1 @c This is part of the Emacs manual.
2 @c Copyright (C) 1985-1987, 1993-1995, 1997, 2001-2012
3 @c Free Software Foundation, Inc.
4 @c See file emacs.texi for copying conditions.
5 @node Glossary, Key Index, Intro, Top
8 @c It would be nice if texinfo could add internal links from one item
9 @c to another here. Eg when we say "see also `foo bar'", there would
10 @c be a hyperlink to the foo bar item.
14 An abbrev is a text string that expands into a different text string
15 when present in the buffer. For example, you might define a few letters
16 as an abbrev for a long phrase that you want to insert frequently.
20 Aborting means getting out of a recursive edit (q.v.@:). The
21 commands @kbd{C-]} and @kbd{M-x top-level} are used for this.
24 @c FIXME? Active Region
27 Alt is the name of a modifier bit that a keyboard input character may
28 have. To make a character Alt, type it while holding down the @key{ALT}
29 key. Such characters are given names that start with @kbd{Alt-}
30 (usually written @kbd{A-} for short). (Note that many terminals have a
31 key labeled @key{ALT} that is really a @key{META} key.) @xref{User
35 See `numeric argument'.
37 @item @acronym{ASCII} character
38 An @acronym{ASCII} character is either an @acronym{ASCII} control
39 character or an @acronym{ASCII} printing character. @xref{User Input}.
41 @item @acronym{ASCII} control character
42 An @acronym{ASCII} control character is the Control version of an upper-case
43 letter, or the Control version of one of the characters @samp{@@[\]^_?}.
45 @item @acronym{ASCII} printing character
46 @acronym{ASCII} printing characters include letters, digits, space, and these
47 punctuation characters: @samp{!@@#$%^&*()_-+=|\~`@{@}[]:;"'<>,.?/}.
50 Auto Fill mode is a minor mode (q.v.@:) in which text that you insert is
51 automatically broken into lines of a given maximum width.
55 Auto saving is the practice of periodically saving the contents of an
56 Emacs buffer in a specially-named file, so that the information will
57 be preserved if the buffer is lost due to a system error or user error.
61 Emacs can automatically load Lisp libraries when a Lisp program requests a
62 function from those libraries. This is called `autoloading'.
63 @xref{Lisp Libraries}.
66 A backtrace is a trace of a series of function calls showing how a
67 program arrived at a certain point. It is used mainly for finding and
68 correcting bugs (q.v.@:). Emacs can display a backtrace when it signals
69 an error or when you type @kbd{C-g} (see `quitting'). @xref{Checklist}.
72 A backup file records the contents that a file had before the current
73 editing session. Emacs makes backup files automatically to help you
74 track down or cancel changes you later regret making. @xref{Backup}.
76 @item Balancing Parentheses
77 Emacs can balance parentheses (or other matching delimiters) either
78 manually or automatically. You do manual balancing with the commands
79 to move over parenthetical groupings (@pxref{Moving by Parens}).
80 Automatic balancing works by blinking or highlighting the delimiter
81 that matches the one you just inserted, or inserting the matching
82 delimiter for you (@pxref{Matching,,Matching Parens}).
84 @item Balanced Expressions
85 A balanced expression is a syntactically recognizable expression, such
86 as a symbol, number, string constant, block, or parenthesized expression
87 in C. @xref{Expressions,Balanced Expressions}.
93 A base buffer is a buffer whose text is shared by an indirect buffer
96 @item Bidirectional Text
97 Some human languages, such as English, are written from left to right.
98 Others, such as Arabic, are written from right to left. Emacs
99 supports both of these forms, as well as any mixture of them---this
100 is `bidirectional text'. @xref{Bidirectional Editing}.
103 To bind a key sequence means to give it a binding (q.v.@:).
107 A key sequence gets its meaning in Emacs by having a binding, which is a
108 command (q.v.@:), a Lisp function that is run when you type that
109 sequence. @xref{Commands,Binding}. Customization often involves
110 rebinding a character to a different command function. The bindings of
111 all key sequences are recorded in the keymaps (q.v.@:). @xref{Keymaps}.
114 Blank lines are lines that contain only whitespace. Emacs has several
115 commands for operating on the blank lines in the buffer. @xref{Blank Lines}.
118 Bookmarks are akin to registers (q.v.@:) in that they record positions
119 in buffers to which you can return later. Unlike registers, bookmarks
120 persist between Emacs sessions. @xref{Bookmarks}.
123 A border is a thin space along the edge of the frame, used just for
124 spacing, not for displaying anything. An Emacs frame has an ordinary
125 external border, outside of everything including the menu bar, plus an
126 internal border that surrounds the text windows, their scroll bars
127 and fringes, and separates them from the menu bar and tool bar. You
128 can customize both borders with options and resources (@pxref{Borders
129 X}). Borders are not the same as fringes (q.v.@:).
132 The buffer is the basic editing unit; one buffer corresponds to one text
133 being edited. You normally have several buffers, but at any time you are
134 editing only one, the `current buffer', though several can be visible
135 when you are using multiple windows or frames (q.v.@:). Most buffers
136 are visiting (q.v.@:) some file. @xref{Buffers}.
138 @item Buffer Selection History
139 Emacs keeps a buffer selection history that records how recently each
140 Emacs buffer has been selected. This is used for choosing a buffer to
141 select. @xref{Buffers}.
144 A bug is an incorrect or unreasonable behavior of a program, or
145 inaccurate or confusing documentation. Emacs developers treat bug
146 reports, both in Emacs code and its documentation, very seriously and
147 ask you to report any bugs you find. @xref{Bugs}.
149 @item Button Down Event
150 A button down event is the kind of input event (q.v.@:) generated
151 right away when you press down on a mouse button. @xref{Mouse Buttons}.
156 @item Byte Compilation
160 @kbd{C-} in the name of a character is an abbreviation for Control.
161 @xref{User Input,C-}.
164 @kbd{C-M-} in the name of a character is an abbreviation for
165 Control-Meta. If your terminal lacks a real @key{META} key, you type
166 a Control-Meta character by typing @key{ESC} and then typing the
167 corresponding Control character. @xref{User Input,C-M-}.
169 @item Case Conversion
170 Case conversion means changing text from upper case to lower case or
171 vice versa. @xref{Case}.
174 Characters form the contents of an Emacs buffer. Also, key sequences
175 (q.v.@:) are usually made up of characters (though they may include
176 other input events as well). @xref{User Input}.
