Document completion styles in Emacs manual; copyedits.

[emacs.git] / doc / emacs / mini.texi

@c This is part of the Emacs manual.
@c Copyright (C) 1985-1987, 1993-1995, 1997, 2000-2011
@c   Free Software Foundation, Inc.
@c See file emacs.texi for copying conditions.
@node Minibuffer, M-x, Basic, Top
@chapter The Minibuffer
@cindex minibuffer

  The @dfn{minibuffer} is where Emacs commands read complicated
arguments, such as file names, buffer names, Emacs command names, or
Lisp expressions.  We call it the ``minibuffer'' because it's a
special-purpose buffer with a small amount of screen space.  You can
use the usual Emacs editing commands in the minibuffer to edit the
argument text.

@cindex prompt
  When the minibuffer is in use, it appears in the echo area, with a
cursor.  The minibuffer starts with a @dfn{prompt} in a distinct
color, usually ending with a colon.  The prompt states what kind of
input is expected, and how it will be used.

  The simplest way to enter a minibuffer argument is to type the text,
then @key{RET} to submit the argument and exit the minibuffer.  You
can cancel the minibuffer, and the command that wants the argument, by
typing @kbd{C-g}.

@cindex default argument
  Sometimes, a @dfn{default argument} appears in the prompt, inside
parentheses before the colon.  This default will be used as the
argument if you just type @key{RET}.  For example, commands that read
buffer names usually show a buffer name as the default; you can type
@key{RET} to operate on that default buffer.

  Since the minibuffer appears in the echo area, it can conflict with
other uses of the echo area.  If an error message or an informative
message is emitted while the minibuffer is active, the message hides
the minibuffer for a few seconds, or until you type something; then
the minibuffer comes back.  While the minibuffer is in use, keystrokes
do not echo.

@menu
* Minibuffer File::       Entering file names with the minibuffer.
* 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.
* Passwords::             Entering passwords in the echo area.
@end menu

@node Minibuffer File
@section Minibuffers for File Names

@cindex default directory
  Commands such as @kbd{C-x C-f} (@code{find-file}) use the minibuffer
to read a file name argument (@pxref{Basic Files}).  When the
minibuffer is used to read a file name, it typically starts out with
some initial text ending in a slash.  This is the @dfn{default
directory}.  For example, it may start out like this:

@example
Find File: /u2/emacs/src/
@end example

@noindent
Here, @samp{Find File:@: } is the prompt and @samp{/u2/emacs/src/} is
the default directory.  If you now type @kbd{buffer.c} as input, that
specifies the file @file{/u2/emacs/src/buffer.c}.  @xref{File Names},
for information about the default directory.

  You can specify the parent directory with @file{..}:
@file{/a/b/../foo.el} is equivalent to @file{/a/foo.el}.
Alternatively, you can use @kbd{M-@key{DEL}} to kill directory names
backwards (@pxref{Words}).

  To specify a file in a completely different directory, you can kill
the entire default with @kbd{C-a C-k} (@pxref{Minibuffer Edit}).
Alternatively, you can ignore the default, and enter an absolute file
name starting with a slash or a tilde after the default directory.
For example, you can specify @file{/etc/termcap} as follows:

@example
Find File: /u2/emacs/src//etc/termcap
@end example

@noindent
@cindex // in file name
@cindex double slash in file name
@cindex slashes repeated in file name
@findex file-name-shadow-mode
Emacs interprets a double slash as ``ignore everything before the
second slash in the pair.''  In the example above,
@file{/u2/emacs/src/} is ignored, so the argument you supplied is
@file{/etc/termcap}.  The ignored part of the file name is dimmed if
the terminal allows it.  (To disable this dimming, turn off File Name
Shadow mode with the command @kbd{M-x file-name-shadow-mode}.)

