally by Emacs. To kill internal buffers as well, call kill-matching-buffers with a prefix argument.

    The Buffer Menu feature is also convenient for killing various buffers. See Operating on Several Buffers.

    If you want to do something special every time a buffer is killed, you can add hook functions to the hook kill-buffer-hook (see Hooks).

    If you run one Emacs session for a period of days, as many people do, it can fill up with buffers that you used several days ago. The command M-x clean-buffer-list is a convenient way to purge them; it kills all the unmodified buffers that you have not used for a long time. An ordinary buffer is killed if it has not been displayed for three days; however, you can specify certain buffers that should never be killed automatically, and others that should be killed if they have been unused for a mere hour. These defaults, and other aspects of this command’s behavior, can be controlled by customizing several options described in the doc string of clean-buffer-list.

    You can also have this buffer purging done for you, once a day, by enabling Midnight mode. Midnight mode operates each day at midnight; at that time, it runs clean-buffer-list, or whichever functions you have placed in the normal hook midnight-hook (see Hooks). To enable Midnight mode, use the Customization buffer to set the variable midnight-mode to t. See Easy Customization Interface.

    20.5 Operating on Several Buffers

    M-x buffer-menu

    Begin editing a buffer listing all Emacs buffers.

    M-x buffer-menu-other-window

    Similar, but do it in another window.

    The Buffer Menu opened by C-x C-b (see Listing Existing Buffers) does not merely list buffers. It also allows you to perform various operations on buffers, through an interface similar to Dired (see Dired, the Directory Editor). You can save buffers, kill them (here called deleting them, for consistency with Dired), or display them.

    To use the Buffer Menu, type C-x C-b and switch to the window displaying the *Buffer List* buffer. You can also type M-x buffer-menu to open the Buffer Menu in the selected window. Alternatively, the command M-x buffer-menu-other-window opens the Buffer Menu in another window, and selects that window.

    The Buffer Menu is a read-only buffer, and can be changed only through the special commands described in this section. The usual cursor motion commands can be used in this buffer. The following commands apply to the buffer described on the current line:


    Flag the buffer for deletion (killing), then move point to the next line (Buffer-menu-delete). The deletion flag is indicated by the character ‘D’ on the line, before the buffer name. The deletion occurs only when you type the x command (see below).


    Like d, but move point up instead of down (Buffer-menu-delete-backwards).


    Flag the buffer for saving (Buffer-menu-save). The save flag is indicated by the character ‘S’ on the line, before the buffer name. The saving occurs only when you type x. You may request both saving and deletion for the same buffer.


    Perform all flagged deletions and saves (Buffer-menu-execute).


    Remove all flags from the current line, and move down (Buffer-menu-unmark). With a prefix argument, moves up after removing the flags.


    Move to the previous line and remove all flags on that line (Buffer-menu-backup-unmark).


    Remove a particular flag from all lines (Buffer-menu-unmark-all-buffers). This asks for a single character, and unmarks buffers marked with that character; typing RET removes all marks.


    Remove all flags from all the lines (Buffer-menu-unmark-all).

    The commands for removing flags, d and C-d, accept a numeric argument as a repeat count.

    The following commands operate immediately on the buffer listed on the current line. They also accept a numeric argument as a repeat count.


    Mark the buffer as unmodified (Buffer-menu-not-modified). See Commands for Saving Files.


    Toggle the buffer’s read-only status (Buffer-menu-toggle-read-only). See Miscellaneous Buffer Operations.


    Visit the buffer as a tags table (Buffer-menu-visit-tags-table). See Selecting a Tags Table.

    The following commands are used to select another buffer or buffers:


    Quit the Buffer Menu (quit-window). The most recent formerly visible buffer is displayed in its place.


    Select this line’s buffer, replacing the *Buffer List* buffer in its window (Buffer-menu-this-window).


    Select this line’s buffer in another window, as if by C-x 4 b, leaving *Buffer List* visible (Buffer-menu-other-window).


