The GNU Emacs FAQ

2.1 What are appropriate messages for the various Emacs mailing lists?

There are various Emacs mailing lists, described at the Emacs Savannah page.

The main ones are: help-gnu-emacs, bug-gnu-emacs, and emacs-devel.

Messages advocating “non-free” software are considered unacceptable on any of the GNU mailing lists, except for the gnu-misc-discuss mailing list. “Non-free” software includes any software for which the end user can’t freely modify the source code and exchange enhancements. Please remove GNU mailing lists from the recipients when posting a reply that recommends such software.

Some of the GNU mailing lists are gatewayed to newsgroups (although the connection is occasionally unreliable). For example, sending an email to The bug-gnu-emacs list has the effect of posting on the newsgroup news:gnu.emacs.help).

Finally, we recommend reading the GNU Kind Communications Guidelines before posting to any GNU lists or newsgroups.

2.2 Where can I read archives for help-gnu-emacs and other GNU lists?

The FSF has maintained archives of all of the GNU mailing lists for many years, although there may be some unintentional gaps in coverage. The archive can be browsed over the web at the GNU mail archive.

Some web-based Usenet search services also archive the gnu.* newsgroups.

2.3 Where should I report bugs and other problems with Emacs?

Please see the Emacs manual for information on how to report bugs. See Checklist for Bug Reports in The GNU Emacs Manual.

Sending bug reports to the help-gnu-emacs mailing list is undesirable because it takes the time of an unnecessarily large group of people, most of whom are just users and have no idea how to fix these problem. The bug-gnu-emacs list reaches a much smaller group of people who are more likely to know what to do and have expressed a wish to receive more messages about Emacs than the others.

If you have reported a bug and you don’t hear about a possible fix, then after a suitable delay (such as a week) it is okay to post on the help list asking if anyone can help you.

If you are unsure whether you have found a bug, consider the following non-exhaustive list, courtesy of RMS:

If Emacs crashes, that is a bug. If Emacs gets compilation errors while building, that is a bug. If Emacs crashes while building, that is a bug. If Lisp code does not do what the documentation says it does, that is a bug.

Anything sent to bug-gnu-emacs@gnu.org also appears in the newsgroup news:gnu.emacs.bug, but please use e-mail instead of news to submit the bug report. This ensures a reliable return address so you can be contacted for further details.

2.4 How do I unsubscribe from a mailing list?

If you are receiving a GNU mailing list named list, you should be able to unsubscribe from it by sending a request to the address list-request@gnu.org. Mailing lists mails normally contain information in either the message header (‘List-Unsubscribe:’) or as a footer that tells you how to unsubscribe.

2.5 How do I contact the FSF?

For up-to-date information, see the FSF contact web-page. You can send general correspondence to info@fsf.org.

For details on how to order items directly from the FSF, see the FSF on-line store.

3.1 I’m just starting Emacs; how do I do basic editing?

Type C-h t to invoke the self-paced tutorial. Just typing C-h enters the help system. The tutorial is available in many foreign languages such as French, German, Japanese, Russian, etc. Use M-x help-with-tutorial-spec-language RET to choose your language and start the tutorial.

Your system administrator may have changed C-h to act like DEL to deal with local keyboards. You can use M-x help-for-help instead to invoke help. To discover what key (if any) invokes help on your system, type M-x where-is RET help-for-help RET. This will print a comma-separated list of key sequences in the echo area. Ignore the last character in each key sequence listed. Each of the resulting key sequences (e.g., F1 is common) invokes help.

Emacs help works best if it is invoked by a single key whose value should be stored in the variable help-char.

Some Emacs slides and tutorials can be found at http://web.psung.name/emacs/.

3.2 How do I find out how to do something in Emacs?

There are several methods for finding out how to do things in Emacs.

• The complete text of the Emacs manual is available via the Info hypertext reader. Type C-h r to display the manual in Info mode. Typing h immediately after entering Info will provide a short tutorial on how to use it.
• To quickly locate the section of the manual which discusses a certain issue, or describes a command or a variable, type C-h i m emacs RET i topic RET, where topic is the name of the topic, the command, or the variable which you are looking for. If this does not land you on the right place in the manual, press , (comma) repeatedly until you find what you need. (The i and , keys invoke the index-searching functions, which look for the topic you type in all the indices of the Emacs manual.)
• You can list all of the commands whose names contain a certain word (actually which match a regular expression) using C-h a (M-x command-apropos).
• The command C-h F (Info-goto-emacs-command-node) prompts for the name of a command, and then attempts to find the section in the Emacs manual where that command is described.
• You can list all of the functions and variables whose names contain a certain word using M-x apropos.
• You can list all of the functions and variables whose documentation matches a regular expression or a string, using M-x apropos-documentation.
• You can order a hardcopy of the manual from the FSF. See How do I get a printed copy of the Emacs manual?.
• You can get a printed reference card listing commands and keys to invoke them. You can order one from the FSF, or you can print your own from the etc/refcards/refcard.tex or etc/refcards/refcard.pdf files in the Emacs distribution. The Emacs distribution comes with translations of the reference card into several languages; look for files named etc/refcards/lang-refcard.*, where lang is a two-letter code of the language. For example, the German version of the reference card is in the files etc/refcards/de-refcard.tex and etc/refcards/de-refcard.pdf.
• There are many other commands in Emacs for getting help and information. To get a list of these commands, type ‘?’ after C-h.

3.3 How do I get a printed copy of the Emacs manual?

You can order a printed copy of the Emacs manual from the FSF. For details see the FSF on-line store.

The full Texinfo source for the manual also comes in the doc/emacs directory of the Emacs distribution, if you’re daring enough to try to print out this several-hundred-page manual yourself (see How do I print a Texinfo file?).

If you absolutely have to print your own copy, and you don’t have TeX, you can get a PostScript or PDF (or HTML) version from

https://www.gnu.org/software/emacs/manual/

See How do I find out how to do something in Emacs?, for how to view the manual from Emacs.

3.4 Where can I get documentation on Emacs Lisp?

Within Emacs, you can type C-h f to get the documentation for a function, C-h v for a variable.

For more information, the Emacs Lisp Reference Manual is available in Info format (see Emacs Lisp in The Emacs Lisp Reference Manual).

You can also order a hardcopy of the manual from the FSF, for details see the FSF on-line store. (This manual is not always in print.)

An HTML version of the Emacs Lisp Reference Manual is available at

https://www.gnu.org/software/emacs/elisp-manual/elisp.html

3.5 How do I install a piece of Texinfo documentation?

Emacs releases come with pre-built Info files, and the normal install process places them in the correct location. This is true for most applications that provide Info files. The following section is only relevant if you want to install extra Info files by hand.

First, you must turn the Texinfo source files into Info files. You may do this using the stand-alone makeinfo program, available as part of the Texinfo package at

https://www.gnu.org/software/texinfo/

For information about the Texinfo format, read the Texinfo manual which comes with the Texinfo package. This manual also comes installed in Info format, so you can read it from Emacs; type C-h i m texinfo RET.

Alternatively, you could use the Emacs command M-x texinfo-format-buffer, after visiting the Texinfo source file of the manual you want to convert.

Neither texinfo-format-buffer nor makeinfo installs the resulting Info files in Emacs’s Info tree. To install Info files, perform these steps:

1. Move the files to the info directory in the installed Emacs distribution. See What are src/config.h, site-lisp/default.el, etc.?, if you don’t know where that is.
2. Run the install-info command, which is part of the Texinfo distribution, to update the main Info directory menu, like this:

    install-info --info-dir=dir-path dir-path/file
   

   where dir-path is the full path to the directory where you copied the produced Info file(s), and file is the name of the Info file you produced and want to install.

   If you don’t have the install-info command installed, you can edit the file info/dir in the installed Emacs distribution, and add a line for the top level node in the Info package that you are installing. Follow the examples already in this file. The format is:

   * Topic: (relative-pathname).  Short description of topic.
   

If you want to install Info files and you don’t have the necessary privileges, you have several options:

• Info files don’t actually need to be installed before being used. You can use a prefix argument for the info command and specify the name of the Info file in the minibuffer. This goes to the node named ‘Top’ in that file. For example, to view an Info file named info-file in your home directory, you can type this:

  C-u C-h i ~/info-file RET
  

  Alternatively, you can feed a file name to the Info-goto-node command (invoked by pressing g in Info mode) by typing the name of the file in parentheses, like this:

  C-h i g (~/info-file) RET
  

• You can create your own Info directory. You can tell Emacs where that Info directory is by adding its pathname to the value of the variable Info-default-directory-list. For example, to use a private Info directory which is a subdirectory of your home directory named Info, you could put this in your init file (see How do I set up an init file properly?):

  (add-to-list 'Info-default-directory-list "~/Info/")
  

  You will need a top-level Info file named dir in this directory which has everything the system dir file has in it, except it should list only entries for Info files in that directory. You might not need it if (fortuitously) all files in this directory were referenced by other dir files. The node lists from all dir files in Info-default-directory-list are merged by the Info system.

3.6 How do I print a Texinfo file?

You can’t get nicely printed output from Info files; you must still have the original Texinfo source file for the manual you want to print.

Assuming you have TeX installed on your system, follow these steps:

1. Make sure the first line of the Texinfo file looks like this:

   \input texinfo
   

   You may need to change ‘texinfo’ to the full pathname of the texinfo.tex file, which comes with Emacs as doc/misc/texinfo.tex (or copy or link it into the current directory).

2. Type texi2dvi texinfo-source, where texinfo-source is the name of the Texinfo source file for which you want to produce a printed copy. The ‘texi2dvi’ script is part of the GNU Texinfo distribution.

   Alternatively, ‘texi2pdf’ produces PDF files.

3. Print the DVI file texinfo-source.dvi in the normal way for printing DVI files at your site. For example, if you have a PostScript printer, run the dvips program to print the DVI file on that printer.

To get more general instructions, retrieve the latest Texinfo package (see How do I install a piece of Texinfo documentation?).

3.7 Can I view Info files without using Emacs?

Yes. Here are some alternative programs:

• info, a stand-alone version of the Info program, comes as part of the Texinfo package. See How do I install a piece of Texinfo documentation?, for details.
• Tkinfo, an Info viewer that runs under X Window system and uses Tcl/Tk. You can get Tkinfo at http://math-www.uni-paderborn.de/~axel/tkinfo/.

3.8 What informational files are available for Emacs?

This isn’t a frequently asked question, but it should be! A variety of informational files about Emacs and relevant aspects of the GNU project are available for you to read.

The following files (and others) are available in the etc directory of the Emacs distribution (see What are src/config.h, site-lisp/default.el, etc.?, if you’re not sure where that is). Many of these files are available via the Emacs ‘Help’ menu, or by typing C-h ? (M-x help-for-help).

COPYING

GNU General Public License

DISTRIB

Emacs Availability Information

MACHINES

Status of Emacs on Various Machines and Systems

NEWS

Emacs news, a history of recent user-visible changes

More GNU and FSF information is available at

https://www.gnu.org and https://www.fsf.org

3.9 Where can I get help in installing Emacs?

See How do I install Emacs?, for some basic installation hints, and see What should I do if I have trouble building Emacs?, if you have problems with the installation.

The GNU Service directory lists companies and individuals willing to sell you help in installing or using Emacs and other GNU software.

3.10 Where can I get the latest version of this FAQ?

The Emacs FAQ is distributed with Emacs in Info format. You can read it by selecting the ‘Emacs FAQ’ option from the ‘Help’ menu of the Emacs menu bar at the top of any Emacs frame, or by typing C-h C-f (M-x view-emacs-FAQ). The very latest version is available in the Emacs development repository (see What is the latest version of Emacs?).

4.1 Where does the name “Emacs” come from?

Emacs originally was an acronym for Editor MACroS. RMS says he “picked the name Emacs because E was not in use as an abbreviation on ITS at the time.” The first Emacs was a set of macros written in 1976 at MIT by RMS for the editor TECO (Text Editor and COrrector, originally Tape Editor and COrrector) under ITS (the Incompatible Timesharing System) on a PDP-10. RMS had already extended TECO with a “real-time” full-screen mode with reprogrammable keys. Emacs was started by Guy Steele as a project to unify the many divergent TECO command sets and key bindings at MIT, and completed by RMS.

Many people have said that TECO code looks a lot like line noise; you can read more on Wikipedia. Someone has written a TECO implementation in Emacs Lisp (to find it, see Where can I get Emacs Lisp packages that don’t come with Emacs?); it would be an interesting project to run the original TECO Emacs inside of Emacs.

For some not-so-serious alternative reasons for Emacs to have that name, check out the file etc/JOKES (see What are src/config.h, site-lisp/default.el, etc.?).

