GNU Emacs Manual

Tenth Edition, Updated for Emacs version 19.28

Richard Stallman

Tenth Edition
Updated for Emacs Version 19.28,
July 1994

ISBN 1-882114-04-3.

Published by the Free Software Foundation
675 Massachusetts Avenue
Cambridge, MA 02139 USA

Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies.

Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided also that the sections entitled “The GNU Manifesto”, “Distribution” and “GNU General Public License” are included exactly as in the original, and provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one.

Permission is granted to copy and distribute translations of this manual into another language, under the above conditions for modified versions, except that the sections entitled “The GNU Manifesto”, “Distribution” and “GNU General Public License” may be included in a translation approved by the Free Software Foundation instead of in the original English.

Cover art by Etienne Suvasa.

Indexes, nodes containing large menus
Distribution		How to get the latest Emacs distribution.
GNU GENERAL PUBLIC LICENSE		The GNU General Public License gives you permission to redistribute GNU Emacs on certain terms; it also explains that there is no warranty.
Introduction		An introduction to Emacs concepts.
• Glossary		The glossary.
• Antinews		Information about Emacs version 18.
• MS-DOS		Using Emacs on MS-DOS (otherwise known as "MS-DOG").
• Manifesto		What’s GNU? Gnu’s Not Unix!
Key (Character) Index		An item for each standard Emacs key sequence.
Command and Function Index		An item for each command name.
Variable Index		An item for each documented variable.
Concept Index		An item for each concept.
Important General Concepts
• Screen		How to interpret what you see on the screen.
• User Input		Kinds of input events (characters, buttons, function keys).
• Keys		Key sequences: what you type to request one editing action.
• Commands		Named functions run by key sequences to do editing.
• Text Characters		Character set for text (the contents of buffers and strings).
• Entering Emacs		Starting Emacs from the shell.
• Exiting		Stopping or killing Emacs.
• Command Arguments		Hairy startup options.
Fundamental Editing Commands
• Basic		The most basic editing commands.
• Minibuffer		Entering arguments that are prompted for.
• M-x		Invoking commands by their names.
• Help		Commands for asking Emacs about its commands.
Important Text-Changing Commands
• Mark		The mark: how to delimit a “region” of text.
• Killing		Killing text.
• Yanking		Recovering killed text. Moving text.
• Accumulating Text		Other ways of copying text.
• Rectangles		Operating on the text inside a rectangle on the screen.
• Registers		Saving a text string or a location in the buffer.
• Display		Controlling what text is displayed.
• Search		Finding or replacing occurrences of a string.
• Fixit		Commands especially useful for fixing typos.
Larger Units of Text
• Files		All about handling files.
• Buffers		Multiple buffers; editing several files at once.
• Windows		Viewing two pieces of text at once.
• Frames		Running the same Emacs session in multiple X windows.
Advanced Features
• Major Modes		Text mode vs. Lisp mode vs. C mode ...
• Indentation		Editing the white space at the beginnings of lines.
• Text		Commands and modes for editing English.
• Programs		Commands and modes for editing programs.
• Building		Compiling, running and debugging programs.
• Abbrevs		How to define text abbreviations to reduce the number of characters you must type.
• Picture		Editing pictures made up of characters using the quarter-plane screen model.
• Sending Mail		Sending mail in Emacs.
• Rmail		Reading mail in Emacs.
• Dired		You can “edit” a directory to manage files in it.
• Calendar/Diary		The calendar and diary facilities.
• GNUS		How to read netnews with Emacs.
• Shell		Executing shell commands from Emacs.
• Emacs Server		Using Emacs as an editing server for `mail`, etc.
• Hardcopy		Printing buffers or regions.
• Sorting		Sorting lines, paragraphs or pages within Emacs.
• Narrowing		Restricting display and editing to a portion of the buffer.
• Two-Column		Splitting apart columns to edit them in side-by-side windows.
• Editing Binary Files		Using Hexl mode to edit binary files.
• Saving Emacs Sessions		Saving Emacs state from one session to the next.
• Recursive Edit		A command can allow you to do editing "within the command". This is called a ‘recursive editing level’.
• Emulation		Emulating some other editors with Emacs.
• Dissociated Press		Dissociating text for fun.
• Amusements		Various games and hacks.
• Customization		Modifying the behavior of Emacs.
Recovery from Problems.
• Quitting		Quitting and aborting.
• Lossage		What to do if Emacs is hung or malfunctioning.
• Bugs		How and when to report a bug.
• Service		How to get help for your own Emacs needs.
Here are some other nodes which are really inferiors of the ones already listed, mentioned here so you can get to them in one step: — The Detailed Node Listing — The Organization of the Screen
• Point		The place in the text where editing commands operate.
• Echo Area		Short messages appear at the bottom of the screen.
• Mode Line		Interpreting the mode line.
Basic Editing Commands
• Inserting Text		Inserting text by simply typing it.
• Moving Point		How to move the cursor to the place where you want to change something.
• Erasing		Deleting and killing text.
• Undo		Undoing recently made changes in the text.
• Files		Visiting, creating, and saving files.
• Help		Asking what a character does.
• Blank Lines		Commands to make or delete blank lines.
• Continuation Lines		Lines too wide for the screen.
• Position Info		What page, line, row, or column is point on?
• Arguments		Numeric arguments for repeating a command.
The Minibuffer
• Minibuffer File		Entering file names with the minibuffer.
• Minibuffer Edit		How to edit in the minibuffer.
• Completion		An abbreviation facility for minibuffer input.
• Minibuffer History		Reusing recent minibuffer arguments.
• Repetition		Re-executing commands that used the minibuffer.
Help
• Help Summary		Brief list of all Help commands.
• Key Help		Asking what a key does in Emacs.