179 Emacs supports a number of character sets, each of which represents a
180 particular alphabet or script. @xref{International}.
182 @item Character Terminal
183 See `text-only terminal'.
186 A click event is the kind of input event (q.v.@:) generated when you
187 press a mouse button and release it without moving the mouse.
188 @xref{Mouse Buttons}.
194 A clipboard is a buffer provided by the window system for transferring
195 text between applications. On the X Window system, the clipboard is
196 provided in addition to the primary selection (q.v.@:); on MS-Windows and Mac,
197 the clipboard is used @emph{instead} of the primary selection.
201 A coding system is an encoding for representing text characters in a
202 file or in a stream of information. Emacs has the ability to convert
203 text to or from a variety of coding systems when reading or writing it.
204 @xref{Coding Systems}.
207 A command is a Lisp function specially defined to be able to serve as a
208 key binding in Emacs. When you type a key sequence (q.v.@:), its
209 binding (q.v.@:) is looked up in the relevant keymaps (q.v.@:) to find
210 the command to run. @xref{Commands}.
212 @item Command History
213 See `minibuffer history'.
216 A command name is the name of a Lisp symbol that is a command
217 (@pxref{Commands}). You can invoke any command by its name using
218 @kbd{M-x} (@pxref{M-x,M-x,Running Commands by Name}).
221 A comment is text in a program which is intended only for humans reading
222 the program, and which is specially marked so that it will be ignored
223 when the program is loaded or compiled. Emacs offers special commands
224 for creating, aligning and killing comments. @xref{Comments}.
227 Common Lisp is a dialect of Lisp (q.v.@:) much larger and more powerful
228 than Emacs Lisp. Emacs provides a subset of Common Lisp in the CL
229 package. @xref{Top, Common Lisp, Overview, cl, Common Lisp Extensions}.
232 Compilation is the process of creating an executable program from source
233 code. Emacs has commands for compiling files of Emacs Lisp code
234 (@pxref{Byte Compilation,,, elisp, the Emacs Lisp
235 Reference Manual}) and programs in C and other languages
236 (@pxref{Compilation}).
239 A complete key is a key sequence that fully specifies one action to be
240 performed by Emacs. For example, @kbd{X} and @kbd{C-f} and @kbd{C-x m}
241 are complete keys. Complete keys derive their meanings from being bound
242 (q.v.@:) to commands (q.v.@:). Thus, @kbd{X} is conventionally bound to
243 a command to insert @samp{X} in the buffer; @kbd{C-x m} is
244 conventionally bound to a command to begin composing a mail message.
248 Completion is what Emacs does when it automatically expands an
249 abbreviation for a name into the entire name. Completion is done for
250 minibuffer (q.v.@:) arguments when the set of possible valid inputs
251 is known; for example, on command names, buffer names, and
252 file names. Completion usually occurs when @key{TAB}, @key{SPC} or
253 @key{RET} is typed. @xref{Completion}.@refill
255 @item Continuation Line
256 When a line of text is longer than the width of the window, it
257 normally (but see `Truncation') takes up more than one screen line
258 when displayed. We say that the text line is continued, and all
259 screen lines used for it after the first are called continuation
260 lines. @xref{Continuation Lines}. A related Emacs feature is
263 @item Control Character
264 A control character is a character that you type by holding down the
265 @key{CTRL} key. Some control characters also have their own keys, so
266 that you can type them without using @key{CTRL}. For example,
267 @key{RET}, @key{TAB}, @key{ESC} and @key{DEL} are all control
268 characters. @xref{User Input}.
271 A copyleft is a notice giving the public legal permission to
272 redistribute and modify a program or other work of art, but requiring
273 modified versions to carry similar permission. Copyright is normally
274 used to keep users divided and helpless; with copyleft we turn that
275 around to empower users and encourage them to cooperate.
277 The particular form of copyleft used by the GNU project is called the
278 GNU General Public License. @xref{Copying}.
281 The @key{CTRL} or ``control'' key is what you hold down
282 in order to enter a control character (q.v.). See also `@kbd{C-}'.
285 The current buffer in Emacs is the Emacs buffer on which most editing
286 commands operate. You can select any Emacs buffer as the current one.
290 The current line is the line that point is on (@pxref{Point}).
292 @item Current Paragraph
293 The current paragraph is the paragraph that point is in. If point is
294 between two paragraphs, the current paragraph is the one that follows
295 point. @xref{Paragraphs}.
298 The current defun is the defun (q.v.@:) that point is in. If point is
299 between defuns, the current defun is the one that follows point.
303 The cursor is the rectangle on the screen which indicates the position
304 (called point; q.v.@:) at which insertion and deletion takes place.
305 The cursor is on or under the character that follows point. Often
306 people speak of `the cursor' when, strictly speaking, they mean
307 `point'. @xref{Point,Cursor}.
310 Customization is making minor changes in the way Emacs works, to
311 reflect your preferences or needs. It is often done by setting
312 variables (@pxref{Variables}) or faces (@pxref{Face Customization}),
313 or by rebinding key sequences (@pxref{Keymaps}).
315 @cindex cut and paste
317 See `killing' and `yanking'.
320 A daemon is a standard term for a system-level process that runs in the
321 background. Daemons are often started when the system first starts up.
322 When Emacs runs in daemon-mode, it runs in the background and does not
323 open a display. You can then connect to it with the
324 @command{emacsclient} program. @xref{Emacs Server}.
326 @item Default Argument
327 The default for an argument is the value that will be assumed if you
328 do not specify one. When the minibuffer is used to read an argument,
329 the default argument is used if you just type @key{RET}.
333 A default is the value that is used for a certain purpose when
334 you do not explicitly specify a value to use.
336 @item Default Directory
337 When you specify a file name that does not start with @samp{/} or @samp{~},
338 it is interpreted relative to the current buffer's default directory.
339 (On MS systems, file names that start with a drive letter
340 @samp{@var{x}:} are treated as absolute, not relative.)
341 @xref{Minibuffer File,Default Directory}.
344 A defun is a major definition at the top level in a program. The name
345 `defun' comes from Lisp, where most such definitions use the construct
346 @code{defun}. @xref{Defuns}.
349 @key{DEL} is a character that runs the command to delete one character
350 of text before the cursor. It is typically either the @key{DELETE}
351 key or the @key{BACKSPACE} key, whichever one is easy to type.
