@c This is part of the Emacs manual.
-@c Copyright (C) 1985, 86, 87, 93, 94, 95, 1997 Free Software Foundation, Inc.
+@c Copyright (C) 1985, 86, 87, 93, 94, 95, 97, 2000, 2001
+@c Free Software Foundation, Inc.
@c See file emacs.texi for copying conditions.
@node Buffers, Windows, Files, Top
@chapter Using Multiple Buffers
@cindex selected buffer
@cindex current buffer
- At any time, one and only one buffer is @dfn{selected}. It is also
-called the @dfn{current buffer}. Often we say that a command operates on
+ At any time, one and only one buffer is @dfn{current}. It is also
+called the @dfn{selected buffer}. Often we say that a command operates on
``the buffer'' as if there were only one; but really this means that the
-command operates on the selected buffer (most commands do).
+command operates on the current buffer (most commands do).
- When Emacs has multiple windows, each window has a chosen buffer which
-is displayed there, but at any time only one of the windows is selected and
-its chosen buffer is the selected buffer. Each window's mode line displays
-the name of the buffer that the window is displaying (@pxref{Windows}).
+ When Emacs has multiple windows, each window has its own chosen
+buffer and displays it; at any time, only one of the windows is
+selected, and its chosen buffer is the current buffer. Each window's
+mode line normally displays the name of the window's chosen buffer
+(@pxref{Windows}).
Each buffer has a name, which can be of any length, and you can select
any buffer by giving its name. Most buffers are made by visiting files,
particular buffer, meaning its value in that buffer can be different from
the value in other buffers. @xref{Locals}.
+@cindex buffer size, maximum
+ A buffer's size cannot be larger than some maximum, which is defined
+by the largest buffer position representable by the @dfn{Emacs integer}
+data type. This is because Emacs tracks buffer positions using that
+data type. For 32-bit machines, the largest buffer size is 128
+megabytes.
+
@menu
* Select Buffer:: Creating a new buffer or reselecting an old one.
* List Buffers:: Getting a list of buffers that exist.
* Kill Buffer:: Killing buffers you no longer need.
* Several Buffers:: How to go through the list of all buffers
and operate variously on several of them.
-* Indirect Buffers:: An indirect buffer shares the text of another buffer.
+* Indirect Buffers:: An indirect buffer shares the text of another buffer.
* Buffer Convenience:: Convenience and customization features for
buffer handling.
@end menu
(@code{switch-to-buffer-other-frame}).
@end table
-@kindex C-x 4 b
-@findex switch-to-buffer-other-window
-@kindex C-x 5 b
-@findex switch-to-buffer-other-frame
@kindex C-x b
@findex switch-to-buffer
To select the buffer named @var{bufname}, type @kbd{C-x b @var{bufname}
@key{RET}}. This runs the command @code{switch-to-buffer} with argument
@var{bufname}. You can use completion on an abbreviation for the buffer
name you want (@pxref{Completion}). An empty argument to @kbd{C-x b}
-specifies the most recently selected buffer that is not displayed in any
-window.@refill
+specifies the buffer that was current most recently among those not
+now displayed in any window.
+
+@kindex C-x 4 b
+@findex switch-to-buffer-other-window
+@vindex even-window-heights
+ To select a buffer in a window other than the current one, type
+@kbd{C-x 4 b @var{bufname} @key{RET}}. This runs the command
+@code{switch-to-buffer-other-window} which displays the buffer
+@var{bufname} in another window. By default, if displaying the buffer
+causes two vertically adjacent windows to be displayed, the heights of
+those windows are evened out; to countermand that and preserve the
+window configuration, set the variable @code{even-window-heights} to
+@code{nil}.
+
+@kindex C-x 5 b
+@findex switch-to-buffer-other-frame
+ Similarly, @kbd{C-x 5 b @var{buffer} @key{RET}} runs the command
+@code{switch-to-buffer-other-frame} which selects a buffer in another
+frame.
+
+@vindex display-buffer-reuse-frames
+ You can control how certain buffers are handled by these commands by
+customizing the variables @code{special-display-buffer-names},
+@code{special-display-regexps}, @code{same-window-buffer-names}, and
+@code{same-window-regexps}. See @ref{Force Same Window}, and
+@ref{Special Buffer Frames}, for more about these variables. In
+addition, if the value of @code{display-buffer-reuse-frames} is
+non-@code{nil}, and the buffer you want to switch to is already
+displayed in some frame, Emacs will raise that frame.