@cindex home directory shorthand
  Emacs interprets @file{~/} as your home directory.  Thus,
@file{~/foo/bar.txt} specifies a file named @file{bar.txt}, inside a
directory named @file{foo}, which is in turn located in your home
directory.  In addition, @file{~@var{user-id}/} means the home
directory of a user whose login name is @var{user-id}.  Any leading
directory name in front of the @file{~} is ignored: thus,
@file{/u2/emacs/~/foo/bar.txt} is equivalent to @file{~/foo/bar.txt}.

  On MS-Windows and MS-DOS systems, where a user doesn't always have a
home directory, Emacs uses several alternatives.  For MS-Windows, see
@ref{Windows HOME}; for MS-DOS, see
@ifnottex
@ref{MS-DOS File Names}.
@end ifnottex
@iftex
@ref{MS-DOS File Names, HOME on MS-DOS,, emacs, the digital version of
the Emacs Manual}.
@end iftex
On these systems, the @file{~@var{user-id}/} construct is supported
only for the current user, i.e., only if @var{user-id} is the current
user's login name.

@vindex insert-default-directory
  To prevent Emacs from inserting the default directory when reading
file names, change the variable @code{insert-default-directory} to
@code{nil}.  In that case, the minibuffer starts out empty.
Nonetheless, relative file name arguments are still interpreted based
on the same default directory.

  You can also enter remote file names in the minibuffer.
@xref{Remote Files}.

@node Minibuffer Edit
@section Editing in the Minibuffer

  The minibuffer is an Emacs buffer, albeit a peculiar one, and the
usual Emacs commands are available for editing the argument text.
(The prompt, however, is @dfn{read-only}, and cannot be changed.)

  Since @key{RET} in the minibuffer submits the argument, you can't
use it to insert a newline.  You can do that with @kbd{C-q C-j}, which
inserts a @kbd{C-j} control character, which is formally equivalent to
a newline character (@pxref{Inserting Text}).  Alternatively, you can
use the @kbd{C-o} (@code{open-line}) command (@pxref{Blank Lines}).

  Inside a minibuffer, the keys @key{TAB}, @key{SPC}, and @kbd{?} are
often bound to @dfn{completion commands}, which allow you to easily
fill in the desired text without typing all of it.  @xref{Completion}.
As with @key{RET}, you can use @kbd{C-q} to insert a @key{TAB},
@key{SPC}, or @samp{?}  character.

  For convenience, @kbd{C-a} (@code{move-beginning-of-line}) in a
minibuffer moves point to the beginning of the argument text, not the
beginning of the prompt.  For example, this allows you to erase the
entire argument with @kbd{C-a C-k}.

@cindex height of minibuffer
@cindex size of minibuffer
@cindex growing minibuffer
@cindex resizing minibuffer
  When the minibuffer is active, the echo area is treated much like an
ordinary Emacs window.  For instance, you can switch to another window
(with @kbd{C-x o}), edit text there, then return to the minibuffer
window to finish the argument.  You can even kill text in another
window, return to the minibuffer window, and yank the text into the
argument.  There are some restrictions on the minibuffer window,
however: for instance, you cannot split it.  @xref{Windows}.

@vindex resize-mini-windows
  Normally, the minibuffer window occupies a single screen line.
However, if you add two or more lines' worth of text into the
minibuffer, it expands automatically to accommodate the text.  The
variable @code{resize-mini-windows} controls the resizing of the
minibuffer.  The default value is @code{grow-only}, which means the
behavior we have just described.  If the value is @code{t}, the
minibuffer window will also shrink automatically if you remove some
lines of text from the minibuffer, down to a minimum of one screen
line.  If the value is @code{nil}, the minibuffer window never changes
size automatically, but you can use the usual window-resizing commands
on it (@pxref{Windows}).

@vindex max-mini-window-height
  The variable @code{max-mini-window-height} controls the maximum
height for resizing the minibuffer window.  A floating-point number
specifies a fraction of the frame's height; an integer specifies the
maximum number of lines; @code{nil} means do not resize the minibuffer
window automatically.  The default value is 0.25.

