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TextFile

Info file emacs, produced by texinfo-format-buffer -*-Text-*-
from file emacs.tex

This file documents the GNU Emacs editor.

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

Permission is granted to copy and distribute modified versions of this
manual under the conditions for verbatim copying, provided also that the
sections entitled "The GNU Manifesto", "Distribution" and "GNU Emacs
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 Emacs General Public License" may be included in a translation
approved by the author instead of in the original English.

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File: emacs Node: Basic, Prev: Command Switches, Up: Top, Next: Undo

Basic Editing Commands
**********************

We now give the basics of how to enter text, make corrections, and
save the text in a file. If this material is new to you, you might
learn it more easily by running the Emacs learn-by-doing tutorial. To
do this, type `Control-h t' (`help-with-tutorial').

Inserting Text
==============

To insert printing characters into the text you are editing, just type
them. This inserts the character into the buffer at the cursor (that is,
at "point"; *Note Point::). The cursor moves forward. Any characters
after the cursor move forward too. If the text in the buffer is
`FOOBAR', with the cursor before the `B', then if you type
`XX', you get `FOOXXBAR', with the cursor still before the
`B'.

To "delete" text you have just inserted, use DEL. DEL
deletes the character BEFORE the cursor (not the one that the cursor
is on top of or under; that is the character AFTER the cursor). The
cursor and all characters after it move backwards. Therefore, if you type
a printing character and then type DEL, they cancel out.

To end a line and start typing a new one, type RET. This inserts
a newline character in the buffer. If point is in the middle of a line,
RET splits the line. Typing DEL when the cursor is at the
beginning of a line rubs out the newline before the line, thus joining the
line with the preceding line.

Emacs will split lines automatically when they become too long, if you
turn on a special mode called "Auto Fill" mode. *Note Filling::, for
how to use Auto Fill mode.

Customization information: DEL in most modes runs the command named
`delete-backward-char'; RET runs the command `newline', and
self-inserting printing characters run the command `self-insert',
which inserts whatever character was typed to invoke it. Some major modes
rebind DEL to other commands.

Direct insertion works for printing characters and SPC, but other
characters act as editing commands and do not insert themselves. If you
need to insert a control character or a character whose code is above 200
octal, you must "quote" it by typing `Control-q' (`quoted-insert') first.
There are two ways to use `C-q':

* `Control-q' followed by any non-graphic character (even `C-g')
inserts that character.
* `Control-q' followed by three octal digits inserts the character
with the specified character code.

A numeric argument to `C-q' specifies how many copies of the
quoted character should be inserted (*Note Arguments::).

If you prefer to have text characters replace (overwrite) existing
text rather than shove it to the right, you can enable Overwrite mode,
a minor mode. *Note Minor Modes::.

Changing the Location of Point
==============================

To do more than insert characters, you have to know how to move
point (*Note Point::). Here are a few of the commands for doing that.

`C-a'
Move to the beginning of the line (`beginning-of-line').
`C-e'
Move to the end of the line (`end-of-line').
`C-f'
Move forward one character (`forward-char').
`C-b'
Move backward one character (`backward-char').
`M-f'
Move forward one word (`forward-word').
`M-b'
Move backward one word (`backward-word').
`C-n'
Move down one line, vertically (`next-line'). This command
attempts to keep the horizontal position unchanged, so if you start in
the middle of one line, you end in the middle of the next. When on
the last line of text, `C-n' creates a new line and moves onto it.
`C-p'
Move up one line, vertically (`previous-line').
`C-l'
Clear the screen and reprint everything (`recenter'). Text moves
on the screen to bring point to the center of the window.
`M-r'
Move point to left margin on the line halfway down the screen or
window (`move-to-window-line'). Text does not move on the
screen. A numeric argument says how many screen lines down from the
top of the window (zero for the top). A negative argument counts from
the bottom (-1 for the bottom).
`C-t'
Transpose two characters, the ones before and after the cursor
(`transpose-chars').
`M-<'
Move to the top of the buffer (`beginning-of-buffer'). With numeric
argument N, move to N/10 of the way from the top. *Note Arguments::,
for more information on numeric arguments.
`M->'
Move to the end of the buffer (`end-of-buffer').
`M-x goto-char'
Read a number N and move cursor to character number N.
Position 1 is the beginning of the buffer.
`M-x goto-line'
Read a number N and move cursor to line number N. Line 1
is the beginning of the buffer.
`C-x C-n'
Use the current column of point as the "semipermanent goal column" for
`C-n' and `C-p' (`set-goal-column'). Henceforth, those
commands always move to this column in each line moved into, or as
close as possible given the contents of the line. This goal column remains
in effect until canceled.
`C-u C-x C-n'
Cancel the goal column. Henceforth, `C-n' and `C-p' once
again try to avoid changing the horizontal position, as usual.

