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1 @c This is part of the Emacs manual.
2 @c Copyright (C) 1985, 1986, 1987, 1993, 1994, 1995, 1997, 2000, 2001,
3 @c 2002, 2003, 2004, 2005, 2006 Free Software Foundation, Inc.
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
10 @dfn{buffer}. Each time you visit a file, a buffer is created to hold the
11 file's text. Each time you invoke Dired, a buffer is created to hold the
12 directory listing. If you send a message with @kbd{C-x m}, a buffer named
13 @samp{*mail*} is used to hold the text of the message. When you ask for a
14 command's documentation, that appears in a buffer called @samp{*Help*}.
15
16 @cindex selected buffer
17 @cindex current buffer
18 At any time, one and only one buffer is @dfn{current}. It is also
19 called the @dfn{selected buffer}. Often we say that a command operates on
20 ``the buffer'' as if there were only one; but really this means that the
21 command operates on the current buffer (most commands do).
22
23 When Emacs has multiple windows, each window has its own chosen
24 buffer and displays it; at any time, only one of the windows is
25 selected, and its chosen buffer is the current buffer. Each window's
26 mode line normally displays the name of the window's chosen buffer
27 (@pxref{Windows}).
28
29 Each buffer has a name, which can be of any length, and you can select
30 any buffer by giving its name. Most buffers are made by visiting files,
31 and their names are derived from the files' names. But you can also create
32 an empty buffer with any name you want. A newly started Emacs has a buffer
33 named @samp{*scratch*} which can be used for evaluating Lisp expressions in
34 Emacs. The distinction between upper and lower case matters in buffer
35 names.
36
37 Each buffer records individually what file it is visiting, whether it is
38 modified, and what major mode and minor modes are in effect in it
39 (@pxref{Major Modes}). Any Emacs variable can be made @dfn{local to} a
40 particular buffer, meaning its value in that buffer can be different from
41 the value in other buffers. @xref{Locals}.
42
43 @cindex buffer size, maximum
44 A buffer's size cannot be larger than some maximum, which is defined
45 by the largest buffer position representable by the @dfn{Emacs integer}
46 data type. This is because Emacs tracks buffer positions using that
47 data type. For 32-bit machines, the largest buffer size is 256
48 megabytes.
49
50 @menu
51 * Select Buffer:: Creating a new buffer or reselecting an old one.
52 * List Buffers:: Getting a list of buffers that exist.
53 * Misc Buffer:: Renaming; changing read-onlyness; copying text.
54 * Kill Buffer:: Killing buffers you no longer need.
55 * Several Buffers:: How to go through the list of all buffers
56 and operate variously on several of them.
57 * Indirect Buffers:: An indirect buffer shares the text of another buffer.
58 * Buffer Convenience:: Convenience and customization features for
59 buffer handling.
60 @end menu
61
62 @node Select Buffer
63 @section Creating and Selecting Buffers
64 @cindex change buffers
65 @cindex switch buffers
66
67 @table @kbd
68 @item C-x b @var{buffer} @key{RET}
69 Select or create a buffer named @var{buffer} (@code{switch-to-buffer}).
70 @item C-x 4 b @var{buffer} @key{RET}
71 Similar, but select @var{buffer} in another window
72 (@code{switch-to-buffer-other-window}).
73 @item C-x 5 b @var{buffer} @key{RET}
74 Similar, but select @var{buffer} in a separate frame
75 (@code{switch-to-buffer-other-frame}).
76 @item C-x @key{LEFT}
77 Select the previous buffer in the list of existing buffers.
78 @item C-x @key{RIGHT}
79 Select the next buffer in the list of existing buffers.
80 @item C-u M-g M-g
81 @itemx C-u M-g g
82 Read a number @var{n} and move to line @var{n} in the most recently
83 selected buffer other than the current buffer.
84 @end table
85
86 @kindex C-x b
87 @findex switch-to-buffer
88 To select the buffer named @var{bufname}, type @kbd{C-x b @var{bufname}
89 @key{RET}}. This runs the command @code{switch-to-buffer} with argument
90 @var{bufname}. You can use completion to enter the buffer
91 name (@pxref{Completion}). An empty argument to @kbd{C-x b}
92 specifies the buffer that was current most recently among those not
93 now displayed in any window.