Most buffers are created by visiting files, or by Emacs commands that
want to display some text, but you can also create a buffer explicitly
file. The buffers are listed in the order that they were current; the
buffers that were current most recently come first.
- @samp{*} at the beginning of a line indicates the buffer is ``modified.''
+ @samp{*} in the first field of a line indicates the buffer is ``modified.''
If several buffers are modified, it may be time to save some with @kbd{C-x s}
(@pxref{Saving}). @samp{%} indicates a read-only buffer. @samp{.} marks the
-selected buffer. Here is an example of a buffer list:@refill
+current buffer. Here is an example of a buffer list:@refill
@smallexample
- MR Buffer Size Mode File
- -- ------ ---- ---- ----
-.* emacs.tex 383402 Texinfo /u2/emacs/man/emacs.tex
- *Help* 1287 Fundamental
- files.el 23076 Emacs-Lisp /u2/emacs/lisp/files.el
- % RMAIL 64042 RMAIL /u/rms/RMAIL
- *% man 747 Dired /u2/emacs/man/
- net.emacs 343885 Fundamental /u/rms/net.emacs
- fileio.c 27691 C /u2/emacs/src/fileio.c
- NEWS 67340 Text /u2/emacs/etc/NEWS
- *scratch* 0 Lisp Interaction
+CRM Buffer Size Mode File
+. * .emacs 3294 Emacs-Lisp ~/.emacs
+ % *Help* 101 Help
+ search.c 86055 C ~/cvs/emacs/src/search.c
+ % src 20959 Dired by name ~/cvs/emacs/src/
+ * *mail* 42 Mail
+ % HELLO 1607 Fundamental ~/cvs/emacs/etc/HELLO
+ % NEWS 481184 Outline ~/cvs/emacs/etc/NEWS
+ *scratch* 191 Lisp Interaction
+ * *Messages* 1554 Fundamental
@end smallexample
@noindent
-Note that the buffer @samp{*Help*} was made by a help request; it is not
-visiting any file. The buffer @code{man} was made by Dired on the
-directory @file{/u2/emacs/man/}. You can list buffers visiting files
-only by giving the command a prefix, i.e. type @kbd{C-u C-x C-b}.
+Note that the buffer @samp{*Help*} was made by a help request; it is
+not visiting any file. The buffer @code{src} was made by Dired on the
+directory @file{~/cvs/emacs/src/}. You can list only buffers that are
+visiting files by giving the command a prefix; for instance, by typing
+@kbd{C-u C-x C-b}.
+
+@code{list-buffers} omits buffers whose name begins with a blank,
+unless they visit files: such buffers are used internally by Emacs.
@need 2000
@node Misc Buffer
@table @kbd
@item C-x C-q
-Toggle read-only status of buffer (@code{vc-toggle-read-only}).
+Toggle read-only status of buffer (@code{toggle-read-only}).
@item M-x rename-buffer @key{RET} @var{name} @key{RET}
Change the name of the current buffer.
@item M-x rename-uniquely
@end table
@kindex C-x C-q
-@findex vc-toggle-read-only
@vindex buffer-read-only
@cindex read-only buffer
A buffer can be @dfn{read-only}, which means that commands to change
-its contents are not allowed. The mode line indicates read-only buffers
-with @samp{%%} or @samp{%*} near the left margin. Read-only buffers are
-usually made by subsystems such as Dired and Rmail that have special
-commands to operate on the text; also by visiting a file whose access
-control says you cannot write it. However, if the variable
-@code{kill-read-only-ok} is set to a non-@code{nil} value, you can kill
-(a.k.a.@: cut) read-only text, see @ref{Killing}.
+its contents are not allowed. The mode line indicates read-only
+buffers with @samp{%%} or @samp{%*} near the left margin. Read-only
+buffers are usually made by subsystems such as Dired and Rmail that
+have special commands to operate on the text; also by visiting a file
+whose access control says you cannot write it.
