* lisp/files.el (file-auto-mode-skip): New var.
[bpt/emacs.git] / doc / emacs / buffers.texi
CommitLineData
6bf7aab6 1@c This is part of the Emacs manual.
acaf905b 2@c Copyright (C) 1985-1987, 1993-1995, 1997, 2000-2012
8838673e 3@c Free Software Foundation, Inc.
6bf7aab6
DL
4@c See file emacs.texi for copying conditions.
5@node Buffers, Windows, Files, Top
6@chapter Using Multiple Buffers
7
8@cindex buffers
9 The text you are editing in Emacs resides in an object called a
a70e06c1
CY
10@dfn{buffer}. Each time you visit a file, a buffer is used to hold
11the file's text. Each time you invoke Dired, a buffer is used to hold
12the directory listing. If you send a message with @kbd{C-x m}, a
13buffer is used to hold the text of the message. When you ask for a
1c64e6ed 14command's documentation, that appears in a buffer named @file{*Help*}.
6bf7aab6 15
ea146ed8
CY
16 Each buffer has a unique name, which can be of any length. When a
17buffer is displayed in a window, its name is shown in the mode line
18(@pxref{Mode Line}). The distinction between upper and lower case
19matters in buffer names. Most buffers are made by visiting files, and
20their names are derived from the files' names; however, you can also
21create an empty buffer with any name you want. A newly started Emacs
1c64e6ed 22has several buffers, including one named @file{*scratch*}, which can
a70e06c1
CY
23be used for evaluating Lisp expressions and is not associated with any
24file (@pxref{Lisp Interaction}).
ea146ed8 25
6bf7aab6
DL
26@cindex selected buffer
27@cindex current buffer
a70e06c1
CY
28 At any time, one and only one buffer is @dfn{selected}; we call it
29the @dfn{current buffer}. We sometimes say that a command operates on
30``the buffer''; this really means that it operates on the current
31buffer. When there is only one Emacs window, the buffer displayed in
32that window is current. When there are multiple windows, the buffer
33displayed in the @dfn{selected window} is current. @xref{Windows}.
ea146ed8 34
a70e06c1
CY
35 Aside from its textual contents, each buffer records several pieces
36of information, such as what file it is visiting (if any), whether it
37is modified, and what major mode and minor modes are in effect
38(@pxref{Modes}). These are stored in @dfn{buffer-local
39variables}---variables that can have a different value in each buffer.
40@xref{Locals}.
6bf7aab6 41
dc53c88b
EZ
42@cindex buffer size, maximum
43 A buffer's size cannot be larger than some maximum, which is defined
a70e06c1
CY
44by the largest buffer position representable by @dfn{Emacs integers}.
45This is because Emacs tracks buffer positions using that data type.
46For typical 64-bit machines, this maximum buffer size is @math{2^61 -
472} bytes, or about 2 EiB. For typical 32-bit machines, the maximum is
48usually @math{2^29 - 2} bytes, or about 512 MiB. Buffer sizes are
49also limited by the amount of memory present in the system.
dc53c88b 50
6bf7aab6
DL
51@menu
52* Select Buffer:: Creating a new buffer or reselecting an old one.
53* List Buffers:: Getting a list of buffers that exist.
8838673e
GM
54* Misc Buffer:: Renaming; changing read-onlyness; copying text.
55* Kill Buffer:: Killing buffers you no longer need.
6bf7aab6 56* Several Buffers:: How to go through the list of all buffers
8838673e 57 and operate variously on several of them.
177c0ea7 58* Indirect Buffers:: An indirect buffer shares the text of another buffer.
b54346bc
DL
59* Buffer Convenience:: Convenience and customization features for
60 buffer handling.
6bf7aab6
DL
61@end menu
62
63@node Select Buffer
64@section Creating and Selecting Buffers
65@cindex change buffers
66@cindex switch buffers
67
68@table @kbd
69@item C-x b @var{buffer} @key{RET}
70Select or create a buffer named @var{buffer} (@code{switch-to-buffer}).
71@item C-x 4 b @var{buffer} @key{RET}
72Similar, but select @var{buffer} in another window
73(@code{switch-to-buffer-other-window}).