94
95 @kindex C-x @key{LEFT}
96 @kindex C-x @key{RIGHT}
97 @findex next-buffer
98 @findex previous-buffer
99 For conveniently switching between a few buffers, use the commands
100 @kbd{C-x @key{LEFT}} and @kbd{C-x @key{RIGHT}}. @kbd{C-x @key{RIGHT}}
101 (@code{previous-buffer}) selects the previous buffer (following the order
102 of most recent selection in the current frame), while @kbd{C-x @key{LEFT}}
103 (@code{next-buffer}) moves through buffers in the reverse direction.
104
105 @kindex C-x 4 b
106 @findex switch-to-buffer-other-window
107 @vindex even-window-heights
108 To select a buffer in a window other than the current one, type
109 @kbd{C-x 4 b @var{bufname} @key{RET}}. This runs the command
110 @code{switch-to-buffer-other-window} which displays the buffer
111 @var{bufname} in another window. By default, if displaying the buffer
112 causes two vertically adjacent windows to be displayed, the heights of
113 those windows are evened out; to countermand that and preserve the
114 window configuration, set the variable @code{even-window-heights} to
115 @code{nil}.
116
117 @kindex C-x 5 b
118 @findex switch-to-buffer-other-frame
119 Similarly, @kbd{C-x 5 b @var{buffer} @key{RET}} runs the command
120 @code{switch-to-buffer-other-frame} which selects a buffer in another
121 frame.
122
123 @vindex display-buffer-reuse-frames
124 You can control how certain buffers are handled by these commands by
125 customizing the variables @code{special-display-buffer-names},
126 @code{special-display-regexps}, @code{same-window-buffer-names}, and
127 @code{same-window-regexps}. See @ref{Force Same Window}, and
128 @ref{Special Buffer Frames}, for more about these variables. In
129 addition, if the value of @code{display-buffer-reuse-frames} is
130 non-@code{nil}, and the buffer you want to switch to is already
131 displayed in some frame, Emacs will just raise that frame.
132
133 Most buffers are created by visiting files, or by Emacs commands that
134 want to display some text, but you can also create a buffer explicitly
135 by typing @kbd{C-x b @var{bufname} @key{RET}}. This makes a new, empty
136 buffer that is not visiting any file, and selects it for editing. Such
137 buffers are used for making notes to yourself. If you try to save one,
138 you are asked for the file name to use. The new buffer's major mode is
139 determined by the value of @code{default-major-mode} (@pxref{Major
140 Modes}).
141
142 Note that @kbd{C-x C-f}, and any other command for visiting a file,
143 can also be used to switch to an existing file-visiting buffer.
144 @xref{Visiting}.
145
146 @kbd{C-u M-g M-g}, that is @code{goto-line} with a prefix argument
147 of just @kbd{C-u}, reads a number @var{n} using the minibuffer,
148 selects the most recently selected buffer other than the current
149 buffer in another window, and then moves point to the beginning of
150 line number @var{n} in that buffer. This is mainly useful in a buffer
151 that refers to line numbers in another buffer: if point is on or just
152 after a number, @code{goto-line} uses that number as the default for
153 @var{n}. Note that prefix arguments other than just @kbd{C-u} behave
154 differently. @kbd{C-u 4 M-g M-g} goes to line 4 in the @emph{current}
155 buffer, without reading a number from the minibuffer. (Remember that
156 @kbd{M-g M-g} without prefix argument reads a number @var{n} and then
157 moves to line number @var{n} in the current buffer.)
158
159 Emacs uses buffer names that start with a space for internal purposes.
160 It treats these buffers specially in minor ways---for example, by
161 default they do not record undo information. It is best to avoid using
162 such buffer names yourself.
163
164 @node List Buffers
165 @section Listing Existing Buffers
166
167 @table @kbd
168 @item C-x C-b
169 List the existing buffers (@code{list-buffers}).
170 @end table
171
172 @cindex listing current buffers
173 @kindex C-x C-b
174 @findex list-buffers
175 To display a list of existing buffers, type @kbd{C-x C-b}. Each
176 line in the list shows one buffer's name, major mode and visited file.
177 The buffers are listed in the order that they were current; the
178 buffers that were current most recently come first.