    Display this line’s buffer in another window, without selecting it (Buffer-menu-switch-other-window).


    Select this line’s buffer in a full-frame window (Buffer-menu-1-window).


    Set up two windows on the current frame, with this line’s buffer selected in one, and a previously current buffer (aside from *Buffer List*) in the other (Buffer-menu-2-window).


    Bury this line’s buffer (Buffer-menu-bury) (i.e., move it to the end of the buffer list).


    Mark this line’s buffer to be displayed in another window if you exit with the v command (Buffer-menu-mark). The display flag is indicated by the character ‘>’ at the beginning of the line. (A single buffer may not have both deletion and display flags.)


    Select this line’s buffer, and also display in other windows any buffers flagged with the m command (Buffer-menu-select). If you have not flagged any buffers, this command is equivalent to 1.

    The following commands affect the entire buffer list:


    Sort the Buffer Menu entries according to their values in the column at point. With a numeric prefix argument n, sort according to the n-th column (tabulated-list-sort).


    Widen the current column width by n (the prefix numeric argument) characters.


    Narrow the current column width by n (the prefix numeric argument) characters.


    Delete, or reinsert, lines for non-file buffers (Buffer-menu-toggle-files-only). This command toggles the inclusion of such buffers in the buffer list.

    Normally, the buffer *Buffer List* is not updated automatically when buffers are created and killed; its contents are just text. If you have created, deleted or renamed buffers, the way to update *Buffer List* to show what you have done is to type g (revert-buffer). You can make this happen regularly every auto-revert-interval seconds if you enable Auto Revert mode in this buffer, as long as it is not marked modified. Global Auto Revert mode applies to the *Buffer List* buffer only if global-auto-revert-non-file-buffers is non-nil. See global-auto-revert-non-file-buffers, for details.

    20.6 Indirect Buffers

    An indirect buffer shares the text of some other buffer, which is called the base buffer of the indirect buffer. In some ways it is a buffer analogue of a symbolic link between files.

    M-x make-indirect-buffer RET base-buffer RET indirect-name RET

    Create an indirect buffer named indirect-name with base buffer base-buffer.

    M-x clone-indirect-buffer RET

    Create an indirect buffer that is a twin copy of the current buffer.

    C-x 4 c

    Create an indirect buffer that is a twin copy of the current buffer, and select it in another window (clone-indirect-buffer-other-window).

    The text of the indirect buffer is always identical to the text of its base buffer; changes made by editing either one are visible immediately in the other. “Text” here includes both the characters and their text properties. But in all other respects, the indirect buffer and its base buffer are completely separate. They can have different names, different values of point, different narrowing, different markers, different overlays, different major modes, and different local variables.

    An indirect buffer cannot visit a file, but its base buffer can. If you try to save the indirect buffer, that actually works by saving the base buffer. Killing the base buffer effectively kills the indirect buffer, but killing an indirect buffer has no effect on its base buffer.

    One way to use indirect buffers is to display multiple views of an outline. See Viewing One Outline in Multiple Views.

    A quick and handy way to make an indirect buffer is with the command C-x 4 c (clone-indirect-buffer-other-window). It creates and selects an indirect buffer whose base buffer is the current buffer. With a numeric argument, it prompts for the name of the indirect buffer; otherwise it uses the name of the current buffer, with a ‘<n>’ suffix added.

    The more general way to make an indirect buffer is with the command M-x make-indirect-buffer. It creates an indirect buffer named indirect-name from a buffer base-buffer, prompting for both using the minibuffer.

    The functions that create indirect buffers run the hook clone-indirect-buffer-hook after creating the indirect buffer. When this hook runs, the newly created indirect buffer is the current buffer.

    Note: When a modification is made to the text of a buffer, the modification hooks are run only in the base buffer, because most of the functions on those hooks are not prepared to work correctly in indirect buffers. So if you need a modification hook function in an indirect buffer, you need to manually add that function to the hook in the base buffer and then make the function operate in the desired indirect buffer.