4.2 What is the latest version of Emacs?

Emacs 29.1.90 is the current version as of this writing. A version number with two components (e.g., ‘28.1’) indicates a released version; three components indicate a development version (e.g., ‘29.0.50’ is what will eventually become ‘29.1’).

Emacs is under active development, hosted at Savannah. Follow the instructions given there to clone the project repository.

Because Emacs undergoes many changes before a release, the version number of a development version is not especially meaningful. It is better to refer to the date on which the sources were retrieved from the development repository. The development version is usually quite robust for every-day use, but if stability is more important to you than the latest features, you may want to stick to the releases.

The following sections list some of the major new features in the last few Emacs releases. For full details of the changes in any version of Emacs, type C-h C-n (M-x view-emacs-news). You can give this command a prefix argument to read about which features were new in older versions.

4.3 What is different about Emacs 29?

Here’s a list of the most important changes in Emacs 29 as compared to Emacs 28 (the full list is too long, and can be read in the Emacs NEWS file by typing C-h n inside Emacs).

• Emacs can now be built with the tree-sitter library, which provides incremental parsing capabilities for several programming languages. Emacs comes with several major modes which use this library for syntax highlighting (a.k.a. “fontification”), indentation, Imenu support, etc. These modes have names lang-ts-mode, where lang is the programming language. For example, c-ts-mode, ruby-ts-mode, etc. There are several new font-lock faces, such as font-lock-number-face and font-lock-operator-face, intended to be used with these modes.
• Emacs can now be built in the PGTK (“pure GTK”) configuration, which supports running Emacs on window systems other than X, such as Wayland and Broadway.
• Emacs now has built-in support for accessing SQLite databases. This requires Emacs to be built with the optional sqlite3 library.
• Emacs comes with the popular use-package package bundled.
• Emacs can now display WebP images, if it was built with the optional libwebp library.
• On X window system, Emacs now supports the XInput2 specification for input events.
• Emacs now comes with a client library for using Language Server Protocol (LSP) servers. This library, named eglot.el (the name stands for “Emacs polyGlot”) provides LSP support for various software development and maintenance features, such as xref, Imenu, ElDoc, etc.
• Emacs can now cope with files with very long lines much better. It no longer hangs when displaying such long lines, and allows reasonably-responsive editing when such lines are present in the visible portion of a buffer.
• Emacs now supports the latest version 15.0 of the Unicode Standard.
• The new mode pixel-scroll-precision-mode allows precise and smooth scrolling of the display at pixel resolution, if your mouse supports this.
• Emacs now supports 24-bit true colors on more terminals.
• On capable X terminal emulators, Emacs now supports setting the X primary selection on TTY frames.
• New convenient commands are now available for inserting, searching, listing, and describing Emoji. These commands are on the C-x 8 e prefix key. The commands C-u C-x = (what-cursor-position) and M-x describe-char now show the names of Emoji sequences at point.
• The Help commands were enhanced:
  • - M-x apropos-variable shows the values of the matching variables.
  • - C-h b activates outline-minor-mode in the buffer, which makes it easier to browse long lists of key bindings.
  • - I in the *Help* buffer displays the corresponding documentation in the Emacs Lisp Reference manual.
  • - New command help-quick displays a buffer with overview of common Help commands.
• Outline Minor mode uses buttons to hide and show outlines.
• Deleted frames can now be undeleted using C-x 5 u, if the optional undelete-frame-mode is enabled.
• You can now delete the entire composed sequence of characters with Delete and edits the composed sequence by turning on the composition-break-at-point option.
• Support is added for many old scripts and writing systems, such as Tai Tham, Brahmi, Tirhuta, Modi, Lepcha, and many others.
• New translations of the Emacs tutorial: Ukrainian and Greek.
• New major modes for Typescript, Csharp, CMake, Go, Rust, and Yaml.

4.4 What is different about Emacs 28?

Emacs 28 has too many new features and changes to list all of them here. We list below a small selection; consult the Emacs NEWS file (C-h n) for the full list of changes in Emacs 28.

• Emacs now optionally supports native compilation of Lisp files. This can improves performance significantly in some cases. To enable this, configure Emacs with the --with-native-compilation option.
• The new NonGNU ELPA archive is enabled by default alongside GNU ELPA. Thus, packages on NonGNU ELPA will appear by default in the list shown by the list-packages command.
• The Cairo graphics library is now used by default if present.
• On GNU/Linux, Emacs now supports loading Secure Computing filters. To use this feature, invoke Emacs with the --seccomp=file command-line switch, where file names a binary file that defines the filtering. See the manual page of the seccomp system call for more details.
• The new themes ‘modus-vivendi’ and ‘modus-operandi’ have been added. They are designed to conform with the highest standard for color-contrast accessibility (WCAG AAA).
• On capable systems, Emacs now correctly displays Emoji and Emoji sequences by default, provided that a suitable font is available.
• New system for displaying documentation for groups of functions (M-x shortdoc-display-group RET).
• Emacs can now support 24-bit color text-mode terminals even if their terminfo database doesn’t state this support in a standard way. Set the COLORTERM environment variable to the value ‘truecolor’ to activate this.
• The strike-through face attribute is now supported on capable text-mode terminals.
• xterm-mouse-mode supports TTY menus.
• A new minor mode context-menu-mode causes mouse-3 (a.k.a. “right-clicks”) of the mouse to pop up context-dependent menus.
• Prefix commands to control the display of the results of the next command. C-x 4 4 command displays the result of command in a new window. C-x 5 5 command displays the results of command in a new frame.
• Emacs now supports “transient” input methods. A transient input method is enabled for inserting a single character, and is then automatically disabled. Select a transient input method with C-u C-x \; enable it (for inserting a single character) with C-x \. New input methods compose (based on X Window System Multi_key sequences) and iso-transl are especially convenient with this feature, when you need to insert a single special character.
• M-y, when invoked after a command that is not a yank command, allows selection of one of the previous kills.
• New minor mode repeat-mode allows to repeat commands with fewer keystrokes.
• Among the many internal changes in this release, we would like to highlight that all files in the tree now use lexical-binding.

4.5 What is different about Emacs 27?

• Emacs now uses the GNU Multiple Precision (GMP) library to support integers whose size is too large to support natively. The integers supported natively are known as “fixnums”, while the larger ones are “bignums”. All the arithmetic, comparison, and logical (also known as “bitwise”) operations where bignums make sense now support both fixnums and bignums.
• Emacs now uses HarfBuzz as its default shaping engine.
• Native support for JSON parsing that is much faster than json.el.
• Cairo drawing is no longer experimental.
• Emacs now uses a “portable dumper” instead of unexec. This improves compatibility with memory allocation on modern systems, and in particular better supports the Address Space Layout Randomization (ASLR) feature, a security technique used by most modern operating systems.
• Emacs can now use the XDG convention for init files.
• Emacs can now be configured using an early init file. The primary purpose is to allow customizing how the package system is initialized given that initialization now happens before loading the regular init file.
• Built-in support for tabs (tab bar and tab line).
• Support for resizing and rotating of images without ImageMagick.

Consult the Emacs NEWS.27 file for the full list of changes in Emacs 27.

4.6 What is different about Emacs 26?

• Emacs now provides a limited form of concurrency with Lisp threads.
• Emacs now supports systemd. The new command-line option --fg-daemon is part of this support, it causes Emacs to run in the foreground instead of forking, as under --daemon.
• Emacs now supports 24-bit true color on text terminals which provide that feature. See How do I get colors and syntax highlighting on a TTY?.
• Emacs on X now supports double-buffering, which eliminates display flickering in most situations.
• You can now scroll the Emacs display horizontally using the mouse or touchpad.
• Emacs display now includes an optional feature for display of line numbers via the display-line-numbers-mode command. This feature is much faster than the equivalent display offered by packages such as linum, and also provides many optional features like relative line numbers.
• The automatic horizontal scrolling of the window display when lines are truncated can now optionally be enabled only for the current line, the line where Emacs shows the cursor. Under this mode, all the other window lines are not scrolled to show characters outside of the viewport.
• Letter-case conversions now honor special cases in Turkish and Greek scripts.
• Support for Enchant is now part of the Emacs spell-checking commands.
• Tramp now supports Google Drive filesystems.
• Emacs can now be built while omitting the details of the machine on which it was built, thus making it easier to produce reproducible builds.
• Security vulnerability related to Enriched Text mode is removed. Enriched mode previously allowed saving display properties as part of text; those properties support evaluating arbitrary Lisp code, which opens a vulnerability for Emacs users receiving Enriched Text from external sources. Execution of arbitrary Lisp forms in display properties decoded by Enriched Text mode is now disabled by default.
• Emacs 26.2 comes with data files imported from the latest Unicode Standard version 11.0.0.

Consult the Emacs NEWS.26 file for the full list of changes in Emacs 26.

4.7 What is different about Emacs 25?

• Emacs can now embed native widgets inside Emacs buffers, if you have gtk3 and webkitgtk3 installed. E.g., to access the embedded webkit browser widget, type M-x xwidget-webkit-browse-url.
• Emacs can now dynamically load external modules compiled as shared libraries.
• C-x 8 has new shorthands for several popular characters, type C-x 8 C-h to list shorthands.
• A new minor mode global-eldoc-mode is enabled by default, and shows in the echo area or in the mode line the argument list of the Emacs Lisp form at point.
• On text terminals that support the “bracketed paste mode” Emacs now uses that mode by default. This mode allows Emacs to distinguish between pasted text and text typed by the user.
• Emacs 25 comes with data files imported from the latest Unicode Standard version 9.0.0.
• The support for bidirectional editing was updated to include all the features mandated by the latest Unicode Standard version 9.0.0.
• Search command can now perform character folding in matches. This is analogous to case folding, but instead of disregarding case variants, it disregards wider classes of distinctions between similar characters, such as matching different variants of double quote characters, ignoring diacritics, etc.
• The Emacs Web Browser EWW was extended to render text using variable-pitch fonts, and got other new features.
• Rmail can now render HTML mail messages, if Emacs is built with libxml2 or if you have the Lynx browser installed.
• VC now has basic support for push commands, implemented for Bzr, Git, and Hg.
• Hide-IfDef mode now support full C/C++ expressions in macros, macro argument expansion, interactive macro evaluation and automatic scanning of #defined symbols.
• New package Xref replaces Etags’s front-end and UI. Xref provides a generic framework and new commands to find and move to definitions of functions, macros, data structures etc., as well as go back to the location where you were before moving to a definition. It supersedes and obsoletes many Etags commands, while still using the etags.el code that reads the TAGS tables as one of its back-ends. As result, the popular key bindings M-. and M-, have been changed to invoke Xref commands.
• The new package Project provides generic infrastructure for dealing with projects.
• Emacs can now draw horizontal scroll bars on some platforms that provide toolkit scroll bars, namely Gtk+, Lucid, Motif and Windows.

Consult the Emacs NEWS.25 file for the full list of changes in Emacs 25.

4.8 What is different about Emacs 24?

• Emacs now includes a package manager. Type M-x list-packages to get started. You can use this to download and automatically install many more Lisp packages.
• Emacs Lisp now supports lexical binding on a per-file basis. In lexical binding, variable references must be located textually within the binding construct. This contrasts with dynamic binding, where programs can refer to variables defined outside their local textual scope. A Lisp file can use a local variable setting of lexical-binding: t to indicate that the contents should be interpreted using lexical binding. See the Emacs Lisp Reference Manual for more details.
• Some human languages, such as English, are written from left to right. Others, such as Arabic, are written from right to left. Emacs now has support for any mixture of these forms—this is “bidirectional text”.
• Handling of text selections has been improved, and now integrates better with external clipboards.
• A new command customize-themes allows you to easily change the appearance of your Emacs.
• Emacs can be compiled with the GTK+ 3 toolkit.
• Support for several new external libraries can be included at compile time:
  • “Security-Enhanced Linux” (SELinux) is a Linux kernel feature that provides more sophisticated file access controls than ordinary “Unix-style” file permissions.
  • The ImageMagick display library. This allows you to display many more image format in Emacs, as well as carry out transformations such as rotations.
  • The GnuTLS library for secure network communications. Emacs uses this transparently for email if your mail server supports it.
  • The libxml2 library for parsing XML structures.
• Much more flexibility in the handling of windows and buffer display.

Consult the Emacs NEWS.24 file for the full list of changes in Emacs 24.