If you set the variable `track-eol' to a non-`nil' value, then
`C-n' and `C-p' when at the end of the starting line move to the
end of the line. Normally, `track-eol' is `nil'.

Erasing Text
============

`DEL'
Delete the character before the cursor (`delete-backward-char').
`C-d'
Delete the character after the cursor (`delete-char').
`C-k'
Kill to the end of the line (`kill-line').
`M-d'
Kill forward to the end of the next word (`kill-word').
`M-DEL'
Kill back to the beginning of the previous word
(`backward-kill-word').

You already know about the DEL key which deletes the character
before the cursor. Another key, `Control-d', deletes the character
after the cursor, causing the rest of the text on the line to shift left.
If `Control-d' is typed at the end of a line, that line and the next
line are joined together.

To erase a larger amount of text, use the `Control-k' key, which
kills a line at a time. If `C-k' is done at the beginning or middle of
a line, it kills all the text up to the end of the line. If `C-k' is
done at the end of a line, it joins that line and the next line.

*Note Killing::, for more flexible ways of killing text.

Files
=====

The commands above are sufficient for creating and altering text in an
Emacs buffer; the more advanced Emacs commands just make things easier.
But to keep any text permanently you must put it in a "file". Files
are named units of text which are stored by the operating system for you to
retrieve later by name. To look at or use the contents of a file in any
way, including editing the file with Emacs, you must specify the file name.

Consider a file named `/usr/rms/foo.c'. In Emacs, to begin editing
this file, type

C-x C-f /usr/rms/foo.c RET

Here the file name is given as an "argument" to the command `C-x C-f'
(`find-file'). That command uses the "minibuffer" to read the argument,
and you type RET to terminate the argument (*Note Minibuffer::).

Emacs obeys the command by "visiting" the file: creating a buffer,
copying the contents of the file into the buffer, and then displaying the
buffer for you to edit. You can make changes in it, and then "save" the
file by typing `C-x C-s' (`save-buffer'). This makes the changes permanent
by copying the altered contents of the buffer back into the file
`/usr/rms/foo.c'. Until then, the changes are only inside your Emacs, and
the file `foo.c' is not changed.

To create a file, just visit the file with `C-x C-f' as if it already
existed. Emacs will make an empty buffer in which you can insert the text
you want to put in the file. When you save your text with `C-x C-s',
the file will be created.

Of course, there is a lot more to learn about using files. *Note Files::.

Help
====

If you forget what a key does, you can find out with the Help character,
which is `C-h'. Type `C-h k' followed by the key you want to know about;
for example, `C-h k C-n' tells you all about what `C-n' does. `C-h' is a
prefix key; `C-h k' is just one of its subcommands (the command
`describe-key'). The other subcommands of `C-h' provide different kinds of
help. Type `C-h' three times to get a description of all the help
facilities. *Note Help::.

* Menu:

* Blank Lines:: Commands to make or delete blank lines.
* Continuation Lines:: Lines too wide for the screen.
* Position Info:: What page, line, row, or column is point on?
* Arguments:: Numeric arguments for repeating a command.

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File: emacs Node: Blank Lines, Prev: Basic, Up: Basic, Next: Continuation Lines

Blank Lines
===========

Here are special commands and techniques for putting in and taking out
blank lines.

`C-o'
Insert one or more blank lines after the cursor (`open-line').
`C-x C-o'
Delete all but one of many consecutive blank lines
(`delete-blank-lines').