• Name Help		Asking about a command, variable or function name.
• Apropos		Asking what pertains to a given topic.
• Library Keywords		Finding Lisp libraries by keywords (topics).
• Misc Help		Other help commands.
The Mark and the Region
• Setting Mark		Commands to set the mark.
• Transient Mark		How to make Emacs highlight the region– when there is one.
• Using Region		Summary of ways to operate on contents of the region.
• Marking Objects		Commands to put region around textual units.
• Mark Ring		Previous mark positions saved so you can go back there.
• Global Mark Ring		Previous mark positions in various buffers.
Deletion and Killing
• Deletion		Commands for deleting small amounts of text and blank areas.
• Killing by Lines		How to kill entire lines of text at one time.
• Other Kill Commands		Commands to kill large regions of text and syntactic units such as words and sentences.
Yanking
• Kill Ring		Where killed text is stored. Basic yanking.
• Appending Kills		Several kills in a row all yank together.
• Earlier Kills		Yanking something killed some time ago.
Registers
• RegPos		Saving positions in registers.
• RegText		Saving text in registers.
• RegRect		Saving rectangles in registers.
• RegConfig		Saving window configurations in registers.
• RegFiles		File names in registers.
• Bookmarks		Bookmarks are like registers, but persistent.
Controlling the Display
• Scrolling		Moving text up and down in a window.
• Horizontal Scrolling		Moving text left and right in a window.
• Selective Display		Hiding lines with lots of indentation.
• Optional Mode Line		Optional mode line features.
• European Display		Displaying (and entering) European characters.
• Display Vars		Information on variables for customizing display.
Searching and Replacement
• Incremental Search		Search happens as you type the string.
• Nonincremental Search		Specify entire string and then search.
• Word Search		Search for sequence of words.
• Regexp Search		Search for match for a regexp.
• Regexps		Syntax of regular expressions.
• Search Case		To ignore case while searching, or not.
• Replace		Search, and replace some or all matches.
• Other Repeating Search		Operating on all matches for some regexp.
Replacement Commands
• Unconditional Replace		Replacing all matches for a string.
• Regexp Replace		Replacing all matches for a regexp.
• Replacement and Case		How replacements preserve case of letters.
• Query Replace		How to use querying.
Commands for Fixing Typos
• Kill Errors		Commands to kill a batch of recently entered text.
• Transpose		Exchanging two characters, words, lines, lists...
• Fixing Case		Correcting case of last word entered.
• Spelling		Apply spelling checker to a word, or a whole file.
File Handling
• File Names		How to type and edit file name arguments.
• Visiting		Visiting a file prepares Emacs to edit the file.
• Saving		Saving makes your changes permanent.
• Reverting		Reverting cancels all the changes not saved.
• Auto Save		Auto Save periodically protects against loss of data.
• File Aliases		Handling multiple names for one file.
• Version Control		Version control systems (RCS and SCCS).
• ListDir		Listing the contents of a file directory.
• Comparing Files		Finding where two files differ.
• Misc File Ops		Other things you can do on files.
Saving Files
• Backup		How Emacs saves the old version of your file.
• Interlocking		How Emacs protects against simultaneous editing of one file by two users.
Version Control
• Concepts of VC		Basic version control information; checking files in and out.
• Editing with VC		Commands for editing a file maintained with version control.
• Variables for Check-in/out		Variables that affect the commands used to check files in or out.
• Log Entries		Logging your changes.
• Change Logs and VC		Generating a change log file from log entries.
• Old Versions		Examining and comparing old versions.
• VC Status		Commands to view the VC status of files and look at log entries.
• Renaming and VC		A command to rename both the source and master file correctly.
• Snapshots		How to make and use snapshots, a set of file versions that can be treated as a unit.
• Version Headers		Inserting version control headers into working files.
Using Multiple Buffers
• Select Buffer		Creating a new buffer or reselecting an old one.
• List Buffers		Getting a list of buffers that exist.
• Misc Buffer		Renaming; changing read-onliness; copying text.
• Kill Buffer		Killing buffers you no longer need.
• Several Buffers		How to go through the list of all buffers and operate variously on several of them.
Multiple Windows
• Basic Window		Introduction to Emacs windows.
• Split Window		New windows are made by splitting existing windows.
• Other Window		Moving to another window or doing something to it.
• Pop Up Window		Finding a file or buffer in another window.
• Change Window		Deleting windows and changing their sizes.
Frames and X Windows
• Mouse Commands		Moving, cutting, and pasting, with the mouse.
• Secondary Selection		Cutting without altering point and mark.
• Mouse References		Using the mouse to select an item from a list.
• Mode Line Mouse		Mouse clicks on the mode line.
• Creating Frames		Creating additional Emacs frames with various contents.
• Special Buffer Frames		You can make certain buffers have their own frames.
• Frame Parameters		Changing the colors and other modes of frames.
• Scroll Bars		How to enable and disable scroll bars; how to use them.
• Menu Bars		Enabling and disabling the menu bar.
• Faces		How to change the display style using faces.
• Modifying Faces		How to change what a particular face looks like.
• Misc X		Iconifying and deleting frames. Region highlighting.
Major Modes
• Choosing Modes		How major modes are specified or chosen.
Indentation
• Indentation Commands		Various commands and techniques for indentation.
• Tab Stops		You can set arbitrary "tab stops" and then indent to the next tab stop when you want to.
• Just Spaces		You can request indentation using just spaces.
Commands for Human Languages
• Words		Moving over and killing words.
• Sentences		Moving over and killing sentences.
• Paragraphs		Moving over paragraphs.