4.9 What is different about Emacs 23?

• Emacs has a new font code that can use multiple font backends, including freetype and fontconfig. Emacs can use the Xft library for anti-aliasing, and the otf and m17n libraries for complex text layout and text shaping.
• The Emacs character set is now a superset of Unicode. Several new language environments have been added.
• Emacs now supports using both X displays and ttys in the same session (‘multi-tty’).
• Emacs can be started as a daemon in the background.
• There is a new NeXTstep port of Emacs. This supports GNUstep and Mac OS X (via the Cocoa libraries). The Carbon port of Emacs, which supported Mac OS X in Emacs 22, has been removed.
• Directory-local variables can now be defined, in a similar manner to file-local variables.
• Transient Mark mode is on by default.

Other changes include: support for serial port access; D-Bus bindings; a new Visual Line mode for line-motion; improved completion; a new mode (‘DocView’) for viewing of PDF, PostScript, and DVI documents; nXML mode (for editing XML documents) is included; VC has been updated for newer version control systems; etc.

Consult the Emacs NEWS.23 file for the full list of changes in Emacs 23.

4.10 What is different about Emacs 22?

• Emacs can be built with GTK+ widgets, and supports drag-and-drop operation on X.
• Emacs 22 features support for GNU/Linux systems on S390 and x86-64 machines, as well as support for the Mac OS X and Cygwin operating systems.
• The native MS-Windows, and Mac OS X builds include full support for images, toolbar, and tooltips.
• Font Lock mode, Auto Compression mode, and File Name Shadow Mode are enabled by default.
• The maximum size of buffers is increased: on 32-bit machines, it is 256 MBytes for Emacs 23.1, and 512 MBytes for Emacs 23.2 and above.
• Links can be followed with mouse-1, in addition to mouse-2.
• Mouse wheel support is enabled by default.
• Window fringes are customizable.
• The mode line of the selected window is now highlighted.
• The minibuffer prompt is displayed in a distinct face.
• Abbrev definitions are read automatically at startup.
• Grep mode is separate from Compilation mode and has many new options and commands specific to grep.
• The original Emacs macro system has been replaced by the new Kmacro package, which provides many new commands and features and a simple interface that uses the function keys F3 and F4. Macros are stored in a macro ring, and can be debugged and edited interactively.
• The Grand Unified Debugger (GUD) can be used with a full graphical user interface to GDB; this provides many features found in traditional development environments, making it easy to manipulate breakpoints, add watch points, display the call stack, etc. Breakpoints are visually indicated in the source buffer.
• Many new modes and packages have been included in Emacs, such as Calc, TRAMP, URL, IDO, CUA, ERC, rcirc, Table, Image-Dired, SES, Ruler, Org, PGG, Flymake, Password, Printing, Reveal, wdired, t-mouse, longlines, savehist, Conf mode, Python mode, DNS mode, etc.
• Leim is now part of Emacs. Unicode support has been much improved, and the following input methods have been added: belarusian, bulgarian-bds, bulgarian-phonetic, chinese-sisheng, croatian, dutch, georgian, latin-alt-postfix, latin-postfix, latin-prefix, latvian-keyboard, lithuanian-numeric, lithuanian-keyboard, malayalam-inscript, rfc1345, russian-computer, sgml, slovenian, tamil-inscript, ucs, ukrainian-computer, vietnamese-telex, and welsh.

  The following language environments have also been added: Belarusian, Bulgarian, Chinese-EUC-TW, Croatian, French, Georgian, Italian, Latin-6, Latin-7, Latvian, Lithuanian, Malayalam, Russian, Slovenian, Swedish, Tajik, Tamil, UTF-8, Ukrainian, Welsh, and Windows-1255.

• In addition, Emacs 22 now includes the Emacs Lisp Reference Manual (see Where can I get documentation on Emacs Lisp?) and the Emacs Lisp Intro.

Consult the Emacs NEWS.22 file for the full list of changes in Emacs 22.

4.11 What is different about Emacs 21?

Emacs 21 features a thorough rewrite of the display engine. The new display engine supports variable-size fonts, images, and can play sounds on platforms which support that. As a result, the visual appearance of Emacs, when it runs on a windowed display, is much more reminiscent of modern GUI programs, and includes 3D widgets (used for the mode line and the scroll bars), a configurable and extensible toolbar, tooltips (a.k.a. balloon help), and other niceties.

In addition, Emacs 21 supports faces on text-only terminals. This means that you can now have colors when you run Emacs on a GNU/Linux console and on xterm with emacs -nw.

Consult the Emacs NEWS.21 file for the full list of changes in Emacs 21.

4.12 What is different about Emacs 20?

The differences between Emacs versions 18 and 19 were rather dramatic; the introduction of frames, faces, and colors on windowing systems was obvious to even the most casual user.

There are differences between Emacs versions 19 and 20 as well, but many are more subtle or harder to find. Among the changes are the inclusion of MULE code for languages that use non-Latin characters and for mixing several languages in the same document; the “Customize” facility for modifying variables without having to use Lisp; and automatic conversion of files from Macintosh, Microsoft, and Unix platforms.

Consult the Emacs NEWS.20 file for the full list of changes in Emacs 20.

4.13 What was XEmacs?

XEmacs was a branch version of Emacs that is no longer actively developed. Originally known as “Lucid Emacs”, XEmacs was forked from a prerelease version of Emacs 19. XEmacs last released a new version on January 30, 2009, which lacks many important features that exist in Emacs. Since its development has stopped, we do not expect to see any new releases.

In the past, it was not uncommon for Emacs packages to include code for compatibility with XEmacs. Nowadays, most built-in and third party packages have either stopped supporting XEmacs or were developed exclusively for Emacs.

If you want to talk about these two versions and distinguish them, please call them “Emacs” and “XEmacs.” To contrast “XEmacs” with “GNU Emacs” would be misleading, since XEmacs too has its origin in the work of the GNU Project. Terms such as “Emacsen” and “(X)Emacs” are not wrong, but they are not very clear, so it is better to write “Emacs and XEmacs.”

5.1 How do I set up an init file properly?

When Emacs is started, it normally tries to load a Lisp program from an initialization file, or init file for short. This file, if it exists, specifies how to initialize Emacs for you. Traditionally, file ~/.emacs is used as the init file, although Emacs also looks at ~/.emacs.el, ~/.emacs.d/init.el, ~/.config/emacs/init.el, or other locations. See Init File in The GNU Emacs Manual.

Emacs includes the Customize facility (see How do I start using Customize?). This allows users who are unfamiliar with Emacs Lisp to modify their init files in a relatively straightforward way, using menus rather than Lisp code.

While Customize might indeed make it easier to configure Emacs, consider taking a bit of time to learn Emacs Lisp and modifying your init file directly. Simple configuration options are described rather completely in Init File in The GNU Emacs Manual, for users interested in performing frequently requested, basic tasks.

In general, new Emacs users should not be provided with init files, because this can cause confusing non-standard behavior. Then they send questions to the help-gnu-emacs mailing list asking why Emacs isn’t behaving as documented.

5.2 How do I start using Customize?

The main Customize entry point is M-x customize RET. This command takes you to a buffer listing all the available Customize groups. From there, you can access all customizable options and faces, change their values, and save your changes to your init file. See Easy Customization in The GNU Emacs Manual.

If you know the name of the group in advance (e.g., “shell”), use M-x customize-group RET.

If you wish to customize a single option, use M-x customize-option RET. This command prompts you for the name of the option to customize, with completion.

5.3 How do I get colors and syntax highlighting on a TTY?

Colors and faces are supported in non-windowed mode, i.e., on Unix and GNU/Linux text-only terminals and consoles, and when invoked as ‘emacs -nw’ on X, MS-DOS and MS-Windows. Emacs automatically detects color support at startup and uses it if available. If you think that your terminal supports colors, but Emacs won’t use them, check the termcap entry for your display type for color-related capabilities.

The command M-x list-colors-display pops up a window which exhibits all the colors Emacs knows about on the current display.

Syntax highlighting is also on by default on text-only terminals.

Emacs 26.1 and later support direct color mode in terminals. If Emacs finds Terminfo capabilities ‘setb24’ and ‘setf24’, 24-bit direct color mode is used. The capability strings are expected to take one 24-bit pixel value as argument and transform the pixel to a string that can be used to send 24-bit colors to the terminal.

Standard terminal definitions don’t support these capabilities and therefore custom definition is needed.

$ cat terminfo-custom.src

xterm-emacs|xterm with 24-bit direct color mode for Emacs,
  use=xterm-256color,
  setb24=\E[48\:2\:\:%p1%{65536}%/%d\:%p1%{256}%/%{255}%&\
     %d\:%p1%{255}%&%dm,
  setf24=\E[38\:2\:\:%p1%{65536}%/%d\:%p1%{256}%/%{255}%&\
     %d\:%p1%{255}%&%dm,

$ tic -x -o ~/.terminfo terminfo-custom.src

$ TERM=xterm-emacs emacs -nw

Emacs 27.1 and later support Terminfo capability ‘RGB’ for detecting 24-bit direct color mode. Multiple standard terminal definitions support this capability.

$ TERM=xterm-direct infocmp | grep seta[bf]

  setab=\E[%?%p1%{8}%<%t4%p1%d%e48\:2\:\:%p1%{65536}%/\
     %d\:%p1%{256}%/%{255}%&%d\:%p1%{255}%&%d%;m,
  setaf=\E[%?%p1%{8}%<%t3%p1%d%e38\:2\:\:%p1%{65536}%/\
     %d\:%p1%{256}%/%{255}%&%d\:%p1%{255}%&%d%;m,

$ TERM=xterm-direct emacs -nw

If your terminal is incompatible with XTerm, you may have to use another TERM definition. Any terminal whose name includes ‘direct’ should be a candidate. The toe command can be used to find out which of these are installed on your system:

$ toe | grep '\-direct'

konsole-direct  konsole with direct-color indexing
vte-direct      vte with direct-color indexing
st-direct       st with direct-color indexing
xterm-direct2   xterm with direct-color indexing (old)
xterm-direct    xterm with direct-color indexing

If Terminfo database is not available, but 24-bit direct color mode is supported, it can still be enabled by defining the environment variable COLORTERM to ‘truecolor’.

Terminals with ‘RGB’ capability treat pixels #000001 - #000007 as indexed colors to maintain backward compatibility with applications that are unaware of direct color mode. Therefore the seven darkest blue shades may not be available. If this is a problem, you can always use custom terminal definition with ‘setb24’ and ‘setf24’.

5.4 How do I debug an init file?

Start Emacs with the ‘-debug-init’ command-line option. This enables the Emacs Lisp debugger before evaluating your init file, and places you in the debugger if something goes wrong. The top line in the trace-back buffer will be the error message, and the second or third line of that buffer will display the Lisp code from your init file that caused the problem.

You can also evaluate an individual function or argument to a function in your init file by moving the cursor to the end of the function or argument and typing C-x C-e (M-x eval-last-sexp).

Use C-h v (M-x describe-variable) to check the value of variables which you are trying to set or use.

5.5 How do I make Emacs display the current line (or column) number?

By default, Emacs displays the current line number of the point in the mode line. You can toggle this feature off or on with the command M-x line-number-mode, or by setting the variable line-number-mode. Note that Emacs will not display the line number if the buffer’s size in bytes is larger than the value of the variable line-number-display-limit.

You can similarly display the current column with M-x column-number-mode, or by putting the form

(setq column-number-mode t)

in your init file (see How do I set up an init file properly?). This feature is off by default.

The "%c" format specifier in the variable mode-line-format will insert the current column’s value into the mode line. See the documentation for mode-line-format (using C-h v mode-line-format RET) for more information on how to set and use this variable.

The ‘display-line-numbers’ package (added to Emacs in version 26.1) displays line numbers in the text area, before each line, like the “set number” capability of ‘vi’. Customize the buffer-local variable display-line-numbers to activate this optional display. Alternatively, you can use the display-line-numbers-mode minor mode or the global global-display-line-numbers-mode. When using these modes, customize display-line-numbers-type with the same value as you would use with display-line-numbers.

5.6 How can I modify the titlebar to contain the current file name?

The contents of an Emacs frame’s titlebar is controlled by the variable frame-title-format, which has the same structure as the variable mode-line-format. (Use C-h v or M-x describe-variable to get information about one or both of these variables.)

