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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 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 @key{LEFT}
71 Select the previous buffer in the list of existing buffers.
72 @item C-x @key{RIGHT}
73 Select the next buffer in the list of existing buffers.
74 @item C-x 4 b @var{buffer} @key{RET}
75 Similar, but select @var{buffer} in another window
76 (@code{switch-to-buffer-other-window}).
77 @item C-x 5 b @var{buffer} @key{RET}
78 Similar, but select @var{buffer} in a separate frame
79 (@code{switch-to-buffer-other-frame}).
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 on an abbreviation for the buffer
91 name you want (@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 prev-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{prev-buffer}) selects the previous buffer (following the order
102 of most recent selection), 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 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 ``modified.''
181 If several buffers are modified, it may be time to save some with @kbd{C-x s}
182 (@pxref{Save Commands}). @samp{%} indicates a read-only buffer. @samp{.} marks the
183 current buffer. Here is an example of a buffer list:@refill
184
185 @smallexample
186 CRM Buffer Size Mode File
187 . * .emacs 3294 Emacs-Lisp ~/.emacs
188 % *Help* 101 Help
189 search.c 86055 C ~/cvs/emacs/src/search.c
190 % src 20959 Dired by name ~/cvs/emacs/src/
191 * *mail* 42 Mail
192 % HELLO 1607 Fundamental ~/cvs/emacs/etc/HELLO
193 % NEWS 481184 Outline ~/cvs/emacs/etc/NEWS
194 *scratch* 191 Lisp Interaction
195 * *Messages* 1554 Fundamental
196 @end smallexample
197
198 @noindent
199 Note that the buffer @samp{*Help*} was made by a help request; it is
200 not visiting any file. The buffer @code{src} was made by Dired on the
201 directory @file{~/cvs/emacs/src/}. You can list only buffers that are
202 visiting files by giving the command a prefix; for instance, by typing
203 @kbd{C-u C-x C-b}.
204
205 @code{list-buffers} omits buffers whose names begin with a space,
206 unless they visit files: such buffers are used internally by Emacs.
207
208 @need 2000
209 @node Misc Buffer
210 @section Miscellaneous Buffer Operations
211
212 @table @kbd
213 @item C-x C-q
214 Toggle read-only status of buffer (@code{toggle-read-only}).
215 @item M-x rename-buffer @key{RET} @var{name} @key{RET}
216 Change the name of the current buffer.
217 @item M-x rename-uniquely
218 Rename the current buffer by adding @samp{<@var{number}>} to the end.
219 @item M-x view-buffer @key{RET} @var{buffer} @key{RET}
220 Scroll through buffer @var{buffer}.
221 @end table
222
223 @kindex C-x C-q
224 @vindex buffer-read-only
225 @cindex read-only buffer
226 A buffer can be @dfn{read-only}, which means that commands to change
227 its contents are not allowed. The mode line indicates read-only
228 buffers with @samp{%%} or @samp{%*} near the left margin. Read-only
229 buffers are usually made by subsystems such as Dired and Rmail that
230 have special commands to operate on the text; also by visiting a file
231 whose access control says you cannot write it.
232
233 @findex toggle-read-only
234 If you wish to make changes in a read-only buffer, use the command
235 @kbd{C-x C-q} (@code{toggle-read-only}). It makes a read-only buffer
236 writable, and makes a writable buffer read-only. This
237 works by setting the variable @code{buffer-read-only}, which has a local
238 value in each buffer and makes the buffer read-only if its value is
239 non-@code{nil}. If you have files under version control, you may find
240 it convenient to bind @kbd{C-x C-q} to @code{vc-toggle-read-only}
241 instead. Then, typing @kbd{C-x C-q} not only changes the read-only
242 flag, but it also checks the file in or out. @xref{Version
243 Control}.
244
245 @findex rename-buffer
246 @kbd{M-x rename-buffer} changes the name of the current buffer. Specify
247 the new name as a minibuffer argument. There is no default. If you
248 specify a name that is in use for some other buffer, an error happens and
249 no renaming is done.
250
251 @findex rename-uniquely
252 @kbd{M-x rename-uniquely} renames the current buffer to a similar
253 name with a numeric suffix added to make it both different and unique.
254 This command does not need an argument. It is useful for creating
255 multiple shell buffers: if you rename the @samp{*shell*} buffer, then
256 do @kbd{M-x shell} again, it makes a new shell buffer named
257 @samp{*shell*}; meanwhile, the old shell buffer continues to exist
258 under its new name. This method is also good for mail buffers,
259 compilation buffers, and most Emacs features that create special
260 buffers with particular names. (With some of these features, such as
261 @kbd{M-x compile}, @kbd{M-x grep} an @kbd{M-x info}, you need to
262 switch to some other buffer before using the command, in order for it
263 to make a different buffer.)