355 Deletion means erasing text without copying it into the kill ring
356 (q.v.@:). The alternative is killing (q.v.@:). @xref{Killing,Deletion}.
358 @item Deletion of Files
359 Deleting a file means erasing it from the file system.
360 (Note that some systems use the concept of a ``trash can'', or ``recycle
361 bin'', to allow you to ``undelete'' files.)
362 @xref{Misc File Ops,Misc File Ops,Miscellaneous File Operations}.
364 @item Deletion of Messages
365 Deleting a message (in Rmail, and other mail clients) means flagging
366 it to be eliminated from your mail file. Until you expunge (q.v.@:)
367 the Rmail file, you can still undelete the messages you have deleted.
368 @xref{Rmail Deletion}.
370 @item Deletion of Windows
371 Deleting a window means eliminating it from the screen. Other windows
372 expand to use up the space. The text that was in the window is not
373 lost, and you can create a new window with the same dimensions as the
374 old if you wish. @xref{Windows}.
377 File directories are named collections in the file system, within which
378 you can place individual files or subdirectories. They are sometimes
379 referred to as ``folders''. @xref{Directories}.
381 @item Directory Local Variable
382 A directory local variable is a local variable (q.v.@:) that applies
383 to all the files within a certain directory. @xref{Directory
387 Dired is the Emacs facility that displays the contents of a file
388 directory and allows you to ``edit the directory'', performing
389 operations on the files in the directory. @xref{Dired}.
391 @item Disabled Command
392 A disabled command is one that you may not run without special
393 confirmation. The usual reason for disabling a command is that it is
394 confusing for beginning users. @xref{Disabling}.
397 Short for `button down event' (q.v.@:).
400 A drag event is the kind of input event (q.v.@:) generated when you
401 press a mouse button, move the mouse, and then release the button.
402 @xref{Mouse Buttons}.
405 A dribble file is a file into which Emacs writes all the characters that
406 you type on the keyboard. Dribble files can be used to make a record
407 for debugging Emacs bugs. Emacs does not make a dribble file unless you
408 tell it to. @xref{Bugs}.
410 @c TODO? Not really appropriate for the user manual I think.
414 The echo area is the bottom line of the screen, used for echoing the
415 arguments to commands, for asking questions, and showing brief messages
416 (including error messages). The messages are stored in the buffer
417 @samp{*Messages*} so you can review them later. @xref{Echo Area}.
420 Echoing is acknowledging the receipt of input events by displaying
421 them (in the echo area). Emacs never echoes single-character key
422 sequences; longer key sequences echo only if you pause while typing
426 We say that a character is electric if it is normally self-inserting
427 (q.v.@:), but the current major mode (q.v.@:) redefines it to do something
428 else as well. For example, some programming language major modes define
429 particular delimiter characters to reindent the line, or insert one or
430 more newlines in addition to self-insertion.
433 End of line is a character or a sequence of characters that indicate
434 the end of a text line. On GNU and Unix systems, this is a newline
435 (q.v.@:), but other systems have other conventions. @xref{Coding
436 Systems,end-of-line}. Emacs can recognize several end-of-line
437 conventions in files and convert between them.
439 @item Environment Variable
440 An environment variable is one of a collection of variables stored by
441 the operating system, each one having a name and a value. Emacs can
442 access environment variables set by its parent shell, and it can set
443 variables in the environment it passes to programs it invokes.
450 An error occurs when an Emacs command cannot execute in the current
451 circumstances. When an error occurs, execution of the command stops
452 (unless the command has been programmed to do otherwise) and Emacs
453 reports the error by displaying an error message (q.v.@:).
455 @c Type-ahead is discarded. Then Emacs is ready to read another
459 An error message is output displayed by Emacs when you ask it to do
460 something impossible (such as, killing text forward when point is at
461 the end of the buffer), or when a command malfunctions in some way.
462 Such messages appear in the echo area, accompanied by a beep.
465 @key{ESC} is a character used as a prefix for typing Meta characters on
466 keyboards lacking a @key{META} key. Unlike the @key{META} key (which,
467 like the @key{SHIFT} key, is held down while another character is
468 typed), you press the @key{ESC} key as you would press a letter key, and
469 it applies to the next character you type.
472 See `balanced expression'.
475 Expunging an Rmail, Gnus newsgroup, or Dired buffer is an operation
476 that truly discards the messages or files you have previously flagged
480 A face is a style of displaying characters. It specifies attributes
481 such as font family and size, foreground and background colors,
482 underline and strike-through, background stipple, etc. Emacs provides
483 features to associate specific faces with portions of buffer text, in
484 order to display that text as specified by the face attributes.
487 @item File Local Variable
488 A file local variable is a local variable (q.v.@:) specified in a
489 given file. @xref{File Variables}. See also `directory variable'.
492 Emacs uses file locking to notice when two different users
493 start to edit one file at the same time. @xref{Interlocking}.
496 @c This is fairly tautological...
497 A file name is a name that refers to a file. File names may be relative
498 or absolute; the meaning of a relative file name depends on the current
499 directory, but an absolute file name refers to the same file regardless
500 of which directory is current. On GNU and Unix systems, an absolute
501 file name starts with a slash (the root directory) or with @samp{~/} or
502 @samp{~@var{user}/} (a home directory). On MS-Windows/MS-DOS, an
503 absolute file name can also start with a drive letter and a colon, e.g.
506 Some people use the term ``pathname'' for file names, but we do not;
507 we use the word ``path'' only in the term ``search path'' (q.v.@:).
509 @item File-Name Component
510 A file-name component names a file directly within a particular
511 directory. On GNU and Unix systems, a file name is a sequence of
512 file-name components, separated by slashes. For example, @file{foo/bar}
513 is a file name containing two components, @samp{foo} and @samp{bar}; it
514 refers to the file named @samp{bar} in the directory named @samp{foo} in
515 the current directory. MS-DOS/MS-Windows file names can also use
516 backslashes to separate components, as in @file{foo\bar}.
519 The fill prefix is a string that should be expected at the beginning
520 of each line when filling is done. It is not regarded as part of the
521 text to be filled. @xref{Filling}.