By default, the titlebar for a frame does contain the name of the buffer currently being visited, except if there is a single frame. In such a case, the titlebar contains Emacs invocation name and the name of the machine at which Emacs was invoked. This is done by setting frame-title-format to the default value of

(multiple-frames "%b" ("" "%b - GNU Emacs at " system-name))

To modify the behavior such that frame titlebars contain the buffer’s name regardless of the number of existing frames, include the following in your init file (see How do I set up an init file properly?):

(setq frame-title-format "%b")

5.7 How do I turn on abbrevs by default just in mode mymode?

Abbrev mode expands abbreviations as you type them. To turn it on in a specific buffer, use M-x abbrev-mode. To turn it on in every buffer by default, put this in your init file (see How do I set up an init file properly?):

(setq-default abbrev-mode t)

To turn it on in a specific mode, use:

(add-hook 'mymode-mode-hook
          (lambda ()
           (setq abbrev-mode t)))

5.8 How do I make Emacs use a certain major mode for certain files?

If you want to use a certain mode foo for all files whose names end with the extension .bar, this will do it for you:

(add-to-list 'auto-mode-alist '("\\.bar\\'" . foo-mode))

Alternatively, put this somewhere in the first line of any file you want to edit in the mode foo (in the second line, if the first line begins with ‘#!’):

-*- foo -*-

The variable interpreter-mode-alist specifies which mode to use when loading an interpreted script (e.g., shell, python, etc.). Emacs determines which interpreter you’re using by examining the first line of the script. Use C-h v (or M-x describe-variable) on interpreter-mode-alist to learn more.

5.9 How can I replace highlighted text with what I type?

Use delete-selection-mode, which you can start automatically by placing the following Lisp form in your init file (see How do I set up an init file properly?):

(delete-selection-mode 1)

According to the documentation string for delete-selection-mode (which you can read using M-x describe-function RET delete-selection-mode RET):

When Delete Selection mode is enabled, typed text replaces the selection if the selection is active. Otherwise, typed text is just inserted at point regardless of any selection.

This mode also allows you to delete (not kill) the highlighted region by pressing DEL.

5.10 How do I control Emacs’s case-sensitivity when searching/replacing?

The value of the variable case-fold-search determines whether searches are case sensitive:

(setq case-fold-search nil) ; make searches case sensitive
(setq case-fold-search t)   ; make searches case insensitive

Similarly, for replacing, the variable case-replace determines whether replacements preserve case.

You can also toggle case sensitivity at will in isearch with M-c.

To change the case sensitivity just for one major mode, use the major mode’s hook. For example:

(add-hook 'foo-mode-hook
          (lambda ()
           (setq case-fold-search nil)))

5.11 How do I search for, delete, or replace unprintable (eight-bit or control) characters?

To search for a single character that appears in the buffer as, for example, ‘\237’, you can type C-s C-q 2 3 7. Searching for all unprintable characters is best done with a regular expression (regexp) search. The easiest regexp to use for the unprintable chars is the complement of the regexp for the printable chars.

• Regexp for the printable chars: ‘[\t\n\r\f -~]’
• Regexp for the unprintable chars: ‘[^\t\n\r\f -~]’

To type these special characters in an interactive argument to isearch-forward-regexp or re-search-forward, you need to use C-q. (‘\t’, ‘\n’, ‘\r’, and ‘\f’ stand respectively for TAB, LFD, RET, and C-l.) So, to search for unprintable characters using re-search-forward:

M-x re-search-forward RET [^ TAB C-q LFD C-q RET C-q C-l SPC -~] RET

Using isearch-forward-regexp:

C-M-s [^ TAB LFD C-q RET C-q C-l SPC -~]

To delete all unprintable characters, simply use replace-regexp:

M-x replace-regexp RET [^ TAB C-q LFD C-q RET C-q C-l SPC -~] RET RET

Replacing is similar to the above. To replace all unprintable characters with a colon, use:

M-x replace-regexp RET [^ TAB C-q LFD C-q RET C-q C-l SPC -~] RET : RET

5.12 How do I input a newline character in isearch or query-replace?

Use C-q C-j. For more information, see Special Input for Incremental Search in The GNU Emacs Manual.

5.13 How do I copy text from the kill ring into the search string?

Use M-y. See Isearch Yank in The GNU Emacs Manual.

5.14 How do I make Emacs wrap words for me?

Use auto-fill-mode, activated by typing M-x auto-fill-mode. The default maximum line width is 70, determined by the variable fill-column. To learn how to turn this on automatically, see How do I turn on auto-fill-mode by default?.

5.15 How do I turn on auto-fill-mode by default?

To turn on auto-fill-mode just once for one buffer, use M-x auto-fill-mode.

To turn it on for every buffer in a certain mode, you must use the hook for that mode. For example, to turn on auto-fill mode for all text buffers, including the following in your init file (see How do I set up an init file properly?):

(add-hook 'text-mode-hook 'turn-on-auto-fill)

If you want auto-fill mode on in all major modes, do this:

(setq-default auto-fill-function 'do-auto-fill)

5.16 How do I change load-path?

In general, you should only add to the load-path. You can add directory /dir/subdir to the load path like this:

(add-to-list 'load-path "/dir/subdir/")

To do this relative to your home directory:

(add-to-list 'load-path "~/mysubdir/")

5.17 How do I use an already running Emacs from another window?

emacsclient, which comes with Emacs, is for editing a file using an already running Emacs rather than starting up a new Emacs. It does this by sending a request to the already running Emacs, which must be expecting the request.

• Setup:

  Emacs must have executed the server-start function for ‘emacsclient’ to work. This can be done either by a command line option:

  emacs -f server-start
  

  or by invoking server-start from init file (see How do I set up an init file properly?):

  (if (some conditions are met) (server-start))
  

  To get your news reader, mail reader, etc., to invoke ‘emacsclient’, try setting the environment variable EDITOR (or sometimes VISUAL) to the value ‘emacsclient’. You may have to specify the full pathname of the ‘emacsclient’ program instead. Examples:

  # csh commands:
  setenv EDITOR emacsclient
  
  # using full pathname
  setenv EDITOR /usr/local/emacs/etc/emacsclient
  
  # sh command:
  EDITOR=emacsclient ; export EDITOR
  

• Normal use:

  When ‘emacsclient’ is run, it connects to the socket and passes its command line options to Emacs, which at the next opportunity will visit the files specified. (Line numbers can be specified just like with Emacs.) The user will have to switch to the Emacs window by hand. When the user is done editing a file, the user can type C-x # (or M-x server-edit) to indicate this. If there is another buffer requested by emacsclient, Emacs will switch to it; otherwise emacsclient will exit, signaling the calling program to continue.

For more information, See Emacs Server in The GNU Emacs Manual.

5.18 How do I make Emacs recognize my compiler’s funny error messages?

Customize the compilation-error-regexp-alist variable.

5.19 How do I change the indentation for switch?

Many people want to indent their switch statements like this:

f()
{
  switch(x) {
    case A:
      x1;
      break;
    case B:
      x2;
      break;
    default:
      x3;
  }
}

To achieve this, add the following line to your init file (see How do I set up an init file properly?):

(c-set-offset 'case-label '+)

5.20 How to customize indentation in C, C++, and Java buffers?

The Emacs cc-mode features an interactive procedure for customizing the indentation style, which is fully explained in the CC Mode manual that is part of the Emacs distribution, see Customization Indentation in The CC Mode Manual. Here’s a short summary of the procedure:

1. Go to the beginning of the first line where you don’t like the indentation and type C-c C-o. Emacs will prompt you for the syntactic symbol; type RET to accept the default it suggests.
2. Emacs now prompts for the offset of this syntactic symbol, showing the default (the current definition) inside parentheses. You can choose one of these:

   0

   No extra indentation.

   +

   Indent one basic offset.

   -

   Outdent one basic offset.

   ++

   Indent two basic offsets

   --

   Outdent two basic offsets.

   *

   Indent half basic offset.

   /

   Outdent half basic offset.

3. After choosing one of these symbols, type C-c C-q to reindent the line or the block according to what you just specified.
4. If you don’t like the result, go back to step 1. Otherwise, add the following line to your init file (see How do I set up an init file properly?):

   (c-set-offset 'syntactic-symbol offset)
   

   where syntactic-symbol is the name Emacs shows in the minibuffer when you type C-c C-o at the beginning of the line, and offset is one of the indentation symbols listed above (+, /, 0, etc.) that you’ve chosen during the interactive procedure.

5. Go to the next line whose indentation is not to your liking and repeat the process there.

It is recommended to put all the resulting (c-set-offset ...) customizations inside a C mode hook, like this:

(defun my-c-mode-hook ()
  (c-set-offset ...)
  (c-set-offset ...))
(add-hook 'c-mode-hook 'my-c-mode-hook)

Using c-mode-hook avoids the need to put a (require 'cc-mode) into your init file, because c-set-offset might be unavailable when cc-mode is not loaded.

Note that c-mode-hook runs for C source files only; use c++-mode-hook for C++ sources, java-mode-hook for Java sources, etc. If you want the same customizations to be in effect in all languages supported by cc-mode, use c-mode-common-hook.

5.21 How do I make Emacs “typeover” or “overwrite” instead of inserting?

M-x overwrite-mode (a minor mode). This toggles overwrite-mode on and off, so exiting from overwrite-mode is as easy as another M-x overwrite-mode.

On some systems, Insert toggles overwrite-mode on and off.

5.22 How do I stop Emacs from beeping on a terminal?

Martin R. Frank writes:

Tell Emacs to use the visible bell instead of the audible bell, and set the visible bell to nothing.

That is, put the following in your TERMCAP environment variable (assuming you have one):

... :vb=: ...

And evaluate the following Lisp form:

(setq visible-bell t)

5.23 How do I turn down the bell volume in Emacs running under X?

On X Window system, you can adjust the bell volume and duration for all programs with the shell command xset.

Invoking xset without any arguments produces some basic information, including the following:

usage:  xset [-display host:dpy] option ...
  To turn bell off:
      -b                b off               b 0
  To set bell volume, pitch and duration:
       b [vol [pitch [dur]]]          b on

5.24 How do I tell Emacs to automatically indent a new line to the indentation of the previous line?

Such behavior is automatic (in Text mode). From the etc/NEWS file for Emacs 20.2:

** In Text mode, now only blank lines separate paragraphs.  This makes
it possible to get the full benefit of Adaptive Fill mode in Text mode,
and other modes derived from it (such as Mail mode).  TAB in Text
mode now runs the command indent-relative; this makes a practical
difference only when you use indented paragraphs.

If you want spaces at the beginning of a line to start a paragraph, use
the new mode, Paragraph Indent Text mode.

If you have auto-fill-mode turned on (see How do I turn on auto-fill-mode by default?), you can tell Emacs to prefix every line with a certain character sequence, the fill prefix. Type the prefix at the beginning of a line, position point after it, and then type C-x . (set-fill-prefix) to set the fill prefix. Thereafter, auto-filling will automatically put the fill prefix at the beginning of new lines, and M-q (fill-paragraph) will maintain any fill prefix when refilling the paragraph.

If you have paragraphs with different levels of indentation, you will have to set the fill prefix to the correct value each time you move to a new paragraph. There are many packages available to deal with this (see Where can I get Emacs Lisp packages that don’t come with Emacs?). Look for “fill” and “indent” keywords for guidance.

5.25 How do I show which parenthesis matches the one I’m looking at?

By default, show-paren-mode is enabled in all editing buffers.

Alternatives to this mode include:

• If you’re looking at a right parenthesis (or brace or bracket) you can delete it and reinsert it. Emacs will momentarily move the cursor to the matching parenthesis.
• C-M-f (forward-sexp) and C-M-b (backward-sexp) will skip over one set of balanced parentheses, so you can see which parentheses match. (You can train it to skip over balanced brackets and braces at the same time by modifying the syntax table.)
• Here is some Emacs Lisp that will make the % key show the matching parenthesis, like in vi. In addition, if the cursor isn’t over a parenthesis, it simply inserts a % like normal.

  ;; By an unknown contributor
  
  (global-set-key "%" 'match-paren)
  
  (defun match-paren (arg)
    "Go to the matching paren if on a paren; otherwise insert %."
    (interactive "p")
    (cond ((looking-at "\\s(") (forward-list 1) (backward-char 1))
          ((looking-at "\\s)") (forward-char 1) (backward-list 1))
          (t (self-insert-command (or arg 1)))))
  

5.26 In C mode, can I show just the lines that will be left after #ifdef commands are handled by the compiler?

M-x hide-ifdef-mode. (This is a minor mode.) You might also want to investigate cpp.el, which is distributed with Emacs.

5.27 How do I repeat a command as many times as possible?

Use the repeat command (C-x z) to repeat the last command. If you preface it with a prefix argument, the prefix arg is applied to the command.

You can also type C-x ESC ESC (repeat-complex-command) to reinvoke commands that used the minibuffer to get arguments. In repeat-complex-command you can type M-p and M-n (and also up-arrow and down-arrow, if your keyboard has these keys) to scan through all the different complex commands you’ve typed.

To repeat a set of commands, use keyboard macros. Use C-x ( and C-x ) to make a keyboard macro that invokes the command and then type C-x e. See Keyboard Macros in The GNU Emacs Manual.

If you’re really desperate for the . command in vi that redoes the last insertion/deletion, use VIPER, a vi emulation mode which comes with Emacs, and which appears to support it.