74@item C-x 5 b @var{buffer} @key{RET}
75Similar, but select @var{buffer} in a separate frame
76(@code{switch-to-buffer-other-frame}).
160bde9c 77@item C-x @key{LEFT}
a70e06c1 78Select the previous buffer in the buffer list (@code{previous-buffer}).
160bde9c 79@item C-x @key{RIGHT}
a70e06c1 80Select the next buffer in the buffer list (@code{next-buffer}).
ac2c0786
LT
81@item C-u M-g M-g
82@itemx C-u M-g g
83Read a number @var{n} and move to line @var{n} in the most recently
84selected buffer other than the current buffer.
6bf7aab6
DL
85@end table
86
6bf7aab6
DL
87@kindex C-x b
88@findex switch-to-buffer
a70e06c1
CY
89 The @kbd{C-x b} (@code{switch-to-buffer}) command reads a buffer
90name using the minibuffer. Then it makes that buffer current, and
91displays it in the currently-selected window. An empty input
92specifies the buffer that was current most recently among those not
2a90dfca 93now displayed in any window.
6bf7aab6 94
a70e06c1
CY
95 While entering the buffer name, you can use the usual completion and
96history commands (@pxref{Minibuffer}). Note that @kbd{C-x b}, and
97related commands, use ``permissive completion with confirmation'' for
98minibuffer completion: if you type @key{RET} immediately after
99completing up to a nonexistent buffer name, Emacs prints
100@samp{[Confirm]} and you must type a second @key{RET} to submit that
101buffer name. @xref{Completion Exit}, for details.
2f4f09a9 102
2a90dfca
DM
103 If you specify a buffer that does not exist, @kbd{C-x b} creates a
104new, empty buffer that is not visiting any file, and selects it for
105editing. The default value of the variable @code{major-mode}
106determines the new buffer's major mode; the default value is
107Fundamental mode. @xref{Major Modes}. One reason to create a new
108buffer is to use it for making temporary notes. If you try to save
562af8bb
DM
109it, Emacs asks for the file name to use, and the buffer's major mode
110is re-established taking that file name into account (@pxref{Choosing
111Modes}).
ea146ed8 112
7354ca01
RS
113@kindex C-x @key{LEFT}
114@kindex C-x @key{RIGHT}
115@findex next-buffer
a3700ef7 116@findex previous-buffer
7354ca01 117 For conveniently switching between a few buffers, use the commands
2a90dfca
DM
118@kbd{C-x @key{LEFT}} and @kbd{C-x @key{RIGHT}}. @kbd{C-x @key{LEFT}}
119(@code{previous-buffer}) selects the previous buffer (following the
120order of most recent selection in the current frame), while @kbd{C-x
121@key{RIGHT}} (@code{next-buffer}) moves through buffers in the reverse
122direction.
7354ca01 123
8f7cad1f
EZ
124@kindex C-x 4 b
125@findex switch-to-buffer-other-window
8f7cad1f 126 To select a buffer in a window other than the current one, type
ea146ed8
CY
127@kbd{C-x 4 b} (@code{switch-to-buffer-other-window}). This prompts
128for a buffer name using the minibuffer, displays that buffer in
0a2132ba 129another window, and selects that window.
8f7cad1f
EZ
130
131@kindex C-x 5 b
132@findex switch-to-buffer-other-frame
ea146ed8
CY
133 Similarly, @kbd{C-x 5 b} (@code{switch-to-buffer-other-frame})
134prompts for a buffer name, displays that buffer in another frame, and
0a2132ba
CY
135selects that frame. If the buffer is already being shown in a window
136on another frame, Emacs selects that window and frame instead of
137creating a new frame.
138
139 @xref{Displaying Buffers}, for how the @kbd{C-x 4 b} and @kbd{C-x 5
140b} commands get the window and/or frame to display in.
ea146ed8
CY
141
142 In addition, @kbd{C-x C-f}, and any other command for visiting a
143file, can also be used to switch to an existing file-visiting buffer.
144@xref{Visiting}.