    20.7 Convenience Features and Customization of Buffer Handling

    This section describes several modes and features that make it more convenient to switch between buffers.

    20.7.1 Making Buffer Names Unique

    When several buffers visit identically-named files, Emacs must give the buffers distinct names. The default method adds a suffix based on the names of the directories that contain the files. For example, if you visit files /foo/bar/mumble/name and /baz/quux/mumble/name at the same time, their buffers will be named ‘name<bar/mumble>’ and ‘name<quux/mumble>’, respectively. Emacs adds as many directory parts as are needed to make a unique name.

    You can choose from several different styles for constructing unique buffer names, by customizing the option uniquify-buffer-name-style.

    The forward naming method includes part of the file’s directory name at the beginning of the buffer name; using this method, buffers visiting the files /u/rms/tmp/Makefile and /usr/projects/zaphod/Makefile would be named ‘tmp/Makefile’ and ‘zaphod/Makefile’.

    In contrast, the post-forward naming method would call the buffers ‘Makefile|tmp’ and ‘Makefile|zaphod’. The default method post-forward-angle-brackets is like post-forward, except that it encloses the unique path in angle brackets. The reverse naming method would call them ‘Makefile\tmp’ and ‘Makefile\zaphod’. The nontrivial difference between post-forward and reverse occurs when just one directory name is not enough to distinguish two files; then reverse puts the directory names in reverse order, so that /top/middle/file becomes ‘file\middle\top’, while post-forward puts them in forward order after the file name, as in ‘file|top/middle’. If uniquify-buffer-name-style is set to nil, the buffer names simply get ‘<2>’, ‘<3>’, etc. appended.

    The value of uniquify-buffer-name-style can be set to a customized function with two arguments base and extra-strings where base is a string and extra-strings is a list of strings. For example the current implementation for post-forward-angle-brackets could be:

    (defun my-post-forward-angle-brackets (base extra-string)
      (concat base \"<\" (mapconcat #'identity extra-string \"/\") \">\"))

    Which rule to follow for putting the directory names in the buffer name is not very important if you are going to look at the buffer names before you type one. But as an experienced user, if you know the rule, you won’t have to look. And then you may find that one rule or another is easier for you to remember and apply quickly.

    20.7.2 Fast minibuffer selection

    Icomplete global minor mode provides a convenient way to quickly select an element among the possible completions in a minibuffer. When enabled, typing in the minibuffer continuously displays a list of possible completions that match the string you have typed.

    At any time, you can type C-j to select the first completion in the list. So the way to select a particular completion is to make it the first in the list. There are two ways to do this. You can type more of the completion name and thus narrow down the list, excluding unwanted completions above the desired one. Alternatively, you can use C-. and C-, to rotate the list until the desired buffer is first.

    M-TAB will select the first completion in the list, like C-j but without exiting the minibuffer, so you can edit it further. This is typically used when entering a file name, where M-TAB can be used a few times to descend in the hierarchy of directories.

    To enable Icomplete mode, type M-x icomplete-mode, or customize the variable icomplete-mode to t (see Easy Customization Interface).

    An alternative to Icomplete mode is Fido mode. This is very similar to Icomplete mode, but retains some functionality from a popular extension called Ido mode (in fact the name is derived from “Fake Ido”). Among other things, in Fido mode, C-s and C-r are also used to rotate the completions list, C-k can be used to delete files and kill buffers in-list. Another noteworthy aspect is that flex is used as the default completion style (see How Completion Alternatives Are Chosen). To change this, add the following to your initialization file (see The Emacs Initialization File):

    (defun my-icomplete-styles ()
      (setq-local completion-styles '(initials flex)))
    (add-hook 'icomplete-minibuffer-setup-hook 'my-icomplete-styles)

    To enable Fido mode, type M-x fido-mode, or customize the variable fido-mode to t (see Easy Customization Interface).

