Go to the previous, next section.
- An abbrev is a text string which expands into a different text string
when present in the buffer. For example, you might define a few letters
as an abbrev for a long phrase that you want to insert frequently.
See section Abbrevs.
- Aborting means getting out of a recursive edit (q.v.). The
commands C-] and M-x top-level are used for this.
See section Quitting and Aborting.
- Alt is the name of a modifier bit which a keyboard input character may
have. To make a character Alt, type it while holding down the ALT
key. Such characters are given names that start with Alt-
(usually written A- for short). (Note that many terminals have a
key labeled ALT which is really a META key.) See section Kinds of User Input.
- Auto Fill Mode
- Auto Fill mode is a minor mode in which text that you insert is
automatically broken into lines of fixed width. See section Filling Text.
- Auto Saving
- Auto saving is the practice of saving the contents of an Emacs buffer in
a specially-named file, so that the information will not be lost if the
buffer is lost due to a system error or user error. See section Auto-Saving: Protection Against Disasters.
- Backup File
- A backup file records the contents that a file had before the current
editing session. Emacs makes backup files automatically to help you
track down or cancel changes you later regret making. See section Backup Files.
- Balance Parentheses
- Emacs can balance parentheses manually or automatically. Manual
balancing is done by the commands to move over balanced expressions
(see section Lists and Sexps). Automatic balancing is done by blinking or
highlighting the parenthesis that matches one just inserted
(see section Automatic Display Of Matching Parentheses).
- To bind a key sequence means to give it a binding (q.v.).
See section Changing Key Bindings Interactively.
- A key sequence gets its meaning in Emacs by having a binding, which is a
command (q.v.), a Lisp function that is run when the user types that
sequence. See section Keys and Commands. Customization often involves
rebinding a character to a different command function. The bindings of
all key sequences are recorded in the keymaps (q.v.). See section Keymaps.
- Blank Lines
- Blank lines are lines that contain only whitespace. Emacs has several
commands for operating on the blank lines in the buffer.
- The buffer is the basic editing unit; one buffer corresponds to one text
being edited. You can have several buffers, but at any time you are
editing only one, the `selected' buffer, though several can be visible
when you are using multiple windows (q.v.). Most buffers are visiting
(q.v.) some file. See section Using Multiple Buffers.
- Buffer Selection History
- Emacs keeps a buffer selection history which records how recently each
Emacs buffer has been selected. This is used for choosing a buffer to
select. See section Using Multiple Buffers.
- Button Down Event
- A button down event is the kind of input event generated right away when
you press a mouse button. See section Rebinding Mouse Buttons.
- C- in the name of a character is an abbreviation for Control.
See section Kinds of User Input.
- C-M- in the name of a character is an abbreviation for
Control-Meta. See section Kinds of User Input.
- Case Conversion
- Case conversion means changing text from upper case to lower case or
vice versa. See section Case Conversion Commands, for the commands for case conversion.
- Characters form the contents of an Emacs buffer; see section Character Set for Text. Also, key sequences (q.v.) are usually made up of
characters (though they may include other input events as well).
See section Kinds of User Input.
- Click Event
- A click event is the kind of input event generated when you press a
mouse button and release it without moving the mouse. See section Rebinding Mouse Buttons.
- A command is a Lisp function specially defined to be able to serve as a
key binding in Emacs. When you type a key sequence (q.v.), its
binding (q.v.) is looked up in the relevant keymaps (q.v.) to find
the command to run. See section Keys and Commands.
- Command Name
- A command name is the name of a Lisp symbol which is a command
(see section Keys and Commands). You can invoke any command by its name using
M-x (see section Running Commands by Name).
- A comment is text in a program which is intended only for humans reading
the program, and which is marked specially so that it will be ignored
when the program is loaded or compiled. Emacs offers special commands
for creating, aligning and killing comments. See section Manipulating Comments.
- Compilation is the process of creating an executable program from source
code. Emacs has commands for compiling files of Emacs Lisp code
(see section `Byte Compilation' in the Emacs Lisp Reference Manual) and programs in C and other languages
(see section Running Compilations under Emacs).
- Complete Key
- A complete key is a key sequence which fully specifies one action to be
performed by Emacs. For example, X and C-f and C-x m
are complete keys. Complete keys derive their meanings from being bound
(q.v.) to commands (q.v.). Thus, X is conventionally bound to
a command to insert `X' in the buffer; C-x m is
conventionally bound to a command to begin composing a mail message.
