Monster Media 1993 #2/Image.iso/os2/e17info.zip/EMACS/19.17/INFO/EMACS-3

GNU Info File | 1993-07-18 | 49KB | 865 lines

This is Info file ../info/emacs, produced by Makeinfo-1.54 from the
input file emacs.texi.
File: emacs,  Node: Inserting Text,  Next: Moving Point,  Up: Basic
Inserting Text
==============
   To insert printing characters into the text you are editing, just
type them.  This inserts the characters you type into the buffer at the
cursor (that is, at "point"; *note Point::.).  The cursor moves
forward, and any text after the cursor moves 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 deletes the preceding newline, thus joining the line with the
preceding line.
   Emacs can 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
`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 the character `Control-q'
(`quoted-insert') first.  (This character's name is normally written
`C-q' for short.)  There are two ways to use `C-q':
   * `C-q' followed by any non-graphic character (even `C-g') inserts
     that character.
   * `C-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::.
File: emacs,  Node: Moving Point,  Next: Erasing,  Prev: Inserting Text,  Up: Basic
Changing the Location of Point
==============================
   To do more than insert characters, you have to know how to move
point (*note Point::.).  The simplest way to do this is with arrow keys
or the left mouse button.
   There are also control and meta characters for cursor motion.  Some
are equivalent to the arrow keys (these date back to the days before
terminals had arrow keys, and are usable on terminals which don't have
them).  Others do more sophisticated things.
`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').
`M-r'
     Move point to left margin, vertically centered in the 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 line).  A negative argument counts
     lines from the bottom (-1 for the bottom line).
`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
another line.  Normally, `track-eol' is `nil'.  *Note Variables::, for
how to set variables such as `track-eol'.
   Normally, `C-n' on the last line of a buffer appends a newline to
it.  If the variable `next-line-add-newlines' is `nil', then `C-n' gets
an error instead (like `C-p' on the first line).
File: emacs,  Node: Erasing,  Next: Basic Files,  Prev: Moving Point,  Up: Basic
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' (`C-d' for short), deletes
the character after the cursor, causing the rest of the text on the
line to shift left.  If `C-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 `C-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.
   If you delete or kill text by mistake, you can use the undo command
to get it back.  *Note Undo::.
   *Note Killing::, for more flexible ways of killing text.
File: emacs,  Node: Basic Files,  Next: Basic Help,  Prev: Erasing,  Up: Basic
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.  Then you can make changes, and "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 you save, the changes exist only inside
Emacs, and the file `foo.c' is unaltered.
   To create a file, just visit the file with `C-x C-f' as if it
already existed.  This creates an empty buffer in which you can insert
the text you want to put in the file.  The file is actually created when
you save this buffer with `C-x C-s'.
   Of course, there is a lot more to learn about using files.  *Note
Files::.
File: emacs,  Node: Basic Help,  Next: Blank Lines,  Prev: Basic Files,  Up: Basic
   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::.
File: emacs,  Node: Blank Lines,  Next: Continuation Lines,  Prev: Basic Help,  Up: Basic
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 a numeric argument to tell it how many blank lines to
make.  *Note Arguments::, for how.
   If you have a fill prefix, then `C-o' command inserts the fill
prefix on the new line, when you use it at the beginning of a line.
*Note Fill Prefix::.
   The easy way to get rid of extra blank lines is with the command
`C-x C-o' (`delete-blank-lines').  `C-x C-o' in a run of several blank
lines deletes all but one of them.  `C-x C-o' on a solitary blank line
deletes that blank line.  When point is on a nonblank line, `C-x C-o'
deletes any blank lines following that nonblank line.
File: emacs,  Node: Continuation Lines,  Next: Position Info,  Prev: Blank Lines,  Up: Basic
Continuation Lines
==================
   If you add too many characters to one line, without breaking it with
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.  Continuation is also called "line wrapping".
   Sometimes it is nice to have Emacs insert newlines automatically when
a line gets too long.  Continuation on the screen does not do that.  Use
Auto Fill mode (*note Filling::.) if that's what you want.
   Instead of continuation, you can display long lines 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.
   You can turn off continuation for a particular buffer by setting the
variable `truncate-lines' to non-`nil' in that buffer.  (*Note
Variables::.)  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::.
   *Note Display Vars::, for additional variables that affect how text
is displayed.
File: emacs,  Node: Position Info,  Next: Arguments,  Prev: Continuation Lines,  Up: Basic
Cursor Position Information
===========================
   Here are commands to get information about the size and position of
parts of the buffer, and to count lines.
`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-x line-number-mode'
     Toggle automatic display of current line number.
`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 the current line number.  `M-x
what-line' computes the current line number and displays it in the echo
area.  `M-x line-number-mode' enables display of the current line
number in the mode line; once you turn this on, the number updates as
you move point, so it remains valid all the time.  *Note Mode Line::.
   Line numbers count from one at the beginning of the buffer.  To go to
a given line by number, use `M-x goto-line'; it prompts you for the
line number.
   By contrast, `M-x what-page' counts pages from the beginning of the
file, and counts lines within the page, printing both numbers.  *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 off limits, `C-x =' prints additional
text describing the currently accessible range.  For example, it might
display this:
     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 accessible ones.  *Note Narrowing::.
   If point is at the end of the buffer (or the end of the accessible
part), `C-x =' omits any description of the character after point.  The
output looks like this:
     point=563026 of 563025(100%)  x=0
File: emacs,  Node: Arguments,  Prev: Position Info,  Up: Basic
Numeric Arguments
=================
   Any Emacs command can be given a "numeric argument" (also called a
"prefix argument").  Some commands interpret the argument as a
repetition count.  For example, giving an argument of ten to the key
`C-f' moves forward ten characters instead of one.  With these
commands, no argument is equivalent to an argument of one.  Negative
arguments tell most such commands to move or act in the opposite
direction.