5.28 What are the valid X resource settings (i.e., stuff in .Xdefaults)?

See X Resources in The GNU Emacs Manual.

You can also use a resource editor, such as editres (for X11R5 and onwards), to look at the resource names for the menu bar, assuming Emacs was compiled with the X toolkit.

5.29 How do I execute (“evaluate”) a piece of Emacs Lisp code?

There are a number of ways to execute (evaluate, in Lisp lingo) an Emacs Lisp form:

• If you want it evaluated every time you run Emacs, put it in a file named .emacs.d/init.el in your home directory. This is known as “your init file,” and contains all of your personal customizations (see How do I set up an init file properly?).
• You can type the form in the *scratch* buffer, and then type LFD (or C-j) after it. The result of evaluating the form will be inserted in the buffer.
• In emacs-lisp-mode, typing C-M-x evaluates a top-level form before or around point.
• Typing C-x C-e in any buffer evaluates the Lisp form immediately before point and prints its value in the echo area.
• Typing M-: or M-x eval-expression allows you to type a Lisp form in the minibuffer which will be evaluated once you press RET.
• You can use M-x load-file to have Emacs evaluate all the Lisp forms in a file. (To do this from Lisp use the function load instead.)

  The functions load-library, eval-region, eval-buffer, require, and autoload are also useful; see Where can I get documentation on Emacs Lisp?, if you want to learn more about them.

5.30 How do I change Emacs’s idea of the TAB character’s length?

Set the default value of the variable tab-width. For example, to set TAB stops every 10 characters, insert the following in your init file (see How do I set up an init file properly?):

(setq-default tab-width 10)

Do not confuse variable tab-width with variable tab-stop-list. The former is used for the display of literal TAB characters. The latter controls what characters are inserted when you press the TAB character in certain modes.

5.31 How do I insert <some text> at the beginning of every line?

To do this to an entire buffer, type M-< M-x replace-regexp RET ^ RET your text RET.

To do this to a region, use string-insert-rectangle. Set the mark (C-SPC) at the beginning of the first line you want to prefix, move the cursor to last line to be prefixed, and type M-x string-insert-rectangle RET. To do this for the whole buffer, type C-x h M-x string-insert-rectangle RET.

If you are trying to prefix a yanked mail message with ‘>’, you might want to set the variable mail-yank-prefix. In Message buffers, you can even use M-; to cite yanked messages (M-; runs the function comment-region, it is a general-purpose mechanism to comment regions) (see How do I change the included text prefix in mail/news followups?).

5.32 How do I make Emacs behave like this: when I go up or down, the cursor should stay in the same column even if the line is too short?

Use M-x picture-mode.

See also the variable track-eol and the command set-goal-column bound to C-x C-n (see Moving Point in The GNU Emacs Manual).

5.33 How do I tell Emacs to iconify itself?

C-z iconifies Emacs when running under X and suspends Emacs otherwise. See Frame Commands in The GNU Emacs Manual.

5.34 How do I use regexps (regular expressions) in Emacs?

See Regexp Backslash in The GNU Emacs Manual.

The or operator is ‘\|’, not ‘|’, and the grouping operators are ‘\(’ and ‘\)’. Also, the string syntax for a backslash is ‘\\’. To specify a regular expression like ‘xxx\(foo\|bar\)’ in a Lisp string, use ‘xxx\\(foo\\|bar\\)’.

Note the doubled backslashes!

• Unlike in Unix grep, sed, etc., a complement character set (‘[^...]’) can match a newline character (LFD a.k.a. C-j a.k.a. ‘\n’), unless newline is mentioned as one of the characters not to match.
• The character syntax regexps (e.g., ‘\sw’) are not meaningful inside character set regexps (e.g., ‘[aeiou]’). (This is actually typical for regexp syntax.)

5.35 How do I perform a replace operation across more than one file?

Dired mode (M-x dired RET, or C-x d) supports the command dired-do-find-regexp-and-replace (Q), which allows users to replace regular expressions in multiple files.

You can use this command to perform search/replace operations on multiple files by following the following steps:

• Assemble a list of files you want to operate on with either find-dired, find-name-dired or find-grep-dired.
• Mark all files in the resulting Dired buffer using t.
• Use Q to start a query-replace-regexp session on the marked files.
• To accept all replacements in each file, hit !.

Another way to do the same thing is to use the “tags” feature of Emacs: it includes the command tags-query-replace which performs a query-replace across all the files mentioned in the TAGS file. See Identifier Search in The GNU Emacs Manual.

5.36 Where is the documentation for etags?

The etags man page should be in the same place as the emacs man page.

Quick command-line switch descriptions are also available. For example, ‘etags -H’.

5.37 How do I disable backup files?

You probably don’t want to do this, since backups are useful, especially when something goes wrong.

To avoid seeing backup files (and other “uninteresting” files) in Dired, load dired-x by adding the following to your init file (see How do I set up an init file properly?):

(with-eval-after-load 'dired
  (require 'dired-x))

With dired-x loaded, C-x M-o toggles omitting in each dired buffer. You can make omitting the default for new dired buffers by putting the following in your init file:

(add-hook 'dired-mode-hook 'dired-omit-mode)

If you’re tired of seeing backup files whenever you do an ‘ls’ at the Unix shell, try GNU ls with the ‘-B’ option. GNU ls is part of the GNU Fileutils package, available from https://ftp.gnu.org and its mirrors (see Where can I get other up-to-date GNU stuff?).

To disable or change the way backups are made, see Backup Names in The GNU Emacs Manual.

You can control where Emacs puts backup files by customizing the variable backup-directory-alist. This variable’s value specifies that files whose names match specific patterns should have their backups put in certain directories. A typical use is to add the element ("." . dir) to force Emacs to put all backup files in the directory dir.

5.38 How do I disable auto-save-mode?

You probably don’t want to do this, since auto-saving is useful, especially when Emacs or your computer crashes while you are editing a document.

Instead, you might want to change the variable auto-save-interval, which specifies how many keystrokes Emacs waits before auto-saving. Increasing this value forces Emacs to wait longer between auto-saves, which might annoy you less.

You might also want to look into Sebastian Kremer’s auto-save package (see Where can I get Emacs Lisp packages that don’t come with Emacs?). This package also allows you to place all auto-save files in one directory, such as /tmp.

To disable or change how auto-save-mode works, see Auto Save in The GNU Emacs Manual.

5.39 Making Emacs write all auxiliary files somewhere else

By default, Emacs may create many new files in the directory where you’re editing a file. If you’re editing the file /home/user/foo.txt, Emacs will create the lock file /home/user/.#foo.txt, the auto-save file /home/user/#foo.txt#, and when you save the file, Emacs will create the backup file /home/user/foo.txt~. (The first two files are deleted when you save the file.)

This may be inconvenient in some setups, so Emacs has mechanisms for changing the locations of all these files.

auto-save-file-name-transforms

(see Auto-Saving in GNU Emacs Lisp Reference Manual).

lock-file-name-transforms

(see File Locks in GNU Emacs Lisp Reference Manual).

backup-directory-alist

(see Making Backups in GNU Emacs Lisp Reference Manual).

For instance, to write all these things to ~/.emacs.d/aux/:

(setq lock-file-name-transforms
      '(("\\`/.*/\\([^/]+\\)\\'" "~/.emacs.d/aux/\\1" t)))
(setq auto-save-file-name-transforms
      '(("\\`/.*/\\([^/]+\\)\\'" "~/.emacs.d/aux/\\1" t)))
(setq backup-directory-alist
      '((".*" . "~/.emacs.d/aux/")))

5.40 How can I go to a certain line given its number?

Are you sure you indeed need to go to a line by its number? Perhaps all you want is to display a line in your source file for which a compiler printed an error message? If so, compiling from within Emacs using the M-x compile and M-x recompile commands is a much more effective way of doing that. Emacs automatically intercepts the compile error messages, inserts them into a special buffer called *compilation*, and lets you visit the locus of each message in the source. Type C-x ` to step through the offending lines one by one (you can also use M-g M-p and M-g M-n to go to the previous and next matches directly). Click mouse-2 or press RET on a message text in the *compilation* buffer to go to the line whose number is mentioned in that message.

But if you indeed need to go to a certain text line, type M-g M-g (which is the default binding of the goto-line function). Emacs will prompt you for the number of the line and go to that line.

You can do this faster by invoking goto-line with a numeric argument that is the line’s number. For example, C-u 286 M-g M-g will jump to line number 286 in the current buffer.

5.41 How can I create or modify new pull-down menu options?

Each menu title (e.g., ‘File’, ‘Edit’, ‘Buffers’) represents a local or global keymap. Selecting a menu title with the mouse displays that keymap’s non-nil contents in the form of a menu.

So to add a menu option to an existing menu, all you have to do is add a new definition to the appropriate keymap. Adding a ‘Forward Word’ item to the ‘Edit’ menu thus requires the following Lisp code:

(define-key global-map
  [menu-bar edit forward]
  '("Forward word" . forward-word))

The first line adds the entry to the global keymap, which includes global menu bar entries. Replacing the reference to global-map with a local keymap would add this menu option only within a particular mode.

The second line describes the path from the menu-bar to the new entry. Placing this menu entry underneath the ‘File’ menu would mean changing the word edit in the second line to file.

The third line is a cons cell whose first element is the title that will be displayed, and whose second element is the function that will be called when that menu option is invoked.

To add a new menu, rather than a new option to an existing menu, we must define an entirely new keymap:

(define-key global-map [menu-bar words]
  (cons "Words" (make-sparse-keymap "Words")))

The above code creates a new sparse keymap, gives it the name ‘Words’, and attaches it to the global menu bar. Adding the ‘Forward Word’ item to this new menu would thus require the following code:

(define-key global-map
  [menu-bar words forward]
  '("Forward word" . forward-word))

Note that because of the way keymaps work, menu options are displayed with the more recently defined items at the top. Thus if you were to define menu options ‘foo’, ‘bar’, and ‘baz’ (in that order), the menu option ‘baz’ would appear at the top, and ‘foo’ would be at the bottom.

One way to avoid this problem is to use the function define-key-after, which works the same as define-key, but lets you modify where items appear. The following Lisp code would insert the ‘Forward Word’ item in the ‘Edit’ menu immediately following the ‘Undo’ item:

(define-key-after
  (lookup-key global-map [menu-bar edit])
  [forward]
  '("Forward word" . forward-word)
  'undo)

Note how the second and third arguments to define-key-after are different from those of define-key, and that we have added a new (final) argument, the function after which our new key should be defined.

To move a menu option from one position to another, simply evaluate define-key-after with the appropriate final argument.

More detailed information—and more examples of how to create and modify menu options—are in the Emacs Lisp Reference Manual, under “Menu Keymaps.” (See Where can I get documentation on Emacs Lisp?, for information on this manual.)

5.42 How do I delete menus and menu options?

The simplest way to remove a menu is to set its keymap to ‘nil’. For example, to delete the ‘Words’ menu (see How can I create or modify new pull-down menu options?), use:

(define-key global-map [menu-bar words] nil)

Similarly, removing a menu option requires redefining a keymap entry to nil. For example, to delete the ‘Forward word’ menu option from the ‘Edit’ menu (we added it in How can I create or modify new pull-down menu options?), use:

(define-key global-map [menu-bar edit forward] nil)

5.43 How do I turn on syntax highlighting?

font-lock-mode is the standard way to have Emacs perform syntax highlighting in the current buffer. It is enabled by default.

With font-lock-mode turned on, different types of text will appear in different colors. For instance, in a programming mode, variables will appear in one face, keywords in a second, and comments in a third.

To turn font-lock-mode off within an existing buffer, use M-x font-lock-mode RET.

Highlighting a buffer with font-lock-mode can take quite a while, and cause an annoying delay in display, so several features exist to work around this.

Turning on font-lock-mode automatically activates Just-In-Time fontification provided by jit-lock-mode. jit-lock-mode defers the fontification of portions of buffer until you actually need to see them, and can also fontify while Emacs is idle. This makes display of the visible portion of a buffer almost instantaneous. For details about customizing jit-lock-mode, type C-h f jit-lock-mode RET.

Different levels of decoration are available, from slight to gaudy. More decoration means you need to wait more time for a buffer to be fontified (or a faster machine). To control how decorated your buffers should become, set the value of font-lock-maximum-decoration in your init file (see How do I set up an init file properly?), with a nil value indicating default (usually minimum) decoration, and a t value indicating the maximum decoration. For the gaudiest possible look, then, include the line

(setq font-lock-maximum-decoration t)

in your init file. You can also set this variable such that different modes are highlighted in a different ways; for more information, see the documentation for font-lock-maximum-decoration with C-h v (or M-x describe-variable RET).

