This is ../info/emacs, produced by makeinfo version 4.0 from emacs.texi.
This is the thirteenth edition of the `GNU Emacs Manual', updated
for Emacs version 20.7.
INFO-DIR-SECTION Editors
START-INFO-DIR-ENTRY
* Emacs: (emacs). The extensible self-documenting text editor.
END-INFO-DIR-ENTRY
Published by the Free Software Foundation 59 Temple Place, Suite 330
Boston, MA 02111-1307 USA
Copyright (C) 1985, 1986, 1987, 1993, 1994, 1995, 1996, 1997, 1998,
1999 Free Software Foundation, Inc.
Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
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Permission is granted to copy and distribute modified versions of
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that the sections entitled "The GNU Manifesto", "Distribution" and "GNU
General Public License" are included exactly as in the original, and
provided that the entire resulting derived work is distributed under the
terms of a permission notice identical to this one.
Permission is granted to copy and distribute translations of this
manual into another language, under the above conditions for modified
versions, except that the sections entitled "The GNU Manifesto",
"Distribution" and "GNU General Public License" may be included in a
translation approved by the Free Software Foundation instead of in the
original English.
File: emacs, Node: Completion Options, Prev: Strict Completion, Up: Completion
Completion Options
------------------
When completion is done on file names, certain file names are usually
ignored. The variable `completion-ignored-extensions' contains a list
of strings; a file whose name ends in any of those strings is ignored
as a possible completion. The standard value of this variable has
several elements including `".o"', `".elc"', `".dvi"' and `"~"'. The
effect is that, for example, `foo' can complete to `foo.c' even though
`foo.o' exists as well. However, if _all_ the possible completions end
in "ignored" strings, then they are not ignored. Ignored extensions do
not apply to lists of completions--those always mention all possible
completions.
Normally, a completion command that finds the next character is
undetermined automatically displays a list of all possible completions.
If the variable `completion-auto-help' is set to `nil', this does not
happen, and you must type `?' to display the possible completions.
The `complete' library implements a more powerful kind of completion
that can complete multiple words at a time. For example, it can
complete the command name abbreviation `p-b' into `print-buffer',
because no other command starts with two words whose initials are `p'
and `b'. To use this library, put `(load "complete")' in your
`~/.emacs' file (*note Init File::).
Icomplete mode presents a constantly-updated display that tells you
what completions are available for the text you've entered so far. The
command to enable or disable this minor mode is `M-x icomplete-mode'.
File: emacs, Node: Minibuffer History, Next: Repetition, Prev: Completion, Up: Minibuffer
Minibuffer History
==================
Every argument that you enter with the minibuffer is saved on a
"minibuffer history list" so that you can use it again later in another
argument. Special commands load the text of an earlier argument in the
minibuffer. They discard the old minibuffer contents, so you can think
of them as moving through the history of previous arguments.
`<UP>'
`M-p'
Move to the next earlier argument string saved in the minibuffer
history (`previous-history-element').
`<DOWN>'
`M-n'
Move to the next later argument string saved in the minibuffer
history (`next-history-element').
`M-r REGEXP <RET>'
Move to an earlier saved argument in the minibuffer history that
has a match for REGEXP (`previous-matching-history-element').
`M-s REGEXP <RET>'
Move to a later saved argument in the minibuffer history that has a
match for REGEXP (`next-matching-history-element').
The simplest way to reuse the saved arguments in the history list is
to move through the history list one element at a time. While in the
minibuffer, use `M-p' or up-arrow (`previous-history-element') to "move
to" the next earlier minibuffer input, and use `M-n' or down-arrow
(`next-history-element') to "move to" the next later input.
The previous input that you fetch from the history entirely replaces
the contents of the minibuffer. To use it as the argument, exit the
minibuffer as usual with <RET>. You can also edit the text before you
reuse it; this does not change the history element that you "moved" to,
but your new argument does go at the end of the history list in its own
right.
For many minibuffer arguments there is a "default" value. In some
cases, the minibuffer history commands know the default value. Then you
can insert the default value into the minibuffer as text by using `M-n'
to move "into the future" in the history. Eventually we hope to make
this feature available whenever the minibuffer has a default value.
There are also commands to search forward or backward through the
history; they search for history elements that match a regular
expression that you specify with the minibuffer. `M-r'
(`previous-matching-history-element') searches older elements in the
history, while `M-s' (`next-matching-history-element') searches newer
elements. By special dispensation, these commands can use the
minibuffer to read their arguments even though you are already in the
minibuffer when you issue them. As with incremental searching, an
uppercase letter in the regular expression makes the search
case-sensitive (*note Search Case::).
All uses of the minibuffer record your input on a history list, but
there are separate history lists for different kinds of arguments. For
example, there is a list for file names, used by all the commands that
read file names. (As a special feature, this history list records the
absolute file name, no more and no less, even if that is not how you
entered the file name.)
There are several other very specific history lists, including one
for command names read by `M-x', one for buffer names, one for arguments
of commands like `query-replace', and one for compilation commands read
by `compile'. Finally, there is one "miscellaneous" history list that
most minibuffer arguments use.
The variable `history-length' specifies the maximum length of a
minibuffer history list; once a list gets that long, the oldest element
is deleted each time an element is added. If the value of
`history-length' is `t', though, there is no maximum length and
elements are never deleted.
