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(Buffers): Add xrefs to Mode Line and Lisp Interaction.

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(Select Buffer): Mention use of minibuffer history.  Describe default
value of default-major-mode.  Mention that C-x 4 b selects the other
window.
(List Buffers): Document CRM indicators in the order they appear.
(Kill Buffer): Document new command kill-matching buffers.
(Several Buffers): Move explanation of the relationship between buffer
list and buffer menu to the top.
(Indirect Buffers): Document new variable clone-indirect-buffer-hook.
This commit is contained in:
Chong Yidong 2008-10-11 17:35:20 +00:00
parent 89774b5f39
commit ea146ed84a
1 changed files with 116 additions and 124 deletions
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240
doc/emacs/buffers.texi
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@ -13,32 +13,31 @@ directory listing. If you send a message with @kbd{C-x m}, a buffer named
@samp{*mail*} is used to hold the text of the message. When you ask for a
command's documentation, that appears in a buffer called @samp{*Help*}.
Each buffer has a unique name, which can be of any length. When a
buffer is displayed in a window, its name is shown in the mode line
(@pxref{Mode Line}). The distinction between upper and lower case
matters in buffer names. Most buffers are made by visiting files, and
their names are derived from the files' names; however, you can also
create an empty buffer with any name you want. A newly started Emacs
has a buffer named @samp{*scratch*}, which is not associated with any
file and can be used for evaluating Lisp expressions in Emacs
(@pxref{Lisp Interaction}).
@cindex selected buffer
@cindex current buffer
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 current buffer (most commands do).
At any time, one and only one buffer is @dfn{current}. This is also
called the @dfn{selected buffer}. We often say that a command
operates on ``the buffer''; this really means that the command
operates on the current buffer (most commands do). When there is only
one Emacs window, the buffer displayed in that window is current.
When there are multiple windows present, the buffer displayed in the
@dfn{selected window} is current. @xref{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,
and their names are derived from the files' names. But you can also create
an empty buffer with any name you want. A newly started Emacs has a buffer
named @samp{*scratch*} which can be used for evaluating Lisp expressions in
Emacs. The distinction between upper and lower case matters in buffer
names.
Each buffer records individually what file it is visiting, whether it is
modified, and what major mode and minor modes are in effect in it
(@pxref{Major Modes}). Any Emacs variable can be made @dfn{local to} a
particular buffer, meaning its value in that buffer can be different from
the value in other buffers. @xref{Locals}.
Each buffer records individually what file it is visiting (if any),
whether it is modified, and what major mode and minor modes are in
effect (@pxref{Major Modes}). Any Emacs variable can be made
@dfn{local to} a 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
@ -85,13 +84,22 @@ selected buffer other than the current buffer.
@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 to enter the buffer
name (@pxref{Completion}). An empty argument to @kbd{C-x b}
specifies the buffer that was current most recently among those not
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}. While entering
the buffer name, you can use the usual minibuffer completion and
history commands (@pxref{Minibuffer}). An empty argument to @kbd{C-x
b} specifies the buffer that was current most recently among those not
now displayed in any window.
If you specify a buffer that does not exist, @kbd{C-x b} creates a
new, empty buffer that is not visiting any file, and selects it for
editing. You can use such a buffer for making temporary notes. If
you try to save it, you are asked for the file name to use. The new
buffer's major mode is determined by the variable
@code{default-major-mode}; the default value is Fundamental mode.
@xref{Major Modes}.
@kindex C-x @key{LEFT}
@kindex C-x @key{RIGHT}
@findex next-buffer
@ -106,19 +114,23 @@ of most recent selection in the current frame), while @kbd{C-x @key{LEFT}}
@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}.
@kbd{C-x 4 b} (@code{switch-to-buffer-other-window}). This prompts
for a buffer name using the minibuffer, displays that buffer in
another window, and selects that 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.
Similarly, @kbd{C-x 5 b} (@code{switch-to-buffer-other-frame})
prompts for a buffer name, displays that buffer in another frame, and
selects that frame.
In addition, @kbd{C-x C-f}, and any other command for visiting a
file, can also be used to switch to an existing file-visiting buffer.
@xref{Visiting}.
@vindex display-buffer-reuse-frames
You can control how certain buffers are handled by these commands by
@ -130,31 +142,18 @@ 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 just 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
by typing @kbd{C-x b @var{bufname} @key{RET}}. This makes a new, empty
buffer that is not visiting any file, and selects it for editing. Such
buffers are used for making notes to yourself. If you try to save one,
you are asked for the file name to use. The new buffer's major mode is
determined by the value of @code{default-major-mode} (@pxref{Major
Modes}).
