1 @c This is part of the Emacs manual.
2 @c Copyright (C) 1985-1987, 1993-1995, 1997, 2000-2017 Free Software
4 @c See file emacs.texi for copying conditions.
6 @chapter Using Multiple 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 used to hold
11 the file's text. Each time you invoke Dired, a buffer is used to hold
12 the directory listing. If you send a message with @kbd{C-x m}, a
13 buffer is used to hold the text of the message. When you ask for a
14 command's documentation, that appears in a buffer named @file{*Help*}.
16 Each buffer has a unique name, which can be of any length. When a
17 buffer is displayed in a window, its name is shown in the mode line
18 (@pxref{Mode Line}). The distinction between upper and lower case
19 matters in buffer names. Most buffers are made by visiting files, and
20 their names are derived from the files' names; however, you can also
21 create an empty buffer with any name you want. A newly started Emacs
22 has several buffers, including one named @file{*scratch*}, which can
23 be used for evaluating Lisp expressions and is not associated with any
24 file (@pxref{Lisp Interaction}).
26 @cindex selected buffer
27 @cindex current buffer
28 At any time, one and only one buffer is @dfn{selected}; we call it
29 the @dfn{current buffer}. We sometimes say that a command operates on
30 ``the buffer''; this really means that it operates on the current
31 buffer. When there is only one Emacs window, the buffer displayed in
32 that window is current. When there are multiple windows, the buffer
33 displayed in the @dfn{selected window} is current. @xref{Windows}.
35 Aside from its textual contents, each buffer records several pieces
36 of information, such as what file it is visiting (if any), whether it
37 is modified, and what major mode and minor modes are in effect
38 (@pxref{Modes}). These are stored in @dfn{buffer-local
39 variables}---variables that can have a different value in each buffer.
42 @cindex buffer size, maximum
43 A buffer's size cannot be larger than some maximum, which is defined
44 by the largest buffer position representable by @dfn{Emacs integers}.
45 This is because Emacs tracks buffer positions using that data type.
46 For typical 64-bit machines, this maximum buffer size is @math{2^{61} - 2}
47 bytes, or about 2 EiB@. For typical 32-bit machines, the maximum is
48 usually @math{2^{29} - 2} bytes, or about 512 MiB@. Buffer sizes are
49 also limited by the amount of memory in the system.
52 * Select Buffer:: Creating a new buffer or reselecting an old one.
53 * List Buffers:: Getting a list of buffers that exist.
54 * Misc Buffer:: Renaming; changing read-only status; copying text.
55 * Kill Buffer:: Killing buffers you no longer need.
56 * Several Buffers:: How to go through the list of all buffers
57 and operate variously on several of them.
58 * Indirect Buffers:: An indirect buffer shares the text of another buffer.
59 * Buffer Convenience:: Convenience and customization features for
64 @section Creating and Selecting Buffers
65 @cindex change buffers
66 @cindex switch buffers
69 @item C-x b @var{buffer} @key{RET}
70 Select or create a buffer named @var{buffer} (@code{switch-to-buffer}).
71 @item C-x 4 b @var{buffer} @key{RET}
72 Similar, but select @var{buffer} in another window
73 (@code{switch-to-buffer-other-window}).
74 @item C-x 5 b @var{buffer} @key{RET}
75 Similar, but select @var{buffer} in a separate frame
76 (@code{switch-to-buffer-other-frame}).
78 Select the previous buffer in the buffer list (@code{previous-buffer}).
80 Select the next buffer in the buffer list (@code{next-buffer}).
83 Read a number @var{n} and move to line @var{n} in the most recently
84 selected buffer other than the current buffer.
88 @findex switch-to-buffer
89 The @kbd{C-x b} (@code{switch-to-buffer}) command reads a buffer
90 name using the minibuffer. Then it makes that buffer current, and
91 displays it in the currently-selected window. An empty input
92 specifies the buffer that was current most recently among those not
93 now displayed in any window.
95 While entering the buffer name, you can use the usual completion and
96 history commands (@pxref{Minibuffer}). Note that @kbd{C-x b}, and
97 related commands, use @dfn{permissive completion with confirmation} for
98 minibuffer completion: if you type @key{RET} immediately after
99 completing up to a nonexistent buffer name, Emacs prints
100 @samp{[Confirm]} and you must type a second @key{RET} to submit that
101 buffer name. @xref{Completion Exit}, for details. For other
102 completion options and features, see @ref{Completion Options}.
