buffers.texi 28 KB
Newer Older
Dave Love's avatar
Dave Love committed
@c This is part of the Emacs manual.
@c Copyright (C) 1985, 86, 87, 93, 94, 95, 97, 2000, 2001, 2004
Dave Love's avatar
Dave Love committed
@c   Free Software Foundation, Inc.
Dave Love's avatar
Dave Love committed
4 5 6 7 8 9 10 11 12 13 14 15 16 17
@c See file emacs.texi for copying conditions.
@node Buffers, Windows, Files, Top
@chapter Using Multiple Buffers

@cindex buffers
  The text you are editing in Emacs resides in an object called a
@dfn{buffer}.  Each time you visit a file, a buffer is created to hold the
file's text.  Each time you invoke Dired, a buffer is created to hold the
directory listing.  If you send a message with @kbd{C-x m}, a buffer named
@samp{*mail*} is used to hold the text of the message.  When you ask for a
command's documentation, that appears in a buffer called @samp{*Help*}.

@cindex selected buffer
@cindex current buffer
18 19
  At any time, one and only one buffer is @dfn{current}.  It is also
called the @dfn{selected buffer}.  Often we say that a command operates on
Dave Love's avatar
Dave Love committed
``the buffer'' as if there were only one; but really this means that the
command operates on the current buffer (most commands do).
Dave Love's avatar
Dave Love committed

Richard M. Stallman's avatar
Richard M. Stallman committed
23 24
  When Emacs has multiple windows, each window has its own chosen
buffer and displays it; at any time, only one of the windows is
selected, and its chosen buffer is the current buffer.  Each window's
Richard M. Stallman's avatar
Richard M. Stallman committed
26 27
mode line normally displays the name of the window's chosen buffer
Dave Love's avatar
Dave Love committed
28 29 30 31 32 33 34 35 36 37 38 39 40 41 42

  Each buffer has a name, which can be of any length, and you can select
any buffer by giving its name.  Most buffers are made by visiting files,
and their names are derived from the files' names.  But you can also create
an empty buffer with any name you want.  A newly started Emacs has a buffer
named @samp{*scratch*} which can be used for evaluating Lisp expressions in
Emacs.  The distinction between upper and lower case matters in buffer

  Each buffer records individually what file it is visiting, whether it is
modified, and what major mode and minor modes are in effect in it
(@pxref{Major Modes}).  Any Emacs variable can be made @dfn{local to} a
particular buffer, meaning its value in that buffer can be different from
the value in other buffers.  @xref{Locals}.

43 44
@cindex buffer size, maximum
  A buffer's size cannot be larger than some maximum, which is defined
Eli Zaretskii's avatar
Eli Zaretskii committed
45 46
by the largest buffer position representable by the @dfn{Emacs integer}
data type.  This is because Emacs tracks buffer positions using that
data type.  For 32-bit machines, the largest buffer size is 256
Eli Zaretskii's avatar
Eli Zaretskii committed

Dave Love's avatar
Dave Love committed
50 51 52 53 54 55 56
* Select Buffer::       Creating a new buffer or reselecting an old one.
* List Buffers::        Getting a list of buffers that exist.
* Misc Buffer::	        Renaming; changing read-onlyness; copying text.
* Kill Buffer::	        Killing buffers you no longer need.
* Several Buffers::     How to go through the list of all buffers
			  and operate variously on several of them.
* Indirect Buffers::    An indirect buffer shares the text of another buffer.
Dave Love's avatar
Dave Love committed
58 59
* Buffer Convenience::  Convenience and customization features for
                          buffer handling.
Dave Love's avatar
Dave Love committed
60 61 62 63 64 65 66 67 68 69
@end menu

@node Select Buffer
@section Creating and Selecting Buffers
@cindex change buffers
@cindex switch buffers