   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.
   You can use a numeric argument to insert multiple copies of a
character.  This is straightforward unless the character is a digit.  To
prevent the digit from becoming part of the argument, type another
`C-u'.  That terminates the argument.  If you then type another digit,
then the digit acts as a self-inserting character and uses the argument
as a repeat count.
   We use the term "prefix argument" as well as "numeric argument" to
emphasize that you type the argument before the command, and to
distinguish these arguments from minibuffer arguments that come after
the command.
File: emacs,  Node: Undo,  Next: Minibuffer,  Prev: Basic,  Up: Top
Undoing Changes
***************
   Emacs allows all changes made in the text of a buffer to be undone,
up to a certain amount of change.  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 back to
where it was before the command that made the change.
   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.
   You cannot undo mere cursor motion; only changes in the buffer
contents save undo information.  However, some cursor motion commands
set the mark, so if you use these commands from time to time, you can
move back to the neighborhoods you have moved through by popping the
mark ring (*note Mark Ring::.).
   When the undo information of a buffer becomes too large, Emacs
discards the oldest undo information from time to time (during garbage
collection).  You can specify how much undo information to keep by
setting two variables: `undo-limit' and `undo-strong-limit'.  Their
values are expressed in units of bytes of space.
   The variable `undo-limit' sets a soft limit: Emacs keeps undo data
for enough commands to reach this size, and perhaps exceed it, but does
not keep data for any earlier commands beyond that.  Its default value
is 20000.  The variable `undo-strong-limit' sets a harsher limit: the
command which pushes the size past this amount is itself forgotten.
Its default value is 30000.
   Regardless of the values of those variables, the most recent change
is never discarded, so there is no danger that garbage collection
occurring right after an unintentional large change might prevent you
from undoing it.
   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 on
some keyboards it is not obvious how to type `C-_'.  `C-x u' is an
alternative you can type in the same fashion on any terminal.
File: emacs,  Node: Minibuffer,  Next: M-x,  Prev: Undo,  Up: Top
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.  You can use the usual Emacs editing commands in
the minibuffer to edit the argument text.
   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 enter 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.
* Minibuffer History::    Reusing recent minibuffer arguments.
* Repetition::          Re-executing commands that used the minibuffer.
File: emacs,  Node: Minibuffer File,  Next: Minibuffer Edit,  Up: Minibuffer
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', you will get the file
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 insert that name, giving these minibuffer contents:
     Find File: /u2/emacs/src//etc/termcap
Two slashes in a row are not normally meaningful in a file name, 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.
File: emacs,  Node: Minibuffer Edit,  Next: Completion,  Prev: Minibuffer File,  Up: Minibuffer
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, you can use the `C-M-v' command
while in the minibuffer to scroll the help text.  This lasts until you
exit the minibuffer.  This feature is especially useful if a completing
minibuffer gives you a list of possible completions.  *Note Other
Window::.
   You can't use a command that reads a minibuffer argument while you
are in the minibuffer window.  This rule is to prevent recursive
minibuffers from confusing novice users.  If you want to be able to use
such commands in the minibuffer, set the variable
`enable-recursive-minibuffers' to a non-`nil' value.
File: emacs,  Node: Completion,  Next: Minibuffer History,  Prev: Minibuffer Edit,  Up: Minibuffer
Completion
==========
   For certain kinds of arguments, you can use "completion" to enter
the argument value.  Completion means that you type part of the
argument, then 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
rebound to complete the text 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 `M-x' uses the minibuffer to read the name of a
command, it provides 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 name characters
implied by the ones already present in the minibuffer, and add those
characters to the ones you have given.  This is what makes it possible
to type `M-x ins SPC b RET' instead of `M-x insert-buffer RET' (for
example).
   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' does not complete to `Foo'.  Completion
does ignore case distinctions for certain arguments in which case does
not matter.
Completion Example
------------------
   A concrete example may help here.  If you type `M-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; instead, TAB displays a list of all possible
completions 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 fills
in 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 command
`minibuffer-complete' when completion is available.
Completion Commands
-------------------
   Here is a list of 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 minibuffer text, but don't go beyond 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 when
completion is available runs the command `minibuffer-complete-word'.
   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.  If the
list of completions is long, you can scroll it with `C-M-v' (*note
Other Window::.).
   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.
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.
`M-p'
     Move to the next earlier argument string saved in the minibuffer
     history (`previous-history-element').
`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, type `M-p' (`previous-history-element') to "move to" the
next earlier minibuffer input, and use `M-n' (`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.
   There are also commands to search forward or backward through the
history.  As of this writing, 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.
   All uses of the minibuffer record your input on a history list, but
there are separate history lists for different kinds of input.  For
example, there is a list for file names, used by all the commands that
read file names.  There is a list for arguments of commands like
`query-replace'.  There are also very specific history lists, such as
the one that `compile' uses for compilation commands.  Finally, there
is one "miscellaneous" history list that most minibuffer arguments use.
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 their arguments, so
that you can repeat the entire command.  In particular, every use of
`M-x' is recorded, 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 reexecute 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
     M-x fo 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 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 command it runs.  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
we show the command together with following arguments.
   `M-x' is defined to run 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
   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'.
   `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 this string:
     a b c f i k l m n p s t v w C-c C-d C-n C-w.  Type C-h for more help:
You should then 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'.
* 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).
* 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 list of commands whose names match REGEXP
     (`command-apropos').
`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').  `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').  Since commands are Lisp functions, 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 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-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').
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 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 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 default in the
prompt, you have typed the name of a defined 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 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::.