8f7cad1f 145
dd186936 146@findex goto-line
ea146ed8
CY
147 @kbd{C-u M-g M-g}, that is @code{goto-line} with a plain prefix
148argument, reads a number @var{n} using the minibuffer, selects the
149most recently selected buffer other than the current buffer in another
150window, and then moves point to the beginning of line number @var{n}
151in that buffer. This is mainly useful in a buffer that refers to line
152numbers in another buffer: if point is on or just after a number,
153@code{goto-line} uses that number as the default for @var{n}. Note
154that prefix arguments other than just @kbd{C-u} behave differently.
155@kbd{C-u 4 M-g M-g} goes to line 4 in the @emph{current} buffer,
156without reading a number from the minibuffer. (Remember that @kbd{M-g
157M-g} without prefix argument reads a number @var{n} and then moves to
158line number @var{n} in the current buffer. @xref{Moving Point}.)
ac2c0786 159
6bf7aab6
DL
160 Emacs uses buffer names that start with a space for internal purposes.
161It treats these buffers specially in minor ways---for example, by
162default they do not record undo information. It is best to avoid using
163such buffer names yourself.
164
165@node List Buffers
166@section Listing Existing Buffers
167
168@table @kbd
169@item C-x C-b
170List the existing buffers (@code{list-buffers}).
171@end table
172
173@cindex listing current buffers
174@kindex C-x C-b
175@findex list-buffers
7354ca01
RS
176 To display a list of existing buffers, type @kbd{C-x C-b}. Each
177line in the list shows one buffer's name, major mode and visited file.
178The buffers are listed in the order that they were current; the
6bf7aab6
DL
179buffers that were current most recently come first.
180
ea146ed8
CY
181 @samp{.} in the first field of a line indicates that the buffer is
182current. @samp{%} indicates a read-only buffer. @samp{*} indicates
16152b76 183that the buffer is ``modified''. If several buffers are modified, it
ea146ed8
CY
184may be time to save some with @kbd{C-x s} (@pxref{Save Commands}).
185Here is an example of a buffer list:
6bf7aab6
DL
186
187@smallexample
b1a25f96 188CRM Buffer Size Mode File
6105130d
MR
189. * .emacs 3294 Emacs-Lisp ~/.emacs
190 % *Help* 101 Help
517b2c37
JB
191 search.c 86055 C ~/cvs/emacs/src/search.c
192 % src 20959 Dired by name ~/cvs/emacs/src/
6105130d 193 * *mail* 42 Mail
517b2c37
JB
194 % HELLO 1607 Fundamental ~/cvs/emacs/etc/HELLO
195 % NEWS 481184 Outline ~/cvs/emacs/etc/NEWS
196 *scratch* 191 Lisp Interaction
517b2c37 197 * *Messages* 1554 Fundamental
6bf7aab6
DL
198@end smallexample
199
200@noindent
1c64e6ed 201The buffer @file{*Help*} was made by a help request (@pxref{Help}); it
ea146ed8
CY
202is not visiting any file. The buffer @code{src} was made by Dired on
203the directory @file{~/cvs/emacs/src/}. You can list only buffers that
204are visiting files by giving the command a prefix argument, as in
564ee37b 205@kbd{C-u C-x C-b}.
6bf7aab6 206
7354ca01 207 @code{list-buffers} omits buffers whose names begin with a space,
4081af2f
EZ
208unless they visit files: such buffers are used internally by Emacs.
209
6bf7aab6
DL
210@node Misc Buffer
211@section Miscellaneous Buffer Operations
212
213@table @kbd
214@item C-x C-q
8f980b27 215Toggle read-only status of buffer (@code{toggle-read-only}).
6bf7aab6
DL
216@item M-x rename-buffer @key{RET} @var{name} @key{RET}
217Change the name of the current buffer.
218@item M-x rename-uniquely
219Rename the current buffer by adding @samp{<@var{number}>} to the end.
220@item M-x view-buffer @key{RET} @var{buffer} @key{RET}
2a90dfca 221Scroll through buffer @var{buffer}. @xref{View Mode}.