524 Filling text means adjusting the position of line-breaks to shift text
525 between consecutive lines, so that all the lines are approximately the
526 same length. @xref{Filling}. Some other editors call this feature
530 Font Lock is a mode that highlights parts of buffer text in different
531 faces, according to the syntax. Some other editors refer to this as
532 ``syntax highlighting''. For example, all comments (q.v.@:)
533 might be colored red. @xref{Font Lock}.
536 A fontset is a named collection of fonts. A fontset specification lists
537 character sets and which font to use to display each of them. Fontsets
538 make it easy to change several fonts at once by specifying the name of a
539 fontset, rather than changing each font separately. @xref{Fontsets}.
541 @item Formfeed Character
545 A frame is a rectangular cluster of Emacs windows. Emacs starts out
546 with one frame, but you can create more. You can subdivide each frame
547 into Emacs windows (q.v.@:). When you are using a window system
548 (q.v.@:), more than one frame can be visible at the same time.
549 @xref{Frames}. Some other editors use the term ``window'' for this,
550 but in Emacs a window means something else.
553 Free software is software that gives you the freedom to share, study
554 and modify it. Emacs is free software, part of the GNU project
555 (q.v.@:), and distributed under a copyleft (q.v.@:) license called the
556 GNU General Public License. @xref{Copying}.
558 @item Free Software Foundation
559 The Free Software Foundation (FSF) is a charitable foundation
560 dedicated to promoting the development of free software (q.v.@:).
561 For more information, see @uref{http://fsf.org/, the FSF website}.
564 On a graphical display (q.v.@:), there's a narrow portion of the frame
565 (q.v.@:) between the text area and the window's border. These
566 ``fringes'' are used to display symbols that provide information about
567 the buffer text (@pxref{Fringes}). Emacs displays the fringe using a
568 special face (q.v.@:) called @code{fringe}. @xref{Faces,fringe}.
571 See `Free Software Foundation'.
574 FTP is an acronym for File Transfer Protocol. This is one standard
575 method for retrieving remote files (q.v.@:).
578 A function key is a key on the keyboard that sends input but does not
579 correspond to any character. @xref{Function Keys}.
582 Global means ``independent of the current environment; in effect
583 throughout Emacs''. It is the opposite of local (q.v.@:). Particular
584 examples of the use of `global' appear below.
587 A global definition of an abbrev (q.v.@:) is effective in all major
588 modes that do not have local (q.v.@:) definitions for the same abbrev.
592 The global keymap (q.v.@:) contains key bindings that are in effect
593 everywhere, except when overridden by local key bindings in a major
594 mode's local keymap (q.v.@:). @xref{Keymaps}.
596 @item Global Mark Ring
597 The global mark ring records the series of buffers you have recently
598 set a mark (q.v.@:) in. In many cases you can use this to backtrack
599 through buffers you have been editing, or in which you have found
600 tags (see `tags table'). @xref{Global Mark Ring}.
602 @item Global Substitution
603 Global substitution means replacing each occurrence of one string by
604 another string throughout a large amount of text. @xref{Replace}.
606 @item Global Variable
607 The global value of a variable (q.v.@:) takes effect in all buffers
608 that do not have their own local (q.v.@:) values for the variable.
612 GNU is a recursive acronym for GNU's Not Unix, and it refers to a
613 Unix-compatible operating system which is free software (q.v.@:).
614 @xref{Manifesto}. GNU is normally used with Linux as the kernel since
615 Linux works better than the GNU kernel. For more information, see
616 @uref{http://www.gnu.org/, the GNU website}.
618 @item Graphic Character
619 Graphic characters are those assigned pictorial images rather than
620 just names. All the non-Meta (q.v.@:) characters except for the
621 Control (q.v.@:) characters are graphic characters. These include
622 letters, digits, punctuation, and spaces; they do not include
623 @key{RET} or @key{ESC}. In Emacs, typing a graphic character inserts
624 that character (in ordinary editing modes). @xref{Inserting Text}.
626 @item Graphical Display
627 A graphical display is one that can display images and multiple fonts.
628 Usually it also has a window system (q.v.@:).
631 Highlighting text means displaying it with a different foreground and/or
632 background color to make it stand out from the rest of the text in the
635 Emacs uses highlighting in several ways. It highlights the region
636 whenever it is active (@pxref{Mark}). Incremental search also
637 highlights matches (@pxref{Incremental Search}). See also `font lock'.
640 Hardcopy means printed output. Emacs has various commands for
641 printing the contents of Emacs buffers. @xref{Printing}.
644 @key{HELP} is the Emacs name for @kbd{C-h} or @key{F1}. You can type
645 @key{HELP} at any time to ask what options you have, or to ask what a
646 command does. @xref{Help}.
649 Help echo is a short message displayed in the echo area (q.v.@:) when
650 the mouse pointer is located on portions of display that require some
651 explanations. Emacs displays help echo for menu items, parts of the
652 mode line, tool-bar buttons, etc. On graphical displays, the messages
653 can be displayed as tooltips (q.v.@:). @xref{Tooltips}.
656 Your home directory contains your personal files. On a multi-user GNU
657 or Unix system, each user has his or her own home directory. When you
658 start a new login session, your home directory is the default
659 directory in which to start. A standard shorthand for your home
660 directory is @samp{~}. Similarly, @samp{~@var{user}} represents the
661 home directory of some other user.
664 A hook is a list of functions to be called on specific occasions, such
665 as saving a buffer in a file, major mode activation, etc. By
666 customizing the various hooks, you can modify Emacs's behavior without
667 changing any of its code. @xref{Hooks}.
670 Hyper is the name of a modifier bit that a keyboard input character may
671 have. To make a character Hyper, type it while holding down the
672 @key{HYPER} key. Such characters are given names that start with
673 @kbd{Hyper-} (usually written @kbd{H-} for short). @xref{User Input}.
676 ``Iff'' means ``if and only if''. This terminology comes from
677 mathematics. Try to avoid using this term in documentation, since
678 many are unfamiliar with it and mistake it for a typo.
681 An inbox is a file in which mail is delivered by the operating system.
682 Rmail transfers mail from inboxes to Rmail files in which the
683 mail is then stored permanently or until explicitly deleted.
686 @item Incremental Search
687 Emacs provides an incremental search facility, whereby Emacs begins
688 searching for a string as soon as you type the first character.
689 As you type more characters, it refines the search. @xref{Incremental Search}.
692 Indentation means blank space at the beginning of a line. Most
693 programming languages have conventions for using indentation to
694 illuminate the structure of the program, and Emacs has special
695 commands to adjust indentation.