    Icomplete mode and Fido mode display the possible completions on the same line as the prompt by default. To display the completion candidates vertically under the prompt, type M-x icomplete-vertical-mode, or customize the variable icomplete-vertical-mode to t (see Easy Customization Interface).

    20.7.3 Customizing Buffer Menus

    M-x bs-show

    Make a list of buffers similarly to M-x list-buffers but customizable.

    M-x ibuffer

    Make a list of buffers and operate on them in Dired-like fashion.

    M-x bs-show pops up a buffer list similar to the one normally displayed by C-x C-b, but whose display you can customize in a more flexible fashion. For example, you can specify the list of buffer attributes to show, the minimum and maximum width of buffer name column, a regexp for names of buffers that will never be shown and those which will always be shown, etc. If you prefer this to the usual buffer list, you can bind this command to C-x C-b. To customize this buffer list, use the bs Custom group (see Easy Customization Interface), or invoke bs-customize.

    MSB global minor mode (“MSB” stands for “mouse select buffer”) provides a different and customizable mouse buffer menu which you may prefer. It replaces the mouse-buffer-menu commands, normally bound to C-Down-mouse-1 and C-F10, with its own commands, and also modifies the menu-bar buffer menu. You can customize the menu in the msb Custom group.

    IBuffer is a major mode for viewing a list of buffers and operating on them in a way analogous to that of Dired (see Dired, the Directory Editor), including filtering, marking, sorting in various ways, and acting on buffers.

    21 Multiple Windows

    Emacs can split a frame into two or many windows. Multiple windows can display parts of different buffers, or different parts of one buffer. Multiple frames always imply multiple windows, because each frame has its own set of windows. Each window belongs to one and only one frame.

    21.1 Concepts of Emacs Windows

    Each Emacs window displays one Emacs buffer at any time. A single buffer may appear in more than one window; if it does, any changes in its text are displayed in all the windows where it appears. But these windows can show different parts of the buffer, because each window has its own value of point.

    At any time, one Emacs window is the selected window; the buffer this window is displaying is the current buffer. On graphical displays, the point is indicated by a solid blinking cursor in the selected window, and by a hollow box in non-selected windows. On text terminals, the cursor is drawn only in the selected window. See Displaying the Cursor.

    Commands to move point affect the value of point for the selected Emacs window only. They do not change the value of point in other Emacs windows, even those showing the same buffer. The same is true for buffer-switching commands such as C-x b; they do not affect other windows at all. However, there are other commands such as C-x 4 b that select a different window and switch buffers in it. Also, all commands that display information in a window, including (for example) C-h f (describe-function) and C-x C-b (list-buffers), usually work by displaying buffers in a nonselected window without affecting the selected window.

    When multiple windows show the same buffer, they can have different regions, because they can have different values of point. However, they all have the same value for the mark, because each buffer has only one mark position.

    Each window has its own mode line, which displays the buffer name, modification status and major and minor modes of the buffer that is displayed in the window. The selected window’s mode line appears in a different color. See The Mode Line, for details.

    21.2 Splitting Windows

    C-x 2

    Split the selected window into two windows, one above the other (split-window-below).

    C-x 3

    Split the selected window into two windows, positioned side by side (split-window-right).


    In the mode line of a window, split that window.

    C-x 2 (split-window-below) splits the selected window into two windows, one above the other. After splitting, the selected window is the upper one, and the newly split-off window is below. Both windows have the same value of point as before, and display the same portion of the buffer (or as close to it as possible). If necessary, the windows are scrolled to keep point on-screen. By default, the two windows each get half the height of the original window. A positive numeric argument specifies how many lines to give to the top window; a negative numeric argument specifies how many lines to give to the bottom window.