6bf7aab6
DL
222@end table
223
224@kindex C-x C-q
6bf7aab6
DL
225@vindex buffer-read-only
226@cindex read-only buffer
227 A buffer can be @dfn{read-only}, which means that commands to change
564ee37b
RS
228its contents are not allowed. The mode line indicates read-only
229buffers with @samp{%%} or @samp{%*} near the left margin. Read-only
230buffers are usually made by subsystems such as Dired and Rmail that
231have special commands to operate on the text; also by visiting a file
232whose access control says you cannot write it.
6bf7aab6 233
8f980b27 234@findex toggle-read-only
da97a9e6
CY
235 The command @kbd{C-x C-q} (@code{toggle-read-only}) makes a read-only
236buffer writable, and makes a writable buffer read-only. This works by
86c60681
CY
237setting the variable @code{buffer-read-only}, which has a local value
238in each buffer and makes the buffer read-only if its value is
239non-@code{nil}.
6bf7aab6
DL
240
241@findex rename-buffer
a3053e27
RS
242 @kbd{M-x rename-buffer} changes the name of the current buffer. You
243specify the new name as a minibuffer argument; there is no default.
244If you specify a name that is in use for some other buffer, an error
245happens and no renaming is done.
6bf7aab6 246
0e04ec0b 247@findex rename-uniquely
eddcfd0e
RS
248 @kbd{M-x rename-uniquely} renames the current buffer to a similar
249name with a numeric suffix added to make it both different and unique.
250This command does not need an argument. It is useful for creating
1c64e6ed 251multiple shell buffers: if you rename the @file{*shell*} buffer, then
eddcfd0e 252do @kbd{M-x shell} again, it makes a new shell buffer named
1c64e6ed 253@file{*shell*}; meanwhile, the old shell buffer continues to exist
eddcfd0e
RS
254under its new name. This method is also good for mail buffers,
255compilation buffers, and most Emacs features that create special
256buffers with particular names. (With some of these features, such as
63c727b2
GM
257@kbd{M-x compile}, @kbd{M-x grep}, you need to switch to some other
258buffer before using the command again, otherwise it will reuse the
259current buffer despite the name change.)
6bf7aab6 260
6bf7aab6 261 The commands @kbd{M-x append-to-buffer} and @kbd{M-x insert-buffer}
2a90dfca
DM
262can also be used to copy text from one buffer to another.
263@xref{Accumulating Text}.
6bf7aab6
DL
264
265@node Kill Buffer
266@section Killing Buffers
267
268@cindex killing buffers
269 If you continue an Emacs session for a while, you may accumulate a
270large number of buffers. You may then find it convenient to @dfn{kill}
271the buffers you no longer need. On most operating systems, killing a
272buffer releases its space back to the operating system so that other
273programs can use it. Here are some commands for killing buffers:
274
6bf7aab6
DL
275@table @kbd
276@item C-x k @var{bufname} @key{RET}
277Kill buffer @var{bufname} (@code{kill-buffer}).
278@item M-x kill-some-buffers
279Offer to kill each buffer, one by one.
ea146ed8
CY
280@item M-x kill-matching-buffers
281Offer to kill all buffers matching a regular expression.
6bf7aab6
DL
282@end table
283
284@findex kill-buffer
6bf7aab6 285@kindex C-x k
6bf7aab6 286 @kbd{C-x k} (@code{kill-buffer}) kills one buffer, whose name you
ab25a0c7
RS
287specify in the minibuffer. The default, used if you type just
288@key{RET} in the minibuffer, is to kill the current buffer. If you
289kill the current buffer, another buffer becomes current: one that was
290current in the recent past but is not displayed in any window now. If
ea146ed8
CY
291you ask to kill a file-visiting buffer that is modified, then you must
292confirm with @kbd{yes} before the buffer is killed.
6bf7aab6 293
ea146ed8
CY
294@findex kill-some-buffers
295 The command @kbd{M-x kill-some-buffers} asks about each buffer, one
296by one. An answer of @kbd{y} means to kill the buffer, just like
297@code{kill-buffer}. This command ignores buffers whose names begin
298with a space, which are used internally by Emacs.
299
300@findex kill-matching-buffers
301 The command @kbd{M-x kill-matching-buffers} prompts for a regular
302expression and kills all buffers whose names match that expression.