  The @kbd{C-M-v} command in the minibuffer scrolls the help text from
commands that display help text of any sort in another window.  You
can also scroll the help text with @kbd{M-@key{prior}} and
@kbd{M-@key{next}} (or, equivalently, @kbd{M-@key{PageUp}} and
@kbd{M-@key{PageDown}}).  This is especially useful with long lists of
possible completions.  @xref{Other Window}.

@vindex enable-recursive-minibuffers
  Emacs normally disallows most commands that use the minibuffer while
the minibuffer is active.  To allow such commands in the minibuffer,
set the variable @code{enable-recursive-minibuffers} to @code{t}.

@node Completion
@section Completion
@c This node is referenced in the tutorial.  When renaming or deleting
@c it, the tutorial needs to be adjusted.
@cindex completion

  You can often use a feature called @dfn{completion} to help enter
arguments.  This means that after you type part of the argument, Emacs
can fill in the rest, or some of it, based on what was typed so far.

@cindex completion alternative
  When completion is available, certain keys (usually @key{TAB},
@key{RET}, and @key{SPC}) are rebound in the minibuffer to special
completion commands (@pxref{Completion Commands}).  These commands
attempt to complete the text in the minibuffer, based on a set of
@dfn{completion alternatives} provided by the command that requested
the argument.  You can usually type @kbd{?} to see a list of
completion alternatives.

  Although completion is usually done in the minibuffer, the feature
is sometimes available in ordinary buffers too.  @xref{Symbol
Completion}.

@menu
* Example: Completion Example.    Examples of using completion.
* Commands: Completion Commands.  A list of completion commands.
* Strict Completion::             Different types of completion.
* Completion Styles::             How completion matches are chosen.
* Options: Completion Options.    Options for completion.
@end menu

@node Completion Example
@subsection Completion Example

@kindex TAB @r{(completion)}
  A simple example may help here.  @kbd{M-x} uses the minibuffer to
read the name of a command, so completion works by matching the
minibuffer text against the names of existing Emacs commands.  Suppose
you wish to run the command @code{auto-fill-mode}.  You can do that by
typing @kbd{M-x auto-fill-mode @key{RET}}, but it is easier to use
completion.

  If you type @kbd{M-x a u @key{TAB}}, the @key{TAB} looks for
completion alternatives (in this case, command names) that start with
@samp{au}.  There are several, including @code{auto-fill-mode} and
@code{autoconf-mode}, but they all begin with @code{auto}, so the
@samp{au} in the minibuffer completes to @samp{auto}.

  If you type @key{TAB} again immediately, it cannot determine the
next character; it could be @samp{-}, @samp{a}, or @samp{c}.  So it
does not add any characters; instead, @key{TAB} displays a list of all
possible completions in another window.

  Next, type @kbd{-f}.  The minibuffer now contains @samp{auto-f}, and
the only command name that starts with this is @code{auto-fill-mode}.
If you now type @key{TAB}, completion fills in the rest of the
argument @samp{auto-fill-mode} into the minibuffer.

  Hence, typing just @kbd{a u @key{TAB} - f @key{TAB}} allows you to
enter @samp{auto-fill-mode}.

@node Completion Commands
@subsection Completion Commands

  Here is a list of the completion commands defined in the minibuffer
when completion is allowed.

@table @kbd
@item @key{TAB}
@findex minibuffer-complete
Complete the text in the minibuffer as much as possible; if unable to
complete, display a list of possible completions
(@code{minibuffer-complete}).
@item @key{SPC}
Complete up to one word from the minibuffer text before point
(@code{minibuffer-complete-word}).  This command is not available for
arguments that often include spaces, such as file names.
@item @key{RET}
Submit the text in the minibuffer as the argument, possibly completing
first (@code{minibuffer-complete-and-exit}).  @xref{Strict Completion}.
@item ?
Display a list of completions (@code{minibuffer-completion-help}).
@end table

@kindex TAB @r{(completion)}
@findex minibuffer-complete
  @key{TAB} (@code{minibuffer-complete}) is the most fundamental
completion command.  It searches for all possible completions that
match the existing minibuffer text, and attempts to complete as much
as it can.  @xref{Completion Styles}, for how completion alternatives
are chosen.