When you want to insert a new line of text before an existing line, you
can do it by typing the new line of text, followed by RET. However,
it may be easier to see what you are doing if you first make a blank line
and then insert the desired text into it. This is easy to do using the key
`C-o' (`open-line'), which inserts a newline after point but leaves
point in front of the newline. After `C-o', type the text for the new
line. `C-o F O O' has the same effect as `F O O RET', except for
the final location of point.

You can make several blank lines by typing `C-o' several times, or by
giving it an argument to tell it how many blank lines to make.
*Note Arguments::, for how.

If you have many blank lines in a row and want to get rid of them, use
`C-x C-o' (`delete-blank-lines'). When point is on a blank line which
is adjacent to at least one other blank line, `C-x C-o' deletes all but
one of the consecutive blank lines, leaving exactly one. With point on a
blank line with no other blank line adjacent to it, the sole blank line is
deleted, leaving none. When point is on a nonblank line, `C-x C-o'
deletes any blank lines following that nonblank line.

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File: emacs Node: Continuation Lines, Prev: Blank Lines, Up: Basic, Next: Position Info

Continuation Lines
==================

If you add too many characters to one line, without breaking it with a
RET, the line will grow to occupy two (or more) lines on the screen,
with a `\' at the extreme right margin of all but the last of them.
The `\' says that the following screen line is not really a distinct
line in the text, but just the "continuation" of a line too long to fit
the screen. Sometimes it is nice to have Emacs insert newlines
automatically when a line gets too long; for this, use Auto Fill mode
(*Note Filling::).

Instead of continuation, long lines can be displayed by "truncation".
This means that all the characters that do not fit in the width of the
screen or window do not appear at all. They remain in the buffer,
temporarily invisible. `$' is used in the last column instead of
`\' to inform you that truncation is in effect.

Continuation can be turned off for a particular buffer by setting the
variable `truncate-lines' to non-`nil' in that buffer. Truncation instead
of continuation also happens whenever horizontal scrolling is in use, and
optionally whenever side-by-side windows are in use (*Note Windows::).
Altering the value of `truncate-lines' makes it local to the current
buffer; until that time, the default value is in effect. The default is
initially `nil'. *Note Locals::.

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File: emacs Node: Position Info, Prev: Continuation Lines, Up: Basic, Next: Arguments

Cursor Position Information
===========================

If you are accustomed to other display editors, you may be surprised that
Emacs does not always display the page number or line number of point in
the mode line. This is because the text is stored in a way that makes it
difficult to compute this information. Displaying them all the time would
be intolerably slow. They are not needed very often in Emacs anyway,
but there are commands to compute them and print them.

`M-x what-page'
Print page number of point, and line number within page.
`M-x what-line'
Print line number of point in the buffer.
`M-='
Print number of lines in the current region (`count-lines-region').
`C-x ='
Print character code of character after point, character position of
point, and column of point (`what-cursor-position').

There are two commands for printing line numbers. `M-x what-line'
counts lines from the beginning of the file and prints the line number
point is on. The first line of the file is line number 1. These numbers
can be used as arguments to `M-x goto-line'. By contrast, `M-x
what-page' counts pages from the beginning of the file, and counts lines
within the page, printing both of them. *Note Pages::.

While on this subject, we might as well mention `M-=' (`count-lines-region'),
which prints the number of lines in the region (*Note Mark::).
*Note Pages::, for the command `C-x l' which counts the lines in the
current page.

The command `C-x =' (`what-cursor-position') can be used to find out
the column that the cursor is in, and other miscellaneous information about
point. It prints a line in the echo area that looks like this:

Char: x (0170) point=65986 of 563027(12%) x=44

(In fact, this is the output produced when point is before the `x=44'
in the example.)

The two values after `Char:' describe the character following point,
first by showing it and second by giving its octal character code.

`point=' is followed by the position of point expressed as a character
count. The front of the buffer counts as position 1, one character later
as 2, and so on. The next, larger number is the total number of characters
in the buffer. Afterward in parentheses comes the position expressed as a
percentage of the total size.

`x=' is followed by the horizontal position of point, in columns from the
left edge of the window.

If the buffer has been narrowed, making some of the text at the beginning and
the end temporarily invisible, `C-x =' prints additional text describing the
current visible range. For example, it might say

Char: x (0170) point=65986 of 563025(12%) <65102 - 68533> x=44

where the two extra numbers give the smallest and largest character position
that point is allowed to assume. The characters between those two positions
are the visible ones. *Note Narrowing::.