698 @item Indirect Buffer
699 An indirect buffer is a buffer that shares the text of another buffer,
700 called its base buffer (q.v.@:). @xref{Indirect Buffers}.
703 Info is the hypertext format used by the GNU project for writing
707 An input event represents, within Emacs, one action taken by the user on
708 the terminal. Input events include typing characters, typing function
709 keys, pressing or releasing mouse buttons, and switching between Emacs
710 frames. @xref{User Input}.
713 An input method is a system for entering non-@acronym{ASCII} text characters by
714 typing sequences of @acronym{ASCII} characters (q.v.@:). @xref{Input Methods}.
717 Insertion means adding text into the buffer, either from the keyboard
718 or from some other place in Emacs.
724 See `incremental search'.
727 Justification means adding extra spaces within lines of text in order
728 to adjust the position of the text edges. @xref{Fill Commands}.
734 Keyboard macros are a way of defining new Emacs commands from
735 sequences of existing ones, with no need to write a Lisp program.
736 You can use a macro to record a sequence of commands, then
737 play them back as many times as you like.
738 @xref{Keyboard Macros}.
740 @cindex keyboard shortcuts
741 @item Keyboard Shortcut
742 A keyboard shortcut is a key sequence (q.v.@:) that invokes a
743 command. What some programs call ``assigning a keyboard shortcut'',
744 Emacs calls ``binding a key sequence''. See `binding'.
747 A key sequence (key, for short) is a sequence of input events (q.v.@:)
748 that are meaningful as a single unit. If the key sequence is enough to
749 specify one action, it is a complete key (q.v.@:); if it is not enough,
750 it is a prefix key (q.v.@:). @xref{Keys}.
753 The keymap is the data structure that records the bindings (q.v.@:) of
754 key sequences to the commands that they run. For example, the global
755 keymap binds the character @kbd{C-n} to the command function
756 @code{next-line}. @xref{Keymaps}.
758 @item Keyboard Translation Table
759 The keyboard translation table is an array that translates the character
760 codes that come from the terminal into the character codes that make up
764 The kill ring is where all text you have killed (see `killing')
765 recently is saved. You can reinsert any of the killed text still in
766 the ring; this is called yanking (q.v.@:). @xref{Yanking}.
769 Killing means erasing text and saving it on the kill ring so it can be
770 yanked (q.v.@:) later. Some other systems call this ``cutting''.
771 Most Emacs commands that erase text perform killing, as opposed to
772 deletion (q.v.@:). @xref{Killing}.
775 Killing a job (such as, an invocation of Emacs) means making it cease
776 to exist. Any data within it, if not saved in a file, is lost.
779 @item Language Environment
780 Your choice of language environment specifies defaults for the input
781 method (q.v.@:) and coding system (q.v.@:). @xref{Language
782 Environments}. These defaults are relevant if you edit
783 non-@acronym{ASCII} text (@pxref{International}).
785 @c TODO? Not really appropriate for the user manual I think.
792 Lisp is a programming language. Most of Emacs is written in a dialect
793 of Lisp, called Emacs Lisp, which is extended with special features that
794 make it especially suitable for text editing tasks.
797 A list is, approximately, a text string beginning with an open
798 parenthesis and ending with the matching close parenthesis. In C mode
799 and other non-Lisp modes, groupings surrounded by other kinds of matched
800 delimiters appropriate to the language, such as braces, are also
801 considered lists. Emacs has special commands for many operations on
802 lists. @xref{Moving by Parens}.
805 Local means ``in effect only in a particular context''; the relevant
806 kind of context is a particular function execution, a particular
807 buffer, or a particular major mode. It is the opposite of `global'
808 (q.v.@:). Specific uses of `local' in Emacs terminology appear below.
811 A local abbrev definition is effective only if a particular major mode
812 is selected. In that major mode, it overrides any global definition
813 for the same abbrev. @xref{Abbrevs}.
816 A local keymap is used in a particular major mode; the key bindings
817 (q.v.@:) in the current local keymap override global bindings of the
818 same key sequences. @xref{Keymaps}.
821 A local value of a variable (q.v.@:) applies to only one buffer.
825 @kbd{M-} in the name of a character is an abbreviation for @key{META},
826 one of the modifier keys that can accompany any character.
827 @xref{User Input,M-}.
830 @kbd{M-C-} in the name of a character is an abbreviation for
831 Control-Meta; it means the same thing as `@kbd{C-M-}' (q.v.@:).
834 @kbd{M-x} is the key sequence that is used to call an Emacs command by
835 name. This is how you run commands that are not bound to key sequences.
836 @xref{M-x,M-x,Running Commands by Name}.
839 Mail means messages sent from one user to another through the computer
840 system, to be read at the recipient's convenience. Emacs has commands for
841 composing and sending mail, and for reading and editing the mail you have
842 received. @xref{Sending Mail}. @xref{Rmail}, for one way to read
845 @item Mail Composition Method
846 A mail composition method is a program runnable within Emacs for editing
847 and sending a mail message. Emacs lets you select from several
848 alternative mail composition methods. @xref{Mail Methods}.
851 The Emacs major modes are a mutually exclusive set of options, each of
852 which configures Emacs for editing a certain sort of text. Ideally,
853 each programming language has its own major mode. @xref{Major Modes}.
856 The space between the usable part of a window (including the
857 fringe) and the window edge.
860 The mark points to a position in the text. It specifies one end of the
861 region (q.v.@:), point being the other end. Many commands operate on
862 all the text from point to the mark. Each buffer has its own mark.
866 The mark ring is used to hold several recent previous locations of the
867 mark, in case you want to move back to them. Each buffer has its
868 own mark ring; in addition, there is a single global mark ring (q.v.@:).
872 The menu bar is a line at the top of an Emacs frame. It contains
873 words you can click on with the mouse to bring up menus, or you can use
874 a keyboard interface to navigate it. @xref{Menu Bars}.
880 Meta is the name of a modifier bit which you can use in a command
881 character. To enter a meta character, you hold down the @key{META}
882 key while typing the character. We refer to such characters with
883 names that start with @kbd{Meta-} (usually written @kbd{M-} for
884 short). For example, @kbd{M-<} is typed by holding down @key{META}
885 and at the same time typing @kbd{<} (which itself is done, on most
886 terminals, by holding down @key{SHIFT} and typing @kbd{,}).