@kindex SPC @r{(completion)}
@findex minibuffer-complete-word
  @key{SPC} (@code{minibuffer-complete-word}) completes like
@key{TAB}, but only up to the next hyphen or space.  If you have
@samp{auto-f} in the minibuffer and type @key{SPC}, it finds that the
completion is @samp{auto-fill-mode}, but it only inserts @samp{ill-},
giving @samp{auto-fill-}.  Another @key{SPC} at this point completes
all the way to @samp{auto-fill-mode}.

@kindex ? @r{(completion)}
@cindex completion list
  If @key{TAB} or @key{SPC} is unable to complete, it displays a list
of matching completion alternatives (if there are any) in another
window.  You can display the same list with @kbd{?}
(@code{minibuffer-completion-help}).  The following commands can be
used with the completion list:

@table @kbd
@findex mouse-choose-completion
@item Mouse-1
@itemx Mouse-2
Clicking mouse button 1 or 2 on a completion alternative chooses it
(@code{mouse-choose-completion}).

@findex switch-to-completions
@item M-v
@itemx @key{PageUp}
@itemx @key{prior}
Typing @kbd{M-v}, while in the minibuffer, selects the window showing
the completion list (@code{switch-to-completions}).  This paves the
way for using the commands below.  @key{PageUp} or @key{prior} does
the same.  You can also select the window in other ways
(@pxref{Windows}).

@findex choose-completion
@item @key{RET}
While in the completion list buffer, this chooses the completion at
point (@code{choose-completion}).

@findex next-completion
@item @key{Right}
While in the completion list buffer, this moves point to the following
completion alternative (@code{next-completion}).

@findex previous-completion
@item @key{Left}
While in the completion list buffer, this moves point to the previous
completion alternative (@code{previous-completion}).
@end table

@node Strict Completion
@subsection Strict Completion

  There are three ways that the @key{RET}
(@code{minibuffer-complete-and-exit}) completion command can act,
depending on how the argument will be used.

@itemize @bullet
@item
@dfn{Strict} completion accepts only known completion candidates.  For
example, when @kbd{C-x k} reads the name of a buffer to kill, only the
name of an existing buffer makes sense.  In strict completion,
@key{RET} refuses to exit if the text in the minibuffer does not
complete to an exact match.

@item
@dfn{Cautious} completion is similar to strict completion, except that
@key{RET} exits only if the text is an already exact match.
Otherwise, @key{RET} does not exit, but it does complete the text.  If
that completes to an exact match, a second @key{RET} will exit.

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

@item
@dfn{Permissive} completion allows any input; the completion
candidates are just suggestions.  For example, when @kbd{C-x C-f}
reads the name of a file to visit, any file name is allowed, including
nonexistent file (in case you want to create a file).  In permissive
completion, @key{RET} does not complete, it just submits the argument
as you have entered it.
@end itemize

  Like the other completion commands, @key{RET} displays a list of all
possible completions whenever it is supposed to complete but is unable
to complete any further.

@node Completion Styles
@subsection How Completion Alternatives Are Chosen
@cindex completion style

  Completion commands work by narrowing a large list of possible
completion alternatives to a smaller subset that ``matches'' what you
have typed in the minibuffer.  In @ref{Completion Example}, we gave a
simple example of such matching.  The procedure of determining what
constitutes a ``match'' is quite intricate.  Emacs attempts to offer
plausible completions under most circumstances.

  Emacs performs completion using one or more @dfn{completion
styles}---sets of criteria for matching minibuffer text to completion
alternatives.  During completion, Emacs tries each completion style in
turn.  If a style yields one or more matches, that is used as the list
of completion alternatives.  If a style produces no matches, Emacs
falls back on the next style.