Also see the documentation for the function font-lock-mode, available by typing C-h f font-lock-mode (M-x describe-function RET font-lock-mode RET).

To print buffers with the faces (i.e., colors and fonts) intact, use M-x ps-print-buffer-with-faces or M-x ps-print-region-with-faces. You will need a way to send text to a PostScript printer, or a PostScript interpreter such as Ghostscript; consult the documentation of the variables ps-printer-name, ps-lpr-command, and ps-lpr-switches for more details.

5.44 How can I force Emacs to scroll only one line when I move past the bottom of the screen?

Customize the scroll-conservatively variable with M-x customize-variable RET scroll-conservatively RET and set it to a large value like, say, 10000. For an explanation of what this means, see Auto Scrolling in The GNU Emacs Manual.

Alternatively, use the following Lisp form in your init file (see How do I set up an init file properly?):

(setq scroll-conservatively most-positive-fixnum)

5.45 How can I edit MS-DOS files using Emacs?

Detection and handling of MS-DOS (and Windows) files is performed transparently. You can open MS-DOS files on a Unix system, edit it, and save it without having to worry about the file format.

When editing an MS-DOS style file, the mode line will indicate that it is a DOS file. On Unix and GNU/Linux systems, and also on a Macintosh, the string ‘(DOS)’ will appear near the left edge of the mode line; on DOS and Windows, where the DOS end-of-line (EOL) format is the default, a backslash (‘\’) will appear in the mode line.

5.46 How can I tell Emacs to fill paragraphs with a single space after each period?

Add the following line to your init file (see How do I set up an init file properly?):

(setq sentence-end-double-space nil)

5.47 Why these strange escape sequences from ls from the Shell mode?

In many systems, ls is aliased to ‘ls --color’, which prints using ANSI color escape sequences. Emacs includes the ansi-color package, which lets Shell mode recognize these escape sequences. It is enabled by default.

5.48 How can I start Emacs in fullscreen mode on MS-Windows?

Beginning with Emacs 24.4 either run Emacs with the ‘--maximized’ command-line option or put the following form in your init file (see How do I set up an init file properly?):

(add-hook 'emacs-startup-hook 'toggle-frame-maximized)

With older versions use the function w32-send-sys-command. For example, you can put the following in your init file:

(add-hook 'emacs-startup-hook
          (lambda () (w32-send-sys-command ?\xF030)))

To avoid the slightly distracting visual effect of Emacs starting with its default frame size and then growing to fullscreen, you can add an ‘Emacs.Geometry’ entry to the Windows Registry settings. See X Resources in The GNU Emacs Manual. To compute the correct values for width and height you use in the Registry settings, first maximize the Emacs frame and then evaluate (frame-height) and (frame-width) with M-:.

Alternatively, you can avoid the visual effect of Emacs changing its frame size entirely in your init file (i.e., without using the Registry), like this:

(setq frame-resize-pixelwise t)
(set-frame-position nil 0 0)
(set-frame-size nil (display-pixel-width) (display-pixel-height) t)

5.49 How can I alleviate the limitations of the Linux console?

If possible, we recommend running Emacs inside fbterm, when in a Linux console. This brings the Linux console on par with most terminal emulators under X. To do this, install fbterm, for example with the package manager of your GNU/Linux distribution, and execute the command

$ fbterm

This will create a sample configuration file ~/.fbtermrc in your home directory. Edit that file and change the options font-names and font-size if necessary. For the former, you can choose one or more of the lines in the output of the following command, separated by commas:

$ fc-list :spacing=mono family | sed 's/ /\\ /g'

Note that you can fine-tune the appearance of the fonts by adding attribute-value pairs, separated by colons, after each font name. For example,

font-names=DejaVu\ Sans\ Mono:style=bold:antialias=false

selects the bold style of the DejaVu Sans Mono font, and disables anti-aliasing.

You can now start Emacs inside fbterm with the command

$ fbterm -- env TERM=fbterm emacs

In some versions of fbterm, setting TERM to ‘fbterm’ can be omitted. To check whether it is needed, start Emacs inside fbterm with the command

$ fbterm -- emacs

and type M-x list-colors-display. If only 8 colors are displayed, it is necessary; if 256 colors are displayed, it isn’t.

You may want to add an alias for that command in your shell configuration file. For example, if you use Bash, you can add the following line to your ~/.bashrc file:

alias emacs="fbterm -- env TERM=fbterm emacs"

or, if you use Emacs both in the Linux console and under X:

[[ "$(tty)" =~ "/dev/tty" ]] && alias emacs="fbterm -- env TERM=fbterm emacs"

The fbterm terminal emulator may define a number of key bindings for its own use, some of which conflict with those that Emacs uses. Execute the following two commands as root to ensure that fbterm does not define these key bindings:

# chmod a-s `which fbterm`
# setcap cap_sys_tty_config=-ep `which fbterm`

If you use Emacs as root, the above is not enough however, because the root user has all privileges. You can use the following command to start Emacs inside fbterm as root while ensuring that fbterm does not define any key bindings for its own use:

# capsh --drop=cap_sys_tty_config -- -c "fbterm -- env TERM=fbterm emacs"

Again you may want to add a shortcut for that command in the shell configuration file of the root user. In this case however, it is not possible to use an alias, because the command line arguments passed to Emacs need to be inserted in the string at the end of the command. A wrapper script or a function can be used to do that. For example, if you use Bash, you can add the following function in the root user ~/.bashrc file:

function emacs ()
{
  CMD="fbterm -- env TERM=fbterm emacs "
  for ARG in "$@"
  do
    CMD="$CMD '$ARG' "
  done
  capsh --drop=cap_sys_tty_config -- -c "$CMD"
}

6.1 Does Emacs have problems with large files?

Emacs has an inherent fixed limitation on the size of buffers. This limit is stricter than the maximum size of objects supported by other programs on the same architecture.

The maximum buffer size on 32-bit machines is 512 MBytes. If Emacs was built using the --with-wide-int flag, the maximum buffer size on 32-bit machines is 2 GB.

Emacs compiled on a 64-bit machine can handle much larger buffers; up to most-positive-fixnum (2.3 exabytes).

Due to things like decoding of multibyte characters, you can only visit files with a size that is roughly half the buffer size limit. When visiting compressed archives, the file size limit will be smaller than that due to decompression.

6.2 How do I get rid of ‘^M’ or echoed commands in my shell buffer?

Try typing M-x comint-strip-ctrl-m RET while in shell-mode to make them go away. If that doesn’t work, you have several options:

For tcsh, put this in your .cshrc (or .tcshrc) file:

if ($?INSIDE_EMACS && $?tcsh)
    unset edit
    stty -icrnl -onlcr -echo susp ^Z
endif

Or put this in your .emacs_tcsh or ~/.emacs.d/init_tcsh.sh file:

unset edit
stty -icrnl -onlcr -echo susp ^Z

Alternatively, use csh in your shell buffers instead of tcsh. One way is:

(setq explicit-shell-file-name "/bin/csh")

and another is to do this in your .cshrc (or .tcshrc) file:

setenv ESHELL /bin/csh

(You must start Emacs over again with the environment variable properly set for this to take effect.)

You can also set the ESHELL environment variable in Emacs Lisp with the following Lisp form,

(setenv "ESHELL" "/bin/csh")

The above solutions try to prevent the shell from producing the ‘^M’ characters in the first place. If this is not possible (e.g., if you use a Windows shell), you can get Emacs to remove these characters from the buffer by adding this to your init file (see How do I set up an init file properly?):

(add-hook 'comint-output-filter-functions #'comint-strip-ctrl-m)

On a related note: if your shell is echoing your input line in the shell buffer, you might want to customize the comint-process-echoes variable in your shell buffers, or try the following command in your shell start-up file:

stty -icrnl -onlcr -echo susp ^Z

6.3 Why do I get an error message when I try to run M-x shell?

This might happen because Emacs tries to look for the shell in a wrong place. If you know where your shell executable is, set the variable explicit-shell-file-name in your init file (see How do I set up an init file properly?) to point to its full file name.

Some people have trouble with Shell Mode on MS-Windows because of intrusive antivirus software; disabling the resident antivirus program solves the problems in those cases.

6.4 Where is the termcap/terminfo entry for terminal type ‘emacs’?

The termcap entry for terminal type ‘emacs’ is ordinarily put in the ‘TERMCAP’ environment variable of subshells. It may help in certain situations (e.g., using rlogin from shell buffer) to add an entry for ‘emacs’ to the system-wide termcap file. Here is a correct termcap entry for ‘emacs’:

emacs:tc=unknown:

To make a terminfo entry for ‘emacs’, use tic or captoinfo. You need to generate /usr/lib/terminfo/e/emacs. It may work to simply copy /usr/lib/terminfo/d/dumb to /usr/lib/terminfo/e/emacs.

Having a termcap/terminfo entry will not enable the use of full screen programs in shell buffers. Use M-x term for that instead.

A workaround to the problem of missing termcap/terminfo entries is to change terminal type ‘emacs’ to type ‘dumb’ or ‘unknown’ in your shell start up file. csh users could put this in their .cshrc files:

if ("$term" == emacs) set term=dumb

6.5 Why does Emacs say ‘Error in init file’?

An error occurred while loading either your init file or the system-wide file site-lisp/default.el. Emacs pops the *Messages* buffer, and puts there some additional information about the error, to provide some hints for debugging.

For information on how to debug your init file, see How do I debug an init file?.

It may be the case that you need to load some package first, or use a hook that will be evaluated after the package is loaded. A common case of this is explained in Why doesn’t this [terminal or window-system setup] code work in my init file, but it works just fine after Emacs starts up?.

6.6 Why does Emacs ignore my X resources (my .Xdefaults file)?

Emacs searches for X resources in the files specified by the following environment variables:

• XFILESEARCHPATH
• XUSERFILESEARCHPATH
• XAPPLRESDIR

This emulates the functionality provided by programs written using the Xt toolkit.

XFILESEARCHPATH and XUSERFILESEARCHPATH should be a list of file names separated by colons. XAPPLRESDIR should be a list of directories separated by colons.

Emacs searches for X resources:

1. specified on the command line, with the ‘-xrm RESOURCESTRING’ option,
2. then in the value of the ‘XENVIRONMENT’ environment variable,
   • - or if that is unset, in the file named ~/.Xdefaults-hostname if it exists (where hostname is the name of the machine Emacs is running on),
3. then in the screen-specific and server-wide resource properties provided by the server,
   • - or if those properties are unset, in the file named ~/.Xdefaults if it exists,
4. then in the files listed in ‘XUSERFILESEARCHPATH’,
   • - or in files named lang/Emacs in directories listed in ‘XAPPLRESDIR’ (where lang is the value of the LANG environment variable), if the ‘LANG’ environment variable is set,
   • - or in files named Emacs in the directories listed in ‘XAPPLRESDIR’
   • - or in ~/lang/Emacs (if the LANG environment variable is set),
   • - or in ~/Emacs,
5. then in the files listed in XFILESEARCHPATH.

6.7 Why don’t my customizations of the frame parameters work?

This probably happens because you have set the frame parameters in the variable initial-frame-alist. That variable holds parameters used only for the first frame created when Emacs starts. To customize the parameters of all frames, change the variable default-frame-alist instead.

These two variables exist because many users customize the initial frame in a special way. For example, you could determine the position and size of the initial frame, but would like to control the geometry of the other frames by individually positioning each one of them.

6.8 How do I edit a file with a ‘$’ in its name?

When entering a file name in the minibuffer, Emacs will attempt to expand a ‘$’ followed by a word as an environment variable. To suppress this behavior, type $$ instead.

6.9 Why does shell mode lose track of the shell’s current directory?

Emacs has no way of knowing when the shell actually changes its directory. This is an intrinsic limitation of Unix. So it tries to guess by recognizing ‘cd’ commands. If you type cd followed by directory with a variable reference (cd $HOME/bin) or with a shell metacharacter (cd ../lib*), Emacs will fail to correctly guess the shell’s new current directory. A huge variety of fixes and enhancements to shell mode for this problem have been written to handle this problem (see How do I find an Emacs Lisp package that does XXX?).

You can tell Emacs the shell’s current directory with the command M-x dirs.

6.10 Are there any security risks in Emacs?

• Third party packages.

  Any package you install into Emacs can run arbitrary code with the same privileges as the Emacs process itself. Be aware of this when you use the package system (e.g. M-x list-packages) with third party archives. Use only third parties that you can trust!

• The file-local-variable feature. (Yes, a risk, but easy to change.)