@table @kbd
@item C-x b @var{buffer} @key{RET}
Select or create a buffer named @var{buffer} (@code{switch-to-buffer}).
70 71 72 73
@item C-x @key{LEFT}
Select the previous buffer in the list of existing buffers.
@item C-x @key{RIGHT}
Select the next buffer in the list of existing buffers.
Dave Love's avatar
Dave Love committed
74 75 76 77 78 79
@item C-x 4 b @var{buffer} @key{RET}
Similar, but select @var{buffer} in another window
@item C-x 5 b @var{buffer} @key{RET}
Similar, but select @var{buffer} in a separate frame
80 81 82 83
@item C-u M-g M-g
@itemx C-u M-g g
Read a number @var{n} and move to line @var{n} in the most recently
selected buffer other than the current buffer.
Dave Love's avatar
Dave Love committed
84 85 86 87 88 89 90 91
@end table

@kindex C-x b
@findex switch-to-buffer
  To select the buffer named @var{bufname}, type @kbd{C-x b @var{bufname}
@key{RET}}.  This runs the command @code{switch-to-buffer} with argument
@var{bufname}.  You can use completion on an abbreviation for the buffer
name you want (@pxref{Completion}).  An empty argument to @kbd{C-x b}
92 93
specifies the buffer that was current most recently among those not
now displayed in any window.
Dave Love's avatar
Dave Love committed

95 96 97 98 99 100 101 102 103 104
@kindex C-x @key{LEFT}
@kindex C-x @key{RIGHT}
@findex next-buffer
@findex prev-buffer
  For conveniently switching between a few buffers, use the commands
@kbd{C-x @key{LEFT}} and @kbd{C-x @key{RIGHT}}.  @kbd{C-x @key{RIGHT}}
(@code{prev-buffer}) selects the previous buffer (following the order
of most recent selection), while @kbd{C-x @key{LEFT}}
(@code{next-buffer}) moves through buffers in the reverse direction.

105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132
@kindex C-x 4 b
@findex switch-to-buffer-other-window
@vindex even-window-heights
  To select a buffer in a window other than the current one, type
@kbd{C-x 4 b @var{bufname} @key{RET}}.  This runs the command
@code{switch-to-buffer-other-window} which displays the buffer
@var{bufname} in another window.  By default, if displaying the buffer
causes two vertically adjacent windows to be displayed, the heights of
those windows are evened out; to countermand that and preserve the
window configuration, set the variable @code{even-window-heights} to

@kindex C-x 5 b
@findex switch-to-buffer-other-frame
  Similarly, @kbd{C-x 5 b @var{buffer} @key{RET}} runs the command
@code{switch-to-buffer-other-frame} which selects a buffer in another

@vindex display-buffer-reuse-frames
  You can control how certain buffers are handled by these commands by
customizing the variables @code{special-display-buffer-names},
@code{special-display-regexps}, @code{same-window-buffer-names}, and
@code{same-window-regexps}.  See @ref{Force Same Window}, and
@ref{Special Buffer Frames}, for more about these variables.  In
addition, if the value of @code{display-buffer-reuse-frames} is
non-@code{nil}, and the buffer you want to switch to is already
displayed in some frame, Emacs will raise that frame.

Dave Love's avatar
Dave Love committed
133 134 135 136 137 138 139 140 141 142 143 144 145
  Most buffers are created by visiting files, or by Emacs commands that
want to display some text, but you can also create a buffer explicitly
by typing @kbd{C-x b @var{bufname} @key{RET}}.  This makes a new, empty
buffer that is not visiting any file, and selects it for editing.  Such
buffers are used for making notes to yourself.  If you try to save one,
you are asked for the file name to use.  The new buffer's major mode is
determined by the value of @code{default-major-mode} (@pxref{Major

  Note that @kbd{C-x C-f}, and any other command for visiting a file,
can also be used to switch to an existing file-visiting buffer.