179
180 @samp{*} in the first field of a line indicates the buffer is
181 ``modified.'' If several buffers are modified, it may be time to save
182 some with @kbd{C-x s} (@pxref{Save Commands}). @samp{%} indicates a
183 read-only buffer. @samp{.} marks the current buffer. Here is an
184 example of a buffer list:@refill
185
186 @smallexample
187 CRM Buffer Size Mode File
188 . * .emacs 3294 Emacs-Lisp ~/.emacs
189 % *Help* 101 Help
190 search.c 86055 C ~/cvs/emacs/src/search.c
191 % src 20959 Dired by name ~/cvs/emacs/src/
192 * *mail* 42 Mail
193 % HELLO 1607 Fundamental ~/cvs/emacs/etc/HELLO
194 % NEWS 481184 Outline ~/cvs/emacs/etc/NEWS
195 *scratch* 191 Lisp Interaction
196 * *Messages* 1554 Fundamental
197 @end smallexample
198
199 @noindent
200 Note that the buffer @samp{*Help*} was made by a help request; it is
201 not visiting any file. The buffer @code{src} was made by Dired on the
202 directory @file{~/cvs/emacs/src/}. You can list only buffers that are
203 visiting files by giving the command a prefix argument, as in
204 @kbd{C-u C-x C-b}.
205
206 @code{list-buffers} omits buffers whose names begin with a space,
207 unless they visit files: such buffers are used internally by Emacs.
208
209 @need 2000
210 @node Misc Buffer
211 @section Miscellaneous Buffer Operations
212
213 @table @kbd
214 @item C-x C-q
215 Toggle read-only status of buffer (@code{toggle-read-only}).
216 @item M-x rename-buffer @key{RET} @var{name} @key{RET}
217 Change the name of the current buffer.
218 @item M-x rename-uniquely
219 Rename the current buffer by adding @samp{<@var{number}>} to the end.
220 @item M-x view-buffer @key{RET} @var{buffer} @key{RET}
221 Scroll through buffer @var{buffer}.
222 @end table
223
224 @kindex C-x C-q
225 @vindex buffer-read-only
226 @cindex read-only buffer
227 A buffer can be @dfn{read-only}, which means that commands to change
228 its contents are not allowed. The mode line indicates read-only
229 buffers with @samp{%%} or @samp{%*} near the left margin. Read-only
230 buffers are usually made by subsystems such as Dired and Rmail that
231 have special commands to operate on the text; also by visiting a file
232 whose access control says you cannot write it.
233
234 @findex toggle-read-only
235 If you wish to make changes in a read-only buffer, use the command
236 @kbd{C-x C-q} (@code{toggle-read-only}). It makes a read-only buffer
237 writable, and makes a writable buffer read-only. This
238 works by setting the variable @code{buffer-read-only}, which has a local
239 value in each buffer and makes the buffer read-only if its value is
240 non-@code{nil}. If you have files under version control, you may find
241 it convenient to bind @kbd{C-x C-q} to @code{vc-toggle-read-only}
242 instead. Then, typing @kbd{C-x C-q} not only changes the read-only
243 flag, but it also checks the file in or out. @xref{Version
244 Control}.
245
246 @findex rename-buffer
247 @kbd{M-x rename-buffer} changes the name of the current buffer. You
248 specify the new name as a minibuffer argument; there is no default.
249 If you specify a name that is in use for some other buffer, an error
250 happens and no renaming is done.
251
252 @findex rename-uniquely
253 @kbd{M-x rename-uniquely} renames the current buffer to a similar
254 name with a numeric suffix added to make it both different and unique.
255 This command does not need an argument. It is useful for creating
256 multiple shell buffers: if you rename the @samp{*shell*} buffer, then
257 do @kbd{M-x shell} again, it makes a new shell buffer named
258 @samp{*shell*}; meanwhile, the old shell buffer continues to exist
259 under its new name. This method is also good for mail buffers,
260 compilation buffers, and most Emacs features that create special
261 buffers with particular names. (With some of these features, such as
262 @kbd{M-x compile}, @kbd{M-x grep} an @kbd{M-x info}, you need to
263 switch to some other buffer before using the command, in order for it
264 to make a different buffer.)
265
266 @findex view-buffer
267 @kbd{M-x view-buffer} is much like @kbd{M-x view-file} (@pxref{Misc
268 File Ops}) except that it examines an already existing Emacs buffer.
269 View mode provides commands for scrolling through the buffer
270 conveniently but not for changing it. When you exit View mode with
271 @kbd{q}, that switches back to the buffer (and the position) which was
272 previously displayed in the window. Alternatively, if you exit View
273 mode with @kbd{e}, the buffer and the value of point that resulted from
274 your perusal remain in effect.