@vindex completion-styles
  The list variable @code{completion-styles} specifies the completion
styles to use.  Each list element is the name of a completion style (a
Lisp symbol).  The default completion styles are (in order):

@table @code
@item basic
A matching completion alternative must have the same beginning as the
text in the minibuffer before point.  Furthermore, if there is any
text in the minibuffer after point, the rest of the completion
alternative must contain that text as a substring.

@findex partial completion
@item partial-completion
This aggressive completion style divides the minibuffer text into
words separated by hyphens or spaces, and completes each word
separately.  (For example, when completing command names,
@samp{em-l-m} completes to @samp{emacs-lisp-mode}.)

Furthermore, a @samp{*} in the minibuffer text is treated as a
@dfn{wildcard}---it matches any character at the corresponding
position in the completion alternative.

@item emacs22
This completion style is similar to @code{basic}, except that it
ignores the text in the minibuffer after point.  It is so-named
because it corresponds to the completion behavior in Emacs 22 and
earlier.
@end table

@noindent
The following additional completion styles are also defined, and you
can add them to @code{completion-styles} if you wish
(@pxref{Customization}):

@table @code
@item substring
A matching completion alternative must contain the text in the
minibuffer before point, and the text in the minibuffer after point,
as substrings (in that same order).

Thus, if the text in the minibuffer is @samp{foobar}, with point
between @samp{foo} and @samp{bar}, that matches
@samp{@var{a}foo@var{b}bar@var{c}}, where @var{a}, @var{b}, and
@var{c} can be any string including the empty string.

@item initials
This very aggressive completion style attempts to complete acronyms
and initialisms.  For example, when completing command names, it
matches @samp{lch} to @samp{list-command-history}.
@end table

@node Completion Options
@subsection Completion Options

@cindex case-sensitivity and completion
@cindex case in completion
  Case is significant when completing case-sensitive arguments, such
as command names.  For example, when completing command names,
@samp{AU} does not complete to @samp{auto-fill-mode}.  Case
differences are ignored when completing arguments in which case does
not matter.

@vindex read-file-name-completion-ignore-case
@vindex read-buffer-completion-ignore-case
  When completing file names, case differences are ignored if the
variable @code{read-file-name-completion-ignore-case} is
non-@code{nil}.  The default value is @code{nil} on systems that have
case-sensitive file-names, such as GNU/Linux; it is non-@code{nil} on
systems that have case-insensitive file-names, such as Microsoft
Windows.  When completing buffer names, case is significant by
default; to ignore case differences, change the variable
@code{read-buffer-completion-ignore-case} to a non-@code{nil} value.

@vindex completion-ignored-extensions
@cindex ignored file names, in completion
  When completing file names, Emacs usually omits certain alternatives
that are considered unlikely to be chosen.  The variable
@code{completion-ignored-extensions} contains a list of strings; a
file name ending in any of those strings is ignored as a completion
alternative.  The standard value of this variable has several elements
including @code{".o"}, @code{".elc"}, and @code{"~"}.  For example, if
a directory contains @samp{foo.c} and @samp{foo.elc}, @samp{foo}
completes to @samp{foo.c}.  However, if @emph{all} possible
completions end in ``ignored'' strings, they are not ignored: in the
previous example, @samp{foo.e} completes to @samp{foo.elc}.
Displaying the completion list disregards
@code{completion-ignored-extensions}; all completions are listed.

@vindex completion-auto-help
  If @code{completion-auto-help} is set to @code{nil}, the completion
commands never display the completion list buffer; you must type
@kbd{?}  to display the list.  If the value is @code{lazy}, Emacs only
shows the completion list buffer on the second attempt to complete.
In other words, if there is nothing to complete, the first @key{TAB}
echoes @samp{Next char not unique}; the second @key{TAB} does the
completion list buffer.