146 147 148 149 150 151 152 153 154 155 156 157 158
  @kbd{C-u M-g M-g}, that is @code{goto-line} with a prefix argument
of just @kbd{C-u}, reads a number @var{n} using the minibuffer,
selects the most recently selected buffer other than the current
buffer in another window, and then moves point to the beginning of
line number @var{n} in that buffer.  This is mainly useful in a buffer
that refers to line numbers in another buffer: if point is on or just
after a number, @code{goto-line} uses that number as the default for
@var{n}.  Note that prefix arguments other than just @kbd{C-u} behave
differently.  @kbd{C-u 4 M-g M-g} goes to line 4 in the @emph{current}
buffer, without reading a number from the minibuffer.  (Remember that
@kbd{M-g M-g} without prefix argument reads a number @var{n} and then
moves to line number @var{n} in the current buffer.)

Dave Love's avatar
Dave Love committed
159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174
  Emacs uses buffer names that start with a space for internal purposes.
It treats these buffers specially in minor ways---for example, by
default they do not record undo information.  It is best to avoid using
such buffer names yourself.

@node List Buffers
@section Listing Existing Buffers

@table @kbd
@item C-x C-b
List the existing buffers (@code{list-buffers}).
@end table

@cindex listing current buffers
@kindex C-x C-b
@findex list-buffers
175 176 177
  To display a list of existing buffers, type @kbd{C-x C-b}.  Each
line in the list shows one buffer's name, major mode and visited file.
The buffers are listed in the order that they were current; the
Dave Love's avatar
Dave Love committed
178 179
buffers that were current most recently come first.

  @samp{*} in the first field of a line indicates the buffer is ``modified.''
Dave Love's avatar
Dave Love committed
181 182
If several buffers are modified, it may be time to save some with @kbd{C-x s}
(@pxref{Saving}).  @samp{%} indicates a read-only buffer.  @samp{.} marks the
current buffer.  Here is an example of a buffer list:@refill
Dave Love's avatar
Dave Love committed
184 185

CRM Buffer                Size  Mode              File
187 188
. * .emacs                3294  Emacs-Lisp        ~/.emacs
 %  *Help*                 101  Help
189 190
    search.c             86055  C                 ~/cvs/emacs/src/search.c
 %  src                  20959  Dired by name     ~/cvs/emacs/src/
  * *mail*                  42  Mail
192 193 194 195
 %  HELLO                 1607  Fundamental       ~/cvs/emacs/etc/HELLO
 %  NEWS                481184  Outline           ~/cvs/emacs/etc/NEWS
    *scratch*              191  Lisp Interaction
  * *Messages*            1554  Fundamental
Dave Love's avatar
Dave Love committed
196 197 198
@end smallexample

Note that the buffer @samp{*Help*} was made by a help request; it is
200 201
not visiting any file.  The buffer @code{src} was made by Dired on the
directory @file{~/cvs/emacs/src/}.  You can list only buffers that are
202 203
visiting files by giving the command a prefix; for instance, by typing
@kbd{C-u C-x C-b}.
Dave Love's avatar
Dave Love committed

  @code{list-buffers} omits buffers whose names begin with a space,
206 207
unless they visit files: such buffers are used internally by Emacs.

Dave Love's avatar
Dave Love committed
208 209 210 211 212 213
@need 2000
@node Misc Buffer
@section Miscellaneous Buffer Operations

@table @kbd
@item C-x C-q
Toggle read-only status of buffer (@code{toggle-read-only}).
Dave Love's avatar
Dave Love committed
215 216 217 218 219 220 221 222 223 224 225 226
@item M-x rename-buffer @key{RET} @var{name} @key{RET}
Change the name of the current buffer.
@item M-x rename-uniquely
Rename the current buffer by adding @samp{<@var{number}>} to the end.
@item M-x view-buffer @key{RET} @var{buffer} @key{RET}
Scroll through buffer @var{buffer}.
@end table

@kindex C-x C-q
@vindex buffer-read-only
@cindex read-only buffer
  A buffer can be @dfn{read-only}, which means that commands to change
227 228 229 230 231
its contents are not allowed.  The mode line indicates read-only
buffers with @samp{%%} or @samp{%*} near the left margin.  Read-only
buffers are usually made by subsystems such as Dired and Rmail that
have special commands to operate on the text; also by visiting a file
whose access control says you cannot write it.
Dave Love's avatar
Dave Love committed