275
276 The commands @kbd{M-x append-to-buffer} and @kbd{M-x insert-buffer}
277 can be used to copy text from one buffer to another. @xref{Accumulating
278 Text}.
279
280 @node Kill Buffer
281 @section Killing Buffers
282
283 @cindex killing buffers
284 If you continue an Emacs session for a while, you may accumulate a
285 large number of buffers. You may then find it convenient to @dfn{kill}
286 the buffers you no longer need. On most operating systems, killing a
287 buffer releases its space back to the operating system so that other
288 programs can use it. Here are some commands for killing buffers:
289
290 @table @kbd
291 @item C-x k @var{bufname} @key{RET}
292 Kill buffer @var{bufname} (@code{kill-buffer}).
293 @item M-x kill-some-buffers
294 Offer to kill each buffer, one by one.
295 @end table
296
297 @findex kill-buffer
298 @findex kill-some-buffers
299 @kindex C-x k
300
301 @kbd{C-x k} (@code{kill-buffer}) kills one buffer, whose name you
302 specify in the minibuffer. The default, used if you type just
303 @key{RET} in the minibuffer, is to kill the current buffer. If you
304 kill the current buffer, another buffer becomes current: one that was
305 current in the recent past but is not displayed in any window now. If
306 you ask to kill a file-visiting buffer that is modified (has unsaved
307 editing), then you must confirm with @kbd{yes} before the buffer is
308 killed.
309
310 The command @kbd{M-x kill-some-buffers} asks about each buffer, one by
311 one. An answer of @kbd{y} means to kill the buffer. Killing the current
312 buffer or a buffer containing unsaved changes selects a new buffer or asks
313 for confirmation just like @code{kill-buffer}.
314
315 The buffer menu feature (@pxref{Several Buffers}) is also convenient
316 for killing various buffers.
317
318 @vindex kill-buffer-hook
319 If you want to do something special every time a buffer is killed, you
320 can add hook functions to the hook @code{kill-buffer-hook} (@pxref{Hooks}).
321
322 @findex clean-buffer-list
323 If you run one Emacs session for a period of days, as many people do,
324 it can fill up with buffers that you used several days ago. The command
325 @kbd{M-x clean-buffer-list} is a convenient way to purge them; it kills
326 all the unmodified buffers that you have not used for a long time. An
327 ordinary buffer is killed if it has not been displayed for three days;
328 however, you can specify certain buffers that should never be killed
329 automatically, and others that should be killed if they have been unused
330 for a mere hour.
331
332 @cindex Midnight mode
333 @vindex midnight-mode
334 @vindex midnight-hook
335 You can also have this buffer purging done for you, every day at
336 midnight, by enabling Midnight mode. Midnight mode operates each day at
337 midnight; at that time, it runs @code{clean-buffer-list}, or whichever
338 functions you have placed in the normal hook @code{midnight-hook}
339 (@pxref{Hooks}).
340
341 To enable Midnight mode, use the Customization buffer to set the
342 variable @code{midnight-mode} to @code{t}. @xref{Easy Customization}.
343
344 @node Several Buffers
345 @section Operating on Several Buffers
346 @cindex buffer menu
347
348 The @dfn{buffer-menu} facility is like a ``Dired for buffers''; it allows
349 you to request operations on various Emacs buffers by editing an Emacs
350 buffer containing a list of them. You can save buffers, kill them
351 (here called @dfn{deleting} them, for consistency with Dired), or display
352 them.
353
354 @table @kbd
355 @item M-x buffer-menu
356 Begin editing a buffer listing all Emacs buffers.
357 @item M-x buffer-menu-other-window.
358 Similar, but do it in another window.
359 @end table
360
361 @findex buffer-menu
362 @findex buffer-menu-other-window
363 The command @code{buffer-menu} writes a list of all Emacs
364 buffers@footnote{Buffers which don't visit files and whose names begin
365 with a space are omitted: these are used internally by Emacs.} into the
366 buffer @samp{*Buffer List*}, and selects that buffer in Buffer Menu
367 mode.
368
369 The buffer is read-only, and can be
370 changed only through the special commands described in this section.