See section Keys.
- Completion is what Emacs does when it automatically fills out an
abbreviation for a name into the entire name. Completion is done for
minibuffer (q.v.) arguments when the set of possible valid inputs
is known; for example, on command names, buffer names, and
file names. Completion occurs when TAB, SPC or RET
is typed. See section Completion.
- Continuation Line
- When a line of text is longer than the width of the window, it
takes up more than one screen line when displayed. We say that the
text line is continued, and all screen lines used for it after the
first are called continuation lines. See section Basic Editing Commands.
- Control Character
- ASCII characters with octal codes 0 through 037, and also code 0177, do
not have graphic images assigned to them. These are the Control
characters. To type a Control character, hold down the CTRL key
and type the corresponding non-Control character. RET, TAB,
ESC, LFD and DEL are all control characters.
See section Kinds of User Input.
When you are using the X Window System, every non-control character has a
corresponding control character variant.
- A copyleft is a notice giving the public legal permission to
redistribute a program or other work of art. Copylefts are used by
left-wing programmers to give people equal rights, just as copyrights
are used by right-wing programmers to gain power over other people.
The particular form of copyleft used by the GNU project is called the
GNU General Public License. See section GNU GENERAL PUBLIC LICENSE.
- Current Buffer
- The current buffer in Emacs is the Emacs buffer on which most editing
commands operate. You can select any Emacs buffer as the current one.
See section Using Multiple Buffers.
- Current Line
- The line point is on (see section Point).
- Current Paragraph
- The paragraph that point is in. If point is between paragraphs, the
current paragraph is the one that follows point. See section Paragraphs.
- Current Defun
- The defun (q.v.) that point is in. If point is between defuns, the
current defun is the one that follows point. See section Defuns.
- The cursor is the rectangle on the screen which indicates the position
called point (q.v.) at which insertion and deletion takes place.
The cursor is on or under the character that follows point. Often
people speak of `the cursor' when, strictly speaking, they mean
`point'. See section Basic Editing Commands.
- Customization is making minor changes in the way Emacs works. It is
often done by setting variables (see section Variables) or by rebinding
key sequences (see section Keymaps).
- Default Argument
- The default for an argument is the value that will be assumed if you
do not specify one. When the minibuffer is used to read an argument,
the default argument is used if you just type RET.
See section The Minibuffer.
- Default Directory
- When you specify a file name that does not start with `/' or `~',
it is interpreted relative to the current buffer's default directory.
See section Minibuffers for File Names.
- A defun is a list at the top level of parenthesis or bracket structure
in a program. It is so named because most such lists in Lisp programs
are calls to the Lisp function
defun. See section Defuns.
- DEL is a character that runs the command to delete one character of
text. See section Basic Editing Commands.
- Deletion means erasing text without copying it into the kill ring
(q.v.). The alternative is killing (q.v.). See section Deletion and Killing.
- Deletion of Files
- Deleting a file means erasing it from the file system.
See section Miscellaneous File Operations.
- Deletion of Messages
- Deleting a message means flagging it to be eliminated from your mail
file. Until you expunge (q.v.) the Rmail file, you can still undelete
the messages you have deleted. See section Deleting Messages.
- Deletion of Windows
- Deleting a window means eliminating it from the screen. Other windows
expand to use up the space. The deleted window can never come back,
but no actual text is thereby lost. See section Multiple Windows.
- File directories are named collections in the file system, within which
you can place individual files or subdirectories. See section File Directories.
- Dired is the Emacs facility that displays the contents of a file
directory and allows you to "edit the directory", performing
operations on the files in the directory. See section Dired, the Directory Editor.
- Disabled Command
- A disabled command is one that you may not run without special
confirmation. The usual reason for disabling a command is that it is
confusing for beginning users. See section Disabling Commands.
- Down Event
- Short for `button down event'.
- Drag Event
- A drag event is the kind of input event generated when you press a mouse
button, move the mouse, and then release the button. See section Rebinding Mouse Buttons.
- Dribble File
- A file into which Emacs writes all the characters that the user types
on the keyboard. Dribble files are used to make a record for
debugging Emacs bugs. Emacs does not make a dribble file unless you
tell it to. See section Reporting Bugs.
- Echo Area
- The echo area is the bottom line of the screen, used for echoing the
arguments to commands, for asking questions, and printing brief messages
(including error messages). The messages are stored in the buffer
`*Messages*' so you can review them later. See section The Echo Area.