104 If you specify a buffer that does not exist, @kbd{C-x b} creates a
105 new, empty buffer that is not visiting any file, and selects it for
106 editing. The default value of the variable @code{major-mode}
107 determines the new buffer's major mode; the default value is
108 Fundamental mode. @xref{Major Modes}. One reason to create a new
109 buffer is to use it for making temporary notes. If you try to save
110 it, Emacs asks for the file name to use, and the buffer's major mode
111 is re-established taking that file name into account (@pxref{Choosing
117 @findex previous-buffer
118 For conveniently switching between a few buffers, use the commands
119 @kbd{C-x @key{LEFT}} and @kbd{C-x @key{RIGHT}}. @kbd{C-x @key{LEFT}}
120 (@code{previous-buffer}) selects the previous buffer (following the
121 order of most recent selection in the current frame), while @kbd{C-x
122 @key{RIGHT}} (@code{next-buffer}) moves through buffers in the reverse
126 @findex switch-to-buffer-other-window
127 To select a buffer in a window other than the current one, type
128 @kbd{C-x 4 b} (@code{switch-to-buffer-other-window}). This prompts
129 for a buffer name using the minibuffer, displays that buffer in
130 another window, and selects that window.
133 @findex switch-to-buffer-other-frame
134 Similarly, @kbd{C-x 5 b} (@code{switch-to-buffer-other-frame})
135 prompts for a buffer name, displays that buffer in another frame, and
136 selects that frame. If the buffer is already being shown in a window
137 on another frame, Emacs selects that window and frame instead of
138 creating a new frame.
140 @xref{Displaying Buffers}, for how the @kbd{C-x 4 b} and @kbd{C-x 5
141 b} commands get the window and/or frame to display in.
143 In addition, @kbd{C-x C-f}, and any other command for visiting a
144 file, can also be used to switch to an existing file-visiting buffer.
148 @kbd{C-u M-g M-g}, that is @code{goto-line} with a plain prefix
149 argument, reads a number @var{n} using the minibuffer, selects the
150 most recently selected buffer other than the current buffer in another
151 window, and then moves point to the beginning of line number @var{n}
152 in that buffer. This is mainly useful in a buffer that refers to line
153 numbers in another buffer: if point is on or just after a number,
154 @code{goto-line} uses that number as the default for @var{n}. Note
155 that prefix arguments other than just @kbd{C-u} behave differently.
156 @kbd{C-u 4 M-g M-g} goes to line 4 in the @emph{current} buffer,
157 without reading a number from the minibuffer. (Remember that @kbd{M-g
158 M-g} without prefix argument reads a number @var{n} and then moves to
159 line number @var{n} in the current buffer. @xref{Moving Point}.)
161 Emacs uses buffer names that start with a space for internal purposes.
162 It treats these buffers specially in minor ways---for example, by
163 default they do not record undo information. It is best to avoid using
164 such buffer names yourself.
167 @section Listing Existing Buffers
171 List the existing buffers (@code{list-buffers}).
174 @cindex listing current buffers
177 To display a list of existing buffers, type @kbd{C-x C-b}. This
178 pops up a buffer menu in a buffer named @file{*Buffer List*}. Each
179 line in the list shows one buffer's name, size, major mode and visited file.
180 The buffers are listed in the order that they were current; the
181 buffers that were current most recently come first. This section
182 describes how the list of buffers is displayed and how to interpret
183 the various indications in the list; see @ref{Several Buffers}, for
184 description of the special mode in the @file{*Buffer List*} buffer and
185 the commands available there.
187 @samp{.} in the first field of a line indicates that the buffer is
188 current. @samp{%} indicates a read-only buffer. @samp{*} indicates
189 that the buffer is modified. If several buffers are modified, it
190 may be time to save some with @kbd{C-x s} (@pxref{Save Commands}).