@findex toggle-read-only
Dave Love's avatar
Dave Love committed
  If you wish to make changes in a read-only buffer, use the command
235 236
@kbd{C-x C-q} (@code{toggle-read-only}).  It makes a read-only buffer
writable, and makes a writable buffer read-only.  This
Dave Love's avatar
Dave Love committed
237 238
works by setting the variable @code{buffer-read-only}, which has a local
value in each buffer and makes the buffer read-only if its value is
239 240 241 242
non-@code{nil}.  If you have files under version control, you may find
it convenient to bind @kbd{C-x C-q} to @code{vc-toggle-read-only}
instead.  Then, typing @kbd{C-x C-q} not only changes the read-only
flag, but it also checks the file in or out.  @xref{Version
Dave Love's avatar
Dave Love committed
243 244 245 246 247 248 249 250

@findex rename-buffer
  @kbd{M-x rename-buffer} changes the name of the current buffer.  Specify
the new name as a minibuffer argument.  There is no default.  If you
specify a name that is in use for some other buffer, an error happens and
no renaming is done.

@findex rename-uniquely
252 253 254 255 256 257 258 259 260 261 262 263
  @kbd{M-x rename-uniquely} renames the current buffer to a similar
name with a numeric suffix added to make it both different and unique.
This command does not need an argument.  It is useful for creating
multiple shell buffers: if you rename the @samp{*Shell*} buffer, then
do @kbd{M-x shell} again, it makes a new shell buffer named
@samp{*Shell*}; meanwhile, the old shell buffer continues to exist
under its new name.  This method is also good for mail buffers,
compilation buffers, and most Emacs features that create special
buffers with particular names.  (With some of these features, such as
@kbd{M-x compile}, @kbd{M-x grep} an @kbd{M-x info}, you need to
switch to some other buffer before using the command, in order for it
to make a different buffer.)
Dave Love's avatar
Dave Love committed
264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300

@findex view-buffer
  @kbd{M-x view-buffer} is much like @kbd{M-x view-file} (@pxref{Misc
File Ops}) except that it examines an already existing Emacs buffer.
View mode provides commands for scrolling through the buffer
conveniently but not for changing it.  When you exit View mode with
@kbd{q}, that switches back to the buffer (and the position) which was
previously displayed in the window.  Alternatively, if you exit View
mode with @kbd{e}, the buffer and the value of point that resulted from
your perusal remain in effect.

  The commands @kbd{M-x append-to-buffer} and @kbd{M-x insert-buffer}
can be used to copy text from one buffer to another.  @xref{Accumulating

@node Kill Buffer
@section Killing Buffers

@cindex killing buffers
  If you continue an Emacs session for a while, you may accumulate a
large number of buffers.  You may then find it convenient to @dfn{kill}
the buffers you no longer need.  On most operating systems, killing a
buffer releases its space back to the operating system so that other
programs can use it.  Here are some commands for killing buffers:

@table @kbd
@item C-x k @var{bufname} @key{RET}
Kill buffer @var{bufname} (@code{kill-buffer}).
@item M-x kill-some-buffers
Offer to kill each buffer, one by one.
@end table

@findex kill-buffer
@findex kill-some-buffers
@kindex C-x k

  @kbd{C-x k} (@code{kill-buffer}) kills one buffer, whose name you
301 302 303 304 305 306 307
specify in the minibuffer.  The default, used if you type just
@key{RET} in the minibuffer, is to kill the current buffer.  If you
kill the current buffer, another buffer becomes current: one that was
current in the recent past but is not displayed in any window now.  If
you ask to kill a file-visiting buffer that is modified (has unsaved
editing), then you must confirm with @kbd{yes} before the buffer is
Dave Love's avatar
Dave Love committed
308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355

  The command @kbd{M-x kill-some-buffers} asks about each buffer, one by
one.  An answer of @kbd{y} means to kill the buffer.  Killing the current
buffer or a buffer containing unsaved changes selects a new buffer or asks
for confirmation just like @code{kill-buffer}.