- Echoing is acknowledging the receipt of commands by displaying them (in
the echo area). Emacs never echoes single-character key sequences;
longer key sequences echo only if you pause while typing them.
- An error occurs when an Emacs command cannot execute in the current
circumstances. When an error occurs, execution of the command stops
(unless the command has been programmed to do otherwise) and Emacs
reports the error by printing an error message (q.v.). Type-ahead
is discarded. Then Emacs is ready to read another editing command.
- Error Message
- An error message is a single line of output displayed by Emacs when the
user asks for something impossible to do (such as, killing text
forward when point is at the end of the buffer). They appear in the
echo area, accompanied by a beep.
- ESC is a character used as a prefix for typing Meta characters on
keyboards lacking a META key. Unlike the META key (which,
like the SHIFT key, is held down while another character is
typed), the ESC key is pressed once and applies to the next
- Expunging an Rmail file or Dired buffer means really discarding the
messages or files you have previously flagged for deletion.
- File Name
- A file name is a name that refers to a file. File names may be relative
or absolute; the meaning of a relative file name depends on the current
directory, but an absolute file name refers to the same file regardless
of which directory is current. On GNU and Unix systems, an absolute
file name starts with a slash (the root directory) or with `~/' or
`~user/' (a home directory).
Some people use the term "pathname" for file names, but we do not;
we use the word "path" only in the term "search path" (q.v.).
- File Name Component
- A file name component names a file directly within a particular
directory. On GNU and Unix systems, a file name is a sequence of file
name components, separated by slashes. For example, `foo/bar' is a
file name containing two components, `foo' and `bar'; it
refers to the file named `bar' in the directory named `foo' in
the current directory.
- Fill Prefix
- The fill prefix is a string that should be expected at the beginning
of each line when filling is done. It is not regarded as part of the
text to be filled. See section Filling Text.
- Filling text means shifting text between consecutive lines so that all
the lines are approximately the same length. See section Filling Text.
- Formatted Text
- Formatted text is text that displays with formatting information while
you edit. Formatting information includes fonts, colors, and specified
margins. See section Editing Formatted Text.
- A frame is a rectangular cluster of Emacs windows. Emacs starts out
with one frame, but you can create more. You can subdivide each frame
into Emacs windows (q.v.). When you are using X windows, all the frames
can be visible at the same time. See section Frames and X Windows.
- Function Key
- A function key is a key on the keyboard that sends input but does not
correspond to any character. See section Rebinding Function Keys.
- Global means `independent of the current environment; in effect
throughout Emacs'. It is the opposite of local (q.v.). Particular
examples of the use of `global' appear below.
- Global Abbrev
- A global definition of an abbrev (q.v.) is effective in all major
modes that do not have local (q.v.) definitions for the same abbrev.
See section Abbrevs.
- Global Keymap
- The global keymap (q.v.) contains key bindings that are in effect
except when overridden by local key bindings in a major mode's local
keymap (q.v.). See section Keymaps.
- Global Mark Ring
- The global mark ring records the series of buffers you have recently set
a mark in. In many cases you can use this to backtrack through buffers
you have been editing in, or in which you have found tags. See section The Global Mark Ring.
- Global Substitution
- Global substitution means replacing each occurrence of one string by
another string through a large amount of text. See section Replacement Commands.
- Global Variable
- The global value of a variable (q.v.) takes effect in all buffers
that do not have their own local (q.v.) values for the variable.
See section Variables.
- Graphic Character
- Graphic characters are those assigned pictorial images rather than
just names. All the non-Meta (q.v.) characters except for the
Control (q.v.) characters are graphic characters. These include
letters, digits, punctuation, and spaces; they do not include
RET or ESC. In Emacs, typing a graphic character inserts
that character (in ordinary editing modes). See section Basic Editing Commands.
- Highlighting text means displaying it with a different foreground and/or
background color to make it stand out from the rest of the text in the
- Hardcopy means printed output. Emacs has commands for making printed
listings of text in Emacs buffers. See section Hardcopy Output.
- You can type HELP at any time to ask what options you have, or to ask
what any command does. The character HELP is really C-h.
See section Help.
- Hyper is the name of a modifier bit which a keyboard input character may
have. To make a character Hyper, type it while holding down the
HYPER key. Such characters are given names that start with
Hyper- (usually written H- for short). See section Kinds of User Input.