303@xref{Regexps}. Like @code{kill-some-buffers}, it asks for
304confirmation before each kill. This command normally ignores buffers
305whose names begin with a space, which are used internally by Emacs.
306To kill internal buffers as well, call @code{kill-matching-buffers}
307with a prefix argument.
308
309 The buffer menu feature is also convenient for killing various
310buffers. @xref{Several Buffers}.
6bf7aab6
DL
311
312@vindex kill-buffer-hook
313 If you want to do something special every time a buffer is killed, you
314can add hook functions to the hook @code{kill-buffer-hook} (@pxref{Hooks}).
315
316@findex clean-buffer-list
317 If you run one Emacs session for a period of days, as many people do,
318it can fill up with buffers that you used several days ago. The command
319@kbd{M-x clean-buffer-list} is a convenient way to purge them; it kills
320all the unmodified buffers that you have not used for a long time. An
321ordinary buffer is killed if it has not been displayed for three days;
322however, you can specify certain buffers that should never be killed
323automatically, and others that should be killed if they have been unused
324for a mere hour.
325
326@cindex Midnight mode
327@vindex midnight-mode
328@vindex midnight-hook
329 You can also have this buffer purging done for you, every day at
ea146ed8
CY
330midnight, by enabling Midnight mode. Midnight mode operates each day
331at midnight; at that time, it runs @code{clean-buffer-list}, or
332whichever functions you have placed in the normal hook
333@code{midnight-hook} (@pxref{Hooks}). To enable Midnight mode, use
334the Customization buffer to set the variable @code{midnight-mode} to
335@code{t}. @xref{Easy Customization}.
6bf7aab6
DL
336
337@node Several Buffers
338@section Operating on Several Buffers
339@cindex buffer menu
340
6bf7aab6
DL
341@table @kbd
342@item M-x buffer-menu
343Begin editing a buffer listing all Emacs buffers.
4081af2f
EZ
344@item M-x buffer-menu-other-window.
345Similar, but do it in another window.
6bf7aab6
DL
346@end table
347
ea146ed8
CY
348 The @dfn{buffer menu} opened by @kbd{C-x C-b} (@pxref{List Buffers})
349does not merely list buffers. It also allows you to perform various
350operations on buffers, through an interface similar to Dired
351(@pxref{Dired}). You can save buffers, kill them (here called
352@dfn{deleting} them, for consistency with Dired), or display them.
353
6bf7aab6 354@findex buffer-menu
4081af2f 355@findex buffer-menu-other-window
ea146ed8 356 To use the buffer menu, type @kbd{C-x C-b} and switch to the window
1c64e6ed 357displaying the @file{*Buffer List*} buffer. You can also type
ea146ed8
CY
358@kbd{M-x buffer-menu} to open the buffer menu in the selected window.
359Alternatively, the command @kbd{M-x buffer-menu-other-window} opens
360the buffer menu in another window, and selects that window.
361
362 The buffer menu is a read-only buffer, and can be changed only
363through the special commands described in this section. The usual
364Emacs cursor motion commands can be used in this buffer. The
365following commands apply to the buffer described on the current line:
6bf7aab6
DL
366
367@table @kbd
368@item d
369Request to delete (kill) the buffer, then move down. The request
370shows as a @samp{D} on the line, before the buffer name. Requested
371deletions take place when you type the @kbd{x} command.
372@item C-d
373Like @kbd{d} but move up afterwards instead of down.
374@item s
375Request to save the buffer. The request shows as an @samp{S} on the
376line. Requested saves take place when you type the @kbd{x} command.
377You may request both saving and deletion for the same buffer.
378@item x
379Perform previously requested deletions and saves.
380@item u
381Remove any request made for the current line, and move down.
382@item @key{DEL}
383Move to previous line and remove any request made for that line.
384@end table
385
386 The @kbd{d}, @kbd{C-d}, @kbd{s} and @kbd{u} commands to add or remove
387flags also move down (or up) one line. They accept a numeric argument
388as a repeat count.
389
390 These commands operate immediately on the buffer listed on the current
391line:
392
393@table @kbd
394@item ~
16152b76 395Mark the buffer ``unmodified''. The command @kbd{~} does this
6bf7aab6
DL
396immediately when you type it.