191 Here is an example of a buffer list:
194 CRM Buffer Size Mode File
195 . * .emacs 3294 Emacs-Lisp ~/.emacs
197 search.c 86055 C ~/cvs/emacs/src/search.c
198 % src 20959 Dired by name ~/cvs/emacs/src/
200 % HELLO 1607 Fundamental ~/cvs/emacs/etc/HELLO
201 % NEWS 481184 Outline ~/cvs/emacs/etc/NEWS
202 *scratch* 191 Lisp Interaction
203 * *Messages* 1554 Messages
207 The buffer @file{*Help*} was made by a help request (@pxref{Help}); it
208 is not visiting any file. The buffer @code{src} was made by Dired on
209 the directory @file{~/cvs/emacs/src/}. You can list only buffers that
210 are visiting files by giving the command a prefix argument, as in
213 @code{list-buffers} omits buffers whose names begin with a space,
214 unless they visit files: such buffers are used internally by Emacs.
217 @section Miscellaneous Buffer Operations
221 Toggle read-only status of buffer (@code{read-only-mode}).
222 @item M-x rename-buffer @key{RET} @var{name} @key{RET}
223 Change the name of the current buffer.
224 @item M-x rename-uniquely
225 Rename the current buffer by adding @samp{<@var{number}>} to the end.
226 @item M-x view-buffer @key{RET} @var{buffer} @key{RET}
227 Scroll through buffer @var{buffer}. @xref{View Mode}.
231 @vindex buffer-read-only
232 @cindex read-only buffer
233 A buffer can be @dfn{read-only}, which means that commands to change
234 its contents are not allowed. The mode line indicates read-only
235 buffers with @samp{%%} or @samp{%*} near the left margin. @xref{Mode
236 Line}. Read-only buffers are usually made by subsystems such as Dired
237 and Rmail that have special commands to operate on the text; also by
238 visiting a file whose access control says you cannot write it.
240 @findex read-only-mode
241 @vindex view-read-only
242 The command @kbd{C-x C-q} (@code{read-only-mode}) makes a read-only
243 buffer writable, and makes a writable buffer read-only. This works by
244 setting the variable @code{buffer-read-only}, which has a local value
245 in each buffer and makes the buffer read-only if its value is
246 non-@code{nil}. If you change the option @code{view-read-only} to a
247 non-@code{nil} value, making the buffer read-only with @kbd{C-x C-q}
248 also enables View mode in the buffer (@pxref{View Mode}).
250 @findex rename-buffer
251 @kbd{M-x rename-buffer} changes the name of the current buffer. You
252 specify the new name as a minibuffer argument; there is no default.
253 If you specify a name that is in use for some other buffer, an error
254 happens and no renaming is done.
256 @findex rename-uniquely
257 @kbd{M-x rename-uniquely} renames the current buffer to a similar
258 name with a numeric suffix added to make it both different and unique.
259 This command does not need an argument. It is useful for creating
260 multiple shell buffers: if you rename the @file{*shell*} buffer, then
261 do @kbd{M-x shell} again, it makes a new shell buffer named
262 @file{*shell*}; meanwhile, the old shell buffer continues to exist
263 under its new name. This method is also good for mail buffers,
264 compilation buffers, and most Emacs features that create special
265 buffers with particular names. (With some of these features, such as
266 @kbd{M-x compile}, @kbd{M-x grep}, you need to switch to some other
267 buffer before using the command again, otherwise it will reuse the
268 current buffer despite the name change.)
270 The commands @kbd{M-x append-to-buffer} and @kbd{M-x insert-buffer}
271 can also be used to copy text from one buffer to another.
272 @xref{Accumulating Text}.
275 @section Killing Buffers
277 @cindex killing buffers
280 If you continue an Emacs session for a while, you may accumulate a
281 large number of buffers. You may then find it convenient to @dfn{kill}
282 the buffers you no longer need. (Some other editors call this
283 operation @dfn{close}, and talk about ``closing the buffer'' or
284 ``closing the file'' visited in the buffer.) On most operating
285 systems, killing a buffer releases its space back to the operating
286 system so that other programs can use it. Here are some commands for
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 @item M-x kill-matching-buffers
295 Offer to kill all buffers matching a regular expression.
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, then you must
306 confirm with @kbd{yes} before the buffer is killed.
308 @findex kill-some-buffers
309 The command @kbd{M-x kill-some-buffers} asks about each buffer, one
310 by one. An answer of @kbd{y} means to kill the buffer, just like
311 @code{kill-buffer}. This command ignores buffers whose names begin
312 with a space, which are used internally by Emacs.