If point is at the end of the buffer (or the end of the visible part),
`C-x =' omits any description of the character after point.
The output looks like

point=563026 of 563025(100%) x=0

Usually `x=0' at the end, because the text usually ends with a newline.

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File: emacs Node: Arguments, Prev: Position Info, Up: Basic

Numeric Arguments
=================

Any Emacs command can be given a "numeric argument". Some commands
interpret the argument as a repetition count. For example, giving an
argument of ten to the key `C-f' (the command `forward-char', move
forward one character) moves forward ten characters. With these commands,
no argument is equivalent to an argument of one. Negative arguments are
allowed. Often they tell a command to move or act backwards.

If your terminal keyboard has a META key, the easiest way to
specify a numeric argument is to type digits and/or a minus sign while
holding down the the META key. For example,
M-5 C-n
would move down five lines. The characters `Meta-1', `Meta-2', and
so on, as well as `Meta--', do this because they are keys bound to
commands (`digit-argument' and `negative-argument') that are
defined to contribute to an argument for the next command.

Another way of specifying an argument is to use the `C-u'
(`universal-argument') command followed by the digits of the argument.
With `C-u', you can type the argument digits without holding
down shift keys. To type a negative argument, start with a minus sign.
Just a minus sign normally means -1. `C-u' works on all terminals.

`C-u' followed by a character which is neither a digit nor a minus sign
has the special meaning of "multiply by four". It multiplies the argument
for the next command by four. `C-u' twice multiplies it by sixteen. Thus,
`C-u C-u C-f' moves forward sixteen characters. This is a good way to move
forward "fast", since it moves about 1/5 of a line in the usual size
screen. Other useful combinations are `C-u C-n', `C-u C-u C-n' (move down
a good fraction of a screen), `C-u C-u C-o' (make "a lot" of blank lines),
and `C-u C-k' (kill four lines).

Some commands care only about whether there is an argument, and not about
its value. For example, the command `M-q' (`fill-paragraph') with
no argument fills text; with an argument, it justifies the text as well.
(*Note Filling::, for more information on `M-q'.) Just `C-u' is a
handy way of providing an argument for such commands.

Some commands use the value of the argument as a repeat count, but do
something peculiar when there is no argument. For example, the command
`C-k' (`kill-line') with argument N kills N lines, including their
terminating newlines. But `C-k' with no argument is special: it kills the
text up to the next newline, or, if point is right at the end of the line,
it kills the newline itself. Thus, two `C-k' commands with no arguments
can kill a nonblank line, just like `C-k' with an argument of one. (*Note
Killing::, for more information on `C-k'.)

A few commands treat a plain `C-u' differently from an ordinary
argument. A few others may treat an argument of just a minus sign
differently from an argument of -1. These unusual cases will be described
when they come up; they are always for reasons of convenience of use of the
individual command.

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File: emacs Node: Undo, Prev: Basic, Up: Top, Next: Minibuffer

Undoing Changes
***************

Emacs allows all changes made in the text of a buffer to be undone,
up to a certain amount of change (8000 characters). Each buffer records
changes individually, and the undo command always applies to the
current buffer. Usually each editing command makes a separate entry
in the undo records, but some commands such as `query-replace'
make many entries, and very simple commands such as self-inserting
characters are often grouped to make undoing less tedious.

`C-x u'
Undo one batch of changes (usually, one command worth) (`undo').
`C-_'
The same.

The command `C-x u' or `C-_' is how you undo. The first time you give
this command, it undoes the last change. Point moves to the text
affected by the undo, so you can see what was undone.

Consecutive repetitions of the `C-_' or `C-x u' commands undo earlier
and earlier changes, back to the limit of what has been recorded. If all
recorded changes have already been undone, the undo command prints an error
message and does nothing.

Any command other than an undo command breaks the sequence of undo
commands. Starting at this moment, the previous undo commands are
considered ordinary changes that can themselves be undone. Thus, you can
redo changes you have undone by typing `C-f' or any other command that
will have no important effect, and then using more undo commands.