File: emacs, Node: Repetition, Prev: Minibuffer History, Up: Minibuffer
Repeating Minibuffer Commands
=============================
Every command that uses the minibuffer at least once is recorded on a
special history list, together with the values of its arguments, so that
you can repeat the entire command. In particular, every use of `M-x'
is recorded there, since `M-x' uses the minibuffer to read the command
name.
`C-x <ESC> <ESC>'
Re-execute a recent minibuffer command (`repeat-complex-command').
`M-x list-command-history'
Display the entire command history, showing all the commands `C-x
<ESC> <ESC>' can repeat, most recent first.
`C-x <ESC> <ESC>' is used to re-execute a recent minibuffer-using
command. With no argument, it repeats the last such command. A
numeric argument specifies which command to repeat; one means the last
one, and larger numbers specify earlier ones.
`C-x <ESC> <ESC>' works by turning the previous command into a Lisp
expression and then entering a minibuffer initialized with the text for
that expression. If you type just <RET>, the command is repeated as
before. You can also change the command by editing the Lisp
expression. Whatever expression you finally submit is what will be
executed. The repeated command is added to the front of the command
history unless it is identical to the most recently executed command
already there.
Even if you don't understand Lisp syntax, it will probably be obvious
which command is displayed for repetition. If you do not change the
text, it will repeat exactly as before.
Once inside the minibuffer for `C-x <ESC> <ESC>', you can use the
minibuffer history commands (`M-p', `M-n', `M-r', `M-s'; *note
Minibuffer History::) to move through the history list of saved entire
commands. After finding the desired previous command, you can edit its
expression as usual and then resubmit it by typing <RET> as usual.
The list of previous minibuffer-using commands is stored as a Lisp
list in the variable `command-history'. Each element is a Lisp
expression which describes one command and its arguments. Lisp programs
can re-execute a command by calling `eval' with the `command-history'
element.
File: emacs, Node: M-x, Next: Help, Prev: Minibuffer, Up: Top
Running Commands by Name
************************
The Emacs commands that are used often or that must be quick to type
are bound to keys--short sequences of characters--for convenient use.
Other Emacs commands that do not need to be brief are not bound to
keys; to run them, you must refer to them by name.
A command name is, by convention, made up of one or more words,
separated by hyphens; for example, `auto-fill-mode' or `manual-entry'.
The use of English words makes the command name easier to remember than
a key made up of obscure characters, even though it is more characters
to type.
The way to run a command by name is to start with `M-x', type the
command name, and finish it with <RET>. `M-x' uses the minibuffer to
read the command name. <RET> exits the minibuffer and runs the
command. The string `M-x' appears at the beginning of the minibuffer
as a "prompt" to remind you to enter the name of a command to be run.
*Note Minibuffer::, for full information on the features of the
minibuffer.
You can use completion to enter the command name. For example, the
command `forward-char' can be invoked by name by typing
M-x forward-char <RET>
or
M-x forw <TAB> c <RET>
Note that `forward-char' is the same command that you invoke with the
key `C-f'. You can run any Emacs command by name using `M-x', whether
or not any keys are bound to it.
If you type `C-g' while the command name is being read, you cancel
the `M-x' command and get out of the minibuffer, ending up at top level.
To pass a numeric argument to the command you are invoking with
`M-x', specify the numeric argument before the `M-x'. `M-x' passes the
argument along to the command it runs. The argument value appears in
the prompt while the command name is being read.
If the command you type has a key binding of its own, Emacs mentions
this in the echo area, two seconds after the command finishes (if you
don't type anything else first). For example, if you type `M-x
forward-word', the message says that you can run the same command more
easily by typing `M-f'. You can turn off these messages by setting
`suggest-key-bindings' to `nil'.
Normally, when describing in this manual a command that is run by
name, we omit the <RET> that is needed to terminate the name. Thus we
might speak of `M-x auto-fill-mode' rather than `M-x auto-fill-mode
<RET>'. We mention the <RET> only when there is a need to emphasize
its presence, such as when we show the command together with following
arguments.
`M-x' works by running the command `execute-extended-command', which
is responsible for reading the name of another command and invoking it.
File: emacs, Node: Help, Next: Mark, Prev: M-x, Up: Top
Help
****
Emacs provides extensive help features accessible through a single
character, `C-h'. `C-h' is a prefix key that is used only for
documentation-printing commands. The characters that you can type after
`C-h' are called "help options". One help option is `C-h'; that is how
you ask for help about using `C-h'. To cancel, type `C-g'. The
function key <F1> is equivalent to `C-h'.
`C-h C-h' (`help-for-help') displays a list of the possible help
options, each with a brief description. Before you type a help option,
you can use <SPC> or <DEL> to scroll through the list.
`C-h' or <F1> means "help" in various other contexts as well. For
example, in the middle of `query-replace', it describes the options
available for how to operate on the current match. After a prefix key,
it displays a list of the alternatives that can follow the prefix key.
(A few prefix keys don't support `C-h', because they define other
meanings for it, but they all support <F1>.)
Most help buffers use a special major mode, Help mode, which lets you
scroll conveniently with <SPC> and <DEL>.
* Menu:
* Help Summary:: Brief list of all Help commands.
* Key Help:: Asking what a key does in Emacs.
* Name Help:: Asking about a command, variable or function name.
* Apropos:: Asking what pertains to a given topic.
* Library Keywords:: Finding Lisp libraries by keywords (topics).