314 @findex kill-matching-buffers
315 The command @kbd{M-x kill-matching-buffers} prompts for a regular
316 expression and kills all buffers whose names match that expression.
317 @xref{Regexps}. Like @code{kill-some-buffers}, it asks for
318 confirmation before each kill. This command normally ignores buffers
319 whose names begin with a space, which are used internally by Emacs.
320 To kill internal buffers as well, call @code{kill-matching-buffers}
321 with a prefix argument.
323 The Buffer Menu feature is also convenient for killing various
324 buffers. @xref{Several Buffers}.
326 @vindex kill-buffer-hook
327 If you want to do something special every time a buffer is killed, you
328 can add hook functions to the hook @code{kill-buffer-hook} (@pxref{Hooks}).
330 @findex clean-buffer-list
331 If you run one Emacs session for a period of days, as many people do,
332 it can fill up with buffers that you used several days ago. The command
333 @kbd{M-x clean-buffer-list} is a convenient way to purge them; it kills
334 all the unmodified buffers that you have not used for a long time. An
335 ordinary buffer is killed if it has not been displayed for three days;
336 however, you can specify certain buffers that should never be killed
337 automatically, and others that should be killed if they have been unused
340 @cindex Midnight mode
341 @vindex midnight-mode
342 @vindex midnight-hook
343 You can also have this buffer purging done for you, once a day,
344 by enabling Midnight mode. Midnight mode operates each day
345 at midnight; at that time, it runs @code{clean-buffer-list}, or
346 whichever functions you have placed in the normal hook
347 @code{midnight-hook} (@pxref{Hooks}). To enable Midnight mode, use
348 the Customization buffer to set the variable @code{midnight-mode} to
349 @code{t}. @xref{Easy Customization}.
351 @node Several Buffers
352 @section Operating on Several Buffers
356 @item M-x buffer-menu
357 Begin editing a buffer listing all Emacs buffers.
358 @item M-x buffer-menu-other-window
359 Similar, but do it in another window.
362 The @dfn{Buffer Menu} opened by @kbd{C-x C-b} (@pxref{List Buffers})
363 does not merely list buffers. It also allows you to perform various
364 operations on buffers, through an interface similar to Dired
365 (@pxref{Dired}). You can save buffers, kill them (here called
366 @dfn{deleting} them, for consistency with Dired), or display them.
369 @findex buffer-menu-other-window
370 To use the Buffer Menu, type @kbd{C-x C-b} and switch to the window
371 displaying the @file{*Buffer List*} buffer. You can also type
372 @kbd{M-x buffer-menu} to open the Buffer Menu in the selected window.
373 Alternatively, the command @kbd{M-x buffer-menu-other-window} opens
374 the Buffer Menu in another window, and selects that window.
376 The Buffer Menu is a read-only buffer, and can be changed only
377 through the special commands described in this section. The usual
378 cursor motion commands can be used in this buffer. The following
379 commands apply to the buffer described on the current line:
383 @findex Buffer-menu-delete
384 @kindex d @r{(Buffer Menu)}
385 Flag the buffer for deletion (killing), then move point to the next
386 line (@code{Buffer-menu-delete}). The deletion flag is indicated by
387 the character @samp{D} on the line, before the buffer name. The
388 deletion occurs only when you type the @kbd{x} command (see below).
391 @findex Buffer-menu-delete-backwards
392 @kindex C-d @r{(Buffer Menu)}
393 Like @kbd{d}, but move point up instead of down
394 (@code{Buffer-menu-delete-backwards}).
397 @findex Buffer-menu-save
398 @kindex s @r{(Buffer Menu)}
399 Flag the buffer for saving (@code{Buffer-menu-save}). The save flag
400 is indicated by the character @samp{S} on the line, before the buffer
401 name. The saving occurs only when you type @kbd{x}. You may request
402 both saving and deletion for the same buffer.
405 @findex Buffer-menu-execute
406 @kindex x @r{(Buffer Menu)}
407 Perform all flagged deletions and saves (@code{Buffer-menu-execute}).
410 @findex Buffer-menu-unmark
411 @kindex u @r{(Buffer Menu)}
412 Remove all flags from the current line, and move down
413 (@code{Buffer-menu-unmark}).
416 @findex Buffer-menu-backup-unmark
417 @kindex DEL @r{(Buffer Menu)}
418 Move to the previous line and remove all flags on that line
419 (@code{Buffer-menu-backup-unmark}).