If you notice that a buffer has been modified accidentally, the easiest
way to recover is to type `C-_' repeatedly until the stars disappear
from the front of the mode line. At this time, all the modifications you
made have been cancelled. If you do not remember whether you changed the
buffer deliberately, type `C-_' once, and when you see the last change
you made undone, you will remember why you made it. If it was an accident,
leave it undone. If it was deliberate, redo the change as described in the
preceding paragraph.

Whenever an undo command makes the stars disappear from the mode line,
it means that the buffer contents are the same as they were when the
file was last read in or saved.

Not all buffers record undo information. Buffers whose names start with
spaces don't; these buffers are used internally by Emacs and its extensions
to hold text that users don't normally look at or edit. Also, minibuffers,
help buffers and documentation buffers don't record undo information.

At most 8000 or so characters of deleted or modified text can be
remembered in any one buffer for reinsertion by the undo command. Also,
there is a limit on the number of individual insert, delete or change
actions that can be remembered.

The reason the `undo' command has two keys, `C-x u' and `C-_', set
up to run it is that it is worthy of a single-character key, but the way to
type `C-_' on some keyboards is not obvious. `C-x u' is an alternative
you can type in the same fashion on any terminal.

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File: emacs Node: Minibuffer, Prev: Undo, Up: Top, Next: M-x

The Minibuffer
**************

The "minibuffer" is the facility used by Emacs commands to read
arguments more complicated than a single number. Minibuffer arguments can
be file names, buffer names, Lisp function names, Emacs command names, Lisp
expressions, and many other things, depending on the command reading the
argument. The usual Emacs editing commands can be used in the minibuffer
to edit the argument.

When the minibuffer is in use, it appears in the echo area, and the
terminal's cursor moves there. The beginning of the minibuffer line
displays a "prompt" which says what kind of input you should supply and
how it will be used. Often this prompt is derived from the name of the
command that the argument is for. The prompt normally ends with a colon.

Sometimes a "default argument" appears in parentheses after the
colon; it too is part of the prompt. The default will be used as the
argument value if you enter an empty argument (e.g., just type RET).
For example, commands that read buffer names always show a default, which
is the name of the buffer that will be used if you type just RET.

The simplest way to give a minibuffer argument is to type the text you
want, terminated by RET which exits the minibuffer. You can get out
of the minibuffer, canceling the command that it was for, by typing
`C-g'.

Since the minibuffer uses the screen space of the echo area, it can
conflict with other ways Emacs customarily uses the echo area. Here is how
Emacs handles such conflicts:

* If a command gets an error while you are in the minibuffer, this does
not cancel the minibuffer. However, the echo area is needed for the
error message and therefore the minibuffer itself is hidden for a
while. It comes back after a few seconds, or as soon as you type
anything.

* If in the minibuffer you use a command whose purpose is to print a
message in the echo area, such as `C-x =', the message is printed
normally, and the minibuffer is hidden for a while. It comes back
after a few seconds, or as soon as you type anything.

* Echoing of keystrokes does not take place while the minibuffer is in
use.

* Menu:

* File: Minibuffer File. Entering file names with the minibuffer.
* Edit: Minibuffer Edit. How to edit in the minibuffer.
* Completion:: An abbreviation facility for minibuffer input.
* Repetition:: Re-executing commands that used the minibuffer.

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File: emacs Node: Minibuffer File, Prev: Minibuffer, Up: Minibuffer, Next: Minibuffer Edit

Minibuffers for File Names
==========================

Sometimes the minibuffer starts out with text in it. For example, when
you are supposed to give a file name, the minibuffer starts out containing
the "default directory", which ends with a slash. This is to inform
you which directory the file will be found in if you do not specify a
directory. For example, the minibuffer might start out with

Find File: /u2/emacs/src/

where `Find File: ' is the prompt. Typing `buffer.c' specifies the file
`/u2/emacs/src/buffer.c'. To find files in nearby directories, use `..';
thus, if you type `../lisp/simple.el', the file that you visit will be the
one named `/u2/emacs/lisp/simple.el'. Alternatively, you can kill with
`M-DEL' the directory names you don't want (*Note Words::).