  If an element of @code{completion-ignored-extensions} ends in a
slash (@file{/}), it's a subdirectory name; that directory and its
contents are ignored.  Elements of
@code{completion-ignored-extensions} that do not end in a slash are
ordinary file names.

@cindex Icomplete mode
@findex icomplete-mode
  Icomplete mode presents a constantly-updated display that tells you
what completions are available for the text you've entered so far.  The
command to enable or disable this minor mode is @kbd{M-x
icomplete-mode}.

@node Minibuffer History
@section Minibuffer History
@cindex minibuffer history
@cindex history of minibuffer input

  Every argument that you enter with the minibuffer is saved in a
@dfn{minibuffer history list} so you can easily use it again later.
You can use the following arguments to quickly fetch an earlier
argument into the minibuffer:

@table @kbd
@item M-p
@itemx @key{Up}
Move to the previous item in the minibuffer history, an earlier
argument (@code{previous-history-element}).
@item M-n
@itemx @key{Down}
Move to the next item in the minibuffer history
(@code{next-history-element}).
@item M-r @var{regexp} @key{RET}
Move to an earlier item in the minibuffer history that
matches @var{regexp} (@code{previous-matching-history-element}).
@item M-s @var{regexp} @key{RET}
Move to a later item in the minibuffer history that matches
@var{regexp} (@code{next-matching-history-element}).
@end table

@kindex M-p @r{(minibuffer history)}
@kindex M-n @r{(minibuffer history)}
@findex next-history-element
@findex previous-history-element
  While in the minibuffer, typing @kbd{M-p} or @key{Up}
(@code{previous-history-element}) moves up through the minibuffer
history list, one item at a time.  Each @kbd{M-p} fetches an earlier
item from the history list into the minibuffer, replacing its existing
contents.  Similarly, typing @kbd{M-n} or @key{Down}
(@code{next-history-element}) moves back down the history list,
fetching later entries into the minibuffer.  You can think of these
commands as ``backwards'' and ``forwards'' through the history list.

  If you type @kbd{M-n} in the minibuffer when there are no later
entries in the minibuffer history (e.g., if you haven't previously
typed @kbd{M-p}), Emacs tries fetching from a list of default
argument: values that you are likely to enter.  You can think of this
as moving through the ``future list'' instead of the ``history list''.

  The input that @kbd{M-p} or @kbd{M-n} fetches into the minibuffer
entirely replaces the existing contents of the minibuffer, so you can
simply type @key{RET} to use it as an argument.  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.

@findex previous-matching-history-element
@findex next-matching-history-element
@kindex M-r @r{(minibuffer history)}
@kindex M-s @r{(minibuffer history)}
  There are also commands to search forward or backward through the
history; they search for history elements that match a regular
expression.  @kbd{M-r} (@code{previous-matching-history-element})
searches older elements in the history, while @kbd{M-s}
(@code{next-matching-history-element}) searches newer elements.  These
commands are unusual: they use the minibuffer to read the regular
expression even though they are invoked from the minibuffer.  As with
incremental searching, an upper-case letter in the regular expression
makes the search case-sensitive (@pxref{Search Case}).  You can also
search through the history using an incremental search (@pxref{Isearch
Minibuffer}).

  All uses of the minibuffer record your input on a history list, but
there are separate history lists for different kinds of arguments.
For example, there is a list for file names, used by all the commands
that read file names.  (As a special feature, this history list
records the absolute file name, even if the name you entered was not
absolute.)

  There are several other specific history lists, including one for
buffer names, one for arguments of commands like @code{query-replace},
one used by @kbd{M-x} for command names, and one used by
@code{compile} for compilation commands.  Finally, there is one
``miscellaneous'' history list that most minibuffer arguments use.

@vindex history-length
  The variable @code{history-length} specifies the maximum length of a
minibuffer history list; adding a new element deletes the oldest
element if the list gets too long.  If the value of
@code{history-length} is @code{t}, there is no maximum length.