264
265 @findex view-buffer
266 @kbd{M-x view-buffer} is much like @kbd{M-x view-file} (@pxref{Misc
267 File Ops}) except that it examines an already existing Emacs buffer.
268 View mode provides commands for scrolling through the buffer
269 conveniently but not for changing it. When you exit View mode with
270 @kbd{q}, that switches back to the buffer (and the position) which was
271 previously displayed in the window. Alternatively, if you exit View
272 mode with @kbd{e}, the buffer and the value of point that resulted from
273 your perusal remain in effect.
274
275 The commands @kbd{M-x append-to-buffer} and @kbd{M-x insert-buffer}
276 can be used to copy text from one buffer to another. @xref{Accumulating
277 Text}.@refill
278
279 @node Kill Buffer
280 @section Killing Buffers
281
282 @cindex killing buffers
283 If you continue an Emacs session for a while, you may accumulate a
284 large number of buffers. You may then find it convenient to @dfn{kill}
285 the buffers you no longer need. On most operating systems, killing a
286 buffer releases its space back to the operating system so that other
287 programs can use it. Here are some commands for killing buffers:
288
289 @table @kbd
290 @item C-x k @var{bufname} @key{RET}
291 Kill buffer @var{bufname} (@code{kill-buffer}).
292 @item M-x kill-some-buffers
293 Offer to kill each buffer, one by one.
294 @end table
295
296 @findex kill-buffer
297 @findex kill-some-buffers
298 @kindex C-x k
299
300 @kbd{C-x k} (@code{kill-buffer}) kills one buffer, whose name you
301 specify in the minibuffer. The default, used if you type just
302 @key{RET} in the minibuffer, is to kill the current buffer. If you
303 kill the current buffer, another buffer becomes current: one that was
304 current in the recent past but is not displayed in any window now. If
305 you ask to kill a file-visiting buffer that is modified (has unsaved
306 editing), then you must confirm with @kbd{yes} before the buffer is
307 killed.
308
309 The command @kbd{M-x kill-some-buffers} asks about each buffer, one by
310 one. An answer of @kbd{y} means to kill the buffer. Killing the current
311 buffer or a buffer containing unsaved changes selects a new buffer or asks
312 for confirmation just like @code{kill-buffer}.
313
314 The buffer menu feature (@pxref{Several Buffers}) is also convenient
315 for killing various buffers.
316
317 @vindex kill-buffer-hook
318 If you want to do something special every time a buffer is killed, you
319 can add hook functions to the hook @code{kill-buffer-hook} (@pxref{Hooks}).
320
321 @findex clean-buffer-list
322 If you run one Emacs session for a period of days, as many people do,
323 it can fill up with buffers that you used several days ago. The command
324 @kbd{M-x clean-buffer-list} is a convenient way to purge them; it kills
325 all the unmodified buffers that you have not used for a long time. An
326 ordinary buffer is killed if it has not been displayed for three days;
327 however, you can specify certain buffers that should never be killed
328 automatically, and others that should be killed if they have been unused
329 for a mere hour.
330
331 @cindex Midnight mode
332 @vindex midnight-mode
333 @vindex midnight-hook
334 You can also have this buffer purging done for you, every day at
335 midnight, by enabling Midnight mode. Midnight mode operates each day at
336 midnight; at that time, it runs @code{clean-buffer-list}, or whichever
337 functions you have placed in the normal hook @code{midnight-hook}
338 (@pxref{Hooks}).
339
340 To enable Midnight mode, use the Customization buffer to set the
341 variable @code{midnight-mode} to @code{t}. @xref{Easy Customization}.
342
343 @node Several Buffers
344 @section Operating on Several Buffers
345 @cindex buffer menu
346
347 The @dfn{buffer-menu} facility is like a ``Dired for buffers''; it allows
348 you to request operations on various Emacs buffers by editing an Emacs
349 buffer containing a list of them. You can save buffers, kill them
350 (here called @dfn{deleting} them, for consistency with Dired), or display
351 them.
352
353 @table @kbd
354 @item M-x buffer-menu
355 Begin editing a buffer listing all Emacs buffers.
356 @item M-x buffer-menu-other-window.