* Language Help:: Help relating to international language support.
* Help Mode:: Special features of Help mode and Help buffers.
* Misc Help:: Other help commands.
File: emacs, Node: Help Summary, Next: Key Help, Up: Help
Help Summary
============
Here is a summary of the defined help commands.
`C-h a REGEXP <RET>'
Display a list of commands whose names match REGEXP
(`apropos-command').
`C-h b'
Display a table of all key bindings in effect now, in this order:
minor mode bindings, major mode bindings, and global bindings
(`describe-bindings').
`C-h c KEY'
Print the name of the command that KEY runs
(`describe-key-briefly'). Here `c' stands for `character'. For
more extensive information on KEY, use `C-h k'.
`C-h f FUNCTION <RET>'
Display documentation on the Lisp function named FUNCTION
(`describe-function'). Since commands are Lisp functions, a
command name may be used.
`C-h h'
Display the `hello' file, which shows examples of various character
sets.
`C-h i'
Run Info, the program for browsing documentation files (`info').
The complete Emacs manual is available on-line in Info.
`C-h k KEY'
Display the name and documentation of the command that KEY runs
(`describe-key').
`C-h l'
Display a description of the last 100 characters you typed
(`view-lossage').
`C-h m'
Display documentation of the current major mode (`describe-mode').
`C-h n'
Display documentation of Emacs changes, most recent first
(`view-emacs-news').
`C-h p'
Find packages by topic keyword (`finder-by-keyword').
`C-h s'
Display current contents of the syntax table, plus an explanation
of what they mean (`describe-syntax'). *Note Syntax::.
`C-h t'
Enter the Emacs interactive tutorial (`help-with-tutorial').
`C-h v VAR <RET>'
Display the documentation of the Lisp variable VAR
(`describe-variable').
`C-h w COMMAND <RET>'
Print which keys run the command named COMMAND (`where-is').
`C-h C CODING <RET>'
Describe coding system CODING (`describe-coding-system').
`C-h C <RET>'
Describe the coding systems currently in use.
`C-h I METHOD <RET>'
Describe an input method (`describe-input-method').
`C-h L LANGUAGE-ENV <RET>'
Describe information on the character sets, coding systems and
input methods used for language environment LANGUAGE-ENV
(`describe-language-environment').
`C-h C-c'
Display the copying conditions for GNU Emacs.
`C-h C-d'
Display information about getting new versions of GNU Emacs.
`C-h C-f FUNCTION <RET>'
Enter Info and go to the node documenting the Emacs function
FUNCTION (`Info-goto-emacs-command-node').
`C-h C-k KEY'
Enter Info and go to the node where the key sequence KEY is
documented (`Info-goto-emacs-key-command-node').
`C-h C-p'
Display information about the GNU Project.
`C-h <TAB> SYMBOL <RET>'
Display the Info documentation on symbol SYMBOL according to the
programming language you are editing (`info-lookup-symbol').
File: emacs, Node: Key Help, Next: Name Help, Prev: Help Summary, Up: Help
Documentation for a Key
=======================
The most basic `C-h' options are `C-h c' (`describe-key-briefly')
and `C-h k' (`describe-key'). `C-h c KEY' prints in the echo area the
name of the command that KEY is bound to. For example, `C-h c C-f'
prints `forward-char'. Since command names are chosen to describe what
the commands do, this is a good way to get a very brief description of
what KEY does.
`C-h k KEY' is similar but gives more information: it displays the
documentation string of the command as well as its name. This is too
big for the echo area, so a window is used for the display.
`C-h c' and `C-h k' work for any sort of key sequences, including
function keys and mouse events.
File: emacs, Node: Name Help, Next: Apropos, Prev: Key Help, Up: Help
Help by Command or Variable Name
================================
`C-h f' (`describe-function') reads the name of a Lisp function
using the minibuffer, then displays that function's documentation string
in a window. Since commands are Lisp functions, you can use this to get
the documentation of a command that you know by name. For example,
C-h f auto-fill-mode <RET>
displays the documentation of `auto-fill-mode'. This is the only way
to get the documentation of a command that is not bound to any key (one
which you would normally run using `M-x').
`C-h f' is also useful for Lisp functions that you are planning to
use in a Lisp program. For example, if you have just written the
expression `(make-vector len)' and want to check that you are using
`make-vector' properly, type `C-h f make-vector <RET>'. Because `C-h
f' allows all function names, not just command names, you may find that
some of your favorite abbreviations that work in `M-x' don't work in
`C-h f'. An abbreviation may be unique among command names yet fail to
be unique when other function names are allowed.
The function name for `C-h f' to describe has a default which is
used if you type <RET> leaving the minibuffer empty. The default is
the function called by the innermost Lisp expression in the buffer
around point, _provided_ that is a valid, defined Lisp function name.
For example, if point is located following the text `(make-vector (car
x)', the innermost list containing point is the one that starts with
`(make-vector', so the default is to describe the function
`make-vector'.
`C-h f' is often useful just to verify that you have the right
spelling for the function name. If `C-h f' mentions a name from the
buffer as the default, that name must be defined as a Lisp function. If
that is all you want to know, just type `C-g' to cancel the `C-h f'
command, then go on editing.
`C-h w COMMAND <RET>' tells you what keys are bound to COMMAND. It
prints a list of the keys in the echo area. If it says the command is
not on any key, you must use `M-x' to run it. `C-h w' runs the command
`where-is'.