- An inbox is a file in which mail is delivered by the operating system.
Rmail transfers mail from inboxes to Rmail files (q.v.) in which the
mail is then stored permanently or until explicitly deleted.
See section Rmail Files and Inboxes.
- Indentation means blank space at the beginning of a line. Most
programming languages have conventions for using indentation to
illuminate the structure of the program, and Emacs has special
commands to adjust indentation.
See section Indentation.
- Indirect Buffer
- An indirect buffer is a buffer that shares the text of another buffer,
called its base buffer. See section Indirect Buffers.
- Input Event
- An input event represents, within Emacs, one action taken by the user on
the terminal. Input events include typing characters, typing function
keys, pressing or releasing mouse buttons, and switching between Emacs
frames. See section Kinds of User Input.
- Insertion means copying text into the buffer, either from the keyboard
or from some other place in Emacs.
- Justification means adding extra spaces to lines of text to make them
come exactly to a specified width. See section Filling Text.
- Keyboard Macro
- Keyboard macros are a way of defining new Emacs commands from
sequences of existing ones, with no need to write a Lisp program.
See section Keyboard Macros.
- Key Sequence
- A key sequence (key, for short) is a sequence of input events (q.v.)
that are meaningful as a single unit. If the key sequence is enough to
specify one action, it is a complete key (q.v.); if it is not enough,
it is a prefix key (q.v.). See section Keys.
- The keymap is the data structure that records the bindings (q.v.) of
key sequences to the commands that they run. For example, the global
keymap binds the character C-n to the command function
next-line. See section Keymaps.
- Keyboard Translation Table
- The keyboard translation table is an array that translates the character
codes that come from the terminal into the character codes that make up
key sequences. See section Keyboard Translations.
- Kill Ring
- The kill ring is where all text you have killed recently is saved.
You can reinsert any of the killed text still in the ring; this is
called yanking (q.v.). See section Yanking.
- Killing means erasing text and saving it on the kill ring so it can be
yanked (q.v.) later. Some other systems call this "cutting".
Most Emacs commands to erase text do killing, as opposed to deletion
(q.v.). See section Deletion and Killing.
- Killing Jobs
- Killing a job (such as, an invocation of Emacs) means making it cease
to exist. Any data within it, if not saved in a file, is lost.
See section Exiting Emacs.
- A list is, approximately, a text string beginning with an open
parenthesis and ending with the matching close parenthesis. In C mode
and other non-Lisp modes, groupings surrounded by other kinds of matched
delimiters appropriate to the language, such as braces, are also
considered lists. Emacs has special commands for many operations on
lists. See section Lists and Sexps.
- Local means `in effect only in a particular context'; the relevant
kind of context is a particular function execution, a particular
buffer, or a particular major mode. It is the opposite of `global'
(q.v.). Specific uses of `local' in Emacs terminology appear below.
- Local Abbrev
- A local abbrev definition is effective only if a particular major mode
is selected. In that major mode, it overrides any global definition
for the same abbrev. See section Abbrevs.
- Local Keymap
- A local keymap is used in a particular major mode; the key bindings
(q.v.) in the current local keymap override global bindings of the
same key sequences. See section Keymaps.
- Local Variable
- A local value of a variable (q.v.) applies to only one buffer.
See section Local Variables.
- M- in the name of a character is an abbreviation for META,
one of the modifier keys that can accompany any character.
See section Kinds of User Input.
- M-C- in the name of a character is an abbreviation for
Control-Meta; it means the same thing as C-M-. If your
terminal lacks a real META key, you type a Control-Meta character by
typing ESC and then typing the corresponding Control character.
See section Kinds of User Input.
- M-x is the key sequence which is used to call an Emacs command by
name. This is how you run commands that are not bound to key sequences.
See section Running Commands by Name.
- Mail means messages sent from one user to another through the computer
system, to be read at the recipient's convenience. Emacs has commands for
composing and sending mail, and for reading and editing the mail you have
received. See section Sending Mail. See section Reading Mail with Rmail, for how to read mail.
- Major Mode
- The Emacs major modes are a mutually exclusive set of options, each of
which configures Emacs for editing a certain sort of text. Ideally,
each programming language has its own major mode. See section Major Modes.
- The mark points to a position in the text. It specifies one end of the
region (q.v.), point being the other end. Many commands operate on
all the text from point to the mark. Each buffer has its own mark.