• Pages		Moving over pages.
• Filling		Filling or justifying text.
• Case		Changing the case of text.
• Text Mode		The major modes for editing text files.
• Outline Mode		The major mode for editing outlines.
• TeX Mode		The major modes for editing input to the formatter TeX.
• Nroff Mode		The major mode for editing input to the formatter nroff.
Filling Text
• Auto Fill		Auto Fill mode breaks long lines automatically.
• Fill Commands		Commands to refill paragraphs and center lines.
• Fill Prefix		Filling when every line is indented or in a comment, etc.
Editing Programs
• Program Modes		Major modes for editing programs.
• Lists		Expressions with balanced parentheses.
• List Commands		The commands for working with list and sexps.
• Defuns		Each program is made up of separate functions. There are editing commands to operate on them.
• Program Indent		Adjusting indentation to show the nesting.
• Matching		Insertion of a close-delimiter flashes matching open.
• Comments		Inserting, killing, and aligning comments.
• Balanced Editing		Inserting two matching parentheses at once, etc.
• Symbol Completion		Completion on symbol names of your program or language.
• Documentation		Getting documentation of functions you plan to call.
• Change Log		Maintaining a change history for your program.
• Tags		Go direct to any function in your program in one command. Tags remembers which file it is in.
• Emerge		A convenient way of merging two versions of a program.
• C Mode		Special commands of C mode (and C++ mode).
• Fortran		Fortran mode and its special features.
• Asm Mode		Asm mode and its special features.
Indentation for Programs
• Basic Indent		Indenting a single line.
• Multi-line Indent		Commands to reindent many lines at once.
• Lisp Indent		Specifying how each Lisp function should be indented.
• C Indent		Choosing an indentation style for C code.
Tags Tables
• Tag Syntax		Tag syntax for various types of code and text files.
• Create Tags Table		Creating a tags table with `etags`.
• Select Tags Table		How to visit a tags table.
• Find Tag		Commands to find the definition of a specific tag.
• Tags Search		Using a tags table for searching and replacing.
• Tags Stepping		Visiting files in a tags table, one by one.
• List Tags		Listing and finding tags defined in a file.
Merging Files with Emerge
• Overview of Emerge		How to start Emerge. Basic concepts.
• Submodes of Emerge		Fast mode vs. Edit mode. Skip Prefers mode and Auto Advance mode.
• State of Difference		You do the merge by specifying state A or B for each difference.
• Merge Commands		Commands for selecting a difference, changing states of differences, etc.
• Exiting Emerge		What to do when you’ve finished the merge.
• Combining in Emerge		How to keep both alternatives for a difference.
• Fine Points of Emerge		Misc.
Compiling and Testing Programs
• Compilation		Compiling programs in languages other than Lisp (C, Pascal, etc.)
• Debuggers		Running symbolic debuggers for non-Lisp programs.
• Executing Lisp		Various modes for editing Lisp programs, with different facilities for running the Lisp programs.
• Libraries		Creating Lisp programs to run in Emacs.
• Interaction		Executing Lisp in an Emacs buffer.
• Eval		Executing a single Lisp expression in Emacs.
• External Lisp		Communicating through Emacs with a separate Lisp.
Running Debuggers Under Emacs
• Starting GUD		How to start a debugger subprocess.
• Debugger Operation		Connection between the debugger and source buffers.
• Commands of GUD		Key bindings for common commands.
• GUD Customization		Defining your own commands for GUD.
Abbrevs
• Abbrev Concepts		Fundamentals of defined abbrevs.
• Defining Abbrevs		Defining an abbrev, so it will expand when typed.
• Expanding Abbrevs		Controlling expansion: prefixes, canceling expansion.
• Editing Abbrevs		Viewing or editing the entire list of defined abbrevs.
• Saving Abbrevs		Saving the entire list of abbrevs for another session.
• Dynamic Abbrevs		Abbreviations for words already in the buffer.
Editing Pictures
• Basic Picture		Basic concepts and simple commands of Picture Mode.
• Insert in Picture		Controlling direction of cursor motion after "self-inserting" characters.
• Tabs in Picture		Various features for tab stops and indentation.
• Rectangles in Picture		Clearing and superimposing rectangles.
Sending Mail
• Mail Format		Format of the mail being composed.
• Mail Headers		Details of permitted mail header fields.
• Mail Aliases		Abbreviating and grouping mail addresses.
• Mail Mode		Special commands for editing mail being composed.
• Distracting NSA		How to distract the NSA’s attention.
Reading Mail with Rmail * Rmail Basics. Basic concepts of Rmail, and simple use.
• Rmail Scrolling		Scrolling through a message.
• Rmail Motion		Moving to another message.
• Rmail Deletion		Deleting and expunging messages.
• Rmail Inbox		How mail gets into the Rmail file.
• Rmail Files		Using multiple Rmail files.
• Rmail Output		Copying message out to files.
• Rmail Labels		Classifying messages by labeling them.
• Rmail Reply		Sending replies to messages you are viewing.
• Rmail Summary		Summaries show brief info on many messages.
• Rmail Sorting		Sorting messages in Rmail.
• Rmail Display		How Rmail displays a message; customization.
• Rmail Editing		Editing message text and headers in Rmail.
• Rmail Digest		Extracting the messages from a digest message.
• Out of Rmail		Converting an Rmail file to mailbox format.
• Rmail Rot13		Reading messages encoded in the rot13 code.
Dired, the Directory Editor
• Dired Enter		How to invoke Dired.
• Dired Commands		Commands in the Dired buffer.
• Dired Deletion		Deleting files with Dired.
• Flagging Many Files		Flagging files based on their names.
• Dired Visiting		Other file operations through Dired.
• Marks vs Flags		Flagging for deletion vs marking.
• Operating on Files		How to copy, rename, print, compress, etc. either one file or several files.
• Shell Commands in Dired		Running a shell command on the marked files.
• Transforming File Names		Using patterns to rename multiple files.
• Comparison in Dired		Running ‘diff’ by way of Dired.