`C-h v' (`describe-variable') is like `C-h f' but describes Lisp
variables instead of Lisp functions. Its default is the Lisp symbol
around or before point, but only if that is the name of a known Lisp
variable. *Note Variables::.
File: emacs, Node: Apropos, Next: Library Keywords, Prev: Name Help, Up: Help
Apropos
=======
A more sophisticated sort of question to ask is, "What are the
commands for working with files?" To ask this question, type `C-h a
file <RET>', which displays a list of all command names that contain
`file', including `copy-file', `find-file', and so on. With each
command name appears a brief description of how to use the command, and
what keys you can currently invoke it with. For example, it would say
that you can invoke `find-file' by typing `C-x C-f'. The `a' in `C-h
a' stands for `Apropos'; `C-h a' runs the command `apropos-command'.
This command normally checks only commands (interactive functions); if
you specify a prefix argument, it checks noninteractive functions as
well.
Because `C-h a' looks only for functions whose names contain the
string you specify, you must use ingenuity in choosing the string. If
you are looking for commands for killing backwards and `C-h a
kill-backwards <RET>' doesn't reveal any, don't give up. Try just
`kill', or just `backwards', or just `back'. Be persistent. Also note
that you can use a regular expression as the argument, for more
flexibility (*note Regexps::).
Here is a set of arguments to give to `C-h a' that covers many
classes of Emacs commands, since there are strong conventions for naming
the standard Emacs commands. By giving you a feel for the naming
conventions, this set should also serve to aid you in developing a
technique for picking `apropos' strings.
char, line, word, sentence, paragraph, region, page, sexp, list,
defun, rect, buffer, frame, window, face, file, dir, register,
mode, beginning, end, forward, backward, next, previous, up, down,
search, goto, kill, delete, mark, insert, yank, fill, indent,
case, change, set, what, list, find, view, describe, default.
To list all user variables that match a regexp, use the command `M-x
apropos-variable'. This command shows only user variables and
customization options by default; if you specify a prefix argument, it
checks all variables.
To list all Lisp symbols that contain a match for a regexp, not just
the ones that are defined as commands, use the command `M-x apropos'
instead of `C-h a'. This command does not check key bindings by
default; specify a numeric argument if you want it to check them.
The `apropos-documentation' command is like `apropos' except that it
searches documentation strings as well as symbol names for matches for
the specified regular expression.
The `apropos-value' command is like `apropos' except that it
searches symbols' values for matches for the specified regular
expression. This command does not check function definitions or
property lists by default; specify a numeric argument if you want it to
check them.
If the variable `apropos-do-all' is non-`nil', the commands above
all behave as if they had been given a prefix argument.
If you want more information about a function definition, variable or
symbol property listed in the Apropos buffer, you can click on it with
`Mouse-2' or move there and type <RET>.
File: emacs, Node: Library Keywords, Next: Language Help, Prev: Apropos, Up: Help
Keyword Search for Lisp Libraries
=================================
The `C-h p' command lets you search the standard Emacs Lisp
libraries by topic keywords. Here is a partial list of keywords you can
use:
abbrev --- abbreviation handling, typing shortcuts, macros.
bib --- support for the bibliography processor `bib'.
c --- C and C++ language support.
calendar --- calendar and time management support.
comm --- communications, networking, remote access to files.
data --- support for editing files of data.
docs --- support for Emacs documentation.
emulations --- emulations of other editors.
extensions --- Emacs Lisp language extensions.
faces --- support for using faces (fonts and colors; *note Faces::).
frames --- support for Emacs frames and window systems.
games --- games, jokes and amusements.
hardware --- support for interfacing with exotic hardware.
help --- support for on-line help systems.
hypermedia --- support for links within text, or other media types.
i18n --- internationalization and alternate character-set support.
internal --- code for Emacs internals, build process, defaults.
languages --- specialized modes for editing programming languages.
lisp --- support for using Lisp (including Emacs Lisp).
local --- libraries local to your site.
maint --- maintenance aids for the Emacs development group.
mail --- modes for electronic-mail handling.
matching --- searching and matching.
news --- support for netnews reading and posting.
non-text --- support for editing files that are not ordinary text.
oop --- support for object-oriented programming.
outlines --- hierarchical outlining.
processes --- process, subshell, compilation, and job control support.
terminals --- support for terminal types.
tex --- support for the TeX formatter.
tools --- programming tools.
unix --- front-ends/assistants for, or emulators of, Unix features.
vms --- support code for VMS.
wp --- word processing.
File: emacs, Node: Language Help, Next: Help Mode, Prev: Library Keywords, Up: Help
Help for International Language Support
=======================================
You can use the command `C-h L' (`describe-language-environment') to
find out the support for a specific language environment. *Note
Language Environments::. This tells you which languages this language
environment is useful for, and lists the character sets, coding
systems, and input methods that go with it. It also shows some sample
text to illustrate scripts.
The command `C-h h' (`view-hello-file') displays the file
`etc/HELLO', which shows how to say "hello" in many languages.
The command `C-h I' (`describe-input-method') describes information
about input methods--either a specified input method, or by default the
input method in use. *Note Input Methods::.
The command `C-h C' (`describe-coding-system') describes information
about coding systems--either a specified coding system, or the ones
currently in use. *Note Coding Systems::.