Note that @kbd{C-x C-f}, and any other command for visiting a file,
can also be used to switch to an existing file-visiting buffer.
@xref{Visiting}.
@kbd{C-u M-g M-g}, that is @code{goto-line} with a prefix argument
of just @kbd{C-u}, reads a number @var{n} using the minibuffer,
selects the most recently selected buffer other than the current
buffer in another window, and then moves point to the beginning of
line number @var{n} in that buffer. This is mainly useful in a buffer
that refers to line numbers in another buffer: if point is on or just
after a number, @code{goto-line} uses that number as the default for
@var{n}. Note that prefix arguments other than just @kbd{C-u} behave
differently. @kbd{C-u 4 M-g M-g} goes to line 4 in the @emph{current}
buffer, without reading a number from the minibuffer. (Remember that
@kbd{M-g M-g} without prefix argument reads a number @var{n} and then
moves to line number @var{n} in the current buffer.)
@kbd{C-u M-g M-g}, that is @code{goto-line} with a plain prefix
argument, reads a number @var{n} using the minibuffer, selects the
most recently selected buffer other than the current buffer in another
window, and then moves point to the beginning of line number @var{n}
in that buffer. This is mainly useful in a buffer that refers to line
numbers in another buffer: if point is on or just after a number,
@code{goto-line} uses that number as the default for @var{n}. Note
that prefix arguments other than just @kbd{C-u} behave differently.
@kbd{C-u 4 M-g M-g} goes to line 4 in the @emph{current} buffer,
without reading a number from the minibuffer. (Remember that @kbd{M-g
M-g} without prefix argument reads a number @var{n} and then moves to
line number @var{n} in the current buffer. @xref{Moving Point}.)
Emacs uses buffer names that start with a space for internal purposes.
It treats these buffers specially in minor ways---for example, by
@ -177,11 +176,11 @@ line in the list shows one buffer's name, major mode and visited file.
The buffers are listed in the order that they were current; the
buffers that were current most recently come first.
@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{Save Commands}). @samp{%} indicates a
read-only buffer. @samp{.} marks the current buffer. Here is an
example of a buffer list:@refill
@samp{.} in the first field of a line indicates that the buffer is
current. @samp{%} indicates a read-only buffer. @samp{*} indicates
that the buffer is ``modified.'' If several buffers are modified, it
may be time to save some with @kbd{C-x s} (@pxref{Save Commands}).
Here is an example of a buffer list:
@smallexample
CRM Buffer Size Mode File
@ -197,16 +196,15 @@ CRM Buffer Size Mode File
@end smallexample
@noindent
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 argument, as in
The buffer @samp{*Help*} was made by a help request (@pxref{Help}); 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 argument, as in
@kbd{C-u C-x C-b}.
@code{list-buffers} omits buffers whose names begin with a space,
unless they visit files: such buffers are used internally by Emacs.
@need 2000
@node Misc Buffer
@section Miscellaneous Buffer Operations
@ -291,28 +289,37 @@ programs can use it. Here are some commands for killing buffers:
Kill buffer @var{bufname} (@code{kill-buffer}).
@item M-x kill-some-buffers
Offer to kill each buffer, one by one.
@item M-x kill-matching-buffers
Offer to kill all buffers matching a regular expression.
@end table
@findex kill-buffer
@findex kill-some-buffers
@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 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.
you ask to kill a file-visiting buffer that is modified, 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
buffer or a buffer containing unsaved changes selects a new buffer or asks
for confirmation just like @code{kill-buffer}.
@findex kill-some-buffers
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, just like
@code{kill-buffer}. This command ignores buffers whose names begin
with a space, which are used internally by Emacs.
The buffer menu feature (@pxref{Several Buffers}) is also convenient
for killing various buffers.
@findex kill-matching-buffers
The command @kbd{M-x kill-matching-buffers} prompts for a regular
expression and kills all buffers whose names match that expression.
@xref{Regexps}. Like @code{kill-some-buffers}, it asks for
confirmation before each kill. This command normally ignores buffers
whose names begin with a space, which are used internally by Emacs.
To kill internal buffers as well, call @code{kill-matching-buffers}
with a prefix argument.
The buffer menu feature is also convenient for killing various
buffers. @xref{Several Buffers}.
@vindex kill-buffer-hook
If you want to do something special every time a buffer is killed, you
@ -332,24 +339,17 @@ for a mere hour.