+@findex toggle-read-only
If you wish to make changes in a read-only buffer, use the command
-@kbd{C-x C-q} (@code{vc-toggle-read-only}). It makes a read-only buffer
-writable, and makes a writable buffer read-only. In most cases, this
+@kbd{C-x C-q} (@code{toggle-read-only}). It makes a read-only buffer
+writable, and makes a writable buffer read-only. This
works by setting the variable @code{buffer-read-only}, which has a local
value in each buffer and makes the buffer read-only if its value is
-non-@code{nil}. If the file is maintained with version control,
-@kbd{C-x C-q} works through the version control system to change the
-read-only status of the file as well as the buffer. @xref{Version
+non-@code{nil}. If you have files under version control, you may find
+it convenient to bind @kbd{C-x C-q} to @code{vc-toggle-read-only}
+instead. Then, typing @kbd{C-x C-q} not only changes the read-only
+flag, but it also checks the file in or out. @xref{Version
Control}.
@findex rename-buffer
buffer releases its space back to the operating system so that other
programs can use it. Here are some commands for killing buffers:
-@c WideCommands
@table @kbd
@item C-x k @var{bufname} @key{RET}
Kill buffer @var{bufname} (@code{kill-buffer}).
@kindex C-x k
@kbd{C-x k} (@code{kill-buffer}) kills one buffer, whose name you
-specify in the minibuffer. The default, used if you type just @key{RET}
-in the minibuffer, is to kill the current buffer. If you kill the
-current buffer, another buffer is selected; one that has been selected
-recently but does not appear in any window now. If you ask to kill a
-file-visiting buffer that is modified (has unsaved editing), then you
-must confirm with @kbd{yes} before the buffer is killed.
+specify in the minibuffer. The default, used if you type just
+@key{RET} in the minibuffer, is to kill the current buffer. If you
+kill the current buffer, another buffer becomes current: one that was
+current in the recent past but is not displayed in any window now. If
+you ask to kill a file-visiting buffer that is modified (has unsaved
+editing), then you must confirm with @kbd{yes} before the buffer is
+killed.
The command @kbd{M-x kill-some-buffers} asks about each buffer, one by
one. An answer of @kbd{y} means to kill the buffer. Killing the current
@table @kbd
@item M-x buffer-menu
Begin editing a buffer listing all Emacs buffers.
+@item M-x buffer-menu-other-window.
+Similar, but do it in another window.
@end table
@findex buffer-menu
- The command @code{buffer-menu} writes a list of all Emacs buffers into
-the buffer @samp{*Buffer List*}, and selects that buffer in Buffer Menu
-mode. The buffer is read-only, and can be changed only through the
-special commands described in this section. The usual Emacs cursor
-motion commands can be used in the @samp{*Buffer List*} buffer. The
-following commands apply to the buffer described on the current line.
+@findex buffer-menu-other-window
+ The command @code{buffer-menu} writes a list of all Emacs
+buffers@footnote{Buffers which don't visit files and whose names begin
+with a space are omitted: these are used internally by Emacs.} into the
+buffer @samp{*Buffer List*}, and selects that buffer in Buffer Menu
+mode. The list in the @samp{*Buffer List*} buffer looks exactly as
+described in @ref{List Buffers}. The buffer is read-only, and can be
+changed only through the special commands described in this section.
+The usual Emacs cursor motion commands can be used in the @samp{*Buffer
+List*} buffer. The following commands apply to the buffer described on
+the current line.
@table @kbd
@item d
Immediately select this line's buffer in a full-screen window.
@item 2
Immediately set up two windows, with this line's buffer in one, and the
-previously selected buffer (aside from the buffer @samp{*Buffer List*})
+previously current buffer (aside from the buffer @samp{*Buffer List*})
in the other.
@item b
Bury the buffer listed on this line.
List*} to show what you have done is to type @kbd{g}
(@code{revert-buffer}) or repeat the @code{buffer-menu} command.
+ The command @code{buffer-menu-other-window} works the same as
+@code{buffer-menu}, except that it displays the buffers list in
+another window.
+
@node Indirect Buffers
@section Indirect Buffers
@cindex indirect buffer
@table @kbd
@findex make-indirect-buffer
-@item M-x make-indirect-buffer @var{base-buffer} @key{RET} @var{indirect-name} @key{RET}
+@item M-x make-indirect-buffer @key{RET} @var{base-buffer} @key{RET} @var{indirect-name} @key{RET}
Create an indirect buffer named @var{indirect-name} whose base buffer
is @var{base-buffer}.