371 The usual Emacs cursor motion commands can be used in the @samp{*Buffer
372 List*} buffer. The following commands apply to the buffer described on
373 the current line.
374
375 @table @kbd
376 @item d
377 Request to delete (kill) the buffer, then move down. The request
378 shows as a @samp{D} on the line, before the buffer name. Requested
379 deletions take place when you type the @kbd{x} command.
380 @item C-d
381 Like @kbd{d} but move up afterwards instead of down.
382 @item s
383 Request to save the buffer. The request shows as an @samp{S} on the
384 line. Requested saves take place when you type the @kbd{x} command.
385 You may request both saving and deletion for the same buffer.
386 @item x
387 Perform previously requested deletions and saves.
388 @item u
389 Remove any request made for the current line, and move down.
390 @item @key{DEL}
391 Move to previous line and remove any request made for that line.
392 @end table
393
394 The @kbd{d}, @kbd{C-d}, @kbd{s} and @kbd{u} commands to add or remove
395 flags also move down (or up) one line. They accept a numeric argument
396 as a repeat count.
397
398 These commands operate immediately on the buffer listed on the current
399 line:
400
401 @table @kbd
402 @item ~
403 Mark the buffer ``unmodified.'' The command @kbd{~} does this
404 immediately when you type it.
405 @item %
406 Toggle the buffer's read-only flag. The command @kbd{%} does
407 this immediately when you type it.
408 @item t
409 Visit the buffer as a tags table. @xref{Select Tags Table}.
410 @end table
411
412 There are also commands to select another buffer or buffers:
413
414 @table @kbd
415 @item q
416 Quit the buffer menu---immediately display the most recent formerly
417 visible buffer in its place.
418 @item @key{RET}
419 @itemx f
420 Immediately select this line's buffer in place of the @samp{*Buffer
421 List*} buffer.
422 @item o
423 Immediately select this line's buffer in another window as if by
424 @kbd{C-x 4 b}, leaving @samp{*Buffer List*} visible.
425 @item C-o
426 Immediately display this line's buffer in another window, but don't
427 select the window.
428 @item 1
429 Immediately select this line's buffer in a full-screen window.
430 @item 2
431 Immediately set up two windows, with this line's buffer selected in
432 one, and the previously current buffer (aside from the buffer
433 @samp{*Buffer List*}) displayed in the other.
434 @item b
435 Bury the buffer listed on this line.
436 @item m
437 Mark this line's buffer to be displayed in another window if you exit
438 with the @kbd{v} command. The request shows as a @samp{>} at the
439 beginning of the line. (A single buffer may not have both a delete
440 request and a display request.)
441 @item v
442 Immediately select this line's buffer, and also display in other windows
443 any buffers previously marked with the @kbd{m} command. If you have not
444 marked any buffers, this command is equivalent to @kbd{1}.
445 @end table
446
447 There is also a command that affects the entire buffer list:
448
449 @table @kbd
450 @item T
451 Delete, or reinsert, lines for non-file buffers. This command toggles
452 the inclusion of such buffers in the buffer list.
453 @end table
454
455 What @code{buffer-menu} actually does is create and switch to a
456 suitable buffer, and turn on Buffer Menu mode in it. Everything else
457 described above is implemented by the special commands provided in
458 Buffer Menu mode. One consequence of this is that you can switch from
459 the @samp{*Buffer List*} buffer to another Emacs buffer, and edit
460 there. You can reselect the @samp{*Buffer List*} buffer later, to
461 perform the operations already requested, or you can kill it, or pay
462 no further attention to it.
463
464 The list in the @samp{*Buffer List*} buffer looks exactly like the
465 buffer list described in @ref{List Buffers}, because they really are
466 the same. The only difference between @code{buffer-menu} and
467 @code{list-buffers} is that @code{buffer-menu} switches to the
468 @samp{*Buffer List*} buffer in the selected window;
469 @code{list-buffers} displays the same buffer in another window. If
470 you run @code{list-buffers} (that is, type @kbd{C-x C-b}) and select
471 the buffer list manually, you can use all of the commands described
472 here.