• Subdirectories in Dired		Adding subdirectories to the Dired buffer.
• Subdirectory Motion		Moving across subdirectories, and up and down.
• Hiding Subdirectories		Making subdirectories visible or invisible.
• Dired Updating		Discarding lines for files of no interest.
• Dired and Find		Using ‘find’ to choose the files for Dired.
The Calendar and the Diary
• Calendar Motion		Moving through the calendar; selecting a date.
• Scroll Calendar		Bringing earlier or later months onto the screen.
• Counting Days		How many days are there between two dates?
• General Calendar		Exiting or recomputing the calendar.
• Holidays		Displaying dates of holidays.
• Sunrise/Sunset		Displaying local times of sunrise and sunset.
• Lunar Phases		Displaying phases of the moon.
• Other Calendars		Converting dates to other calendar systems.
• Diary		Displaying events from your diary.
• Appointments		Reminders when it’s time to do something.
• Daylight Savings		How to specify when daylight savings time is active.
Movement in the Calendar
• Calendar Unit Motion		Moving by days, weeks, months, and years.
• Move to Beginning or End		Moving to start/end of weeks, months, and years.
• Specified Dates		Moving to the current date or another specific date.
Conversion To and From Other Calendars
• Calendar Systems		The calendars Emacs understands (aside from Gregorian).
• To Other Calendar		Converting the selected date to various calendars.
• From Other Calendar		Moving to a date specified in another calendar.
• Mayan Calendar		Moving to a date specified in a Mayan calendar.
The Diary
• Diary Commands		Viewing diary entries and associated calendar dates.
• Format of Diary File		Entering events in your diary.
• Date Formats		Various ways you can specify dates.
• Adding to Diary		Commands to create diary entries.
• Special Diary Entries		Anniversaries, blocks of dates, cyclic entries, etc.
GNUS
• Buffers of GNUS		The Newsgroups, Summary and Article buffers.
• GNUS Startup		What you should know about starting GNUS.
• Summary of GNUS		A short description of the basic GNUS commands.
Running Shell Commands from Emacs
• Single Shell		How to run one shell command and return.
• Interactive Shell		Permanent shell taking input via Emacs.
• Shell Mode		Special Emacs commands used with permanent shell.
• Shell History		Repeating previous commands in a shell buffer.
• Shell Options		Options for customizing Shell mode.
• Remote Host		Connecting to another computer.
Customization
• Minor Modes		Each minor mode is one feature you can turn on independently of any others.
• Variables		Many Emacs commands examine Emacs variables to decide what to do; by setting variables, you can control their functioning.
• Keyboard Macros		A keyboard macro records a sequence of keystrokes to be replayed with a single command.
• Key Bindings		The keymaps say what command each key runs. By changing them, you can "redefine keys".
• Keyboard Translations		If your keyboard passes an undesired code for a key, you can tell Emacs to substitute another code.
• Syntax		The syntax table controls how words and expressions are parsed.
• Init File		How to write common customizations in the ‘`.emacs`’ file.
Variables
• Examining		Examining or setting one variable’s value.
• Edit Options		Examining or editing list of all variables’ values.
• Hooks		Hook variables let you specify programs for parts of Emacs to run on particular occasions.
• Locals		Per-buffer values of variables.
• File Variables		How files can specify variable values.
Keyboard Macros
• Basic Kbd Macro		Defining and running keyboard macros.
• Save Kbd Macro		Giving keyboard macros names; saving them in files.
• Kbd Macro Query		Keyboard macros that do different things each use.
Customizing Key Bindings
• Keymaps		Generalities. The global keymap.
• Prefix Keymaps		Keymaps for prefix keys.
• Local Keymaps		Major and minor modes have their own keymaps.
• Minibuffer Maps		The minibuffer uses its own local keymaps.
• Rebinding		How to redefine one key’s meaning conveniently.
• Init Rebinding		Rebinding keys with your init file, ‘`.emacs`’.
• Function Keys		Rebinding terminal function keys.
• Named ASCII Chars		Distinguishing <TAB> from `C-i`, and so on.
• Mouse Buttons		Rebinding mouse buttons in Emacs.
• Disabling		Disabling a command means confirmation is required before it can be executed. This is done to protect beginners from surprises.
The Init File, ‘`~/.emacs`’
• Init Syntax		Syntax of constants in Emacs Lisp.
• Init Examples		How to do some things with an init file.
• Terminal Init		Each terminal type can have an init file.
• Find Init		How Emacs finds the init file.
Dealing with Emacs Trouble
• DEL Gets Help		What to do if <DEL> doesn’t delete.
• Stuck Recursive		‘[...]’ in mode line around the parentheses.
• Screen Garbled		Garbage on the screen.
• Text Garbled		Garbage in the text.
• Unasked-for Search		Spontaneous entry to incremental search.
• Emergency Escape		Emergency escape— What to do if Emacs stops responding.
• Total Frustration		When you are at your wits’ end.
Reporting Bugs
• Criteria		Have you really found a bug?
• Understanding Bug Reporting		How to report a bug effectively.
• Checklist		Steps to follow for a good bug report.
• Sending Patches		How to send a patch for GNU Emacs.
Command Line Options and Arguments
• Ordinary Arguments		Arguments to visit files, load libraries, and call functions.
• Initial Options		Arguments that must come at the start of the command.
• Command Example		Examples of using command line arguments.
• Resume Arguments		Specifying arguments when you resume a running Emacs.
• Environment		Environment variables that Emacs uses.
• Display X		Changing the default display and using remote login.
• Font X		Choosing a font for text, under X.
• Colors X		Choosing colors, under X.
• Window Size X		Start-up window size, under X.
• Borders X		Internal and external borders, under X.
• Icons X		Choosing what sort of icon to use, under X.
• Resources X		Advanced use of classes and resources, under X.
Environment Variables
• General Variables		Environment variables that all versions of Emacs use.
• Misc Variables		Certain system specific variables.