You can also type an absolute file name, one starting with a slash or a
tilde, ignoring the default directory. For example, to find the file
`/etc/termcap', just type the name, giving

Find File: /u2/emacs/src//etc/termcap

Two slashes in a row are not normally meaningful in Unix file names, but
they are allowed in GNU Emacs. They mean, "ignore everything before the
second slash in the pair." Thus, `/u2/emacs/src/' is ignored, and
you get the file `/etc/termcap'.

If you set `insert-default-directory' to `nil', the default directory
is not inserted in the minibuffer. This way, the minibuffer starts out
empty. But the name you type, if relative, is still interpreted with
respect to the same default directory.

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File: emacs Node: Minibuffer Edit, Prev: Minibuffer File, Up: Minibuffer, Next: Completion

Editing in the Minibuffer
=========================

The minibuffer is an Emacs buffer (albeit a peculiar one), and the usual
Emacs commands are available for editing the text of an argument you are
entering.

Since RET in the minibuffer is defined to exit the minibuffer,
inserting a newline into the minibuffer must be done with `C-o' or with
`C-q LFD'. (Recall that a newline is really the LFD
character.)

The minibuffer has its own window which always has space on the screen
but acts as if it were not there when the minibuffer is not in use. When
the minibuffer is in use, its window is just like the others; you can
switch to another window with `C-x o', edit text in other windows and
perhaps even visit more files, before returning to the minibuffer to submit
the argument. You can kill text in another window, return to the
minibuffer window, and then yank the text to use it in the argument.
*Note Windows::.

There are some restrictions on the use of the minibuffer window, however.
You cannot switch buffers in it---the minibuffer and its window are
permanently attached. Also, you cannot split or kill the minibuffer
window. But you can make it taller in the normal fashion with `C-x ^'.

If while in the minibuffer you issue a command that displays help text
of any sort in another window, then that window is identified as the
one to scroll if you type `C-M-v' while in the minibuffer. This
lasts until you exit the minibuffer. This feature comes into play
if a completing minibuffer gives you a list of possible completions.

Recursive use of the minibuffer is supported by Emacs. However, it is
easy to do this by accident (because of autorepeating keyboards, for
example) and get confused. Therefore, most Emacs commands that use the
minibuffer refuse to operate if the minibuffer window is selected. If the
minibuffer is active but you have switched to a different window, recursive
use of the minibuffer is allowed---if you know enough to try to do this,
you probably will not get confused.

If you set the variable `enable-recursive-minibuffers' to be
non-`nil', recursive use of the minibuffer is always allowed.

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File: emacs Node: Completion, Prev: Minibuffer Edit, Up: Minibuffer, Next: Repetition

Completion
==========

When appropriate, the minibuffer provides a "completion" facility.
This means that you type enough of the argument to determine the rest,
based on Emacs's knowledge of which arguments make sense, and Emacs visibly
fills in the rest, or as much as can be determined from the part you have
typed.

When completion is available, certain keys---TAB, RET, and SPC---are
redefined to complete an abbreviation present in the minibuffer into a
longer string that it stands for, by matching it against a set of
"completion alternatives" provided by the command reading the argument.
`?' is defined to display a list of possible completions of what you
have inserted.

For example, when the minibuffer is being used by `Meta-x' to read
the name of a command, it is given a list of all available Emacs command
names to complete against. The completion keys match the text in the
minibuffer against all the command names, find any additional characters of
the name that are implied by the ones already present in the minibuffer,
and add those characters to the ones you have given.

Case is normally significant in completion, because it is significant in
most of the names that you can complete (buffer names, file names and
command names). Thus, `fo' will not complete to `Foo'. When you
are completing a name in which case does not matter, case may be ignored
for completion's sake if the program said to do so.

Completion Example
------------------

A concrete example may help here. If you type `Meta-x au TAB', the TAB
looks for alternatives (in this case, command names) that start with `au'.
There are only two: `auto-fill-mode' and `auto-save-mode'. These are the
same as far as `auto-', so the `au' in the minibuffer changes to `auto-'.

If you type TAB again immediately, there are multiple possibilities
for the very next character---it could be `s' or `f'---so no more
characters are added; but a list of all possible completions is displayed
in another window.