    If you change the variable split-window-keep-point to nil, C-x 2 instead adjusts the portion of the buffer displayed by the two windows, as well as the value of point in each window, in order to keep the text on the screen as close as possible to what it was before; furthermore, if point was in the lower half of the original window, the bottom window is selected instead of the upper one.

    C-x 3 (split-window-right) splits the selected window into two side-by-side windows. The left window is the selected one; the right window displays the same portion of the same buffer, and has the same value of point. A positive numeric argument specifies how many columns to give the left window; a negative numeric argument specifies how many columns to give the right window.

    When you split a window with C-x 3, each resulting window occupies less than the full width of the frame. If it becomes too narrow, the buffer may be difficult to read if continuation lines are in use (see Continuation Lines). Therefore, Emacs automatically switches to line truncation if the window width becomes narrower than 50 columns. This truncation occurs regardless of the value of the variable truncate-lines (see Line Truncation); it is instead controlled by the variable truncate-partial-width-windows. If the value of this variable is a positive integer (the default is 50), that specifies the minimum total width for a partial-width window before automatic line truncation occurs; if the value is nil, automatic line truncation is disabled; and for any other non-nil value, Emacs truncates lines in every partial-width window regardless of its width. The total width of a window is in column units as reported by window-total-width (see Window Sizes in The Emacs Lisp Reference Manual), it includes the fringes, the continuation and truncation glyphs, the margins, and the scroll bar.

    On text terminals, side-by-side windows are separated by a vertical divider which is drawn using the vertical-border face.

    If you click C-mouse-2 in the mode line of a window, that splits the window, putting a vertical divider where you click. Depending on how Emacs is compiled, you can also split a window by clicking C-mouse-2 in the scroll bar, which puts a horizontal divider where you click (this feature does not work when Emacs uses GTK+ scroll bars).

    By default, when you split a window, Emacs gives each of the resulting windows dimensions that are an integral multiple of the default font size of the frame. That might subdivide the screen estate unevenly between the resulting windows. If you set the variable window-resize-pixelwise to a non-nil value, Emacs will give each window the same number of pixels (give or take one pixel if the initial dimension was an odd number of pixels). Note that when a frame’s pixel size is not a multiple of the frame’s character size, at least one window may get resized pixelwise even if this option is nil.

    21.3 Using Other Windows

    C-x o

    Select another window (other-window).


    Scroll the next window upward (scroll-other-window).


    Scroll the next window downward (scroll-other-window-down).


    Recenter the next window (recenter-other-window).


    mouse-1, in the text area of a window, selects the window and moves point to the position clicked. Clicking in the mode line selects the window without moving point in it.

    With the keyboard, you can switch windows by typing C-x o (other-window). That is an o, for “other”, not a zero. When there are more than two windows, this command moves through all the windows in a cyclic order, generally top to bottom and left to right. After the rightmost and bottommost window, it goes back to the one at the upper left corner. A numeric argument means to move several steps in the cyclic order of windows. A negative argument moves around the cycle in the opposite order. When the minibuffer is active, the minibuffer window is the last window in the cycle; you can switch from the minibuffer window to one of the other windows, and later switch back and finish supplying the minibuffer argument that is requested. See Editing in the Minibuffer.

    The other-window command will normally only switch to the next window in the current frame (unless otherwise configured). If you work in a multi-frame environment and you want windows in all frames to be part of the cycle, you can rebind C-x o to the next-window-any-frame command. (See Changing Key Bindings Interactively, for how to rebind a command.)

    The usual scrolling commands (see Controlling the Display) apply to the selected window only, but there are also commands to scroll the next window. C-M-v (scroll-other-window) scrolls the window that C-x o would select. In other respects, the command behaves like C-v; both move the buffer text upward relative to the window, and take positive and negative arguments. (In the minibuffer, C-M-v scrolls the help window associated with the minibuffer, if any, rather than the next window in the standard cyclic order; see Editing in the Minibuffer.) C-M-S-v (scroll-other-window-down) scrolls the next window downward in a similar way. Likewise, C-M-S-l (recenter-other-window) behaves like C-l (recenter-top-bottom) in the next window.