Distribution

GNU Emacs is free software; this means that everyone is free to use it and free to redistribute it on certain conditions. GNU Emacs is not in the public domain; it is copyrighted and there are restrictions on its distribution, but these restrictions are designed to permit everything that a good cooperating citizen would want to do. What is not allowed is to try to prevent others from further sharing any version of GNU Emacs that they might get from you. The precise conditions are found in the GNU General Public License that comes with Emacs and also appears following this section.

The easiest way to get a copy of GNU Emacs is from someone else who has it. You need not ask for our permission to do so, or tell any one else; just copy it. If you have access to the Internet, you can get the latest distribution version of GNU Emacs from host ‘prep.ai.mit.edu’ using anonymous login. See the file ‘/pub/gnu/GETTING.GNU.SOFTWARE’ on that host to find out about your options for copying and which files to use.

You may also receive GNU Emacs when you buy a computer. Computer manufacturers are free to distribute copies on the same terms that apply to everyone else. These terms require them to give you the full sources, including whatever changes they may have made, and to permit you to redistribute the GNU Emacs received from them under the usual terms of the General Public License. In other words, the program must be free for you when you get it, not just free for the manufacturer.

You can also order copies of GNU Emacs from the Free Software Foundation, on various magnetic media or on CD-ROM. This is a convenient and reliable way to get a copy; it is also a good way to help fund our work. (The Foundation has always received most of its funds in this way.) An order form is included at the end of manuals printed by the Foundation. It is also included in the file ‘etc/ORDERS’ in the Emacs distribution. For further information, write to

Free Software Foundation
675 Mass Ave
Cambridge, MA 02139
USA

The income from distribution fees goes to support the foundation’s purpose: the development of new free software, and improvements to our existing programs including GNU Emacs.