422 @findex Buffer-menu-unmark-all-buffers
423 @kindex M-DEL @r{(Buffer Menu)}
424 Remove a particular flag from all lines
425 (@code{Buffer-menu-unmark-all-buffers}).
428 @findex Buffer-menu-unmark-all
429 @kindex U @r{(Buffer Menu)}
430 Remove all flags from all the lines
431 (@code{Buffer-menu-unmark-all}).
435 The commands for adding or removing flags, @kbd{d}, @kbd{C-d}, @kbd{s}
436 and @kbd{u}, all accept a numeric argument as a repeat count.
438 The following commands operate immediately on the buffer listed on
439 the current line. They also accept a numeric argument as a repeat
444 @findex Buffer-menu-not-modified
445 @kindex ~ @r{(Buffer Menu)}
446 Mark the buffer as unmodified (@code{Buffer-menu-not-modified}).
447 @xref{Save Commands}.
450 @findex Buffer-menu-toggle-read-only
451 @kindex % @r{(Buffer Menu)}
452 Toggle the buffer's read-only status
453 (@code{Buffer-menu-toggle-read-only}). @xref{Misc Buffer}.
456 @findex Buffer-menu-visit-tags-table
457 @kindex % @r{(Buffer Menu)}
458 Visit the buffer as a tags table
459 (@code{Buffer-menu-visit-tags-table}). @xref{Select Tags Table}.
462 The following commands are used to select another buffer or buffers:
467 @kindex q @r{(Buffer Menu)}
468 Quit the Buffer Menu (@code{quit-window}). The most recent formerly
469 visible buffer is displayed in its place.
473 @findex Buffer-menu-this-window
474 @kindex f @r{(Buffer Menu)}
475 @kindex RET @r{(Buffer Menu)}
476 Select this line's buffer, replacing the @file{*Buffer List*} buffer
477 in its window (@code{Buffer-menu-this-window}).
480 @findex Buffer-menu-other-window
481 @kindex o @r{(Buffer Menu)}
482 Select this line's buffer in another window, as if by @kbd{C-x 4 b},
483 leaving @file{*Buffer List*} visible
484 (@code{Buffer-menu-other-window}).
487 @findex Buffer-menu-switch-other-window
488 @kindex C-o @r{(Buffer Menu)}
489 Display this line's buffer in another window, without selecting it
490 (@code{Buffer-menu-switch-other-window}).
493 @findex Buffer-menu-1-window
494 @kindex 1 @r{(Buffer Menu)}
495 Select this line's buffer in a full-frame window
496 (@code{Buffer-menu-1-window}).
499 @findex Buffer-menu-2-window
500 @kindex 2 @r{(Buffer Menu)}
501 Set up two windows on the current frame, with this line's buffer
502 selected in one, and a previously current buffer (aside from
503 @file{*Buffer List*}) in the other (@code{Buffer-menu-2-window}).
506 @findex Buffer-menu-bury
507 @kindex b @r{(Buffer Menu)}
508 Bury this line's buffer (@code{Buffer-menu-bury}).
511 @findex Buffer-menu-mark
512 @kindex m @r{(Buffer Menu)}
513 Mark this line's buffer to be displayed in another window if you exit
514 with the @kbd{v} command (@code{Buffer-menu-mark}). The display flag
515 is indicated by the character @samp{>} at the beginning of the line.
516 (A single buffer may not have both deletion and display flags.)
519 @findex Buffer-menu-select
520 @kindex v @r{(Buffer Menu)}
521 Select this line's buffer, and also display in other windows any
522 buffers flagged with the @kbd{m} command (@code{Buffer-menu-select}).
523 If you have not flagged any buffers, this command is equivalent to
527 The following commands affect the entire buffer list:
531 @findex tabulated-list-sort
532 @kindex S @r{(Buffer Menu)}
533 Sort the Buffer Menu entries according to their values in the column
534 at point. With a numeric prefix argument @var{n}, sort according to
535 the @var{n}-th column (@code{tabulated-list-sort}).
538 @findex Buffer-menu-toggle-files-only
539 @kindex T @r{(Buffer Menu)}
540 Delete, or reinsert, lines for non-file buffers
541 (@code{Buffer-menu-toggle-files-only}). This command toggles the
542 inclusion of such buffers in the buffer list.