357 Similar, but do it in another window.
358 @end table
359
360 @findex buffer-menu
361 @findex buffer-menu-other-window
362 The command @code{buffer-menu} writes a list of all Emacs
363 buffers@footnote{Buffers which don't visit files and whose names begin
364 with a space are omitted: these are used internally by Emacs.} into the
365 buffer @samp{*Buffer List*}, and selects that buffer in Buffer Menu
366 mode.
367
368 The buffer is read-only, and can be
369 changed only through the special commands described in this section.
370 The usual Emacs cursor motion commands can be used in the @samp{*Buffer
371 List*} buffer. The following commands apply to the buffer described on
372 the current line.
373
374 @table @kbd
375 @item d
376 Request to delete (kill) the buffer, then move down. The request
377 shows as a @samp{D} on the line, before the buffer name. Requested
378 deletions take place when you type the @kbd{x} command.
379 @item C-d
380 Like @kbd{d} but move up afterwards instead of down.
381 @item s
382 Request to save the buffer. The request shows as an @samp{S} on the
383 line. Requested saves take place when you type the @kbd{x} command.
384 You may request both saving and deletion for the same buffer.
385 @item x
386 Perform previously requested deletions and saves.
387 @item u
388 Remove any request made for the current line, and move down.
389 @item @key{DEL}
390 Move to previous line and remove any request made for that line.
391 @end table
392
393 The @kbd{d}, @kbd{C-d}, @kbd{s} and @kbd{u} commands to add or remove
394 flags also move down (or up) one line. They accept a numeric argument
395 as a repeat count.
396
397 These commands operate immediately on the buffer listed on the current
398 line:
399
400 @table @kbd
401 @item ~
402 Mark the buffer ``unmodified.'' The command @kbd{~} does this
403 immediately when you type it.
404 @item %
405 Toggle the buffer's read-only flag. The command @kbd{%} does
406 this immediately when you type it.
407 @item t
408 Visit the buffer as a tags table. @xref{Select Tags Table}.
409 @end table
410
411 There are also commands to select another buffer or buffers:
412
413 @table @kbd
414 @item q
415 Quit the buffer menu---immediately display the most recent formerly
416 visible buffer in its place.
417 @item @key{RET}
418 @itemx f
419 Immediately select this line's buffer in place of the @samp{*Buffer
420 List*} buffer.
421 @item o
422 Immediately select this line's buffer in another window as if by
423 @kbd{C-x 4 b}, leaving @samp{*Buffer List*} visible.
424 @item C-o
425 Immediately display this line's buffer in another window, but don't
426 select the window.
427 @item 1
428 Immediately select this line's buffer in a full-screen window.
429 @item 2
430 Immediately set up two windows, with this line's buffer selected in
431 one, and the previously current buffer (aside from the buffer
432 @samp{*Buffer List*}) displayed in the other.
433 @item b
434 Bury the buffer listed on this line.
435 @item m
436 Mark this line's buffer to be displayed in another window if you exit
437 with the @kbd{v} command. The request shows as a @samp{>} at the
438 beginning of the line. (A single buffer may not have both a delete
439 request and a display request.)
440 @item v
441 Immediately select this line's buffer, and also display in other windows
442 any buffers previously marked with the @kbd{m} command. If you have not
443 marked any buffers, this command is equivalent to @kbd{1}.
444 @end table
445
446 There is also a command that affects the entire buffer list:
447
448 @table @kbd
449 @item T
450 Delete, or reinsert, lines for non-file buffers. This command toggles
451 the inclusion of such buffers in the buffer list.
452 @end table
453
454 What @code{buffer-menu} actually does is create and switch to a
455 suitable buffer, and turn on Buffer Menu mode in it. Everything else
456 described above is implemented by the special commands provided in
457 Buffer Menu mode. One consequence of this is that you can switch from
458 the @samp{*Buffer List*} buffer to another Emacs buffer, and edit
459 there. You can reselect the @samp{*Buffer List*} buffer later, to
460 perform the operations already requested, or you can kill it, or pay
461 no further attention to it.
462
463 The list in the @samp{*Buffer List*} buffer looks exactly like the
464 buffer list described in @ref{List Buffers}, because they really are
465 the same. The only difference between @code{buffer-menu} and
466 @code{list-buffers} is that @code{buffer-menu} switches to the
467 @samp{*Buffer List*} buffer in the selected window;
468 @code{list-buffers} displays the same buffer in another window. If
469 you run @code{list-buffers} (that is, type @kbd{C-x C-b}) and select
470 the buffer list manually, you can use all of the commands described
471 here.