If you find GNU Emacs useful, please send a donation to the Free Software Foundation to support our work. Donations to the Free Software Foundation are tax deductible. If you use GNU Emacs at your workplace, suggest that the company make a donation. If company policy is unsympathetic to the idea of donating to charity, you might instead suggest ordering a CD-ROM from the Foundation occasionally, or subscribing to periodic updates.

GNU GENERAL PUBLIC LICENSE

Version 2, June 1991

Copyright © 1989, 1991 Free Software Foundation, Inc.
675 Mass Ave, Cambridge, MA 02139, USA

Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.

Preamble

The licenses for most software are designed to take away your freedom to share and change it. By contrast, the GNU General Public License is intended to guarantee your freedom to share and change free software—to make sure the software is free for all its users. This General Public License applies to most of the Free Software Foundation’s software and to any other program whose authors commit to using it. (Some other Free Software Foundation software is covered by the GNU Library General Public License instead.) You can apply it to your programs, too.

When we speak of free software, we are referring to freedom, not price. Our General Public Licenses are designed to make sure that you have the freedom to distribute copies of free software (and charge for this service if you wish), that you receive source code or can get it if you want it, that you can change the software or use pieces of it in new free programs; and that you know you can do these things.

To protect your rights, we need to make restrictions that forbid anyone to deny you these rights or to ask you to surrender the rights. These restrictions translate to certain responsibilities for you if you distribute copies of the software, or if you modify it.

For example, if you distribute copies of such a program, whether gratis or for a fee, you must give the recipients all the rights that you have. You must make sure that they, too, receive or can get the source code. And you must show them these terms so they know their rights.

We protect your rights with two steps: (1) copyright the software, and (2) offer you this license which gives you legal permission to copy, distribute and/or modify the software.

Also, for each author’s protection and ours, we want to make certain that everyone understands that there is no warranty for this free software. If the software is modified by someone else and passed on, we want its recipients to know that what they have is not the original, so that any problems introduced by others will not reflect on the original authors’ reputations.

Finally, any free program is threatened constantly by software patents. We wish to avoid the danger that redistributors of a free program will individually obtain patent licenses, in effect making the program proprietary. To prevent this, we have made it clear that any patent must be licensed for everyone’s free use or not licensed at all.

The precise terms and conditions for copying, distribution and modification follow.

This License applies to any program or other work which contains a notice placed by the copyright holder saying it may be distributed under the terms of this General Public License. The “Program”, below, refers to any such program or work, and a “work based on the Program” means either the Program or any derivative work under copyright law: that is to say, a work containing the Program or a portion of it, either verbatim or with modifications and/or translated into another language. (Hereinafter, translation is included without limitation in the term “modification”.) Each licensee is addressed as “you”.
Activities other than copying, distribution and modification are not covered by this License; they are outside its scope. The act of running the Program is not restricted, and the output from the Program is covered only if its contents constitute a work based on the Program (independent of having been made by running the Program). Whether that is true depends on what the Program does.
You may copy and distribute verbatim copies of the Program’s source code as you receive it, in any medium, provided that you conspicuously and appropriately publish on each copy an appropriate copyright notice and disclaimer of warranty; keep intact all the notices that refer to this License and to the absence of any warranty; and give any other recipients of the Program a copy of this License along with the Program.
You may charge a fee for the physical act of transferring a copy, and you may at your option offer warranty protection in exchange for a fee.
You may modify your copy or copies of the Program or any portion of it, thus forming a work based on the Program, and copy and distribute such modifications or work under the terms of Section 1 above, provided that you also meet all of these conditions:
1. You must cause the modified files to carry prominent notices stating that you changed the files and the date of any change.
2. You must cause any work that you distribute or publish, that in whole or in part contains or is derived from the Program or any part thereof, to be licensed as a whole at no charge to all third parties under the terms of this License.
3. If the modified program normally reads commands interactively when run, you must cause it, when started running for such interactive use in the most ordinary way, to print or display an announcement including an appropriate copyright notice and a notice that there is no warranty (or else, saying that you provide a warranty) and that users may redistribute the program under these conditions, and telling the user how to view a copy of this License. (Exception: if the Program itself is interactive but does not normally print such an announcement, your work based on the Program is not required to print an announcement.)
These requirements apply to the modified work as a whole. If identifiable sections of that work are not derived from the Program, and can be reasonably considered independent and separate works in themselves, then this License, and its terms, do not apply to those sections when you distribute them as separate works. But when you distribute the same sections as part of a whole which is a work based on the Program, the distribution of the whole must be on the terms of this License, whose permissions for other licensees extend to the entire whole, and thus to each and every part regardless of who wrote it.

Thus, it is not the intent of this section to claim rights or contest your rights to work written entirely by you; rather, the intent is to exercise the right to control the distribution of derivative or collective works based on the Program.