    If you set mouse-autoselect-window to a non-nil value, moving the mouse over a different window selects that window. This feature is off by default.

    21.4 Displaying in Another Window

    C-x 4 is a prefix key for a variety of commands that switch to a buffer in a different window—either another existing window, or a new window created by splitting the selected window. See How display-buffer works, for how Emacs picks or creates the window to use.

    C-x 4 b bufname RET

    Select buffer bufname in another window (switch-to-buffer-other-window). See Creating and Selecting Buffers.

    C-x 4 C-o bufname RET

    Display buffer bufname in some window, without trying to select it (display-buffer). See Displaying a Buffer in a Window, for details about how the window is chosen.

    C-x 4 f filename RET

    Visit file filename and select its buffer in another window (find-file-other-window). See Visiting Files.

    C-x 4 d directory RET

    Select a Dired buffer for directory directory in another window (dired-other-window). See Dired, the Directory Editor.

    C-x 4 m

    Start composing a mail message, similar to C-x m (see Sending Mail), but in another window (compose-mail-other-window).

    C-x 4 .

    Find the definition of an identifier, similar to M-. (see Find Identifier References), but in another window (xref-find-definitions-other-window).

    C-x 4 r filename RET

    Visit file filename read-only, and select its buffer in another window (find-file-read-only-other-window). See Visiting Files.

    C-x 4 4

    A more general prefix command affects the buffer displayed by the next command invoked immediately after this prefix command. It requests the buffer of the next command to be displayed in another window.

    C-x 4 1

    This general prefix command requests the buffer of the next command to be displayed in the same window.

    21.5 Deleting and Resizing Windows

    C-x 0

    Delete the selected window (delete-window).

    C-x 1

    Delete all windows in the selected frame except the selected window (delete-other-windows).

    C-x 4 0

    Delete the selected window and kill the buffer that was showing in it (kill-buffer-and-window). The last character in this key sequence is a zero.

    C-x w 0 RET buffer RET

    Delete windows showing the specified buffer.

    C-x ^

    Make selected window taller (enlarge-window).

    C-x }

    Make selected window wider (enlarge-window-horizontally).

    C-x {

    Make selected window narrower (shrink-window-horizontally).

    C-x -

    Shrink this window if its buffer doesn’t need so many lines (shrink-window-if-larger-than-buffer).

    C-x +

    Make all windows the same height (balance-windows).

    To delete the selected window, type C-x 0 (delete-window). (That is a zero.) Once a window is deleted, the space that it occupied is given to an adjacent window (but not the minibuffer window, even if that is active at the time). Deleting the window has no effect on the buffer it used to display; the buffer continues to exist, and you can still switch to it with C-x b. The option delete-window-choose-selected controls which window is chosen as the new selected window instead (see Deleting Windows in The Emacs Lisp Reference Manual).

    C-x 4 0 (kill-buffer-and-window) is a stronger command than C-x 0; it kills the current buffer and then deletes the selected window.

    C-x 1 (delete-other-windows) deletes all the windows, except the selected one; the selected window expands to use the whole frame. (This command cannot be used while the minibuffer window is active; attempting to do so signals an error.)

    M-x delete-windows-on deletes windows that show a specific buffer. It prompts for the buffer, defaulting to the current buffer. With prefix argument of zero, C-u 0, this command deletes windows only on the current display’s frames.

    The command C-x ^ (enlarge-window) makes the selected window one line taller, taking space from a vertically adjacent window without changing the height of the frame. With a positive numeric argument, this command increases the window height by that many lines; with a negative argument, it reduces the height by that many lines. If there are no vertically adjacent windows (i.e., the window is at the full frame height), that signals an error. The command also signals an error if you attempt to reduce the height of any window below a certain minimum number of lines, specified by the variable window-min-height (the default is 4).