If you go on to type `f TAB', this TAB sees `auto-f'. The only command
name starting this way is `auto-fill-mode', so completion inserts the rest
of that. You now have `auto-fill-mode' in the minibuffer after typing just
`au TAB f TAB'. Note that TAB has this effect because in the minibuffer it
is bound to the function `minibuffer-complete' when completion is supposed
to be done.

Completion Commands
-------------------

Here is a list of all the completion commands, defined in the minibuffer
when completion is available.

`TAB'
Complete the text in the minibuffer as much as possible
(`minibuffer-complete').
`SPC'
Complete the text in the minibuffer but don't add or fill out more
than one word (`minibuffer-complete-word').
`RET'
Submit the text in the minibuffer as the argument, possibly completing
first as described below (`minibuffer-complete-and-exit').
`?'
Print a list of all possible completions of the text in the minibuffer
(`minibuffer-list-completions').

SPC completes much like TAB, but never goes beyond the next hyphen or
space. If you have `auto-f' in the minibuffer and type SPC, it finds that
the completion is `auto-fill-mode', but it stops completing after `fill-'.
This gives `auto-fill-'. Another SPC at this point completes all the way
to `auto-fill-mode'. SPC in the minibuffer runs the function
`minibuffer-complete-word' when completion is available.

There are three different ways that RET can work in completing
minibuffers, depending on how the argument will be used.

* "Strict" completion is used when it is meaningless to give any
argument except one of the known alternatives. For example, when
`C-x k' reads the name of a buffer to kill, it is meaningless to
give anything but the name of an existing buffer. In strict
completion, RET refuses to exit if the text in the minibuffer
does not complete to an exact match.

* "Cautious" completion is similar to strict completion, except that
RET exits only if the text was an exact match already, not
needing completion. If the text is not an exact match, RET does
not exit, but it does complete the text. If it completes to an exact
match, a second RET will exit.

Cautious completion is used for reading file names for files that must
already exist.

* "Permissive" completion is used when any string whatever is
meaningful, and the list of completion alternatives is just a guide.
For example, when `C-x C-f' reads the name of a file to visit, any
file name is allowed, in case you want to create a file. In
permissive completion, RET takes the text in the minibuffer
exactly as given, without completing it.

The completion commands display a list of all possible completions in a
window whenever there is more than one possibility for the very next
character. Also, typing `?' explicitly requests such a list. The
list of completions counts as help text, so `C-M-v' typed in the
minibuffer scrolls the list.

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. If the only possible completions are files that end in "ignored"
strings, then they are not ignored.

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.

▶1f◀
File: emacs Node: Repetition, Prev: Completion, 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 the minibuffer arguments,
so that you can repeat the command easily. In particular, every
use of `Meta-x' is recorded, since `M-x' uses the minibuffer to
read the command name.

`C-x ESC'
Re-execute a recent minibuffer command (`repeat-complex-command').
`M-p'
Within `C-x ESC', move to previous recorded command
(`previous-complex-command').
`M-n'
Within `C-x ESC', move to next more recent recorded command
(`next-complex-command').
`M-x list-command-history'
Display the entire command history, showing all the commands
`C-x ESC' can repeat, most recent first.

`C-x 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' 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,
you can be sure it will repeat exactly as before.

Once inside the minibuffer for `C-x ESC', if the command shown
to you is not the one you want to repeat, you can move around the list of
previous commands using `M-n' and `M-p'. `M-p' replaces the
contents of the minibuffer with the next earlier recorded command, and
`M-n' replaces them with the next later command. After finding the
desired previous command, you can edit its expression as usual and then
resubmit it by typing RET as usual. Any editing you have done on the
command to be repeated is lost if you use `M-n' or `M-p'.

`M-p' is more useful than `M-n', since more often you will
initially request to repeat the most recent command and then decide to
repeat an older one instead. These keys are specially defined within
`C-x ESC' to run the commands `previous-complex-command' and
`next-complex-command'.

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 reexecute
a command by feeding the corresponding `command-history' element to
`eval'.

▶1f◀
File: emacs Node: M-x, Prev: Minibuffer, Up: Top, Next: Help

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.
Any command can be run by name, even if it is also runnable by keys.

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.