In addition, mere aggregation of another work not based on the Program with the Program (or with a work based on the Program) on a volume of a storage or distribution medium does not bring the other work under the scope of this License.
You may copy and distribute the Program (or a work based on it, under Section 2) in object code or executable form under the terms of Sections 1 and 2 above provided that you also do one of the following:
1. Accompany it with the complete corresponding machine-readable source code, which must be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange; or,
2. Accompany it with a written offer, valid for at least three years, to give any third party, for a charge no more than your cost of physically performing source distribution, a complete machine-readable copy of the corresponding source code, to be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange; or,
3. Accompany it with the information you received as to the offer to distribute corresponding source code. (This alternative is allowed only for noncommercial distribution and only if you received the program in object code or executable form with such an offer, in accord with Subsection b above.)
The source code for a work means the preferred form of the work for making modifications to it. For an executable work, complete source code means all the source code for all modules it contains, plus any associated interface definition files, plus the scripts used to control compilation and installation of the executable. However, as a special exception, the source code distributed need not include anything that is normally distributed (in either source or binary form) with the major components (compiler, kernel, and so on) of the operating system on which the executable runs, unless that component itself accompanies the executable.

If distribution of executable or object code is made by offering access to copy from a designated place, then offering equivalent access to copy the source code from the same place counts as distribution of the source code, even though third parties are not compelled to copy the source along with the object code.
You may not copy, modify, sublicense, or distribute the Program except as expressly provided under this License. Any attempt otherwise to copy, modify, sublicense or distribute the Program is void, and will automatically terminate your rights under this License. However, parties who have received copies, or rights, from you under this License will not have their licenses terminated so long as such parties remain in full compliance.
You are not required to accept this License, since you have not signed it. However, nothing else grants you permission to modify or distribute the Program or its derivative works. These actions are prohibited by law if you do not accept this License. Therefore, by modifying or distributing the Program (or any work based on the Program), you indicate your acceptance of this License to do so, and all its terms and conditions for copying, distributing or modifying the Program or works based on it.
Each time you redistribute the Program (or any work based on the Program), the recipient automatically receives a license from the original licensor to copy, distribute or modify the Program subject to these terms and conditions. You may not impose any further restrictions on the recipients’ exercise of the rights granted herein. You are not responsible for enforcing compliance by third parties to this License.
If, as a consequence of a court judgment or allegation of patent infringement or for any other reason (not limited to patent issues), conditions are imposed on you (whether by court order, agreement or otherwise) that contradict the conditions of this License, they do not excuse you from the conditions of this License. If you cannot distribute so as to satisfy simultaneously your obligations under this License and any other pertinent obligations, then as a consequence you may not distribute the Program at all. For example, if a patent license would not permit royalty-free redistribution of the Program by all those who receive copies directly or indirectly through you, then the only way you could satisfy both it and this License would be to refrain entirely from distribution of the Program.
If any portion of this section is held invalid or unenforceable under any particular circumstance, the balance of the section is intended to apply and the section as a whole is intended to apply in other circumstances.

It is not the purpose of this section to induce you to infringe any patents or other property right claims or to contest validity of any such claims; this section has the sole purpose of protecting the integrity of the free software distribution system, which is implemented by public license practices. Many people have made generous contributions to the wide range of software distributed through that system in reliance on consistent application of that system; it is up to the author/donor to decide if he or she is willing to distribute software through any other system and a licensee cannot impose that choice.

This section is intended to make thoroughly clear what is believed to be a consequence of the rest of this License.
If the distribution and/or use of the Program is restricted in certain countries either by patents or by copyrighted interfaces, the original copyright holder who places the Program under this License may add an explicit geographical distribution limitation excluding those countries, so that distribution is permitted only in or among countries not thus excluded. In such case, this License incorporates the limitation as if written in the body of this License.
The Free Software Foundation may publish revised and/or new versions of the General Public License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns.
Each version is given a distinguishing version number. If the Program specifies a version number of this License which applies to it and “any later version”, you have the option of following the terms and conditions either of that version or of any later version published by the Free Software Foundation. If the Program does not specify a version number of this License, you may choose any version ever published by the Free Software Foundation.
If you wish to incorporate parts of the Program into other free programs whose distribution conditions are different, write to the author to ask for permission. For software which is copyrighted by the Free Software Foundation, write to the Free Software Foundation; we sometimes make exceptions for this. Our decision will be guided by the two goals of preserving the free status of all derivatives of our free software and of promoting the sharing and reuse of software generally.
BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM “AS IS” WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION.
IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES.

How to Apply These Terms to Your New Programs

If you develop a new program, and you want it to be of the greatest possible use to the public, the best way to achieve this is to make it free software which everyone can redistribute and change under these terms.