  The buffer menu feature (@pxref{Several Buffers}) is also convenient
for killing various buffers.

@vindex kill-buffer-hook
  If you want to do something special every time a buffer is killed, you
can add hook functions to the hook @code{kill-buffer-hook} (@pxref{Hooks}).

@findex clean-buffer-list
  If you run one Emacs session for a period of days, as many people do,
it can fill up with buffers that you used several days ago.  The command
@kbd{M-x clean-buffer-list} is a convenient way to purge them; it kills
all the unmodified buffers that you have not used for a long time.  An
ordinary buffer is killed if it has not been displayed for three days;
however, you can specify certain buffers that should never be killed
automatically, and others that should be killed if they have been unused
for a mere hour.

@cindex Midnight mode
@vindex midnight-mode
@vindex midnight-hook
  You can also have this buffer purging done for you, every day at
midnight, by enabling Midnight mode.  Midnight mode operates each day at
midnight; at that time, it runs @code{clean-buffer-list}, or whichever
functions you have placed in the normal hook @code{midnight-hook}

  To enable Midnight mode, use the Customization buffer to set the
variable @code{midnight-mode} to @code{t}.  @xref{Easy Customization}.

@node Several Buffers
@section Operating on Several Buffers
@cindex buffer menu

  The @dfn{buffer-menu} facility is like a ``Dired for buffers''; it allows
you to request operations on various Emacs buffers by editing an Emacs
buffer containing a list of them.  You can save buffers, kill them
(here called @dfn{deleting} them, for consistency with Dired), or display

@table @kbd
@item M-x buffer-menu
Begin editing a buffer listing all Emacs buffers.
356 357
@item M-x buffer-menu-other-window.
Similar, but do it in another window.
Dave Love's avatar
Dave Love committed
358 359 360
@end table

@findex buffer-menu
361 362 363
@findex buffer-menu-other-window
  The command @code{buffer-menu} writes a list of all Emacs
buffers@footnote{Buffers which don't visit files and whose names begin
364 365
with a space are omitted: these are used internally by Emacs.} into the
buffer @samp{*Buffer List*}, and selects that buffer in Buffer Menu
366 367 368

  The buffer is read-only, and can be
369 370 371 372
changed only through the special commands described in this section.
The usual Emacs cursor motion commands can be used in the @samp{*Buffer
List*} buffer.  The following commands apply to the buffer described on
the current line.
Dave Love's avatar
Dave Love committed
373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429

@table @kbd
@item d
Request to delete (kill) the buffer, then move down.  The request
shows as a @samp{D} on the line, before the buffer name.  Requested
deletions take place when you type the @kbd{x} command.
@item C-d
Like @kbd{d} but move up afterwards instead of down.
@item s
Request to save the buffer.  The request shows as an @samp{S} on the
line.  Requested saves take place when you type the @kbd{x} command.
You may request both saving and deletion for the same buffer.
@item x
Perform previously requested deletions and saves.
@item u
Remove any request made for the current line, and move down.
@item @key{DEL}
Move to previous line and remove any request made for that line.
@end table

  The @kbd{d}, @kbd{C-d}, @kbd{s} and @kbd{u} commands to add or remove
flags also move down (or up) one line.  They accept a numeric argument
as a repeat count.

  These commands operate immediately on the buffer listed on the current

@table @kbd
@item ~
Mark the buffer ``unmodified.''  The command @kbd{~} does this
immediately when you type it.
@item %
Toggle the buffer's read-only flag.  The command @kbd{%} does
this immediately when you type it.
@item t
Visit the buffer as a tags table.  @xref{Select Tags Table}.
@end table

  There are also commands to select another buffer or buffers:

@table @kbd
@item q
Quit the buffer menu---immediately display the most recent formerly
visible buffer in its place.
@item @key{RET}
@itemx f
Immediately select this line's buffer in place of the @samp{*Buffer
List*} buffer.
@item o
Immediately select this line's buffer in another window as if by
@kbd{C-x 4 b}, leaving @samp{*Buffer List*} visible.
@item C-o
Immediately display this line's buffer in another window, but don't
select the window.
@item 1
Immediately select this line's buffer in a full-screen window.
@item 2
430 431 432
Immediately set up two windows, with this line's buffer selected in
one, and the previously current buffer (aside from the buffer
@samp{*Buffer List*}) displayed in the other.
Dave Love's avatar
Dave Love committed
433 434 435 436 437 438 439 440 441 442 443 444 445
@item b
Bury the buffer listed on this line.
@item m
Mark this line's buffer to be displayed in another window if you exit
with the @kbd{v} command.  The request shows as a @samp{>} at the
beginning of the line.  (A single buffer may not have both a delete
request and a display request.)
@item v
Immediately select this line's buffer, and also display in other windows
any buffers previously marked with the @kbd{m} command.  If you have not
marked any buffers, this command is equivalent to @kbd{1}.
@end table

446 447 448 449 450 451 452 453 454 455
  There is also a command that affects the entire buffer list:

@table @kbd
@item T
Delete, or reinsert, lines for non-file buffers.  This command toggles
the inclusion of such buffers in the buffer list.
@end table

  What @code{buffer-menu} actually does is create and switch to a
suitable buffer, and turn on Buffer Menu mode in it.  Everything else
Dave Love's avatar
Dave Love committed
456 457
described above is implemented by the special commands provided in
Buffer Menu mode.  One consequence of this is that you can switch from
458 459 460 461 462 463 464 465 466 467 468 469 470 471
the @samp{*Buffer List*} buffer to another Emacs buffer, and edit
there.  You can reselect the @samp{*Buffer List*} buffer later, to
perform the operations already requested, or you can kill it, or pay
no further attention to it.

  The list in the @samp{*Buffer List*} buffer looks exactly like the
buffer list described in @ref{List Buffers}, because they really are
the same.  The only difference between @code{buffer-menu} and
@code{list-buffers} is that @code{buffer-menu} switches to the
@samp{*Buffer List*} buffer in the selected window;
@code{list-buffers} displays the same buffer in another window.  If
you run @code{list-buffers} (that is, type @kbd{C-x C-b}) and select
the buffer list manually, you can use all of the commands described
Dave Love's avatar
Dave Love committed

  Normally, the buffer @samp{*Buffer List*} is not updated automatically when
Dave Love's avatar
Dave Love committed
474 475 476 477 478
buffers are created and killed; its contents are just text.  If you have
created, deleted or renamed buffers, the way to update @samp{*Buffer
List*} to show what you have done is to type @kbd{g}
(@code{revert-buffer}) or repeat the @code{buffer-menu} command.

479 480 481 482 483 484 485
  The @samp{*Buffer List*} buffer does automatically update every
@code{auto-revert-interval} seconds if you enable Auto Revert mode in
it.  (As long as it is not marked modified.)  Global Auto Revert mode
does not update the @samp{*Buffer List*} buffer by default, but it
does if @code{global-auto-revert-non-file-buffers} is non-@code{nil}.
@inforef{Autorevert,, emacs-xtra}, for details.

486 487 488 489
  The command @code{buffer-menu-other-window} works the same as
@code{buffer-menu}, except that it displays the buffers list in
another window.

Dave Love's avatar
Dave Love committed
490 491 492 493 494 495 496 497 498 499 500
@node Indirect Buffers
@section Indirect Buffers
@cindex indirect buffer
@cindex base buffer

  An @dfn{indirect buffer} shares the text of some other buffer, which
is called the @dfn{base buffer} of the indirect buffer.  In some ways it
is the analogue, for buffers, of a symbolic link between files.