397@item %
398Toggle the buffer's read-only flag. The command @kbd{%} does
399this immediately when you type it.
400@item t
401Visit the buffer as a tags table. @xref{Select Tags Table}.
402@end table
403
404 There are also commands to select another buffer or buffers:
405
406@table @kbd
407@item q
408Quit the buffer menu---immediately display the most recent formerly
409visible buffer in its place.
410@item @key{RET}
411@itemx f
1c64e6ed 412Immediately select this line's buffer in place of the @file{*Buffer
6bf7aab6
DL
413List*} buffer.
414@item o
415Immediately select this line's buffer in another window as if by
1c64e6ed 416@kbd{C-x 4 b}, leaving @file{*Buffer List*} visible.
6bf7aab6
DL
417@item C-o
418Immediately display this line's buffer in another window, but don't
419select the window.
420@item 1
421Immediately select this line's buffer in a full-screen window.
422@item 2
041aabd8
LT
423Immediately set up two windows, with this line's buffer selected in
424one, and the previously current buffer (aside from the buffer
1c64e6ed 425@file{*Buffer List*}) displayed in the other.
6bf7aab6
DL
426@item b
427Bury the buffer listed on this line.
428@item m
429Mark this line's buffer to be displayed in another window if you exit
430with the @kbd{v} command. The request shows as a @samp{>} at the
431beginning of the line. (A single buffer may not have both a delete
432request and a display request.)
433@item v
434Immediately select this line's buffer, and also display in other windows
435any buffers previously marked with the @kbd{m} command. If you have not
436marked any buffers, this command is equivalent to @kbd{1}.
437@end table
438
7354ca01
RS
439 There is also a command that affects the entire buffer list:
440
441@table @kbd
442@item T
443Delete, or reinsert, lines for non-file buffers. This command toggles
444the inclusion of such buffers in the buffer list.
445@end table
446
447 What @code{buffer-menu} actually does is create and switch to a
448suitable buffer, and turn on Buffer Menu mode in it. Everything else
6bf7aab6
DL
449described above is implemented by the special commands provided in
450Buffer Menu mode. One consequence of this is that you can switch from
1c64e6ed
GM
451the @file{*Buffer List*} buffer to another Emacs buffer, and edit
452there. You can reselect the @file{*Buffer List*} buffer later, to
7354ca01
RS
453perform the operations already requested, or you can kill it, or pay
454no further attention to it.
455
1c64e6ed 456 Normally, the buffer @file{*Buffer List*} is not updated
a3053e27
RS
457automatically when buffers are created and killed; its contents are
458just text. If you have created, deleted or renamed buffers, the way
1c64e6ed 459to update @file{*Buffer List*} to show what you have done is to type
a3053e27
RS
460@kbd{g} (@code{revert-buffer}). You can make this happen regularly
461every @code{auto-revert-interval} seconds if you enable Auto Revert
462mode in this buffer, as long as it is not marked modified. Global
1c64e6ed 463Auto Revert mode applies to the @file{*Buffer List*} buffer only if
a3053e27 464@code{global-auto-revert-non-file-buffers} is non-@code{nil}.
bbe9cbb8 465@iftex
eca2d6cd 466@inforef{Autorevert,, emacs-xtra}, for details.
bbe9cbb8
EZ
467@end iftex
468@ifnottex
469@xref{Autorevert, global-auto-revert-non-file-buffers}, for details.
470@end ifnottex
471
6bf7aab6
DL
472@node Indirect Buffers
473@section Indirect Buffers
474@cindex indirect buffer
475@cindex base buffer
476
477 An @dfn{indirect buffer} shares the text of some other buffer, which
478is called the @dfn{base buffer} of the indirect buffer. In some ways it
479is the analogue, for buffers, of a symbolic link between files.
480
481@table @kbd
482@findex make-indirect-buffer
52ec6cdc 483@item M-x make-indirect-buffer @key{RET} @var{base-buffer} @key{RET} @var{indirect-name} @key{RET}
6bf7aab6
DL
484Create an indirect buffer named @var{indirect-name} whose base buffer
485is @var{base-buffer}.
f16874ce
EZ
486@findex clone-indirect-buffer
487@item M-x clone-indirect-buffer @key{RET}
488Create an indirect buffer that is a twin copy of the current buffer.