887 @xref{User Input,Meta}.
889 On some terminals, the @key{META} key is actually labeled @key{ALT}
893 A Meta character is one whose character code includes the Meta bit.
896 The minibuffer is the window that appears when necessary inside the
897 echo area (q.v.@:), used for reading arguments to commands.
900 @item Minibuffer History
901 The minibuffer history records the text you have specified in the past
902 for minibuffer arguments, so you can conveniently use the same text
903 again. @xref{Minibuffer History}.
906 A minor mode is an optional feature of Emacs, which can be switched on
907 or off independently of all other features. Each minor mode has a
908 command to turn it on or off. Some minor modes are global (q.v.@:),
909 and some are local (q.v.@:). @xref{Minor Modes}.
911 @item Minor Mode Keymap
912 A minor mode keymap is a keymap that belongs to a minor mode and is
913 active when that mode is enabled. Minor mode keymaps take precedence
914 over the buffer's local keymap, just as the local keymap takes
915 precedence over the global keymap. @xref{Keymaps}.
918 The mode line is the line at the bottom of each window (q.v.@:), giving
919 status information on the buffer displayed in that window. @xref{Mode
922 @item Modified Buffer
923 A buffer (q.v.@:) is modified if its text has been changed since the
924 last time the buffer was saved (or since it was created, if it
925 has never been saved). @xref{Saving}.
928 Moving text means erasing it from one place and inserting it in
929 another. The usual way to move text is by killing (q.v.@:) it and then
930 yanking (q.v.@:) it. @xref{Killing}.
933 MULE refers to the Emacs features for editing multilingual
934 non-@acronym{ASCII} text using multibyte characters (q.v.@:).
935 @xref{International}.
937 @item Multibyte Character
938 A multibyte character is a character that takes up several bytes in a
939 buffer. Emacs uses multibyte characters to represent non-@acronym{ASCII} text,
940 since the number of non-@acronym{ASCII} characters is much more than 256.
941 @xref{International Chars, International Characters}.
944 A named mark is a register (q.v.@:), in its role of recording a
945 location in text so that you can move point to that location.
949 Narrowing means creating a restriction (q.v.@:) that limits editing in
950 the current buffer to only a part of the text. Text outside that part
951 is inaccessible for editing (or viewing) until the boundaries are
952 widened again, but it is still there, and saving the file saves it
953 all. @xref{Narrowing}.
956 Control-J characters in the buffer terminate lines of text and are
957 therefore also called newlines. See `End of Line'.
962 @code{nil} is a value usually interpreted as a logical ``false''. Its
963 opposite is @code{t}, interpreted as ``true''.
965 @item Numeric Argument
966 A numeric argument is a number, specified before a command, to change
967 the effect of the command. Often the numeric argument serves as a
968 repeat count. @xref{Arguments}.
971 Overwrite mode is a minor mode. When it is enabled, ordinary text
972 characters replace the existing text after point rather than pushing
973 it to one side. @xref{Minor Modes}.
976 A package is a collection of Lisp code that you download and
977 automatically install from within Emacs. Packages provide a
978 convenient way to add new features. @xref{Packages}.
981 A page is a unit of text, delimited by formfeed characters (@acronym{ASCII}
982 control-L, code 014) at the beginning of a line. Some Emacs
983 commands are provided for moving over and operating on pages.
987 Paragraphs are the medium-size unit of human-language text. There are
988 special Emacs commands for moving over and operating on paragraphs.
992 We say that certain Emacs commands parse words or expressions in the
993 text being edited. Really, all they know how to do is find the other
994 end of a word or expression.
997 Point is the place in the buffer at which insertion and deletion
998 occur. Point is considered to be between two characters, not at one
999 character. The terminal's cursor (q.v.@:) indicates the location of
1000 point. @xref{Point}.
1002 @item Prefix Argument
1003 See `numeric argument'.
1006 A prefix key is a key sequence (q.v.@:) whose sole function is to
1007 introduce a set of longer key sequences. @kbd{C-x} is an example of
1008 prefix key; any two-character sequence starting with @kbd{C-x} is
1009 therefore a legitimate key sequence. @xref{Keys}.
1011 @c I don't think this kind of thing needs to be here.
1013 @item Primary Rmail File
1014 Your primary Rmail file is the file named @samp{RMAIL} in your home
1015 directory. That's where Rmail stores your incoming mail, unless you
1016 specify a different file name. @xref{Rmail}.
1019 @item Primary Selection
1020 The primary selection is one particular X selection (q.v.@:); it is the
1021 selection that most X applications use for transferring text to and from
1024 The Emacs kill commands set the primary selection and the yank command
1025 uses the primary selection when appropriate. @xref{Killing}.
1028 A prompt is text used to ask you for input. Displaying a prompt
1029 is called prompting. Emacs prompts always appear in the echo area
1030 (q.v.@:). One kind of prompting happens when the minibuffer is used to
1031 read an argument (@pxref{Minibuffer}); the echoing that happens when
1032 you pause in the middle of typing a multi-character key sequence is also
1033 a kind of prompting (@pxref{Echo Area}).
1036 Query-replace is an interactive string replacement feature provided by
1037 Emacs. @xref{Query Replace}.
1040 Quitting means canceling a partially typed command or a running
1041 command, using @kbd{C-g} (or @kbd{C-@key{BREAK}} on MS-DOS). @xref{Quitting}.
1044 Quoting means depriving a character of its usual special significance.
1045 The most common kind of quoting in Emacs is with @kbd{C-q}. What
1046 constitutes special significance depends on the context and on
1047 convention. For example, an ``ordinary'' character as an Emacs command
1048 inserts itself; so in this context, a special character is any character
1049 that does not normally insert itself (such as @key{DEL}, for example),
1050 and quoting it makes it insert itself as if it were not special. Not
1051 all contexts allow quoting. @xref{Inserting Text,Quoting}.
1053 @item Quoting File Names
1054 Quoting a file name turns off the special significance of constructs
1055 such as @samp{$}, @samp{~} and @samp{:}. @xref{Quoted File Names}.
1057 @item Read-Only Buffer
1058 A read-only buffer is one whose text you are not allowed to change.
1059 Normally Emacs makes buffers read-only when they contain text which
1060 has a special significance to Emacs; for example, Dired buffers.