@table @kbd
@findex make-indirect-buffer
@item M-x make-indirect-buffer @key{RET} @var{base-buffer} @key{RET} @var{indirect-name} @key{RET}
Dave Love's avatar
Dave Love committed
502 503
Create an indirect buffer named @var{indirect-name} whose base buffer
is @var{base-buffer}.
504 505 506
@findex clone-indirect-buffer
@item M-x clone-indirect-buffer @key{RET}
Create an indirect buffer that is a twin copy of the current buffer.
Dave Love's avatar
Dave Love committed
@item C-x 4 c
508 509 510 511
@kindex C-x 4 c
@findex clone-indirect-buffer-other-window
Create an indirect buffer that is a twin copy of the current buffer, and
select it in another window (@code{clone-indirect-buffer-other-window}).
Dave Love's avatar
Dave Love committed
512 513 514 515 516 517 518 519 520 521 522 523 524 525 526 527
@end table

  The text of the indirect buffer is always identical to the text of its
base buffer; changes made by editing either one are visible immediately
in the other.  But in all other respects, the indirect buffer and its
base buffer are completely separate.  They have different names,
different values of point, different narrowing, different markers,
different major modes, and different local variables.

  An indirect buffer cannot visit a file, but its base buffer can.  If
you try to save the indirect buffer, that actually works by saving the
base buffer.  Killing the base buffer effectively kills the indirect
buffer, but killing an indirect buffer has no effect on its base buffer.

  One way to use indirect buffers is to display multiple views of an
outline.  @xref{Outline Views}.
Dave Love's avatar
Dave Love committed

529 530 531 532 533
  A quick and handy way to make an indirect buffer is with the command
@kbd{M-x clone-indirect-buffer}.  It creates and selects an indirect
buffer whose base buffer is the current buffer.  With a numeric
argument, it prompts for the name of the indirect buffer; otherwise it
defaults to the name of the current buffer, modifying it by adding a
@samp{<@var{n}>} suffix if required.  @kbd{C-x 4 c}
(@code{clone-indirect-buffer-other-window}) works like @kbd{M-x
536 537 538 539 540 541 542 543
clone-indirect-buffer}, but it selects the new buffer in another

  The more general way to make an indirect buffer is with the command
@kbd{M-x make-indirect-buffer}.  It creates an indirect buffer from
buffer @var{base-buffer}, under the name @var{indirect-name}.  It
prompts for both @var{base-buffer} and @var{indirect-name} using the

Dave Love's avatar
Dave Love committed
545 546 547
@node Buffer Convenience
@section Convenience Features and Customization of Buffer Handling

Richard M. Stallman's avatar
Richard M. Stallman committed
548 549 550
   This section describes several modes and features that make it more
convenient to switch between buffers.

Dave Love's avatar
Dave Love committed
* Uniquify::               Making buffer names unique with directory parts.
Dave Love's avatar
Dave Love committed
* Iswitchb::               Switching between buffers with substrings.
* Buffer Menus::           Configurable buffer menu.
Dave Love's avatar
Dave Love committed
555 556 557
@end menu

@node Uniquify
@subsection Making Buffer Names Unique
Dave Love's avatar
Dave Love committed
559 560 561

@cindex unique buffer names
@cindex directories in buffer names
562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 579 580 581 582 583 584 585 586 587 588 589 590 591 592 593
  When several buffers visit identically-named files, Emacs must give
the buffers distinct names.  The usual method for making buffer names
unique adds @samp{<2>}, @samp{<3>}, etc. to the end of the buffer
names (all but one of them).

@vindex uniquify-buffer-name-style
  Other methods work by adding parts of each file's directory to the
buffer name.  To select one, customize the variable
@code{uniquify-buffer-name-style} (@pxref{Easy Customization}).

  For instance, the @code{forward} naming method puts part of the
directory name at the beginning of the buffer name; using this method,
buffers visiting @file{/u/mernst/tmp/Makefile} and
@file{/usr/projects/zaphod/Makefile} would be named
@samp{tmp/Makefile} and @samp{zaphod/Makefile}, respectively (instead
of @samp{Makefile} and @samp{Makefile<2>}).

  By contrast, the @code{post-forward} naming method would call the
buffers @samp{Makefile|tmp} and @samp{Makefile|zaphod}, and the
@code{reverse} naming method would call them @samp{Makefile\tmp} and
@samp{Makefile\zaphod}.  The nontrivial difference between
@code{post-forward} and @code{reverse} occurs when just one directory
name is not enough to distinguish two files; then @code{reverse} puts
the directory names in reverse order, so that @file{/top/middle/file}
becomes @samp{file\middle\top}, while @code{post-forward} puts them in
forward order after the file name, as in @samp{file|top/middle}.