473
474 Normally, the buffer @samp{*Buffer List*} is not updated
475 automatically when buffers are created and killed; its contents are
476 just text. If you have created, deleted or renamed buffers, the way
477 to update @samp{*Buffer List*} to show what you have done is to type
478 @kbd{g} (@code{revert-buffer}). You can make this happen regularly
479 every @code{auto-revert-interval} seconds if you enable Auto Revert
480 mode in this buffer, as long as it is not marked modified. Global
481 Auto Revert mode applies to the @samp{*Buffer List*} buffer only if
482 @code{global-auto-revert-non-file-buffers} is non-@code{nil}.
483 @inforef{Autorevert,, emacs-xtra}, for details.
484
485 The command @code{buffer-menu-other-window} works the same as
486 @code{buffer-menu}, except that it displays the buffers list in
487 another window.
488
489 @node Indirect Buffers
490 @section Indirect Buffers
491 @cindex indirect buffer
492 @cindex base buffer
493
494 An @dfn{indirect buffer} shares the text of some other buffer, which
495 is called the @dfn{base buffer} of the indirect buffer. In some ways it
496 is the analogue, for buffers, of a symbolic link between files.
497
498 @table @kbd
499 @findex make-indirect-buffer
500 @item M-x make-indirect-buffer @key{RET} @var{base-buffer} @key{RET} @var{indirect-name} @key{RET}
501 Create an indirect buffer named @var{indirect-name} whose base buffer
502 is @var{base-buffer}.
503 @findex clone-indirect-buffer
504 @item M-x clone-indirect-buffer @key{RET}
505 Create an indirect buffer that is a twin copy of the current buffer.
506 @item C-x 4 c
507 @kindex C-x 4 c
508 @findex clone-indirect-buffer-other-window
509 Create an indirect buffer that is a twin copy of the current buffer, and
510 select it in another window (@code{clone-indirect-buffer-other-window}).
511 @end table
512
513 The text of the indirect buffer is always identical to the text of its
514 base buffer; changes made by editing either one are visible immediately
515 in the other. But in all other respects, the indirect buffer and its
516 base buffer are completely separate. They have different names,
517 different values of point, different narrowing, different markers,
518 different major modes, and different local variables.
519
520 An indirect buffer cannot visit a file, but its base buffer can. If
521 you try to save the indirect buffer, that actually works by saving the
522 base buffer. Killing the base buffer effectively kills the indirect
523 buffer, but killing an indirect buffer has no effect on its base buffer.
524
525 One way to use indirect buffers is to display multiple views of an
526 outline. @xref{Outline Views}.
527
528 A quick and handy way to make an indirect buffer is with the command
529 @kbd{M-x clone-indirect-buffer}. It creates and selects an indirect
530 buffer whose base buffer is the current buffer. With a numeric
531 argument, it prompts for the name of the indirect buffer; otherwise it
532 uses the name of the current buffer, with a @samp{<@var{n}>} suffix
533 added. @kbd{C-x 4 c} (@code{clone-indirect-buffer-other-window})
534 works like @kbd{M-x clone-indirect-buffer}, but it selects the new
535 buffer in another window.
536
537 The more general way to make an indirect buffer is with the command
538 @kbd{M-x make-indirect-buffer}. It creates an indirect buffer from
539 buffer @var{base-buffer}, under the name @var{indirect-name}. It
540 prompts for both @var{base-buffer} and @var{indirect-name} using the
541 minibuffer.
542
543 @node Buffer Convenience
544 @section Convenience Features and Customization of Buffer Handling
545
546 This section describes several modes and features that make it more
547 convenient to switch between buffers.
548
549 @menu
550 * Uniquify:: Making buffer names unique with directory parts.
551 * Iswitchb:: Switching between buffers with substrings.
552 * Buffer Menus:: Configurable buffer menu.
553 @end menu
554
555 @node Uniquify
556 @subsection Making Buffer Names Unique
557
558 @cindex unique buffer names
559 @cindex directories in buffer names
560 When several buffers visit identically-named files, Emacs must give
561 the buffers distinct names. The usual method for making buffer names
562 unique adds @samp{<2>}, @samp{<3>}, etc. to the end of the buffer
563 names (all but one of them).
564
565 @vindex uniquify-buffer-name-style
566 Other methods work by adding parts of each file's directory to the
567 buffer name. To select one, customize the variable
568 @code{uniquify-buffer-name-style} (@pxref{Easy Customization}).