472
473 Normally, the buffer @samp{*Buffer List*} is not updated automatically when
474 buffers are created and killed; its contents are just text. If you have
475 created, deleted or renamed buffers, the way to update @samp{*Buffer
476 List*} to show what you have done is to type @kbd{g}
477 (@code{revert-buffer}) or repeat the @code{buffer-menu} command.
478
479 The @samp{*Buffer List*} buffer does automatically update every
480 @code{auto-revert-interval} seconds if you enable Auto Revert mode in
481 it. (As long as it is not marked modified.) Global Auto Revert mode
482 does not update the @samp{*Buffer List*} buffer by default, but it
483 does if @code{global-auto-revert-non-file-buffers} is non-@code{nil}.
484 @inforef{Autorevert,, emacs-xtra}, for details.
485
486 The command @code{buffer-menu-other-window} works the same as
487 @code{buffer-menu}, except that it displays the buffers list in
488 another window.
489
490 @node Indirect Buffers
491 @section Indirect Buffers
492 @cindex indirect buffer
493 @cindex base buffer
494
495 An @dfn{indirect buffer} shares the text of some other buffer, which
496 is called the @dfn{base buffer} of the indirect buffer. In some ways it
497 is the analogue, for buffers, of a symbolic link between files.
498
499 @table @kbd
500 @findex make-indirect-buffer
501 @item M-x make-indirect-buffer @key{RET} @var{base-buffer} @key{RET} @var{indirect-name} @key{RET}
502 Create an indirect buffer named @var{indirect-name} whose base buffer
503 is @var{base-buffer}.
504 @findex clone-indirect-buffer
505 @item M-x clone-indirect-buffer @key{RET}
506 Create an indirect buffer that is a twin copy of the current buffer.
507 @item C-x 4 c
508 @kindex C-x 4 c
509 @findex clone-indirect-buffer-other-window
510 Create an indirect buffer that is a twin copy of the current buffer, and
511 select it in another window (@code{clone-indirect-buffer-other-window}).
512 @end table
513
514 The text of the indirect buffer is always identical to the text of its
515 base buffer; changes made by editing either one are visible immediately
516 in the other. But in all other respects, the indirect buffer and its
517 base buffer are completely separate. They have different names,
518 different values of point, different narrowing, different markers,
519 different major modes, and different local variables.
520
521 An indirect buffer cannot visit a file, but its base buffer can. If
522 you try to save the indirect buffer, that actually works by saving the
523 base buffer. Killing the base buffer effectively kills the indirect
524 buffer, but killing an indirect buffer has no effect on its base buffer.
525
526 One way to use indirect buffers is to display multiple views of an
527 outline. @xref{Outline Views}.
528
529 A quick and handy way to make an indirect buffer is with the command
530 @kbd{M-x clone-indirect-buffer}. It creates and selects an indirect
531 buffer whose base buffer is the current buffer. With a numeric
532 argument, it prompts for the name of the indirect buffer; otherwise it
533 defaults to the name of the current buffer, modifying it by adding a
534 @samp{<@var{n}>} suffix if required. @kbd{C-x 4 c}
535 (@code{clone-indirect-buffer-other-window}) works like @kbd{M-x
536 clone-indirect-buffer}, but it selects the new buffer in another
537 window.
538
539 The more general way to make an indirect buffer is with the command
540 @kbd{M-x make-indirect-buffer}. It creates an indirect buffer from
541 buffer @var{base-buffer}, under the name @var{indirect-name}. It
542 prompts for both @var{base-buffer} and @var{indirect-name} using the
543 minibuffer.
544
545 @node Buffer Convenience
546 @section Convenience Features and Customization of Buffer Handling
547
548 This section describes several modes and features that make it more
549 convenient to switch between buffers.
550
551 @menu
552 * Uniquify:: Making buffer names unique with directory parts.
553 * Iswitchb:: Switching between buffers with substrings.
554 * Buffer Menus:: Configurable buffer menu.
555 @end menu
556
557 @node Uniquify
558 @subsection Making Buffer Names Unique
559
560 @cindex unique buffer names
561 @cindex directories in buffer names
562 When several buffers visit identically-named files, Emacs must give
563 the buffers distinct names. The usual method for making buffer names
564 unique adds @samp{<2>}, @samp{<3>}, etc. to the end of the buffer
565 names (all but one of them).
566
567 @vindex uniquify-buffer-name-style
568 Other methods work by adding parts of each file's directory to the
569 buffer name. To select one, customize the variable
570 @code{uniquify-buffer-name-style} (@pxref{Easy Customization}).