See section The Mark and the Region.
- Mark Ring
- The mark ring is used to hold several recent previous locations of the
mark, just in case you want to move back to them. Each buffer has its
own mark ring; in addition, there is a single global mark ring (q.v.).
See section The Mark Ring.
- Menu Bar
- The menu bar is the line at the top of an Emacs frame. It contains
words you can click on with the mouse to bring up menus. The menu bar
feature is supported only with X. See section Menu Bars.
- See `mail'.
- Meta is the name of a modifier bit which a command character may have.
It is present in a character if the character is typed with the
META key held down. Such characters are given names that start
with Meta- (usually written M- for short). For example,
M-< is typed by holding down META and at the same time
typing < (which itself is done, on most terminals, by holding
down SHIFT and typing ,). See section Kinds of User Input.
- Meta Character
- A Meta character is one whose character code includes the Meta bit.
- The minibuffer is the window that appears when necessary inside the
echo area (q.v.), used for reading arguments to commands.
See section The Minibuffer.
- Minibuffer History
- The minibuffer history records the text you have specified in the past
for minibuffer arguments, so you can conveniently use the same text
again. See section Minibuffer History.
- Minor Mode
- A minor mode is an optional feature of Emacs which can be switched on
or off independently of all other features. Each minor mode has a
command to turn it on or off. See section Minor Modes.
- Minor Mode Keymap
- A keymap that belongs to a minor mode and is active when that mode is
enabled. Minor mode keymaps take precedence over the buffer's local
keymap, just as the local keymap takes precedence over the global
keymap. See section Keymaps.
- Mode Line
- The mode line is the line at the bottom of each window (q.v.), giving
status information on the buffer displayed in that window. See section The Mode Line.
- Modified Buffer
- A buffer (q.v.) is modified if its text has been changed since the
last time the buffer was saved (or since when it was created, if it
has never been saved). See section Saving Files.
- Moving Text
- Moving text means erasing it from one place and inserting it in
another. The usual way to move text by killing (q.v.) and then
yanking (q.v.). See section Deletion and Killing.
- Named Mark
- A named mark is a register (q.v.) in its role of recording a
location in text so that you can move point to that location.
See section Registers.
- Narrowing means creating a restriction (q.v.) that limits editing in
the current buffer to only a part of the text in the buffer. Text
outside that part is inaccessible to the user until the boundaries are
widened again, but it is still there, and saving the file saves it
all. See section Narrowing.
- Linefeed characters in the buffer terminate lines of text and are
therefore also called newlines. See section Character Set for Text.
- Numeric Argument
- A numeric argument is a number, specified before a command, to change
the effect of the command. Often the numeric argument serves as a
repeat count. See section Numeric Arguments.
- Overwrite Mode
- Overwrite mode is a minor mode. When it is enabled, ordinary text
characters replace the existing text after point rather than pushing
it to the right. See section Minor Modes.
- A page is a unit of text, delimited by formfeed characters (ASCII
control-L, code 014) coming at the beginning of a line. Some Emacs
commands are provided for moving over and operating on pages.
See section Pages.
- Paragraphs are the medium-size unit of English text. There are
special Emacs commands for moving over and operating on paragraphs.
See section Paragraphs.
- We say that certain Emacs commands parse words or expressions in the
text being edited. Really, all they know how to do is find the other
end of a word or expression. See section The Syntax Table.
- Point is the place in the buffer at which insertion and deletion
occur. Point is considered to be between two characters, not at one
character. The terminal's cursor (q.v.) indicates the location of
point. See section Basic Editing Commands.
- Prefix Argument
- See `numeric argument'.
- Prefix Key
- A prefix key is a key sequence (q.v.) whose sole function is to
introduce a set of longer key sequences. C-x is an example of
prefix key; any two-character sequence starting with C-x is
therefore a legitimate key sequence. See section Keys.
- Primary Rmail File
- Your primary Rmail file is the file named `RMAIL' in your home
directory. That's where Rmail stores your incoming mail, unless you
specify a different file name. See section Reading Mail with Rmail.
- Primary Selection
- The primary selection is one particular X selection (q.v.); it is the
selection that most X applications use for transferring text to and from
The Emacs kill commands set the primary selection and the yank command
uses the primary selection when appropriate. See section Deletion and Killing.