@vindex history-delete-duplicates
  The variable @code{history-delete-duplicates} specifies whether to
delete duplicates in history.  If it is non-@code{nil}, adding a new
element deletes from the list all other elements that are equal to it.
The default is @code{nil}.

@node Repetition
@section Repeating Minibuffer Commands
@cindex command history
@cindex history of commands

  Every command that uses the minibuffer once is recorded on a special
history list, the @dfn{command history}, together with the values of
its arguments, so that you can repeat the entire command.  In
particular, every use of @kbd{M-x} is recorded there, since @kbd{M-x}
uses the minibuffer to read the command name.

@findex list-command-history
@table @kbd
@item C-x @key{ESC} @key{ESC}
Re-execute a recent minibuffer command from the command history
 (@code{repeat-complex-command}).
@item M-x list-command-history
Display the entire command history, showing all the commands
@kbd{C-x @key{ESC} @key{ESC}} can repeat, most recent first.
@end table

@kindex C-x ESC ESC
@findex repeat-complex-command
  @kbd{C-x @key{ESC} @key{ESC}} is used to re-execute a recent command
that used the minibuffer.  With no argument, it repeats the last such
command.  A numeric argument specifies which command to repeat; 1
means the last one, 2 the previous, and so on.

  @kbd{C-x @key{ESC} @key{ESC}} works by turning the previous command
into a Lisp expression and then entering a minibuffer initialized with
the text for that expression.  Even if you don't understand Lisp
syntax, it will probably be obvious which command is displayed for
repetition.  If you type just @key{RET}, that repeats the command
unchanged.  You can also change the command by editing the Lisp
expression before you execute it.  The repeated command is added to
the front of the command history unless it is identical to the most
recent item.

  Once inside the minibuffer for @kbd{C-x @key{ESC} @key{ESC}}, you can
use the minibuffer history commands (@kbd{M-p}, @kbd{M-n}, @kbd{M-r},
@kbd{M-s}; @pxref{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 repeat it by typing
@key{RET}.

@vindex isearch-resume-in-command-history
  Incremental search does not, strictly speaking, use the minibuffer.
Therefore, although it behaves like a complex command, it normally
does not appear in the history list for @kbd{C-x @key{ESC} @key{ESC}}.
You can make incremental search commands appear in the history by
setting @code{isearch-resume-in-command-history} to a non-@code{nil}
value.  @xref{Incremental Search}.

@vindex command-history
  The list of previous minibuffer-using commands is stored as a Lisp
list in the variable @code{command-history}.  Each element is a Lisp
expression which describes one command and its arguments.  Lisp programs
can re-execute a command by calling @code{eval} with the
@code{command-history} element.

@node Passwords
@section Entering passwords

Sometimes, you may need to enter a password into Emacs.  For instance,
when you tell Emacs to visit a file on another machine via a network
protocol such as FTP, you often need to supply a password to gain
access to the machine (@pxref{Remote Files}).

  Entering a password is, in a basic sense, similar to using a
minibuffer.  Emacs displays a prompt in the echo area (such as
@samp{Password: }); after you type the required password, press
@key{RET} to submit it.  To prevent others from seeing your password,
every character you type is displayed as a dot (@samp{.}) instead of
its usual form.

  Most of the features and commands associated with the minibuffer can
@emph{not} be used when entering a password.  There is no history or
completion, and you cannot change windows or perform any other action
with Emacs until you have submitted the password.

  While you are typing the password, you may press @key{DEL} to delete
backwards, removing the last character entered.  @key{C-u} deletes
everything you have typed so far.  @kbd{C-g} quits the password prompt
(@pxref{Quitting}).  @kbd{C-y} inserts the current kill into the
password (@pxref{Killing}).  You may type either @key{RET} or
@key{ESC} to submit the password.  Any other self-inserting character
key inserts the associated character into the password, and all other
input is ignored.