File: emacs, Node: Help Mode, Next: Misc Help, Prev: Language Help, Up: Help
Help Mode Commands
==================
Help buffers provide the commands of View mode (*note Misc File
Ops::), plus a few special commands of their own.
`<SPC>'
Scroll forward.
`<DEL>'
Scroll backward.
`<RET>'
Follow a cross reference at point.
`<TAB>'
Move point forward to the next cross reference.
`S-<TAB>'
Move point back to the previous cross reference.
`Mouse-2'
Follow a cross reference that you click on.
When a command name (*note Running Commands by Name: M-x.) or
variable name (*note Variables::) appears in the documentation, it
normally appears inside paired single-quotes. You can click on the name
with `Mouse-2', or move point there and type <RET>, to view the
documentation of that command or variable. Use `C-c C-b' to retrace
your steps.
There are convenient commands for moving point to cross references in
the help text. <TAB> (`help-next-ref') moves point down to the next
cross reference. Use `S-<TAB>' to move point up to the previous cross
reference (`help-previous-ref').
File: emacs, Node: Misc Help, Prev: Help Mode, Up: Help
Other Help Commands
===================
`C-h i' (`info') runs the Info program, which is used for browsing
through structured documentation files. The entire Emacs manual is
available within Info. Eventually all the documentation of the GNU
system will be available. Type `h' after entering Info to run a
tutorial on using Info.
If you specify a numeric argument, `C-h i' prompts for the name of a
documentation file. This way, you can browse a file which doesn't have
an entry in the top-level Info menu. It is also handy when you need to
get to the documentation quickly, and you know the exact name of the
file.
There are two special help commands for accessing Emacs documentation
through Info. `C-h C-f FUNCTION <RET>' enters Info and goes straight
to the documentation of the Emacs function FUNCTION. `C-h C-k KEY'
enters Info and goes straight to the documentation of the key KEY.
These two keys run the commands `Info-goto-emacs-command-node' and
`Info-goto-emacs-key-command-node'.
When editing a program, if you have an Info version of the manual for
the programming language, you can use the command `C-h C-i' to refer to
the manual documentation for a symbol (keyword, function or variable).
The details of how this command works depend on the major mode.
If something surprising happens, and you are not sure what commands
you typed, use `C-h l' (`view-lossage'). `C-h l' prints the last 100
command characters you typed in. If you see commands that you don't
know, you can use `C-h c' to find out what they do.
Emacs has numerous major modes, each of which redefines a few keys
and makes a few other changes in how editing works. `C-h m'
(`describe-mode') prints documentation on the current major mode, which
normally describes all the commands that are changed in this mode.
`C-h b' (`describe-bindings') and `C-h s' (`describe-syntax')
present other information about the current Emacs mode. `C-h b'
displays a list of all the key bindings now in effect; the local
bindings defined by the current minor modes first, then the local
bindings defined by the current major mode, and finally the global
bindings (*note Key Bindings::). `C-h s' displays the contents of the
syntax table, with explanations of each character's syntax (*note
Syntax::).
You can get a similar list for a particular prefix key by typing
`C-h' after the prefix key. (There are a few prefix keys for which
this does not work--those that provide their own bindings for `C-h'.
One of these is <ESC>, because `<ESC> C-h' is actually `C-M-h', which
marks a defun.)
The other `C-h' options display various files of useful information.
`C-h C-w' displays the full details on the complete absence of
warranty for GNU Emacs. `C-h n' (`view-emacs-news') displays the file
`emacs/etc/NEWS', which contains documentation on Emacs changes
arranged chronologically. `C-h F' (`view-emacs-FAQ') displays the
Emacs frequently-answered-questions list. `C-h t'
(`help-with-tutorial') displays the learn-by-doing Emacs tutorial.
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which tells you the conditions you must obey in distributing copies of
Emacs. `C-h C-d' (`describe-distribution') displays the file
`emacs/etc/DISTRIB', which tells you how you can order a copy of the
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general information about the GNU Project.
File: emacs, Node: Mark, Next: Killing, Prev: Help, Up: Top
The Mark and the Region
***********************
Many Emacs commands operate on an arbitrary contiguous part of the
current buffer. To specify the text for such a command to operate on,
you set "the mark" at one end of it, and move point to the other end.
The text between point and the mark is called "the region". Emacs
highlights the region whenever there is one, if you enable Transient
Mark mode (*note Transient Mark::).
You can move point or the mark to adjust the boundaries of the
region. It doesn't matter which one is set first chronologically, or
which one comes earlier in the text. Once the mark has been set, it
remains where you put it until you set it again at another place. Each
Emacs buffer has its own mark, so that when you return to a buffer that
had been selected previously, it has the same mark it had before.
Many commands that insert text, such as `C-y' (`yank') and `M-x
insert-buffer', position point and the mark at opposite ends of the
inserted text, so that the region contains the text just inserted.
Aside from delimiting the region, the mark is also useful for
remembering a spot that you may want to go back to. To make this
feature more useful, each buffer remembers 16 previous locations of the
mark in the "mark ring".
* Menu:
* Setting Mark:: Commands to set the mark.
* Transient Mark:: How to make Emacs highlight the region--
when there is one.
* Using Region:: Summary of ways to operate on contents of the region.
* Marking Objects:: Commands to put region around textual units.
* Mark Ring:: Previous mark positions saved so you can go back there.
* Global Mark Ring:: Previous mark positions in various buffers.