- A prompt is text printed to ask the user for input. Displaying a prompt
is called prompting. Emacs prompts always appear in the echo area
(q.v.). One kind of prompting happens when the minibuffer is used to
read an argument (see section The Minibuffer); the echoing which happens when
you pause in the middle of typing a multi-character key sequence is also
a kind of prompting (see section The Echo Area).
- Quitting means canceling a partially typed command or a running
command, using C-g. See section Quitting and Aborting.
- Quoting means depriving a character of its usual special significance.
In Emacs this is usually done with C-q. What constitutes special
significance depends on the context and on convention. For example,
an "ordinary" character as an Emacs command inserts itself; so in
this context, a special character is any character that does not
normally insert itself (such as DEL, for example), and quoting
it makes it insert itself as if it were not special. Not all contexts
allow quoting. See section Basic Editing Commands.
- Read-Only Buffer
- A read-only buffer is one whose text you are not allowed to change.
Normally Emacs makes buffers read-only when they contain text which
has a special significance to Emacs; for example, Dired buffers.
Visiting a file that is write protected also makes a read-only buffer.
See section Using Multiple Buffers.
- A rectangle consists of the text in a given range of columns on a given
range of lines. Normally you specify a rectangle by putting point at
one corner and putting the mark at the opposite corner.
See section Rectangles.
- Recursive Editing Level
- A recursive editing level is a state in which part of the execution of
a command involves asking the user to edit some text. This text may
or may not be the same as the text to which the command was applied.
The mode line indicates recursive editing levels with square brackets
(`[' and `]'). See section Recursive Editing Levels.
- Redisplay is the process of correcting the image on the screen to
correspond to changes that have been made in the text being edited.
See section The Organization of the Screen.
- See `regular expression'.
- The region is the text between point (q.v.) and the mark (q.v.).
Many commands operate on the text of the region. See section The Mark and the Region.
- Registers are named slots in which text or buffer positions or
rectangles can be saved for later use. See section Registers.
- Regular Expression
- A regular expression is a pattern that can match various text strings;
for example, `l[0-9]+' matches `l' followed by one or more
digits. See section Syntax of Regular Expressions.
- Repeat Count
- See `numeric argument'.
- See `global substitution'.
- A buffer's restriction is the amount of text, at the beginning or the
end of the buffer, that is temporarily inaccessible. Giving a buffer a
nonzero amount of restriction is called narrowing (q.v.).
See section Narrowing.
- RET is a character that in Emacs runs the command to insert a
newline into the text. It is also used to terminate most arguments
read in the minibuffer (q.v.). See section Kinds of User Input.
- Rmail File
- An Rmail file is a file containing text in a special format used by
Rmail for storing mail. See section Reading Mail with Rmail.
- Saving a buffer means copying its text into the file that was visited
(q.v.) in that buffer. This is the way text in files actually gets
changed by your Emacs editing. See section Saving Files.
- Scroll Bar
- A scroll bar is a tall thin hollow box that appears at the side of a
window. You can use mouse commands in the scroll bar to scroll the
window. The scroll bar feature is supported only with X. See section Scroll Bars.
- Scrolling means shifting the text in the Emacs window so as to see a
different part of the buffer. See section Controlling the Display.
- Searching means moving point to the next occurrence of a specified
string or the next match for a specified regular expression.
See section Searching and Replacement.
- Search Path
- A search path is a list of directory names, to be used for searching for
files for certain purposes. For example, the variable
holds a search path for finding Lisp library files. See section Libraries of Lisp Code for Emacs.
- Secondary Selection
- The secondary selection is one particular X selection; some X
applications can use it for transferring text to and from other
applications. Emacs has special mouse commands for transferring text
using the secondary selection. See section Secondary Selection.
- Selecting a buffer means making it the current (q.v.) buffer.
See section Using Multiple Buffers.
- The X window system allows an application program to specify named
selections whose values are text. A program can also read the
selections that other programs have set up. This is the principal way
of transferring text between window applications. Emacs has commands to
work with the primary (q.v.) selection and the secondary (q.v.)
- Self-documentation is the feature of Emacs which can tell you what any
command does, or give you a list of all commands related to a topic
you specify. You ask for self-documentation with the help character,
C-h. See section Help.
- Emacs has commands for moving by or killing by sentences.
See section Sentences.
- A sexp (short for `s-expression') is the basic syntactic unit of Lisp
in its textual form: either a list, or Lisp atom. Many Emacs commands
operate on sexps. The term `sexp' is generalized to languages other
than Lisp, to mean a syntactically recognizable expression.