    Similarly, C-x } (enlarge-window-horizontally) makes the selected window wider, and C-x { (shrink-window-horizontally) makes it narrower. These commands signal an error if you attempt to reduce the width of any window below a certain minimum number of columns, specified by the variable window-min-width (the default is 10).

    Mouse clicks on the mode line (see Mode Line Mouse Commands) or on window dividers (see Window Dividers) provide another way to change window heights and to split or delete windows.

    C-x - (shrink-window-if-larger-than-buffer) reduces the height of the selected window, if it is taller than necessary to show the whole text of the buffer it is displaying. It gives the extra lines to other windows in the frame.

    You can also use C-x + (balance-windows) to even out the heights of all the windows in the selected frame.

    21.6 Displaying a Buffer in a Window

    It is a common Emacs operation to display or pop up some buffer in response to a user command. There are several different ways in which commands do this.

    Many commands, like C-x C-f (find-file), by default display the buffer by “taking over” the selected window, expecting that the user’s attention will be diverted to that buffer.

    Some commands try to display intelligently, trying not to take over the selected window, e.g., by splitting off a new window and displaying the desired buffer there. Such commands, which include the various help commands (see Help), work by calling display-buffer internally. See How display-buffer works, for details.

    Other commands do the same as display-buffer, and additionally select the displaying window so that you can begin editing its buffer. The command M-g M-n (next-error) is one example (see Compilation Mode). Such commands work by calling the function pop-to-buffer internally. See Switching to a Buffer in a Window in The Emacs Lisp Reference Manual.

    Commands with names ending in -other-window behave like display-buffer, except that they never display in the selected window. Several of these commands are bound in the C-x 4 prefix key (see Displaying in Another Window).

    Commands with names ending in -other-frame behave like display-buffer, except that they (i) never display in the selected window and (ii) prefer to either create a new frame or use a window on some other frame to display the desired buffer. Several of these commands are bound in the C-x 5 prefix key.

    21.6.1 How display-buffer works

    The display-buffer command (as well as commands that call it internally) chooses a window to display by following the steps given below. See Choosing a Window for Displaying a Buffer in The Emacs Lisp Reference Manual, for details about how to alter this sequence of steps.

    • If the buffer should be displayed in the selected window regardless of other considerations, reuse the selected window. By default, this step is skipped, but you can tell Emacs not to skip it by adding a regular expression matching the buffer’s name together with a reference to the display-buffer-same-window action function (see Action Functions for Buffer Display in The Emacs Lisp Reference Manual) to the option display-buffer-alist (see Choosing a Window for Displaying a Buffer in The Emacs Lisp Reference Manual). For example, to display the buffer *scratch* preferably in the selected window write:
       '(("\\*scratch\\*" (display-buffer-same-window))))

      By default, display-buffer-alist is nil.

    • Otherwise, if the buffer is already displayed in an existing window, reuse that window. Normally, only windows on the selected frame are considered, but windows on other frames are also reusable if you use the corresponding reusable-frames action alist entry (see Action Alists for Buffer Display in The Emacs Lisp Reference Manual). See the next step for an example of how to do that.
    • Otherwise, optionally create a new frame and display the buffer there. By default, this step is skipped. To enable it, change the value of the option display-buffer-base-action (see Choosing a Window for Displaying a Buffer in The Emacs Lisp Reference Manual) as follows:
       '((display-buffer-reuse-window display-buffer-pop-up-frame)
         (reusable-frames . 0)))

      This customization will also try to make the preceding step search for a reusable window on all visible or iconified frames.

    • Otherwise, try to create a new window by splitting a window on the selected frame, and display the buffer in that new window.

      The split can be either vertical or horizontal, depending on the variables split-height-threshold and split-width-threshold. These variables should have integer values. If split-height-threshold is smaller than the chosen window’s height, the split puts the new window below. Otherwise, if split-width-threshold is smaller than the window’s width, the split puts the new window on the right. If neither condition holds, Emacs tries to split so that the new window is below—but only if the window was not split before (to avoid excessive splitting).