File: emacs, Node: Setting Mark, Next: Transient Mark, Up: Mark
Setting the Mark
================
Here are some commands for setting the mark:
`C-<SPC>'
Set the mark where point is (`set-mark-command').
`C-@'
The same.
`C-x C-x'
Interchange mark and point (`exchange-point-and-mark').
`Drag-Mouse-1'
Set point and the mark around the text you drag across.
`Mouse-3'
Set the mark where point is, then move point to where you click
(`mouse-save-then-kill').
For example, suppose you wish to convert part of the buffer to upper
case, using the `C-x C-u' (`upcase-region') command, which operates on
the text in the region. You can first go to the beginning of the text
to be capitalized, type `C-<SPC>' to put the mark there, move to the
end, and then type `C-x C-u'. Or, you can set the mark at the end of
the text, move to the beginning, and then type `C-x C-u'.
The most common way to set the mark is with the `C-<SPC>' command
(`set-mark-command'). This sets the mark where point is. Then you can
move point away, leaving the mark behind.
There are two ways to set the mark with the mouse. You can drag
mouse button one across a range of text; that puts point where you
release the mouse button, and sets the mark at the other end of that
range. Or you can click mouse button three, which sets the mark at
point (like `C-<SPC>') and then moves point (like `Mouse-1'). Both of
these methods copy the region into the kill ring in addition to setting
the mark; that gives behavior consistent with other window-driven
applications, but if you don't want to modify the kill ring, you must
use keyboard commands to set the mark. *Note Mouse Commands::.
Ordinary terminals have only one cursor, so there is no way for Emacs
to show you where the mark is located. You have to remember. The usual
solution to this problem is to set the mark and then use it soon, before
you forget where it is. Alternatively, you can see where the mark is
with the command `C-x C-x' (`exchange-point-and-mark') which puts the
mark where point was and point where the mark was. The extent of the
region is unchanged, but the cursor and point are now at the previous
position of the mark. In Transient Mark mode, this command reactivates
the mark.
`C-x C-x' is also useful when you are satisfied with the position of
point but want to move the other end of the region (where the mark is);
do `C-x C-x' to put point at that end of the region, and then move it.
A second use of `C-x C-x', if necessary, puts the mark at the new
position with point back at its original position.
There is no such character as `C-<SPC>' in ASCII; when you type
<SPC> while holding down <CTRL>, what you get on most ordinary
terminals is the character `C-@'. This key is actually bound to
`set-mark-command'. But unless you are unlucky enough to have a
terminal where typing `C-<SPC>' does not produce `C-@', you might as
well think of this character as `C-<SPC>'. Under X, `C-<SPC>' is
actually a distinct character, but its binding is still
`set-mark-command'.
File: emacs, Node: Transient Mark, Next: Using Region, Prev: Setting Mark, Up: Mark
Transient Mark Mode
===================
Emacs can highlight the current region, using X Windows. But
normally it does not. Why not?
Highlighting the region doesn't work well ordinarily in Emacs,
because once you have set a mark, there is _always_ a region (in that
buffer). And highlighting the region all the time would be a nuisance.
You can turn on region highlighting by enabling Transient Mark mode.
This is a more rigid mode of operation in which the region "lasts" only
temporarily, so you must set up a region for each command that uses
one. In Transient Mark mode, most of the time there is no region;
therefore, highlighting the region when it exists is convenient.
To enable Transient Mark mode, type `M-x transient-mark-mode'. This
command toggles the mode, so you can repeat the command to turn off the
mode.
Here are the details of Transient Mark mode:
* To set the mark, type `C-<SPC>' (`set-mark-command'). This makes
the mark active; as you move point, you will see the region
highlighting grow and shrink.
* The mouse commands for specifying the mark also make it active.
So do keyboard commands whose purpose is to specify a region,
including `M-@', `C-M-@', `M-h', `C-M-h', `C-x C-p', and `C-x h'.
* When the mark is active, you can execute commands that operate on
the region, such as killing, indenting, or writing to a file.
* Any change to the buffer, such as inserting or deleting a
character, deactivates the mark. This means any subsequent
command that operates on a region will get an error and refuse to
operate. You can make the region active again by typing `C-x C-x'.
* Commands like `M->' and `C-s' that "leave the mark behind" in
addition to some other primary purpose do not activate the new
mark. You can activate the new region by executing `C-x C-x'
(`exchange-point-and-mark').
* `C-s' when the mark is active does not alter the mark.
* Quitting with `C-g' deactivates the mark.
Highlighting of the region uses the `region' face; you can customize
how the region is highlighted by changing this face. *Note Face
Customization::.
When multiple windows show the same buffer, they can have different
regions, because they can have different values of point (though they
all share one common mark position). Ordinarily, only the selected
window highlights its region (*note Windows::). However, if the
variable `highlight-nonselected-windows' is non-`nil', then each window
highlights its own region (provided that Transient Mark mode is enabled
and the window's buffer's mark is active).
When Transient Mark mode is not enabled, every command that sets the
mark also activates it, and nothing ever deactivates it.
If the variable `mark-even-if-inactive' is non-`nil' in Transient
Mark mode, then commands can use the mark and the region even when it
is inactive. Region highlighting appears and disappears just as it
normally does in Transient Mark mode, but the mark doesn't really go
away when the highlighting disappears.
Transient Mark mode is also sometimes known as "Zmacs mode" because
the Zmacs editor on the MIT Lisp Machine handled the mark in a similar
way.