See section Lists and Sexps.
- Simultaneous Editing
- Simultaneous editing means two users modifying the same file at once.
Simultaneous editing if not detected can cause one user to lose his
work. Emacs detects all cases of simultaneous editing and warns one of
the users to investigate. See section Protection against Simultaneous Editing.
- A string is a kind of Lisp data object which contains a sequence of
characters. Many Emacs variables are intended to have strings as
values. The Lisp syntax for a string consists of the characters in the
string with a `"' before and another `"' after. A `"'
that is part of the string must be written as `\"' and a `\'
that is part of the string must be written as `\\'. All other
characters, including newline, can be included just by writing them
inside the string; however, backslash sequences as in C, such as
`\n' for newline or `\241' using an octal character code, are
allowed as well.
- String Substitution
- See `global substitution'.
- Syntax Table
- The syntax table tells Emacs which characters are part of a word,
which characters balance each other like parentheses, etc.
See section The Syntax Table.
- Super is the name of a modifier bit which a keyboard input character may
have. To make a character Super, type it while holding down the
SUPER key. Such characters are given names that start with
Super- (usually written s- for short). See section Kinds of User Input.
- Tags Table
- A tags table is a file that serves as an index to the function
definitions in one or more other files. See section Tags Tables.
- Termscript File
- A termscript file contains a record of all characters sent by Emacs to
the terminal. It is used for tracking down bugs in Emacs redisplay.
Emacs does not make a termscript file unless you tell it to.
See section Reporting Bugs.
- Two meanings (see section Commands for Human Languages):
- Data consisting of a sequence of characters, as opposed to binary
numbers, images, graphics commands, executable programs, and the like.
The contents of an Emacs buffer are always text in this sense.
- Data consisting of written human language, as opposed to programs,
or following the stylistic conventions of human language.
- Top Level
- Top level is the normal state of Emacs, in which you are editing the
text of the file you have visited. You are at top level whenever you
are not in a recursive editing level (q.v.) or the minibuffer
(q.v.), and not in the middle of a command. You can get back to top
level by aborting (q.v.) and quitting (q.v.). See section Quitting and Aborting.
- Transposing two units of text means putting each one into the place
formerly occupied by the other. There are Emacs commands to transpose
two adjacent characters, words, sexps (q.v.) or lines
(see section Transposing Text).
- Truncating text lines in the display means leaving out any text on a
line that does not fit within the right margin of the window
displaying it. See also `continuation line'.
See section Basic Editing Commands.
- Undoing means making your previous editing go in reverse, bringing
back the text that existed earlier in the editing session.
See section Undoing Changes.
- User Option
- A user option is a variable (q.v.) that exists so that you can customize
Emacs by setting it to a new value. See section Variables.
- A variable is an object in Lisp that can store an arbitrary value.
Emacs uses some variables for internal purposes, and has others (known
as `user options' (q.v.)) just so that you can set their values to
control the behavior of Emacs. The variables used in Emacs that you
are likely to be interested in are listed in the Variables Index in
this manual. See section Variables, for information on variables.
- Version Control
- Version control systems keep track of multiple versions of a source file.
They provide a more powerful alternative to keeping backup files (q.v.).
See section Version Control.
- Visiting a file means loading its contents into a buffer (q.v.)
where they can be edited. See section Visiting Files.
- Whitespace is any run of consecutive formatting characters (space,
tab, newline, and backspace).
- Widening is removing any restriction (q.v.) on the current buffer;
it is the opposite of narrowing (q.v.). See section Narrowing.
- Emacs divides a frame (q.v.) into one or more windows, each of which
can display the contents of one buffer (q.v.) at any time.
See section The Organization of the Screen, for basic information on how Emacs uses the screen.
See section Multiple Windows, for commands to control the use of windows.
- Word Abbrev
- Synonymous with `abbrev'.
- Word Search
- Word search is searching for a sequence of words, considering the
punctuation between them as insignificant. See section Word Search.
- WYSIWYG stands for "What you see is what you get." Emacs generally
provides WYSIWYG editing for files of characters; in Enriched mode
(see section Editing Formatted Text), it provides WYSIWYG editing for files that
include text formatting information.
- Yanking means reinserting text previously killed. It can be used to
undo a mistaken kill, or for copying or moving text. Some other
systems call this "pasting". See section Yanking.
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