    • Otherwise, display the buffer in a window previously showing it. Normally, only windows on the selected frame are considered, but with a suitable reusable-frames action alist entry (see above) the window may be also on another frame.
    • Otherwise, display the buffer in an existing window on the selected frame.
    • If all the above methods fail for whatever reason, create a new frame and display the buffer there.

    21.6.2 Displaying non-editable buffers.

    Some buffers are shown in windows for perusal rather than for editing. Help commands (see Help) typically use a buffer called *Help* for that purpose, minibuffer completion (see Completion) uses a buffer called *Completions*, etc. Such buffers are usually displayed only for a short period of time.

    Normally, Emacs chooses the window for such temporary displays via display-buffer, as described in the previous subsection. The *Completions* buffer, on the other hand, is normally displayed in a window at the bottom of the selected frame, regardless of the number of windows already shown on that frame.

    If you prefer Emacs to display a temporary buffer in a different fashion, customize the variable display-buffer-alist (see Choosing a Window for Displaying a Buffer in The Emacs Lisp Reference Manual) appropriately. For example, to display *Completions* always below the selected window, use the following form in your initialization file (see The Emacs Initialization File):

     '(("\\*Completions\\*" display-buffer-below-selected)))

    The *Completions* buffer is also special in the sense that Emacs usually tries to make its window just as large as necessary to display all of its contents. To resize windows showing other temporary displays, like, for example, the *Help* buffer, turn on the minor mode (see Minor Modes) temp-buffer-resize-mode (see Temporary Displays in The Emacs Lisp Reference Manual).

    The maximum size of windows resized by temp-buffer-resize-mode can be controlled by customizing the options temp-buffer-max-height and temp-buffer-max-width (see Temporary Displays in The Emacs Lisp Reference Manual), and cannot exceed the size of the containing frame.

    21.7 Convenience Features for Window Handling

    Winner mode is a global minor mode that records the changes in the window configuration (i.e., how the frames are partitioned into windows), so that you can undo them. You can toggle Winner mode with M-x winner-mode, or by customizing the variable winner-mode. When the mode is enabled, C-c left (winner-undo) undoes the last window configuration change. If you change your mind while undoing, you can redo the changes you had undone using C-c right (M-x winner-redo). To prevent Winner mode from binding C-c left and C-c right, you can customize the variable winner-dont-bind-my-keys to a non-nil value. By default, Winner mode stores a maximum of 200 window configurations per frame, but you can change that by modifying the variable winner-ring-size. If there are some buffers whose windows you wouldn’t want Winner mode to restore, add their names to the list variable winner-boring-buffers or to the regexp winner-boring-buffers-regexp.

    Follow mode (M-x follow-mode) synchronizes several windows on the same buffer so that they always display adjacent sections of that buffer. See Follow Mode.

    The Windmove package defines commands for moving directionally between neighboring windows in a frame. M-x windmove-right selects the window immediately to the right of the currently selected one, and similarly for the left, up, and down counterparts. windmove-default-keybindings binds these commands to S-right etc.; doing so disables shift selection for those keys (see Shift Selection). In the same way as key bindings can be defined for commands that select windows directionally, you can use windmove-display-default-keybindings to define keybindings for commands that specify in what direction to display the window for the buffer that the next command is going to display. Also there is windmove-delete-default-keybindings to define keybindings for commands that delete windows directionally, and windmove-swap-states-default-keybindings that defines key bindings for commands that swap the window contents of the selected window with the window in the specified direction.

    The command M-x compare-windows lets you compare the text shown in different windows. See Comparing Files.

    Scroll All mode (M-x scroll-all-mode) is a global minor mode that causes scrolling commands and point motion commands to apply to every single window.

    21.8 Window Tab Line