  There is an Emacs feature that allows the setting of local values for variables when editing a file by including specially formatted text near the end of the file. This feature also includes the ability to have arbitrary Emacs Lisp code evaluated when the file is visited. Obviously, there is a potential for Trojan horses to exploit this feature.

  Emacs has a list of local variables that are known to be safe to set. If a file tries to set any variable outside this list, it asks the user to confirm whether the variables should be set. You can also tell Emacs whether to allow the evaluation of Emacs Lisp code found at the bottom of files by setting the variable enable-local-eval.

  See File Variables in The GNU Emacs Manual.

• Browsing the web.

  Emacs relies on C libraries to parse images, and historically, many of these have had exploitable weaknesses. If you’re browsing the web with the eww browser, it will usually download and display images using these libraries. If an image library has a weakness, it may be used by an attacker to gain access.

6.11 Dired says, ‘no file on this line’ when I try to do something.

Dired uses a regular expression to find the beginning of a file name. In a long Unix-style directory listing (‘ls -l’), the file name starts after the date. The regexp has thus been written to look for the date. By default, it should understand dates and times regardless of the language, but if your directory listing has an unusual format, Dired may get confused.

There are two approaches to solving this. The first one involves setting things up so that ‘ls -l’ outputs a more standard format. See your OS manual for more information.

The second approach involves changing the regular expression used by dired, directory-listing-before-filename-regexp.

7.1 How do I install Emacs?

This answer is meant for users of Unix and Unix-like systems. Users of other operating systems should see See Where can I get Emacs for macOS, MS Windows, etc?.

Most GNU/Linux distributions provide pre-built Emacs packages. If Emacs is not installed already, you can install it by running (as root) a command such as ‘dnf install emacs’ (Red Hat and derivatives; use ‘yum’ in older distributions) or ‘apt-get install emacs’ (Debian and derivatives).

If you want to compile Emacs yourself, read the file INSTALL in the source distribution. In brief:

• First download the Emacs sources. See Where can I get other up-to-date GNU stuff?, for a list of sites that make them available. On https://ftp.gnu.org, the main GNU distribution site, sources are available as

  https://ftp.gnu.org/pub/gnu/emacs/emacs-VERSION.tar.xz

  (Replace ‘VERSION’ with the relevant version number, e.g., ‘28.1’.)

• Next uncompress and extract the source files. This requires the xz and tar programs, which are standard utilities. If your system does not have them, these can also be downloaded from https://ftp.gnu.org.

  GNU tar can uncompress and extract in a single-step:

  tar -axvf emacs-VERSION.tar.xz
  

• At this point, the Emacs sources should be sitting in a directory called emacs-VERSION. On most common Unix and Unix-like systems, you should be able to compile Emacs with the following commands:

  cd emacs-VERSION
  ./configure         # configure Emacs for your particular system
  make                # use Makefile to build components, then Emacs
  

  If the make completes successfully, you can go on to install it. (See What should I do if I have trouble building Emacs?, if you weren’t successful.)

• By default, Emacs is installed in /usr/local. To actually install files, become the superuser and type

  make install
  

  Note that ‘make install’ will overwrite /usr/local/bin/emacs and any Emacs Info files that might be in /usr/local/share/info/.

7.2 Where can I get Emacs for macOS, MS Windows, etc?

Emacs supports macOS natively. See the file nextstep/INSTALL in the distribution.

There is a separate FAQ for Emacs on MS-Windows, see FAQ for Emacs on MS Windows.

Emacs supports GNUstep natively. See the file nextstep/INSTALL in the distribution.

To build Emacs from source for MS-DOS, see the instructions in the file msdos/INSTALL in the distribution. The DOS port builds and runs on plain DOS, and also on all versions of MS-Windows from version 3.X onwards, including Windows XP and Vista. Pre-built binaries may be available at https://www.delorie.com/pub/djgpp/current/v2gnu/emacs.README

For a list of other implementations of Emacs (and Emacs look-alikes), consult the list of “Emacs implementations and literature,” available at

https://www.finseth.com/emacs.html

Note that while many of these programs look similar to Emacs, they often lack certain features, such as the Emacs Lisp extension language.

7.3 What should I do if I have trouble building Emacs?

First look in the file etc/PROBLEMS (where you unpack the Emacs source) to see if there is already a solution for your problem. Next, look for other questions in this FAQ that have to do with Emacs installation and compilation problems.

If you’d like to have someone look at your problem and help solve it, see Where can I get help in installing Emacs?.

If you cannot find a solution in the documentation, please report the problem (see Where should I report bugs and other problems with Emacs?).

8.1 Downloading Emacs

Information on downloading Emacs is available at the Emacs website.

See How do I install Emacs?, for information on how to obtain and build the latest version of Emacs, and see Where can I get other up-to-date GNU stuff?, for a list of archive sites that make GNU software available.

8.2 How do I find an Emacs Lisp package that does XXX?

The command C-h p (finder-by-keyword) allows you to browse the packages that come with Emacs.

For advice on how to find extra packages that are not part of Emacs, see Where can I get Emacs Lisp packages that don’t come with Emacs?.

Other techniques that might be useful:

Typing M-x apropos RET python RET lists all functions and variables containing the string ‘python’.

You can look through your computer’s lisp directory (see What are src/config.h, site-lisp/default.el, etc.?). The Lisp source to most packages contains a short description of what they do and how they should be used.

8.3 Where can I get Emacs Lisp packages that don’t come with Emacs?

The easiest way to add more features to your Emacs is to use the command M-x list-packages. This contacts the GNU ELPA and NonGNU ELPA (“Emacs Lisp Package Archive”) servers and fetches the list of additional packages that they offer. You can browse the resulting *Packages* buffer to see what is available, and then Emacs can automatically download and install the packages that you select. See Packages in The GNU Emacs Manual.

GNU ELPA contains GNU packages that are available for use with Emacs, but are distributed separately from Emacs itself, for reasons of space, etc. NonGNU ELPA contains a selection of third-party packages that can not be included in GNU ELPA because their copyright has not yet been assigned to the Free Software Foundation.²

The GNU Emacs sources mailing list is automatically sent an email when a new version of a GNU ELPA or NonGNU ELPA package is released.³

There are other Emacs Lisp package archives. To use additional archives, you can customize the package-archives variable. Those archives have no affiliation with GNU Emacs, and we do not monitor how they are maintained. They may pay close attention to correctness and safety of the code, or they may give only cursory attention.

Also, packages hosted on these other archives may encourage or require you to install and use nonfree programs. Unless you can verify that a package is free software, and that it functions without installing any nonfree software, we recommend for your freedom’s sake that you stay away from it.

The Emacs Wiki contains pointers to some additional extensions. WikEmacs is an alternative wiki for Emacs.

It is impossible for us to list here all the sites that offer Emacs Lisp packages. If you are interested in a specific feature, then after checking Emacs itself, GNU ELPA, and NonGNU ELPA, a web search is often the best way to find results.

8.4 Spell-checkers

Various spell-checkers are compatible with Emacs, including:

Hunspell

https://hunspell.github.io/

GNU Aspell

http://aspell.net/

Ispell

http://fmg-www.cs.ucla.edu/geoff/ispell.html

Enchant

https://abiword.github.io/enchant/

8.5 Where can I get other up-to-date GNU stuff?

The most up-to-date official GNU software is normally kept at

https://ftp.gnu.org/pub/gnu

A list of sites mirroring ‘ftp.gnu.org’ can be found at

https://www.gnu.org/prep/ftp

8.6 I don’t have enough disk space to install Emacs

GNU Zile is a lightweight Emacs clone. Zile is short for ‘Zile Is Lossy Emacs’. It has all of Emacs’s basic editing features. The Zile binary typically has a size of about 130 kbytes, so this can be useful if you are in an extremely space-restricted environment. More information is available from

https://www.gnu.org/software/zile/

9.1 How do I bind keys (including function keys) to commands?

Keys can be bound to commands either interactively or in your init file (see How do I set up an init file properly?). To interactively bind keys for all modes, type M-x global-set-key RET key cmd RET.

To bind a key just in the current major mode, type M-x local-set-key RET key cmd RET.

See Key Bindings in The GNU Emacs Manual.

To make the process of binding keys interactively easier, use the following “trick”: First bind the key interactively, then immediately type C-x ESC ESC C-a C-k C-g. Now, the command needed to bind the key is in the kill ring, and can be yanked into your init file. If the key binding is global, no changes to the command are required. For example,

(global-set-key [f1] 'help-for-help)

can be placed directly into your init file. If the key binding is local, the command is used in conjunction with the ‘add-hook’ function. For example, in TeX mode, a local binding might be

(add-hook 'tex-mode-hook
  (lambda ()
   (local-set-key [f1] 'help-for-help)))

• Control characters in key sequences, in the form yanked from the kill ring are given in their graphic form—i.e., CTRL is shown as ‘^’, TAB as a set of spaces (usually 8), etc. You may want to convert these into their vector or string forms.
• If a prefix key of the character sequence to be bound is already bound as a complete key, then you must unbind it before the new binding. For example, if ESC { is previously bound:

  (global-unset-key [?\e ?{])   ;;   or
  (local-unset-key [?\e ?{])
  

• Aside from commands and “lambda lists,” a vector or string also can be bound to a key and thus treated as a macro. For example:

  (global-set-key [f10] [?\C-x?\e?\e?\C-a?\C-k?\C-g])  ;;  or
  (global-set-key [f10] "\C-x\e\e\C-a\C-k\C-g")
  

9.2 Why does Emacs say ‘Key sequence XXX uses invalid prefix characters’?

Usually, one of two things has happened. In one case, the control character in the key sequence has been misspecified (e.g., ‘C-f’ used instead of ‘\C-f’ within a Lisp expression). In the other case, a prefix key in the keystroke sequence you were trying to bind was already bound as a complete key. Historically, the ‘ESC [’ prefix was usually the problem, in which case you should evaluate either of these forms before attempting to bind the key sequence:

(global-unset-key [?\e ?[])  ;;  or
(global-unset-key "\e[")

9.3 Why doesn’t this [terminal or window-system setup] code work in my init file, but it works just fine after Emacs starts up?

During startup, Emacs initializes itself according to a given code/file order. If some of the code executed in your init file (see How do I set up an init file properly?) needs to be postponed until the initial terminal or window-system setup code has been executed but is not, then you will experience this problem (this code/file execution order is not enforced after startup).

To postpone the execution of Emacs Lisp code until after terminal or window-system setup, treat the code as a lambda list and add it to emacs-startup-hook (or tty-setup-hook in Emacs 24.4 and newer). For example,

(add-hook 'emacs-startup-hook
          (lambda ()
           (when (string-match "\\`vt220" (or (getenv "TERM") ""))
             ;; Make vt220's "Do" key behave like M-x:
             (global-set-key [do] 'execute-extended-command))))

For information on what Emacs does every time it is started, see the lisp/startup.el file.

9.4 How do I tell what characters or symbols my function or arrow keys emit?

Type C-h c then the function or arrow keys. The command will return either a function key symbol or character sequence (see the Emacs documentation for an explanation). This works for other keys as well.

9.5 How do I set the X key “translations” for Emacs?

Emacs is not written using the Xt library by default, so there are no “translations” to be set. (We aren’t sure how to set such translations if you do build Emacs with Xt; please let us know if you’ve done this!)

The only way to affect the behavior of keys within Emacs is through xmodmap (outside Emacs) or define-key (inside Emacs). The define-key command should be used in conjunction with the local-function-key-map map. For instance,

(define-key function-key-map [M-TAB] [?\M-\t])

defines the M-TAB key sequence.

9.6 Why does the Backspace key invoke help?

The Backspace key (on most keyboards) generates ASCII code 8. C-h sends the same code. In Emacs by default C-h invokes help-command. This is intended to be easy to remember since the first letter of ‘help’ is ‘h’. The easiest solution to this problem is to use C-h (and Backspace) for help and DEL (the Delete key) for deleting the previous character.

For many people this solution may be problematic:

• They normally use Backspace outside of Emacs for deleting the previous character. This can be solved by making DEL the command for deleting the previous character outside of Emacs. On many Unix systems, this command will remap DEL:

  stty erase '^?'
  

• The user may prefer the Backspace key for deleting the previous character because it is more conveniently located on their keyboard or because they don’t even have a separate Delete key. In this case, the Backspace key should be made to behave like Delete. There are several methods.
  • - Some terminals (e.g., VT3## terminals) and terminal emulators (e.g., TeraTerm) allow the character generated by the Backspace key to be changed from a setup menu.
  • - You may be able to get a keyboard that is completely programmable, or a terminal emulator that supports remapping of any key to any other key.
  • - You can control the effect of the Backspace and Delete keys, on both dumb terminals and a windowed displays, by customizing the option normal-erase-is-backspace-mode, or by invoking M-x normal-erase-is-backspace. See the documentation of these symbols (see Where can I get documentation on Emacs Lisp?) for more info.
  • - It is possible to swap the Backspace and DEL keys inside Emacs:

    (keyboard-translate ?\C-h ?\C-?)
    