569
570 For instance, the @code{forward} naming method puts part of the
571 directory name at the beginning of the buffer name; using this method,
572 buffers visiting @file{/u/mernst/tmp/Makefile} and
573 @file{/usr/projects/zaphod/Makefile} would be named
574 @samp{tmp/Makefile} and @samp{zaphod/Makefile}, respectively (instead
575 of @samp{Makefile} and @samp{Makefile<2>}).
576
577 By contrast, the @code{post-forward} naming method would call the
578 buffers @samp{Makefile|tmp} and @samp{Makefile|zaphod}, and the
579 @code{reverse} naming method would call them @samp{Makefile\tmp} and
580 @samp{Makefile\zaphod}. The nontrivial difference between
581 @code{post-forward} and @code{reverse} occurs when just one directory
582 name is not enough to distinguish two files; then @code{reverse} puts
583 the directory names in reverse order, so that @file{/top/middle/file}
584 becomes @samp{file\middle\top}, while @code{post-forward} puts them in
585 forward order after the file name, as in @samp{file|top/middle}.
586
587 Which rule to follow for putting the directory names in the buffer
588 name is not very important if you are going to @emph{look} at the
589 buffer names before you type one. But as an experienced user, if you
590 know the rule, you won't have to look. And then you may find that one
591 rule or another is easier for you to remember and apply quickly.
592
593 @node Iswitchb
594 @subsection Switching Between Buffers using Substrings
595
596 @findex iswitchb-mode
597 @cindex Iswitchb mode
598 @cindex mode, Iswitchb
599 @kindex C-x b @r{(Iswitchb mode)}
600 @kindex C-x 4 b @r{(Iswitchb mode)}
601 @kindex C-x 5 b @r{(Iswitchb mode)}
602 @kindex C-x 4 C-o @r{(Iswitchb mode)}
603
604 Iswitchb global minor mode provides convenient switching between
605 buffers using substrings of their names. It replaces the normal
606 definitions of @kbd{C-x b}, @kbd{C-x 4 b}, @kbd{C-x 5 b}, and @kbd{C-x
607 4 C-o} with alternative commands that are somewhat ``smarter.''
608
609 When one of these commands prompts you for a buffer name, you can
610 type in just a substring of the name you want to choose. As you enter
611 the substring, Iswitchb mode continuously displays a list of buffers
612 that match the substring you have typed.
613
614 At any time, you can type @key{RET} to select the first buffer in
615 the list. So the way to select a particular buffer is to make it the
616 first in the list. There are two ways to do this. You can type more
617 of the buffer name and thus narrow down the list, excluding unwanted
618 buffers above the desired one. Alternatively, you can use @kbd{C-s}
619 and @kbd{C-r} to rotate the list until the desired buffer is first.
620
621 @key{TAB} while entering the buffer name performs completion on the
622 string you have entered, based on the displayed list of buffers.
623
624 To enable Iswitchb mode, type @kbd{M-x iswitchb-mode}, or customize
625 the variable @code{iswitchb-mode} to @code{t} (@pxref{Easy
626 Customization}).
627
628 @node Buffer Menus
629 @subsection Customizing Buffer Menus
630
631 @findex bs-show
632 @cindex buffer list, customizable
633 @table @kbd
634 @item M-x bs-show
635 Make a list of buffers similarly to @kbd{M-x list-buffers} but
636 customizable.
637 @end table
638
639 @kbd{M-x bs-show} pops up a buffer list similar to the one normally
640 displayed by @kbd{C-x C-b} but which you can customize. If you prefer
641 this to the usual buffer list, you can bind this command to @kbd{C-x
642 C-b}. To customize this buffer list, use the @code{bs} Custom group
643 (@pxref{Easy Customization}).
644
645 @findex msb-mode
646 @cindex mode, MSB
647 @cindex MSB mode
648 @cindex buffer menu
649 @findex mouse-buffer-menu
650 @kindex C-Down-Mouse-1
651 MSB global minor mode (``MSB'' stands for ``mouse select buffer'')
652 provides a different and customizable mouse buffer menu which you may
653 prefer. It replaces the bindings of @code{mouse-buffer-menu},
654 normally on @kbd{C-Down-Mouse-1}, and the menu bar buffer menu. You
655 can customize the menu in the @code{msb} Custom group.
656
657 @ignore
658 arch-tag: 08c43460-f4f4-4b43-9cb5-1ea9ad991695
659 @end ignore