File: emacs, Node: Using Region, Next: Marking Objects, Prev: Transient Mark, Up: Mark
Operating on the Region
=======================
Once you have a region and the mark is active, here are some of the
ways you can operate on the region:
* Kill it with `C-w' (*note Killing::).
* Save it in a register with `C-x r s' (*note Registers::).
* Save it in a buffer or a file (*note Accumulating Text::).
* Convert case with `C-x C-l' or `C-x C-u' (*note Case::).
* Indent it with `C-x <TAB>' or `C-M-\' (*note Indentation::).
* Fill it as text with `M-x fill-region' (*note Filling::).
* Print hardcopy with `M-x print-region' (*note Hardcopy::).
* Evaluate it as Lisp code with `M-x eval-region' (*note Lisp
Eval::).
Most commands that operate on the text in the region have the word
`region' in their names.
File: emacs, Node: Marking Objects, Next: Mark Ring, Prev: Using Region, Up: Mark
Commands to Mark Textual Objects
================================
Here are the commands for placing point and the mark around a textual
object such as a word, list, paragraph or page.
`M-@'
Set mark after end of next word (`mark-word'). This command and
the following one do not move point.
`C-M-@'
Set mark after end of next Lisp expression (`mark-sexp').
`M-h'
Put region around current paragraph (`mark-paragraph').
`C-M-h'
Put region around current Lisp defun (`mark-defun').
`C-x h'
Put region around entire buffer (`mark-whole-buffer').
`C-x C-p'
Put region around current page (`mark-page').
`M-@' (`mark-word') puts the mark at the end of the next word, while
`C-M-@' (`mark-sexp') puts it at the end of the next Lisp expression.
These commands handle arguments just like `M-f' and `C-M-f'.
Other commands set both point and mark, to delimit an object in the
buffer. For example, `M-h' (`mark-paragraph') moves point to the
beginning of the paragraph that surrounds or follows point, and puts
the mark at the end of that paragraph (*note Paragraphs::). It prepares
the region so you can indent, case-convert, or kill a whole paragraph.
`C-M-h' (`mark-defun') similarly puts point before and the mark
after the current or following defun (*note Defuns::). `C-x C-p'
(`mark-page') puts point before the current page, and mark at the end
(*note Pages::). The mark goes after the terminating page delimiter
(to include it), while point goes after the preceding page delimiter
(to exclude it). A numeric argument specifies a later page (if
positive) or an earlier page (if negative) instead of the current page.
Finally, `C-x h' (`mark-whole-buffer') sets up the entire buffer as
the region, by putting point at the beginning and the mark at the end.
In Transient Mark mode, all of these commands activate the mark.
File: emacs, Node: Mark Ring, Next: Global Mark Ring, Prev: Marking Objects, Up: Mark
The Mark Ring
=============
Aside from delimiting the region, the mark is also useful for
remembering a spot that you may want to go back to. To make this
feature more useful, each buffer remembers 16 previous locations of the
mark, in the "mark ring". Commands that set the mark also push the old
mark onto this ring. To return to a marked location, use `C-u C-<SPC>'
(or `C-u C-@'); this is the command `set-mark-command' given a numeric
argument. It moves point to where the mark was, and restores the mark
from the ring of former marks. Thus, repeated use of this command
moves point to all of the old marks on the ring, one by one. The mark
positions you move through in this way are not lost; they go to the end
of the ring.
Each buffer has its own mark ring. All editing commands use the
current buffer's mark ring. In particular, `C-u C-<SPC>' always stays
in the same buffer.
Many commands that can move long distances, such as `M-<'
(`beginning-of-buffer'), start by setting the mark and saving the old
mark on the mark ring. This is to make it easier for you to move back
later. Searches set the mark if they move point. You can tell when a
command sets the mark because it displays `Mark Set' in the echo area.
If you want to move back to the same place over and over, the mark
ring may not be convenient enough. If so, you can record the position
in a register for later retrieval (*note RegPos::).
The variable `mark-ring-max' specifies the maximum number of entries
to keep in the mark ring. If that many entries exist and another one
is pushed, the last one in the list is discarded. Repeating `C-u
C-<SPC>' cycles through the positions currently in the ring.
The variable `mark-ring' holds the mark ring itself, as a list of
marker objects, with the most recent first. This variable is local in
every buffer.
File: emacs, Node: Global Mark Ring, Prev: Mark Ring, Up: Mark
The Global Mark Ring
====================
In addition to the ordinary mark ring that belongs to each buffer,
Emacs has a single "global mark ring". It records a sequence of
buffers in which you have recently set the mark, so you can go back to
those buffers.
Setting the mark always makes an entry on the current buffer's mark
ring. If you have switched buffers since the previous mark setting, the
new mark position makes an entry on the global mark ring also. The
result is that the global mark ring records a sequence of buffers that
you have been in, and, for each buffer, a place where you set the mark.
The command `C-x C-<SPC>' (`pop-global-mark') jumps to the buffer
and position of the latest entry in the global ring. It also rotates
the ring, so that successive uses of `C-x C-<SPC>' take you to earlier
and earlier buffers.
File: emacs, Node: Killing, Next: Yanking, Prev: Mark, Up: Top
Deletion and Killing
====================
Most commands which erase text from the buffer save it in the kill
ring so that you can move or copy it to other parts of the buffer.