    This is the recommended method of forcing Backspace to act as DEL, because it works even in modes which bind DEL to something other than delete-backward-char.

    Similarly, you could remap DEL to act as C-d, which by default deletes forward:

    (keyboard-translate ?\C-? ?\C-d)
    

    See How do I swap two keys?, for further details about keyboard-translate.

  • - Another approach is to switch key bindings and put help on C-x h instead:

    (global-set-key "\C-h" 'delete-backward-char)
    
    ;; overrides mark-whole-buffer
    (global-set-key "\C-xh" 'help-command)
    

    This method is not recommended, though: it only solves the problem for those modes which bind DEL to delete-backward-char. Modes which bind DEL to something else, such as view-mode, will not work as you expect when you press the Backspace key. For this reason, we recommend the keyboard-translate method, shown above.

    Other popular key bindings for help are M-? and C-x ?.

  Don’t try to bind DEL to help-command, because there are many modes that have local bindings of DEL that will interfere.

When Emacs runs on a windowed display, it binds the Delete key to a command which deletes the character at point, to make Emacs more consistent with keyboard operation on these systems.

For more information about troubleshooting this problem, see If DEL Fails to Delete in The GNU Emacs Manual.

9.7 How do I swap two keys?

You can swap two keys (or key sequences) by using the keyboard-translate function. For example, to turn C-h into DEL and DEL to C-h, use

(keyboard-translate ?\C-h ?\C-?)  ; translate 'C-h' to DEL
(keyboard-translate ?\C-? ?\C-h)  ; translate DEL to 'C-h'.

The first key sequence of the pair after the function identifies what is produced by the keyboard; the second, what is matched for in the keymaps.

However, in the specific case of C-h and DEL, you should toggle normal-erase-is-backspace-mode instead of calling keyboard-translate. See DEL Does Not Delete in The GNU Emacs Manual.

Keyboard translations are not the same as key bindings in keymaps. Emacs contains numerous keymaps that apply in different situations, but there is only one set of keyboard translations, and it applies to every character that Emacs reads from the terminal. Keyboard translations take place at the lowest level of input processing; the keys that are looked up in keymaps contain the characters that result from keyboard translation.

9.8 How do I produce C-XXX with my keyboard?

On terminals (but not under X), some common “aliases” are:

C-2 or C-SPC

C-@

C-6

C-^

C-7 or C-S--

C-_

C-4

C-\

C-5

C-]

C-/

C-?

Often other aliases exist; use the C-h c command and try CTRL with all of the digits on your keyboard to see what gets generated. You can also try the C-h w command if you know the name of the command.

9.9 What if I don’t have a Meta key?

On many keyboards, the Alt key acts as Meta, so try it.

Instead of typing M-a, you can type ESC a. In fact, Emacs converts M-a internally into ESC a anyway (depending on the value of meta-prefix-char). Note that you press Meta and a together, but with ESC, you press ESC, release it, and then press a.

9.10 What if I don’t have an Escape key?

Type C-[ instead. This should send ASCII code 27 just like an Escape key would. C-3 may also work on some terminal (but not under X). For many terminals (notably DEC terminals) F11 generates ESC. If not, the following form can be used to bind it:

;; F11 is the documented ESC replacement on DEC terminals.
(define-key function-key-map [f11] [?\e])

9.11 Can I make my Compose Character key behave like a Meta key?

On a dumb terminal such as a VT220, no. It is rumored that certain VT220 clones could have their Compose key configured this way. If you’re using X, you might be able to do this with the xmodmap command.

9.12 How do I bind a combination of modifier key and function key?

You can represent modified function keys in vector format by adding prefixes to the function key symbol. For example (from the Emacs documentation):

(global-set-key [?\C-x right] 'forward-page)

where ‘?\C-x’ is the Lisp character constant for the character C-x.

You can use the modifier keys Control, Meta, Hyper, Super, Alt, and Shift with function keys. To represent these modifiers, prepend the strings ‘C-’, ‘M-’, ‘H-’, ‘s-’, ‘A-’, and ‘S-’ to the symbol name. Here is how to make H-M-RIGHT move forward a word:

(global-set-key [H-M-right] 'forward-word)

• Not all modifiers are permitted in all situations. Hyper, Super, and Alt are not available on Unix character terminals. Non-ASCII keys and mouse events (e.g., C-= and mouse-1) also fall under this category.

See How do I bind keys (including function keys) to commands?, for general key binding instructions.

9.13 Why doesn’t my Meta key work in an xterm window?

See Single-Byte Character Set Support in The GNU Emacs Manual.

If the advice in the Emacs manual fails, try all of these methods before asking for further help:

• You may have big problems using mwm as your window manager. (Does anyone know a good generic solution to allow the use of the Meta key in Emacs with mwm?)
• For X11: Make sure it really is a Meta key. Use xev to find out what keysym your Meta key generates. It should be either Meta_L or Meta_R. If it isn’t, use xmodmap to fix the situation. If Meta does generate Meta_L or Meta_R, but M-x produces a non-ASCII character, put this in your ~/.Xdefaults file:

   XTerm*eightBitInput:   false
   XTerm*eightBitOutput:  true
  

• Make sure the pty the xterm is using is passing 8 bit characters. ‘stty -a’ (or ‘stty everything’) should show ‘cs8’ somewhere. If it shows ‘cs7’ instead, use ‘stty cs8 -istrip’ (or ‘stty pass8’) to fix it.
• If there is an rlogin connection between xterm and Emacs, the ‘-8’ argument may need to be given to rlogin to make it pass all 8 bits of every character.
• If all else fails, you can make xterm generate ESC W when you type M-W, which is the same conversion Emacs would make if it got the M-W anyway. In X11R4, the following resource specification will do this:

  XTerm.VT100.EightBitInput: false
  

  (This changes the behavior of the insert-eight-bit action.)

  With older xterms, you can specify this behavior with a translation:

  XTerm.VT100.Translations: #override \
    Meta<KeyPress>: string(0x1b) insert()
  

  You might have to replace ‘Meta’ with ‘Alt’.

10.1 How do I make Emacs display 8-bit characters?

See Single-byte Character Set Support in The GNU Emacs Manual. On a Unix, when Emacs runs on a text-only terminal display or is invoked with ‘emacs -nw’, you typically need to use set-terminal-coding-system to tell Emacs what the terminal can display, even after setting the language environment; otherwise non-ASCII characters will display as ‘?’. On other operating systems, such as MS-DOS and MS-Windows, Emacs queries the OS about the character set supported by the display, and sets up the required terminal coding system automatically.

10.2 How do I input eight-bit characters?

Various methods are available for input of eight-bit characters. See Single-byte Character Set Support in The GNU Emacs Manual. For more sophisticated methods, see Input Methods in The GNU Emacs Manual.

10.3 Where is an Emacs that can handle Semitic (right-to-left) alphabets?

Emacs supports display and editing of bidirectional scripts, such as Arabic, Farsi, and Hebrew.

10.4 How do I add fonts for use with Emacs?

First, download and install the BDF font files and any auxiliary packages they need. The GNU Intlfonts distribution can be found on the GNU Software Directory Web site.

Next, if you are on X Window system, issue the following two commands from the shell’s prompt:

  xset +fp /usr/local/share/emacs/fonts
  xset fp rehash

(Modify the first command if you installed the fonts in a directory that is not /usr/local/share/emacs/fonts.) You also need to arrange for these two commands to run whenever you log in, e.g., by adding them to your window-system startup file, such as ~/.xsessionrc or ~/.gnomerc.

Now, add the following line to your init file (see How do I set up an init file properly?):

  (add-to-list 'bdf-directory-list "/usr/share/emacs/fonts/bdf")

(Again, modify the file name if you installed the fonts elsewhere.)

Finally, if you wish to use the installed fonts with ps-print, add the following line to your init file:

  (setq ps-multibyte-buffer 'bdf-font-except-latin)

You can now use the Emacs font menu to select the ‘bdf: 16-dot medium’ fontset, or you can select it by setting the default font in your init file:

  (set-frame-font "fontset-bdf")

11.1 How do I change the included text prefix in mail/news followups?

If you read mail with Rmail, set the variable mail-yank-prefix. For Gnus, set message-yank-prefix. For VM, set vm-included-text-prefix. For mh-e, set mh-ins-buf-prefix.

For fancier control of citations, use Supercite (see the Supercite Manual in The Supercite Manual).

To prevent Emacs from including various headers of the replied-to message, set the value of mail-yank-ignored-headers to an appropriate regexp.

11.2 How do I save a copy of outgoing mail?

You can either mail yourself a copy by including a ‘BCC’ header in the mail message, or store a copy of the message directly to a file by including an ‘FCC’ header.

If you use standard mail, you can automatically create a ‘BCC’ to yourself by putting

(setq mail-self-blind t)

in your init file (see How do I set up an init file properly?). You can automatically include an ‘FCC’ field by putting something like the following in your init file:

(setq mail-archive-file-name (expand-file-name "~/outgoing"))

The output file will be in Unix mail format.

If you use mh-e, add an ‘FCC’ or ‘BCC’ field to your components file.

It does not work to put ‘set record filename’ in the .mailrc file.

11.3 Why doesn’t Emacs expand my aliases when sending mail?

See The Emacs Manual in The Emacs Manual.

• Normally, Emacs expands aliases when you send the message. To expand them before this, use M-x expand-mail-aliases.
• Emacs normally only reads the .mailrc file once per session, when you start to compose your first mail message. If you edit the file after this, you can use M-x build-mail-aliases to make Emacs reread it.
• If you like, you can expand mail aliases as abbrevs, as soon as you type them in. To enable this feature, execute the following:

  (add-hook 'mail-mode-hook 'mail-abbrevs-setup)
  

  Note that the aliases are expanded automatically only after you type a word-separator character (e.g., RET or ,). You can force their expansion by moving point to the end of the alias and typing C-x a e (M-x expand-abbrev).

11.4 How can I sort the messages in my Rmail folder?

In Rmail, type C-c C-s C-h to get a list of sorting functions and their key bindings.

11.5 Why does Rmail need to write to /var/spool/mail?

This is the behavior of the movemail program which Rmail uses. This indicates that movemail is configured to use lock files.

RMS writes:

Certain systems require lock files to interlock access to mail files. On these systems, movemail must write lock files, or you risk losing mail. You simply must arrange to let movemail write them.

Other systems use the flock system call to interlock access. On these systems, you should configure movemail to use flock.

11.6 How can I force Rmail to reply to the sender of a message, but not the other recipients?

Ron Isaacson says: When you hit r to reply in Rmail, by default it Ccs all of the original recipients (everyone on the original ‘To’ and ‘CC’ lists). With a prefix argument (i.e., typing C-u before r), it replies only to the sender. However, going through the whole C-u business every time you want to reply is a pain. This is the best fix I’ve been able to come up with:

(defun rmail-reply-t ()
  "Reply only to the sender of the current message. (See rmail-reply.)"
  (interactive)
  (rmail-reply t))

(add-hook 'rmail-mode-hook
  (lambda ()
    (define-key rmail-mode-map "r" 'rmail-reply-t)
    (define-key rmail-mode-map "R" 'rmail-reply)))

11.7 How do I make Emacs automatically start my mail/news reader?

To start Emacs in Gnus:

emacs -f gnus

in Rmail:

emacs -f rmail

A more convenient way to start with Gnus:

alias gnus 'emacs -f gnus'
gnus

It is probably unwise to automatically start your mail or news reader from your init file. This would cause problems if you needed to run two copies of Emacs at the same time. Also, this would make it difficult for you to start Emacs quickly when you needed to.

11.8 How do I read news under Emacs?

Use M-x gnus. For more information on Gnus, see the Gnus Manual in The Gnus Manual, which includes the Gnus FAQ in The Gnus Manual.

11.9 How do I make Gnus faster?

From the Gnus FAQ (see How do I read news under Emacs?):

If you have a slow machine, or are just really impatient, there are a few things you can do to make Gnus run faster.

Set gnus-check-new-newsgroups and gnus-check-bogus-newsgroups to nil to make startup faster.

Set gnus-show-threads, gnus-use-cross-reference and gnus-nov-is-evil to nil to make entering and exiting the summary buffer faster.

11.10 How do I catch up all newsgroups in Gnus?

In the *Newsgroup* buffer, type M-< C-x ( c y C-x ) M-0 C-x e

Leave off the initial M-< if you only want to catch up from point to the end of the *Newsgroup* buffer.