@findex clone-indirect-buffer
@item M-x clone-indirect-buffer @key{RET}
Create an indirect buffer that is a twin copy of the current buffer.
+@item C-x 4 c
@kindex C-x 4 c
@findex clone-indirect-buffer-other-window
Create an indirect buffer that is a twin copy of the current buffer, and
One way to use indirect buffers is to display multiple views of an
outline. @xref{Outline Views}.
- The command @kbd{M-x make-indirect-buffer} creates an indirect buffer
-whose name is @var{indirect-name} and whose text is identical to that of
-the buffer @var{base-buffer}. It prompts for both @var{base-buffer} and
-@var{indirect-name}.
-
- The command @kbd{M-x clone-indirect-buffer} creates an indirect buffer
-whose base buffer is the current buffer, and also selects the
-newly-created indirect buffer. With a numeric argument, it prompts for
-the name of the indirect buffer; otherwise it defaults to the name of
-the current buffer, modifying it by adding a @samp{<@var{n}>} prefix if
-required. @kbd{C-x 4 c} (@code{clone-indirect-buffer-other-window})
-works like @kbd{M-x clone-indirect-buffer}, but it selects the cloned
-buffer in another window.
+@cindex multiple @samp{*info*} and @samp{*Help*} buffers
+ A quick and handy way to make an indirect buffer is with the command
+@kbd{M-x clone-indirect-buffer}. It creates and selects an indirect
+buffer whose base buffer is the current buffer. With a numeric
+argument, it prompts for the name of the indirect buffer; otherwise it
+defaults to the name of the current buffer, modifying it by adding a
+@samp{<@var{n}>} prefix if required. @kbd{C-x 4 c}
+(@code{clone-indirect-buffer-other-window}) works like @kbd{M-x
+clone-indirect-buffer}, but it selects the cloned buffer in another
+window. These commands come in handy if you want to create new
+@samp{*info*} or @samp{*Help*} buffers, for example.
+
+ The more general way is with the command @kbd{M-x
+make-indirect-buffer}. It creates an indirect buffer from buffer
+@var{base-buffer}, under the name @var{indirect-name}. It prompts for
+both @var{base-buffer} and @var{indirect-name} using the minibuffer.
@node Buffer Convenience
@section Convenience Features and Customization of Buffer Handling
+ This section describes several modes and features that make it more
+convenient to switch between buffers.
+
@menu
-* Uniquify::
-* BS::
-* Iswitchb::
-* MSB::
+* Uniquify:: Buffer names can contain directory parts.
+* Iswitchb:: Switching between buffers with substrings.
+* Buffer Menus:: Configurable buffer menu.
@end menu
@node Uniquify
-@subsection Directory Names in Buffer Names
+@subsection Making Buffer Names Unique
-@findex toggle-uniquify-buffer-names
-@vindex uniquify-buffer-name-style
@cindex unique buffer names
@cindex directories in buffer names
-Emacs's standard method for making buffer names unique adds @samp{<2>},
-@samp{<3>}, etc. to the end of (all but one of) the buffers. The
-Uniquify package replaces that behavior, for buffers visiting files and
-dired buffers. It implements a uniquification that adds parts of the
-file name until the buffer names are unique. For instance, buffers
-visiting @file{/u/mernst/tmp/Makefile} and
-@file{/usr/projects/zaphod/Makefile} would be named @samp{tmp/Makefile}
-and @samp{zaphod/Makefile}, respectively (instead of @samp{Makefile}
-and @samp{Makefile<2>}). You can turn on this mode and select other
-buffer name styles by customizing the user option
-@code{uniquify-buffer-name-style}. The command @kbd{M-x
-toggle-uniquify-buffer-names} can also be used to toggle the mode.
-
-@node BS
-@subsection BS Mode: Configurable Buffer Menus
+ When several buffers visit identically-named files, Emacs must give
+the buffers distinct names. The usual method for making buffer names
+unique adds @samp{<2>}, @samp{<3>}, etc. to the end of the buffer
+names (all but one of them).
+
+@vindex uniquify-buffer-name-style
+ Other methods work by adding parts of each file's directory to the
+buffer name. To select one, customize the variable
+@code{uniquify-buffer-name-style} (@pxref{Easy Customization}).