112c140f 489@item C-x 4 c
f16874ce
EZ
490@kindex C-x 4 c
491@findex clone-indirect-buffer-other-window
492Create an indirect buffer that is a twin copy of the current buffer, and
493select it in another window (@code{clone-indirect-buffer-other-window}).
6bf7aab6
DL
494@end table
495
496 The text of the indirect buffer is always identical to the text of its
497base buffer; changes made by editing either one are visible immediately
498in the other. But in all other respects, the indirect buffer and its
ea146ed8 499base buffer are completely separate. They can have different names,
6bf7aab6
DL
500different values of point, different narrowing, different markers,
501different major modes, and different local variables.
502
503 An indirect buffer cannot visit a file, but its base buffer can. If
504you try to save the indirect buffer, that actually works by saving the
505base buffer. Killing the base buffer effectively kills the indirect
506buffer, but killing an indirect buffer has no effect on its base buffer.
507
508 One way to use indirect buffers is to display multiple views of an
509outline. @xref{Outline Views}.
b54346bc 510
ea146ed8 511@vindex clone-indirect-buffer-hook
564ee37b
RS
512 A quick and handy way to make an indirect buffer is with the command
513@kbd{M-x clone-indirect-buffer}. It creates and selects an indirect
514buffer whose base buffer is the current buffer. With a numeric
515argument, it prompts for the name of the indirect buffer; otherwise it
160bde9c
LT
516uses the name of the current buffer, with a @samp{<@var{n}>} suffix
517added. @kbd{C-x 4 c} (@code{clone-indirect-buffer-other-window})
518works like @kbd{M-x clone-indirect-buffer}, but it selects the new
ea146ed8
CY
519buffer in another window. These functions run the hook
520@code{clone-indirect-buffer-hook} after creating the indirect buffer.
eddcfd0e
RS
521
522 The more general way to make an indirect buffer is with the command
523@kbd{M-x make-indirect-buffer}. It creates an indirect buffer from
524buffer @var{base-buffer}, under the name @var{indirect-name}. It
525prompts for both @var{base-buffer} and @var{indirect-name} using the
526minibuffer.
f16874ce 527
b54346bc
DL
528@node Buffer Convenience
529@section Convenience Features and Customization of Buffer Handling
530
85d6c6e7
RS
531 This section describes several modes and features that make it more
532convenient to switch between buffers.
533
b54346bc 534@menu
7354ca01 535* Uniquify:: Making buffer names unique with directory parts.
d04efc64 536* Iswitchb:: Switching between buffers with substrings.
177c0ea7 537* Buffer Menus:: Configurable buffer menu.
b54346bc
DL
538@end menu
539
540@node Uniquify
564ee37b 541@subsection Making Buffer Names Unique
b54346bc 542
b54346bc
DL
543@cindex unique buffer names
544@cindex directories in buffer names
564ee37b
RS
545 When several buffers visit identically-named files, Emacs must give
546the buffers distinct names. The usual method for making buffer names
547unique adds @samp{<2>}, @samp{<3>}, etc. to the end of the buffer
548names (all but one of them).
549
550@vindex uniquify-buffer-name-style
551 Other methods work by adding parts of each file's directory to the
5dbbdd33 552buffer name. To select one, load the library @file{uniquify} (e.g.
64f3bde2 553using @code{(require 'uniquify)}), and customize the variable
564ee37b
RS
554@code{uniquify-buffer-name-style} (@pxref{Easy Customization}).
555
df7593dd
KB
556 To begin with, the @code{forward} naming method includes part of the
557file's directory name at the beginning of the buffer name; using this
558method, buffers visiting the files @file{/u/rms/tmp/Makefile} and
564ee37b
RS
559@file{/usr/projects/zaphod/Makefile} would be named
560@samp{tmp/Makefile} and @samp{zaphod/Makefile}, respectively (instead
561of @samp{Makefile} and @samp{Makefile<2>}).