1061 Visiting a file that is write-protected also makes a read-only buffer.
1065 A rectangle consists of the text in a given range of columns on a given
1066 range of lines. Normally you specify a rectangle by putting point at
1067 one corner and putting the mark at the diagonally opposite corner.
1070 @item Recursive Editing Level
1071 A recursive editing level is a state in which part of the execution of
1072 a command involves asking you to edit some text. This text may
1073 or may not be the same as the text to which the command was applied.
1074 The mode line indicates recursive editing levels with square brackets
1075 (@samp{[} and @samp{]}). @xref{Recursive Edit}.
1078 Redisplay is the process of correcting the image on the screen to
1079 correspond to changes that have been made in the text being edited.
1080 @xref{Screen,Redisplay}.
1083 See `regular expression'.
1086 The region is the text between point (q.v.@:) and the mark (q.v.@:).
1087 Many commands operate on the text of the region. @xref{Mark,Region}.
1090 Registers are named slots in which text, buffer positions, or
1091 rectangles can be saved for later use. @xref{Registers}. A related
1092 Emacs feature is `bookmarks' (q.v.@:).
1094 @item Regular Expression
1095 A regular expression is a pattern that can match various text strings;
1096 for example, @samp{a[0-9]+} matches @samp{a} followed by one or more
1097 digits. @xref{Regexps}.
1100 A remote file is a file that is stored on a system other than your own.
1101 Emacs can access files on other computers provided that they are
1102 connected to the same network as your machine, and (obviously) that
1103 you have a supported method to gain access to those files.
1104 @xref{Remote Files}.
1107 See `numeric argument'.
1110 See `global substitution'.
1113 A buffer's restriction is the amount of text, at the beginning or the
1114 end of the buffer, that is temporarily inaccessible. Giving a buffer a
1115 nonzero amount of restriction is called narrowing (q.v.@:); removing
1116 a restriction is called widening (q.v.@:). @xref{Narrowing}.
1119 @key{RET} is a character that in Emacs runs the command to insert a
1120 newline into the text. It is also used to terminate most arguments
1121 read in the minibuffer (q.v.@:). @xref{User Input,Return}.
1124 Reverting means returning to the original state. Emacs lets you
1125 revert a buffer by re-reading its file from disk. @xref{Reverting}.
1127 @c Seems too obvious, also there is nothing special about the format
1131 An Rmail file is a file containing text in the format used by
1132 Rmail for storing mail. @xref{Rmail}.
1136 Saving a buffer means copying its text into the file that was visited
1137 (q.v.@:) in that buffer. This is the way text in files actually gets
1138 changed by your Emacs editing. @xref{Saving}.
1141 A scroll bar is a tall thin hollow box that appears at the side of a
1142 window. You can use mouse commands in the scroll bar to scroll the
1143 window. The scroll bar feature is supported only under windowing
1144 systems. @xref{Scroll Bars}.
1147 Scrolling means shifting the text in the Emacs window so as to see a
1148 different part of the buffer. @xref{Scrolling}.
1151 Searching means moving point to the next occurrence of a specified
1152 string or the next match for a specified regular expression.
1156 A search path is a list of directory names, to be used for searching for
1157 files for certain purposes. For example, the variable @code{load-path}
1158 holds a search path for finding Lisp library files. @xref{Lisp Libraries}.
1160 @item Secondary Selection
1161 The secondary selection is one particular X selection (q.v.@:); some X
1162 applications can use it for transferring text to and from other
1163 applications. Emacs has special mouse commands for transferring text
1164 using the secondary selection. @xref{Secondary Selection}.
1166 @item Selected Frame
1167 The selected frame is the one your input currently operates on.
1170 @item Selected Window
1171 The selected window is the one your input currently operates on.
1172 @xref{Basic Window}.
1174 @item Selecting a Buffer
1175 Selecting a buffer means making it the current (q.v.@:) buffer.
1176 @xref{Select Buffer}.
1179 Windowing systems allow an application program to specify
1180 selections whose values are text. A program can also read the
1181 selections that other programs have set up. This is the principal way
1182 of transferring text between window applications. Emacs has commands to
1183 work with the primary (q.v.@:) selection and the secondary (q.v.@:)
1184 selection, and also with the clipboard (q.v.@:).
1186 @item Self-Documentation
1187 Self-documentation is the feature of Emacs that can tell you what any
1188 command does, or give you a list of all commands related to a topic
1189 you specify. You ask for self-documentation with the help character,
1190 @kbd{C-h}. @xref{Help}.
1192 @item Self-Inserting Character
1193 A character is self-inserting if typing that character inserts that
1194 character in the buffer. Ordinary printing and whitespace characters
1195 are self-inserting in Emacs, except in certain special major modes.
1198 Emacs has commands for moving by or killing by sentences.
1202 Within Emacs, you can start a `server' process, which listens for
1203 connections from `clients'. This offers a faster alternative to
1204 starting several Emacs instances. @xref{Emacs Server}. See also
1207 @c This is only covered in the lispref, not the user manual.
1209 @item Session Manager
1210 Some window systems (q.v.@:) provide a tool called a `session manager'.
1211 This offers the ability to save your windows when you log off,
1212 and restore them after you log in again.
1216 A sexp (short for ``s-expression'') is the basic syntactic unit of
1217 Lisp in its textual form: either a list, or Lisp atom. Sexps are also
1218 the balanced expressions (q.v.@:) of the Lisp language; this is why
1219 the commands for editing balanced expressions have `sexp' in their
1220 name. @xref{Expressions,Sexps}.
1222 @item Simultaneous Editing
1223 Simultaneous editing means two users modifying the same file at once.
1224 Simultaneous editing, if not detected, can cause one user to lose his
1225 or her work. Emacs detects all cases of simultaneous editing, and
1226 warns one of the users to investigate.
1227 @xref{Interlocking,Interlocking,Simultaneous Editing}.
1230 @key{SPC} is the space character, which you enter by pressing the
1234 The speedbar is a special tall frame that provides fast access to Emacs
1235 buffers, functions within those buffers, Info nodes, and other
1236 interesting parts of text within Emacs. @xref{Speedbar}.
1238 @item Spell Checking
1239 Spell checking means checking correctness of the written form of each
1240 one of the words in a text. Emacs can use various external
1241 spelling-checker programs to check the spelling of parts of a buffer
1242 via a convenient user interface. @xref{Spelling}.