545 Normally, the buffer @file{*Buffer List*} is not updated
546 automatically when buffers are created and killed; its contents are
547 just text. If you have created, deleted or renamed buffers, the way
548 to update @file{*Buffer List*} to show what you have done is to type
549 @kbd{g} (@code{revert-buffer}). You can make this happen regularly
550 every @code{auto-revert-interval} seconds if you enable Auto Revert
551 mode in this buffer, as long as it is not marked modified. Global
552 Auto Revert mode applies to the @file{*Buffer List*} buffer only if
553 @code{global-auto-revert-non-file-buffers} is non-@code{nil}.
555 @inforef{Autorevert,, emacs-xtra}, for details.
558 @xref{Autorevert, global-auto-revert-non-file-buffers}, for details.
561 @node Indirect Buffers
562 @section Indirect Buffers
563 @cindex indirect buffer
566 An @dfn{indirect buffer} shares the text of some other buffer, which
567 is called the @dfn{base buffer} of the indirect buffer. In some ways it
568 is a buffer analogue of a symbolic link between files.
571 @findex make-indirect-buffer
572 @item M-x make-indirect-buffer @key{RET} @var{base-buffer} @key{RET} @var{indirect-name} @key{RET}
573 Create an indirect buffer named @var{indirect-name} with base buffer
575 @findex clone-indirect-buffer
576 @item M-x clone-indirect-buffer @key{RET}
577 Create an indirect buffer that is a twin copy of the current buffer.
580 @findex clone-indirect-buffer-other-window
581 Create an indirect buffer that is a twin copy of the current buffer, and
582 select it in another window (@code{clone-indirect-buffer-other-window}).
585 The text of the indirect buffer is always identical to the text of its
586 base buffer; changes made by editing either one are visible immediately
587 in the other. But in all other respects, the indirect buffer and its
588 base buffer are completely separate. They can have different names,
589 different values of point, different narrowing, different markers,
590 different major modes, and different local variables.
592 An indirect buffer cannot visit a file, but its base buffer can. If
593 you try to save the indirect buffer, that actually works by saving the
594 base buffer. Killing the base buffer effectively kills the indirect
595 buffer, but killing an indirect buffer has no effect on its base buffer.
597 One way to use indirect buffers is to display multiple views of an
598 outline. @xref{Outline Views}.
600 @vindex clone-indirect-buffer-hook
601 A quick and handy way to make an indirect buffer is with the command
602 @kbd{M-x clone-indirect-buffer}. It creates and selects an indirect
603 buffer whose base buffer is the current buffer. With a numeric
604 argument, it prompts for the name of the indirect buffer; otherwise it
605 uses the name of the current buffer, with a @samp{<@var{n}>} suffix
606 added. @kbd{C-x 4 c} (@code{clone-indirect-buffer-other-window})
607 works like @kbd{M-x clone-indirect-buffer}, but it selects the new
608 buffer in another window. These functions run the hook
609 @code{clone-indirect-buffer-hook} after creating the indirect buffer.
611 The more general way to make an indirect buffer is with the command
612 @kbd{M-x make-indirect-buffer}. It creates an indirect buffer
613 named @var{indirect-name} from a buffer @var{base-buffer}, prompting for
614 both using the minibuffer.
616 @node Buffer Convenience
617 @section Convenience Features and Customization of Buffer Handling
619 This section describes several modes and features that make it more
620 convenient to switch between buffers.
623 * Uniquify:: Making buffer names unique with directory parts.
624 * Icomplete:: Fast minibuffer selection.
625 * Buffer Menus:: Configurable buffer menu.
629 @subsection Making Buffer Names Unique
631 @cindex unique buffer names
632 @cindex directories in buffer names
633 When several buffers visit identically-named files, Emacs must give
634 the buffers distinct names. The default method adds a suffix based on
635 the names of the directories that contain the files. For example, if
636 you visit files @file{/foo/bar/mumble/name} and
637 @file{/baz/quux/mumble/name} at the same time, their buffers will be
638 named @samp{name<bar/mumble>} and @samp{name<quux/mumble>}, respectively.
639 Emacs adds as many directory parts as are needed to make a unique name.
641 @vindex uniquify-buffer-name-style
642 You can choose from several different styles for constructing unique
643 buffer names, by customizing the option @code{uniquify-buffer-name-style}.