To do so, attach the following notices to the program. It is safest to attach them to the start of each source file to most effectively convey the exclusion of warranty; and each file should have at least the “copyright” line and a pointer to where the full notice is found.

one line to give the program's name and an idea of what it does.
Copyright (C) 19yy  name of author

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

Also add information on how to contact you by electronic and paper mail.

If the program is interactive, make it output a short notice like this when it starts in an interactive mode:

Gnomovision version 69, Copyright (C) 19yy name of author
Gnomovision comes with ABSOLUTELY NO WARRANTY; for details
type `show w'.  This is free software, and you are welcome
to redistribute it under certain conditions; type `show c' 
for details.

The hypothetical commands ‘show w’ and ‘show c’ should show the appropriate parts of the General Public License. Of course, the commands you use may be called something other than ‘show w’ and ‘show c’; they could even be mouse-clicks or menu items—whatever suits your program.

You should also get your employer (if you work as a programmer) or your school, if any, to sign a “copyright disclaimer” for the program, if necessary. Here is a sample; alter the names:

Yoyodyne, Inc., hereby disclaims all copyright
interest in the program `Gnomovision'
(which makes passes at compilers) written 
by James Hacker.

signature of Ty Coon, 1 April 1989
Ty Coon, President of Vice

This General Public License does not permit incorporating your program into proprietary programs. If your program is a subroutine library, you may consider it more useful to permit linking proprietary applications with the library. If this is what you want to do, use the GNU Library General Public License instead of this License.

Introduction

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

We say that Emacs is a display editor because normally the text being edited is visible on the screen and is updated automatically as you type your commands. @xref{Screen,Display}.

We call it a real-time editor because the display is updated very frequently, usually after each character or pair of characters you type. This minimizes the amount of information you must keep in your head as you edit. @xref{Basic,Real-time,Basic Editing}.

We call Emacs advanced because it provides facilities that go beyond simple insertion and deletion: controlling subprocesses; automatic indentation of programs; viewing two or more files at once; and dealing in terms of characters, words, lines, sentences, paragraphs, and pages, as well as expressions and comments in several different programming languages.

Self-documenting means that at any time you can type a special character, Control-h, to find out what your options are. You can also use it to find out what any command does, or to find all the commands that pertain to a topic. @xref{Help}.

Customizable means that you can change the definitions of Emacs commands in little ways. For example, if you use a programming language in which comments start with ‘<**’ and end with ‘**>’, you can tell the Emacs comment manipulation commands to use those strings (@pxref{Comments}). Another sort of customization is rearrangement of the command set. For example, if you prefer the four basic cursor motion commands (up, down, left and right) on keys in a diamond pattern on the keyboard, you can rebind the keys that way. @xref{Customization}.

Extensible means that you can go beyond simple customization and write entirely new commands, programs in the Lisp language to be run by Emacs’s own Lisp interpreter. Emacs is an “on-line extensible” system, which means that it is divided into many functions that call each other, any of which can be redefined in the middle of an editing session. Almost any part of Emacs can be replaced without making a separate copy of all of Emacs. Most of the editing commands of Emacs are written in Lisp already; the few exceptions could have been written in Lisp but are written in C for efficiency. Although only a programmer can write an extension, anybody can use it afterward.

When run under the X Window System, Emacs provides its own menus and convenient bindings to mouse buttons. But Emacs can provide many of the benefits of a window system on a text-only terminal. For instance, you can look at or edit several files at once, move text between them, and edit files at the same time as you run shell commands.

Key (Character) Index

Command and Function Index

Variable Index

Concept Index

Distribution
GNU GENERAL PUBLIC LICENSE
- Preamble
- How to Apply These Terms to Your New Programs
Introduction
Key (Character) Index
Command and Function Index
Variable Index
Concept Index

Short Table of Contents

Distribution
GNU GENERAL PUBLIC LICENSE
Introduction
Key (Character) Index
Command and Function Index
Variable Index
Concept Index

About This Document

This document was generated on December 25, 2022 using texi2html 5.0.

The buttons in the navigation panels have the following meaning:

Button	Name	Go to	From 1.2.3 go to
[ << ]	FastBack	Beginning of this chapter or previous chapter	1
[ < ]	Back	Previous section in reading order	1.2.2
[ Up ]	Up	Up section	1.2
[ > ]	Forward	Next section in reading order	1.2.4
[ >> ]	FastForward	Next chapter	2
[Top]	Top	Cover (top) of document
[Contents]	Contents	Table of contents
[Index]	Index	Index
[ ? ]	About	About (help)

where the Example assumes that the current position is at Subsubsection One-Two-Three of a document of the following structure:

1. Section One
- 1.1 Subsection One-One
  - ...
- 1.2 Subsection One-Two
  - 1.2.1 Subsubsection One-Two-One
  - 1.2.2 Subsubsection One-Two-Two
  - 1.2.3 Subsubsection One-Two-Three <== Current Position
  - 1.2.4 Subsubsection One-Two-Four
- 1.3 Subsection One-Three
  - ...
- 1.4 Subsection One-Four

This document was generated on December 25, 2022 using texi2html 5.0.