  Which rule to follow for putting the directory names in the buffer
name is not very important if you are going to @emph{look} at the
buffer names before you type one.  But as an experienced user, if you
know the rule, you won't have to look.  And then you may find that one
rule or another is easier for you to remember and utilize fast.
Dave Love's avatar
Dave Love committed

Dave Love's avatar
Dave Love committed
595 596 597 598 599 600 601 602 603 604 605
@node Iswitchb
@subsection Switching Between Buffers using Substrings

@findex iswitchb-mode
@cindex Iswitchb mode
@cindex mode, Iswitchb
@kindex C-x b @r{(Iswitchb mode)}
@kindex C-x 4 b @r{(Iswitchb mode)}
@kindex C-x 5 b @r{(Iswitchb mode)}
@kindex C-x 4 C-o @r{(Iswitchb mode)}

606 607 608 609
  Iswitchb global minor mode provides convenient switching between
buffers using substrings of their names.  It replaces the normal
definitions of @kbd{C-x b}, @kbd{C-x 4 b}, @kbd{C-x 5 b}, and @kbd{C-x
4 C-o} with alternative commands that are somewhat ``smarter.''
Dave Love's avatar
Dave Love committed

611 612 613 614
  When one of these commands prompts you for a buffer name, you can
type in just a substring of the name you want to choose.  As you enter
the substring, Iswitchb mode continuously displays a list of buffers
that match the substring you have typed.
Dave Love's avatar
Dave Love committed

616 617 618 619 620 621 622 623 624 625
  At any time, you can type @key{RET} to select the first buffer in
the list.  So the way to select a particular buffer is to make it the
first in the list.  There are two ways to do this.  You can type more
of the buffer name and thus narrow down the list, excluding unwanted
buffers above the desired one.  Alternatively, you can use @kbd{C-s}
and @kbd{C-r} to rotate the list until the desired buffer is first.

  @key{TAB} while entering the buffer name performs completion on the
string you have entered, based on the displayed list of buffers.

Richard M. Stallman's avatar
Richard M. Stallman committed
626 627 628 629
  To enable Iswitchb mode, type @kbd{M-x iswitchb-mode}, or customize
the variable @code{iswitchb-mode} to @code{t} (@pxref{Easy

630 631
@node Buffer Menus
@subsection Customizing Buffer Menus
Dave Love's avatar
Dave Love committed

Dave Love's avatar
Dave Love committed
633 634 635 636 637 638 639 640
@findex bs-show
@cindex buffer list, customizable
@table @kbd
@item M-x bs-show
Make a list of buffers similarly to @kbd{M-x list-buffers} but
@end table

641 642 643 644 645
  @kbd{M-x bs-show} pops up a buffer list similar to the one normally
displayed by @kbd{C-x C-b} but which you can customize.  If you prefer
this to the usual buffer list, you can bind this command to @kbd{C-x
C-b}.  To customize this buffer list, use the @code{bs} Custom group
(@pxref{Easy Customization}).
Dave Love's avatar
Dave Love committed
646 647 648 649 650 651

@findex msb-mode
@cindex mode, MSB
@cindex MSB mode
@cindex buffer menu
@findex mouse-buffer-menu
652 653 654 655 656 657
@kindex C-Down-Mouse-1
  MSB global minor mode (``MSB'' stands for ``mouse select buffer'')
provides a different and customizable mouse buffer menu which you may
prefer.  It replaces the bindings of @code{mouse-buffer-menu},
normally on @kbd{C-Down-Mouse-1}, and the menu bar buffer menu.  You
can customize the menu in the @code{msb} Custom group.
Miles Bader's avatar
Miles Bader committed
658 659 660 661

   arch-tag: 08c43460-f4f4-4b43-9cb5-1ea9ad991695
@end ignore