571
572 For instance, the @code{forward} naming method puts part of the
573 directory name at the beginning of the buffer name; using this method,
574 buffers visiting @file{/u/mernst/tmp/Makefile} and
575 @file{/usr/projects/zaphod/Makefile} would be named
576 @samp{tmp/Makefile} and @samp{zaphod/Makefile}, respectively (instead
577 of @samp{Makefile} and @samp{Makefile<2>}).
578
579 By contrast, the @code{post-forward} naming method would call the
580 buffers @samp{Makefile|tmp} and @samp{Makefile|zaphod}, and the
581 @code{reverse} naming method would call them @samp{Makefile\tmp} and
582 @samp{Makefile\zaphod}. The nontrivial difference between
583 @code{post-forward} and @code{reverse} occurs when just one directory
584 name is not enough to distinguish two files; then @code{reverse} puts
585 the directory names in reverse order, so that @file{/top/middle/file}
586 becomes @samp{file\middle\top}, while @code{post-forward} puts them in
587 forward order after the file name, as in @samp{file|top/middle}.
588
589 Which rule to follow for putting the directory names in the buffer
590 name is not very important if you are going to @emph{look} at the
591 buffer names before you type one. But as an experienced user, if you
592 know the rule, you won't have to look. And then you may find that one
593 rule or another is easier for you to remember and utilize fast.
594
595 @node Iswitchb
596 @subsection Switching Between Buffers using Substrings
597
598 @findex iswitchb-mode
599 @cindex Iswitchb mode
600 @cindex mode, Iswitchb
601 @kindex C-x b @r{(Iswitchb mode)}
602 @kindex C-x 4 b @r{(Iswitchb mode)}
603 @kindex C-x 5 b @r{(Iswitchb mode)}
604 @kindex C-x 4 C-o @r{(Iswitchb mode)}
605
606 Iswitchb global minor mode provides convenient switching between
607 buffers using substrings of their names. It replaces the normal
608 definitions of @kbd{C-x b}, @kbd{C-x 4 b}, @kbd{C-x 5 b}, and @kbd{C-x
609 4 C-o} with alternative commands that are somewhat ``smarter.''
610
611 When one of these commands prompts you for a buffer name, you can
612 type in just a substring of the name you want to choose. As you enter
613 the substring, Iswitchb mode continuously displays a list of buffers
614 that match the substring you have typed.
615
616 At any time, you can type @key{RET} to select the first buffer in
617 the list. So the way to select a particular buffer is to make it the
618 first in the list. There are two ways to do this. You can type more
619 of the buffer name and thus narrow down the list, excluding unwanted
620 buffers above the desired one. Alternatively, you can use @kbd{C-s}
621 and @kbd{C-r} to rotate the list until the desired buffer is first.
622
623 @key{TAB} while entering the buffer name performs completion on the
624 string you have entered, based on the displayed list of buffers.
625
626 To enable Iswitchb mode, type @kbd{M-x iswitchb-mode}, or customize
627 the variable @code{iswitchb-mode} to @code{t} (@pxref{Easy
628 Customization}).
629
630 @node Buffer Menus
631 @subsection Customizing Buffer Menus
632
633 @findex bs-show
634 @cindex buffer list, customizable
635 @table @kbd
636 @item M-x bs-show
637 Make a list of buffers similarly to @kbd{M-x list-buffers} but
638 customizable.
639 @end table
640
641 @kbd{M-x bs-show} pops up a buffer list similar to the one normally
642 displayed by @kbd{C-x C-b} but which you can customize. If you prefer
643 this to the usual buffer list, you can bind this command to @kbd{C-x
644 C-b}. To customize this buffer list, use the @code{bs} Custom group
645 (@pxref{Easy Customization}).
646
647 @findex msb-mode
648 @cindex mode, MSB
649 @cindex MSB mode
650 @cindex buffer menu
651 @findex mouse-buffer-menu
652 @kindex C-Down-Mouse-1
653 MSB global minor mode (``MSB'' stands for ``mouse select buffer'')
654 provides a different and customizable mouse buffer menu which you may
655 prefer. It replaces the bindings of @code{mouse-buffer-menu},
656 normally on @kbd{C-Down-Mouse-1}, and the menu bar buffer menu. You
657 can customize the menu in the @code{msb} Custom group.
658
659 @ignore
660 arch-tag: 08c43460-f4f4-4b43-9cb5-1ea9ad991695
661 @end ignore