645 The @code{forward} naming method includes part of the file's
646 directory name at the beginning of the buffer name; using this method,
647 buffers visiting the files @file{/u/rms/tmp/Makefile} and
648 @file{/usr/projects/zaphod/Makefile} would be named
649 @samp{tmp/Makefile} and @samp{zaphod/Makefile}.
651 In contrast, the @code{post-forward} naming method would call the
652 buffers @samp{Makefile|tmp} and @samp{Makefile|zaphod}. The default
653 method @code{post-forward-angle-brackets} is like @code{post-forward},
654 except that it encloses the unique path in angle brackets. The
655 @code{reverse} naming method would call them @samp{Makefile\tmp} and
656 @samp{Makefile\zaphod}. The nontrivial difference between
657 @code{post-forward} and @code{reverse} occurs when just one directory
658 name is not enough to distinguish two files; then @code{reverse} puts
659 the directory names in reverse order, so that @file{/top/middle/file}
660 becomes @samp{file\middle\top}, while @code{post-forward} puts them in
661 forward order after the file name, as in @samp{file|top/middle}. If
662 @code{uniquify-buffer-name-style} is set to @code{nil}, the buffer
663 names simply get @samp{<2>}, @samp{<3>}, etc.@: appended.
665 Which rule to follow for putting the directory names in the buffer
666 name is not very important if you are going to @emph{look} at the
667 buffer names before you type one. But as an experienced user, if you
668 know the rule, you won't have to look. And then you may find that one
669 rule or another is easier for you to remember and apply quickly.
672 @subsection Fast minibuffer selection
674 @findex icomplete-mode
675 @cindex Icomplete mode
677 Icomplete global minor mode provides a convenient way to quickly select an
678 element among the possible completions in a minibuffer. When enabled, typing
679 in the minibuffer continuously displays a list of possible completions that
680 match the string you have typed.
682 At any time, you can type @kbd{C-j} to select the first completion in
683 the list. So the way to select a particular completion is to make it the
684 first in the list. There are two ways to do this. You can type more
685 of the completion name and thus narrow down the list, excluding unwanted
686 completions above the desired one. Alternatively, you can use @kbd{C-.}
687 and @kbd{C-,} to rotate the list until the desired buffer is first.
689 @kbd{M-@key{TAB}} will select the first completion in the list, like
690 @kbd{C-j} but without exiting the minibuffer, so you can edit it
691 further. This is typically used when entering a file name, where
692 @kbd{M-@key{TAB}} can be used a few times to descend in the hierarchy
695 To enable Icomplete mode, type @kbd{M-x icomplete-mode}, or customize
696 the variable @code{icomplete-mode} to @code{t} (@pxref{Easy
700 @subsection Customizing Buffer Menus
703 @cindex buffer list, customizable
706 Make a list of buffers similarly to @kbd{M-x list-buffers} but
709 Make a list of buffers and operate on them in Dired-like fashion.
713 @kbd{M-x bs-show} pops up a buffer list similar to the one normally
714 displayed by @kbd{C-x C-b}, but whose display you can customize in a
715 more flexible fashion. For example, you can specify the list of
716 buffer attributes to show, the minimum and maximum width of buffer
717 name column, a regexp for names of buffers that will never be shown
718 and those which will always be shown, etc. If you prefer
719 this to the usual buffer list, you can bind this command to @kbd{C-x
720 C-b}. To customize this buffer list, use the @code{bs} Custom group
721 (@pxref{Easy Customization}), or invoke @kbd{bs-customize}.
726 @findex mouse-buffer-menu
727 @kindex C-Down-mouse-1
728 MSB global minor mode (``MSB'' stands for ``mouse select buffer'')
729 provides a different and customizable mouse buffer menu which you may
730 prefer. It replaces the bindings of @code{mouse-buffer-menu},
731 normally on @kbd{C-Down-mouse-1} and @kbd{C-@key{F10}}, and the menu
732 bar buffer menu. You can customize the menu in the @code{msb} Custom
736 IBuffer is a major mode for viewing a list of buffers and operating
737 on them in a way analogous to that of Dired (@pxref{Dired}), including
738 filtering, marking, sorting in various ways, and acting on buffers.