+
+ For instance, the @code{forward} naming method puts part of the
+directory name at the beginning of the buffer name; using this method,
+buffers visiting @file{/u/mernst/tmp/Makefile} and
+@file{/usr/projects/zaphod/Makefile} would be named
+@samp{tmp/Makefile} and @samp{zaphod/Makefile}, respectively (instead
+of @samp{Makefile} and @samp{Makefile<2>}).
+
+ By contrast, the @code{post-forward} naming method would call the
+buffers @samp{Makefile|tmp} and @samp{Makefile|zaphod}, and the
+@code{reverse} naming method would call them @samp{Makefile\tmp} and
+@samp{Makefile\zaphod}. The nontrivial difference between
+@code{post-forward} and @code{reverse} occurs when just one directory
+name is not enough to distinguish two files; then @code{reverse} puts
+the directory names in reverse order, so that @file{/top/middle/file}
+becomes @samp{file\middle\top}, while @code{post-forward} puts them in
+forward order after the file name, as in @samp{file|top/middle}.
+
+ Which rule to follow for putting the directory names in the buffer
+name is not very important if you are going to @emph{look} at the
+buffer names before you type one. But as an experienced user, if you
+know the rule, you won't have to look. And then you may find that one
+rule or another is easier for you to remember and utilize fast.
@node Iswitchb
-@subsection Iswitchb Mode: Switching Between Buffers using Substrings
+@subsection Switching Between Buffers using Substrings
+
+@findex iswitchb-mode
+@cindex Iswitchb mode
+@cindex mode, Iswitchb
+@kindex C-x b @r{(Iswitchb mode)}
+@kindex C-x 4 b @r{(Iswitchb mode)}
+@kindex C-x 5 b @r{(Iswitchb mode)}
+@kindex C-x 4 C-o @r{(Iswitchb mode)}
+
+ Iswitchb global minor mode provides convenient switching between
+buffers using substrings of their names. It replaces the normal
+definitions of @kbd{C-x b}, @kbd{C-x 4 b}, @kbd{C-x 5 b}, and @kbd{C-x
+4 C-o} with alternative commands that are somewhat ``smarter.''
+
+ When one of these commands prompts you for a buffer name, you can
+type in just a substring of the name you want to choose. As you enter
+the substring, Iswitchb mode continuously displays a list of buffers
+that match the substring you have typed.
+
+ At any time, you can type @key{RET} to select the first buffer in
+the list. So the way to select a particular buffer is to make it the
+first in the list. There are two ways to do this. You can type more
+of the buffer name and thus narrow down the list, excluding unwanted
+buffers above the desired one. Alternatively, you can use @kbd{C-s}
+and @kbd{C-r} to rotate the list until the desired buffer is first.
+
+ @key{TAB} while entering the buffer name performs completion on the
+string you have entered, based on the displayed list of buffers.
+
+ To enable Iswitchb mode, type @kbd{M-x iswitchb-mode}, or customize
+the variable @code{iswitchb-mode} to @code{t} (@pxref{Easy
+Customization}).
+
+@node Buffer Menus
+@subsection Customizing Buffer Menus
+
+@findex bs-show
+@cindex buffer list, customizable
+@table @kbd
+@item M-x bs-show
+Make a list of buffers similarly to @kbd{M-x list-buffers} but
+customizable.
+@end table
-@node MSB
-@subsection MSB Mode: Customizable Buffer Selection with Multiple Menus
+ @kbd{M-x bs-show} pops up a buffer list similar to the one normally
+displayed by @kbd{C-x C-b} but which you can customize. If you prefer
+this to the usual buffer list, you can bind this command to @kbd{C-x
+C-b}. To customize this buffer list, use the @code{bs} Custom group
+(@pxref{Easy Customization}).
+
+@findex msb-mode
+@cindex mode, MSB
+@cindex MSB mode
+@cindex buffer menu
+@findex mouse-buffer-menu
+@kindex C-Down-Mouse-1
+ MSB global minor mode (``MSB'' stands for ``mouse select buffer'')
+provides a different and customizable mouse buffer menu which you may
+prefer. It replaces the bindings of @code{mouse-buffer-menu},
+normally on @kbd{C-Down-Mouse-1}, and the menu bar buffer menu. You
+can customize the menu in the @code{msb} Custom group.
+
+@ignore
+ arch-tag: 08c43460-f4f4-4b43-9cb5-1ea9ad991695
+@end ignore
HCoop / bpt / emacs.git / blobdiff