These commands are known as "kill" commands. The rest of the commands
that erase text do not save it in the kill ring; they are known as
"delete" commands. (This distinction is made only for erasure of text
in the buffer.) If you do a kill or delete command by mistake, you can
use the `C-x u' (`undo') command to undo it (*note Undo::).
The delete commands include `C-d' (`delete-char') and <DEL>
(`delete-backward-char'), which delete only one character at a time,
and those commands that delete only spaces or newlines. Commands that
can destroy significant amounts of nontrivial data generally kill. The
commands' names and individual descriptions use the words `kill' and
`delete' to say which they do.
* Menu:
* Deletion:: Commands for deleting small amounts of text and
blank areas.
* Killing by Lines:: How to kill entire lines of text at one time.
* Other Kill Commands:: Commands to kill large regions of text and
syntactic units such as words and sentences.
File: emacs, Node: Deletion, Next: Killing by Lines, Up: Killing
Deletion
--------
`C-d'
Delete next character (`delete-char').
`<DEL>'
Delete previous character (`delete-backward-char').
`M-\'
Delete spaces and tabs around point (`delete-horizontal-space').
`M-<SPC>'
Delete spaces and tabs around point, leaving one space
(`just-one-space').
`C-x C-o'
Delete blank lines around the current line (`delete-blank-lines').
`M-^'
Join two lines by deleting the intervening newline, along with any
indentation following it (`delete-indentation').
The most basic delete commands are `C-d' (`delete-char') and <DEL>
(`delete-backward-char'). `C-d' deletes the character after point, the
one the cursor is "on top of." This doesn't move point. <DEL> deletes
the character before the cursor, and moves point back. You can delete
newlines like any other characters in the buffer; deleting a newline
joins two lines. Actually, `C-d' and <DEL> aren't always delete
commands; when given arguments, they kill instead, since they can erase
more than one character this way.
The other delete commands are those which delete only whitespace
characters: spaces, tabs and newlines. `M-\'
(`delete-horizontal-space') deletes all the spaces and tab characters
before and after point. `M-<SPC>' (`just-one-space') does likewise but
leaves a single space after point, regardless of the number of spaces
that existed previously (even zero).
`C-x C-o' (`delete-blank-lines') deletes all blank lines after the
current line. If the current line is blank, it deletes all blank lines
preceding the current line as well (leaving one blank line, the current
line).
`M-^' (`delete-indentation') joins the current line and the previous
line, by deleting a newline and all surrounding spaces, usually leaving
a single space. *Note M-^: Indentation.
File: emacs, Node: Killing by Lines, Next: Other Kill Commands, Prev: Deletion, Up: Killing
Killing by Lines
----------------
`C-k'
Kill rest of line or one or more lines (`kill-line').
The simplest kill command is `C-k'. If given at the beginning of a
line, it kills all the text on the line, leaving it blank. When used
on a blank line, it kills the whole line including its newline. To kill
an entire non-blank line, go to the beginning and type `C-k' twice.
More generally, `C-k' kills from point up to the end of the line,
unless it is at the end of a line. In that case it kills the newline
following point, thus merging the next line into the current one.
Spaces and tabs that you can't see at the end of the line are ignored
when deciding which case applies, so if point appears to be at the end
of the line, you can be sure `C-k' will kill the newline.
When `C-k' is given a positive argument, it kills that many lines
and the newlines that follow them (however, text on the current line
before point is spared). With a negative argument -N, it kills N lines
preceding the current line (together with the text on the current line
before point). Thus, `C-u - 2 C-k' at the front of a line kills the
two previous lines.
`C-k' with an argument of zero kills the text before point on the
current line.
If the variable `kill-whole-line' is non-`nil', `C-k' at the very
beginning of a line kills the entire line including the following
newline. This variable is normally `nil'.
File: emacs, Node: Other Kill Commands, Prev: Killing by Lines, Up: Killing
Other Kill Commands
-------------------
`C-w'
Kill region (from point to the mark) (`kill-region').
`M-d'
Kill word (`kill-word'). *Note Words::.
`M-<DEL>'
Kill word backwards (`backward-kill-word').
`C-x <DEL>'
Kill back to beginning of sentence (`backward-kill-sentence').
*Note Sentences::.
`M-k'
Kill to end of sentence (`kill-sentence').
`C-M-k'
Kill sexp (`kill-sexp'). *Note Lists::.
`M-z CHAR'
Kill through the next occurrence of CHAR (`zap-to-char').
A kill command which is very general is `C-w' (`kill-region'), which
kills everything between point and the mark. With this command, you
can kill any contiguous sequence of characters, if you first set the
region around them.
A convenient way of killing is combined with searching: `M-z'
(`zap-to-char') reads a character and kills from point up to (and
including) the next occurrence of that character in the buffer. A
numeric argument acts as a repeat count. A negative argument means to
search backward and kill text before point.
Other syntactic units can be killed: words, with `M-<DEL>' and `M-d'
(*note Words::); sexps, with `C-M-k' (*note Lists::); and sentences,
with `C-x <DEL>' and `M-k' (*note Sentences::).
You can use kill commands in read-only buffers. They don't actually
change the buffer, and they beep to warn you of that, but they do copy
the text you tried to kill into the kill ring, so you can yank it into
other buffers. Most of the kill commands move point across the text
they copy in this way, so that successive kill commands build up a
single kill ring entry as usual.