1245 A string is a kind of Lisp data object that contains a sequence of
1246 characters. Many Emacs variables are intended to have strings as
1247 values. The Lisp syntax for a string consists of the characters in the
1248 string with a @samp{"} before and another @samp{"} after. A @samp{"}
1249 that is part of the string must be written as @samp{\"} and a @samp{\}
1250 that is part of the string must be written as @samp{\\}. All other
1251 characters, including newline, can be included just by writing them
1252 inside the string; however, backslash sequences as in C, such as
1253 @samp{\n} for newline or @samp{\241} using an octal character code, are
1256 @item String Substitution
1257 See `global substitution'.
1259 @item Syntax Highlighting
1263 The syntax table tells Emacs which characters are part of a word,
1264 which characters balance each other like parentheses, etc.
1265 @xref{Syntax Tables,, Syntax Tables, elisp, The Emacs Lisp Reference
1269 Super is the name of a modifier bit that a keyboard input character may
1270 have. To make a character Super, type it while holding down the
1271 @key{SUPER} key. Such characters are given names that start with
1272 @kbd{Super-} (usually written @kbd{s-} for short). @xref{User Input}.
1275 Suspending Emacs means stopping it temporarily and returning control
1276 to its parent process, which is usually a shell. Unlike killing a job
1277 (q.v.@:), you can later resume the suspended Emacs job without losing
1278 your buffers, unsaved edits, undo history, etc. @xref{Exiting}.
1281 @key{TAB} is the tab character. In Emacs it is typically used for
1282 indentation or completion.
1285 A tags table is a file that serves as an index to the function
1286 definitions in one or more other files. @xref{Tags}.
1288 @item Termscript File
1289 A termscript file contains a record of all characters sent by Emacs to
1290 the terminal. It is used for tracking down bugs in Emacs redisplay.
1291 Emacs does not make a termscript file unless you tell it to.
1295 `Text' has two meanings (@pxref{Text}):
1299 Data consisting of a sequence of characters, as opposed to binary
1300 numbers, executable programs, and the like. The basic contents of an
1301 Emacs buffer (aside from the text properties, q.v.@:) are always text
1304 Data consisting of written human language (as opposed to programs),
1305 or following the stylistic conventions of human language.
1308 @item Text-only Terminal
1309 A text-only terminal is a display that is limited to displaying text in
1310 character units. Such a terminal cannot control individual pixels it
1311 displays. Emacs supports a subset of display features on text-only
1314 @item Text Properties
1315 Text properties are annotations recorded for particular characters in
1316 the buffer. Images in the buffer are recorded as text properties;
1317 they also specify formatting information. @xref{Editing Format Info}.
1320 A theme is a set of customizations (q.v.@:) that give Emacs a
1321 particular appearance or behavior. For example, you might use a theme
1322 for your favorite set of faces (q.v.@:).
1325 The tool bar is a line (sometimes multiple lines) of icons at the top
1326 of an Emacs frame. Clicking on one of these icons executes a command.
1327 You can think of this as a graphical relative of the menu bar (q.v.@:).
1331 Tooltips are small windows displaying a help echo (q.v.@:) text, which
1332 explains parts of the display, lists useful options available via mouse
1333 clicks, etc. @xref{Tooltips}.
1336 Top level is the normal state of Emacs, in which you are editing the
1337 text of the file you have visited. You are at top level whenever you
1338 are not in a recursive editing level (q.v.@:) or the minibuffer
1339 (q.v.@:), and not in the middle of a command. You can get back to top
1340 level by aborting (q.v.@:) and quitting (q.v.@:). @xref{Quitting}.
1342 @c FIXME? Transient Mark Mode
1345 Transposing two units of text means putting each one into the place
1346 formerly occupied by the other. There are Emacs commands to transpose
1347 two adjacent characters, words, balanced expressions (q.v.@:) or lines
1348 (@pxref{Transpose}).
1351 See `deletion of files'.
1354 Truncating text lines in the display means leaving out any text on a
1355 line that does not fit within the right margin of the window
1356 displaying it. See also `continuation line'.
1357 @xref{Continuation Lines,Truncation}.
1360 See `text-only terminal'.
1363 Undoing means making your previous editing go in reverse, bringing
1364 back the text that existed earlier in the editing session.
1368 Unix is a class of multi-user computer operating systems with a long
1369 history. There are several implementations today. The GNU project
1370 (q.v.@:) aims to develop a complete Unix-like operating system that
1371 is free software (q.v.@:).
1374 A user option is a face (q.v.@:) or a variable (q.v.@:) that exists so
1375 that you can customize Emacs by setting it to a new value.
1376 @xref{Easy Customization}.
1379 A variable is an object in Lisp that can store an arbitrary value.
1380 Emacs uses some variables for internal purposes, and has others (known
1381 as `user options'; q.v.@:) just so that you can set their values to
1382 control the behavior of Emacs. The variables used in Emacs that you
1383 are likely to be interested in are listed in the Variables Index in
1384 this manual (@pxref{Variable Index}). @xref{Variables}, for
1385 information on variables.
1387 @item Version Control
1388 Version control systems keep track of multiple versions of a source file.
1389 They provide a more powerful alternative to keeping backup files (q.v.@:).
1390 @xref{Version Control}.
1393 Visiting a file means loading its contents into a buffer (q.v.@:)
1394 where they can be edited. @xref{Visiting}.
1397 Whitespace is any run of consecutive formatting characters (space,
1398 tab, newline, and backspace).
1401 Widening is removing any restriction (q.v.@:) on the current buffer;
1402 it is the opposite of narrowing (q.v.@:). @xref{Narrowing}.
1405 Emacs divides a frame (q.v.@:) into one or more windows, each of which
1406 can display the contents of one buffer (q.v.@:) at any time.
1407 @xref{Screen}, for basic information on how Emacs uses the screen.
1408 @xref{Windows}, for commands to control the use of windows. Some
1409 other editors use the term ``window'' for what we call a `frame'
1413 A window system is software that operates on a graphical display
1414 (q.v.@:), to subdivide the screen so that multiple applications can
1415 have their] own windows at the same time. All modern operating systems
1416 include a window system.
1422 Word search is searching for a sequence of words, considering the
1423 punctuation between them as insignificant. @xref{Word Search}.
1426 Yanking means reinserting text previously killed (q.v.@:). It can be
1427 used to undo a mistaken kill, or for copying or moving text. Some
1428 other systems call this ``pasting''. @xref{Yanking}.