Emacs uses the minibuffer for reading input for many different purposes;
on this occasion, the string `M-x' is displayed at the beginning of
the minibuffer as a "prompt" to remind you that your input should be
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

M-x fo TAB c RET

Note that `forward-char' is the same command that you invoke with
the key `C-f'. Any command (interactively callable function) defined
in Emacs can be called by its 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 function which it calls. The argument
value appears in the prompt while the command name is being read.

Normally, when describing 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 describing a sequence of input that contains a
command name and arguments that follow it.

`M-x' is defined to run the command `execute-extended-command',
which is responsible for reading the name of another command and invoking
it.

▶1f◀
File: emacs Node: Help, Prev: M-x, Up: Top, Next: Mark

Help
****

Emacs provides extensive help features which revolve around 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'.

`C-h C-h' prints a list of the possible help options, and then asks
you to go ahead and type the option. It prompts with a string

A, B, C, F, I, K, L, M, N, S, T, V, W, C-c, C-d, C-n, C-w or C-h for more help:

and you should type one of those characters.

Typing a third `C-h' displays a description of what the options mean;
it still waits for you to type an option. To cancel, type `C-g'.

Here is a summary of the defined help commands.

`C-h a STRING RET'
Display list of commands whose names contain STRING
(`command-apropos').
`C-h b'
Display a table of all key bindings in effect now; local bindings of
the current major mode first, followed by all global bindings
(`describe-bindings').
`C-h c KEY'
Print the name of the command that KEY runs (`describe-key-briefly').
`c' is 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'). Note that commands are Lisp functions, so
a command name may be used.
`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 name and documentation of the command 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 s'
Display current contents of the syntax table, plus an explanation of
what they mean (`describe-syntax').
`C-h t'
Display the Emacs 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').

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
command does, 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 KEY is bound to as well as
its name. This is too big for the echo area, so a window is used for the
display.

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 is known by name. For example,

C-h f auto-fill-mode RET

displays the documentation of `auto-fill-mode'. This is the only
way to see the documentation of a command that is not bound to any key
(one which you would normally call 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 code
`(make-vector len)' and want to be sure 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 default in the
prompt, you have typed the name of a defined Lisp function. If that tells
you what you want to know, just type `C-g' to cancel the `C-h f'
command and 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. Alternatively, it says that the
command is not on any keys, which implies that you must use `M-x' to call
it.

`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::.

Apropos
=======

A more sophisticated sort of question to ask is, "What are the commands
for working with files?" For this, type `C-h a file RET', which displays a
list of all command names that contain `file', such as `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 Lisp
function `command-apropos'.

Because `C-h a' looks only for functions whose names contain the
string which 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.
Pretend you are playing Adventure. Also note that you can use a
regular expression as the argument (*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,
buffer, screen, window, 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.

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'.

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 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 several 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 of the current major
mode first, followed by 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::).

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 t' (`help-with-tutorial') displays the learn-by-doing Emacs tutorial.
`C-h C-c' (`describe-copying') displays the file `emacs/etc/COPYING', 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 latest version of Emacs.

▶1f◀
File: emacs Node: Mark, Prev: Help, Up: Top, Next: Killing

The Mark and the Region
***********************

There are many Emacs commands which 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".
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 until it is set again at another
place. The mark remains fixed with respect to the preceding character if
text is inserted or deleted in the buffer. 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 the mark at one end of the inserted
text---the opposite end from where point is positioned, 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,
Emacs remembers 16 previous locations of the mark, in the `mark ring'.

* Menu:

* Setting Mark:: Commands to set the mark.
* 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.

▶1f◀
File: emacs Node: Setting Mark, Prev: Mark, Up: Mark, Next: Using Region

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').

For example, if you wish to convert part of the buffer to all upper-case,
you can use 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'. Most
commands that operate on the text in the region have the word `region'
in their names.

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. It is actually incorrect to
speak of the character `C-SPC'; there is no such character. When
you type SPC while holding down CTRL, what you get on most
terminals is the character `C-@'. This is the key 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'.

Since terminals have only one cursor, 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. But 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 location of the mark.

`C-x C-x' is also useful when you are satisfied with the location of
point but want to move the mark; do `C-x C-x' to put point there and
then you can move it. A second use of `C-x C-x', if necessary, puts
the mark at the new location with point back at its original location.

▶1f◀

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