@vindex midnight-mode
@vindex midnight-hook
You can also have this buffer purging done for you, every day at
midnight, by enabling Midnight mode. Midnight mode operates each day at
midnight; at that time, it runs @code{clean-buffer-list}, or whichever
functions you have placed in the normal hook @code{midnight-hook}
(@pxref{Hooks}).
To enable Midnight mode, use the Customization buffer to set the
variable @code{midnight-mode} to @code{t}. @xref{Easy Customization}.
midnight, by enabling Midnight mode. Midnight mode operates each day
at midnight; at that time, it runs @code{clean-buffer-list}, or
whichever functions you have placed in the normal hook
@code{midnight-hook} (@pxref{Hooks}). To enable Midnight mode, use
the Customization buffer to set the variable @code{midnight-mode} to
@code{t}. @xref{Easy Customization}.
@node Several Buffers
@section Operating on Several Buffers
@cindex buffer menu
The @dfn{buffer-menu} facility is like a ``Dired for buffers''; it allows
you to request operations on various Emacs buffers by editing an Emacs
buffer containing a list of them. You can save buffers, kill them
(here called @dfn{deleting} them, for consistency with Dired), or display
them.
@table @kbd
@item M-x buffer-menu
Begin editing a buffer listing all Emacs buffers.
@ -357,19 +357,24 @@ Begin editing a buffer listing all Emacs buffers.
Similar, but do it in another window.
@end table
The @dfn{buffer menu} opened by @kbd{C-x C-b} (@pxref{List Buffers})
does not merely list buffers. It also allows you to perform various
operations on buffers, through an interface similar to Dired
(@pxref{Dired}). You can save buffers, kill them (here called
@dfn{deleting} them, for consistency with Dired), or display them.
@findex buffer-menu
@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.
To use the buffer menu, type @kbd{C-x C-b} and switch to the window
displaying the @samp{*Buffer List*} buffer. You can also type
@kbd{M-x buffer-menu} to open the buffer menu in the selected window.
Alternatively, the command @kbd{M-x buffer-menu-other-window} opens
the buffer menu in another window, and selects that window.
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.
The buffer menu is a read-only buffer, and can be changed only
through the special commands described in this section. The usual
Emacs cursor motion commands can be used in this buffer. The
following commands apply to the buffer described on the current line:
@table @kbd
@item d
@ -460,16 +465,6 @@ there. You can reselect the @samp{*Buffer List*} buffer later, to
perform the operations already requested, or you can kill it, or pay
no further attention to it.
The list in the @samp{*Buffer List*} buffer looks exactly like the
buffer list described in @ref{List Buffers}, because they really are
the same. The only difference between @code{buffer-menu} and
@code{list-buffers} is that @code{buffer-menu} switches to the
@samp{*Buffer List*} buffer in the selected window;
@code{list-buffers} displays the same buffer in another window. If
you run @code{list-buffers} (that is, type @kbd{C-x C-b}) and select
the buffer list manually, you can use all of the commands described
here.
Normally, the buffer @samp{*Buffer List*} is not updated
automatically when buffers are created and killed; its contents are
just text. If you have created, deleted or renamed buffers, the way
@ -486,11 +481,6 @@ Auto Revert mode applies to the @samp{*Buffer List*} buffer only if
@xref{Autorevert, global-auto-revert-non-file-buffers}, for details.
@end ifnottex
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
@ -518,7 +508,7 @@ select it in another window (@code{clone-indirect-buffer-other-window}).
The text of the indirect buffer is always identical to the text of its
base buffer; changes made by editing either one are visible immediately
in the other. But in all other respects, the indirect buffer and its
base buffer are completely separate. They have different names,
base buffer are completely separate. They can have different names,
different values of point, different narrowing, different markers,
different major modes, and different local variables.
@ -530,6 +520,7 @@ buffer, but killing an indirect buffer has no effect on its base buffer.
One way to use indirect buffers is to display multiple views of an
outline. @xref{Outline Views}.
@vindex clone-indirect-buffer-hook
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
@ -537,7 +528,8 @@ argument, it prompts for the name of the indirect buffer; otherwise it
uses the name of the current buffer, with a @samp{<@var{n}>} suffix
added. @kbd{C-x 4 c} (@code{clone-indirect-buffer-other-window})
works like @kbd{M-x clone-indirect-buffer}, but it selects the new
buffer in another window.
buffer in another window. These functions run the hook
@code{clone-indirect-buffer-hook} after creating the indirect buffer.
The more general way to make an indirect buffer is with the command
@kbd{M-x make-indirect-buffer}. It creates an indirect buffer from