562
df7593dd 563 In contrast, the @code{post-forward} naming method would call the
564ee37b
RS
564buffers @samp{Makefile|tmp} and @samp{Makefile|zaphod}, and the
565@code{reverse} naming method would call them @samp{Makefile\tmp} and
566@samp{Makefile\zaphod}. The nontrivial difference between
567@code{post-forward} and @code{reverse} occurs when just one directory
568name is not enough to distinguish two files; then @code{reverse} puts
569the directory names in reverse order, so that @file{/top/middle/file}
570becomes @samp{file\middle\top}, while @code{post-forward} puts them in
571forward order after the file name, as in @samp{file|top/middle}.
572
573 Which rule to follow for putting the directory names in the buffer
574name is not very important if you are going to @emph{look} at the
575buffer names before you type one. But as an experienced user, if you
576know the rule, you won't have to look. And then you may find that one
a3053e27 577rule or another is easier for you to remember and apply quickly.
b54346bc 578
1ea14188
DL
579@node Iswitchb
580@subsection Switching Between Buffers using Substrings
581
582@findex iswitchb-mode
583@cindex Iswitchb mode
584@cindex mode, Iswitchb
585@kindex C-x b @r{(Iswitchb mode)}
586@kindex C-x 4 b @r{(Iswitchb mode)}
587@kindex C-x 5 b @r{(Iswitchb mode)}
588@kindex C-x 4 C-o @r{(Iswitchb mode)}
589
564ee37b
RS
590 Iswitchb global minor mode provides convenient switching between
591buffers using substrings of their names. It replaces the normal
592definitions of @kbd{C-x b}, @kbd{C-x 4 b}, @kbd{C-x 5 b}, and @kbd{C-x
16152b76 5934 C-o} with alternative commands that are somewhat ``smarter''.
1ea14188 594
564ee37b
RS
595 When one of these commands prompts you for a buffer name, you can
596type in just a substring of the name you want to choose. As you enter
597the substring, Iswitchb mode continuously displays a list of buffers
598that match the substring you have typed.
1ea14188 599
564ee37b
RS
600 At any time, you can type @key{RET} to select the first buffer in
601the list. So the way to select a particular buffer is to make it the
602first in the list. There are two ways to do this. You can type more
603of the buffer name and thus narrow down the list, excluding unwanted
604buffers above the desired one. Alternatively, you can use @kbd{C-s}
605and @kbd{C-r} to rotate the list until the desired buffer is first.
606
607 @key{TAB} while entering the buffer name performs completion on the
608string you have entered, based on the displayed list of buffers.
609
85d6c6e7
RS
610 To enable Iswitchb mode, type @kbd{M-x iswitchb-mode}, or customize
611the variable @code{iswitchb-mode} to @code{t} (@pxref{Easy
612Customization}).
613
564ee37b
RS
614@node Buffer Menus
615@subsection Customizing Buffer Menus
b54346bc 616
d04efc64 617@findex bs-show
d04efc64
DL
618@cindex buffer list, customizable
619@table @kbd
620@item M-x bs-show
621Make a list of buffers similarly to @kbd{M-x list-buffers} but
622customizable.
d04efc64
DL
623@end table
624
564ee37b
RS
625 @kbd{M-x bs-show} pops up a buffer list similar to the one normally
626displayed by @kbd{C-x C-b} but which you can customize. If you prefer
627this to the usual buffer list, you can bind this command to @kbd{C-x
628C-b}. To customize this buffer list, use the @code{bs} Custom group
629(@pxref{Easy Customization}).
1ea14188
DL
630
631@findex msb-mode
632@cindex mode, MSB
633@cindex MSB mode
634@cindex buffer menu
635@findex mouse-buffer-menu
564ee37b
RS
636@kindex C-Down-Mouse-1
637 MSB global minor mode (``MSB'' stands for ``mouse select buffer'')
638provides a different and customizable mouse buffer menu which you may
639prefer. It replaces the bindings of @code{mouse-buffer-menu},
640normally on @kbd{C-Down-Mouse-1}, and the menu bar buffer menu. You
641can customize the menu in the @code{msb} Custom group.