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6bf7aab6 | 1 | @c This is part of the Emacs manual. |
acaf905b | 2 | @c Copyright (C) 1985-1987, 1993-1995, 1997, 2000-2012 |
8838673e | 3 | @c Free Software Foundation, Inc. |
6bf7aab6 DL |
4 | @c See file emacs.texi for copying conditions. |
5 | @node Buffers, Windows, Files, Top | |
6 | @chapter Using Multiple Buffers | |
7 | ||
8 | @cindex buffers | |
9 | The text you are editing in Emacs resides in an object called a | |
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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 | |
1c64e6ed | 14 | command's documentation, that appears in a buffer named @file{*Help*}. |
6bf7aab6 | 15 | |
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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 | |
1c64e6ed | 22 | has several buffers, including one named @file{*scratch*}, which can |
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23 | be used for evaluating Lisp expressions and is not associated with any |
24 | file (@pxref{Lisp Interaction}). | |
ea146ed8 | 25 | |
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26 | @cindex selected buffer |
27 | @cindex current buffer | |
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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}. | |
ea146ed8 | 34 | |
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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. | |
40 | @xref{Locals}. | |
6bf7aab6 | 41 | |
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42 | @cindex buffer size, maximum |
43 | A buffer's size cannot be larger than some maximum, which is defined | |
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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 - | |
47 | 2} 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 present in the system. | |
dc53c88b | 50 | |
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51 | @menu |
52 | * Select Buffer:: Creating a new buffer or reselecting an old one. | |
53 | * List Buffers:: Getting a list of buffers that exist. | |
8838673e GM |
54 | * Misc Buffer:: Renaming; changing read-onlyness; copying text. |
55 | * Kill Buffer:: Killing buffers you no longer need. | |
6bf7aab6 | 56 | * Several Buffers:: How to go through the list of all buffers |
8838673e | 57 | and operate variously on several of them. |
177c0ea7 | 58 | * Indirect Buffers:: An indirect buffer shares the text of another buffer. |
b54346bc DL |
59 | * Buffer Convenience:: Convenience and customization features for |
60 | buffer handling. | |
6bf7aab6 DL |
61 | @end menu |
62 | ||
63 | @node Select Buffer | |
64 | @section Creating and Selecting Buffers | |
65 | @cindex change buffers | |
66 | @cindex switch buffers | |
67 | ||
68 | @table @kbd | |
69 | @item C-x b @var{buffer} @key{RET} | |
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}). | |
160bde9c | 77 | @item C-x @key{LEFT} |
a70e06c1 | 78 | Select the previous buffer in the buffer list (@code{previous-buffer}). |
160bde9c | 79 | @item C-x @key{RIGHT} |
a70e06c1 | 80 | Select the next buffer in the buffer list (@code{next-buffer}). |
ac2c0786 LT |
81 | @item C-u M-g M-g |
82 | @itemx C-u M-g g | |
83 | Read a number @var{n} and move to line @var{n} in the most recently | |
84 | selected buffer other than the current buffer. | |
6bf7aab6 DL |
85 | @end table |
86 | ||
6bf7aab6 DL |
87 | @kindex C-x b |
88 | @findex switch-to-buffer | |
a70e06c1 CY |
89 | The @kbd{C-x b} (@code{switch-to-buffer}) command reads a buffer |
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 | |
2a90dfca | 93 | now displayed in any window. |
6bf7aab6 | 94 | |
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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 ``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. | |
2f4f09a9 | 102 | |
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103 | If you specify a buffer that does not exist, @kbd{C-x b} creates a |
104 | new, empty buffer that is not visiting any file, and selects it for | |
105 | editing. The default value of the variable @code{major-mode} | |
106 | determines the new buffer's major mode; the default value is | |
107 | Fundamental mode. @xref{Major Modes}. One reason to create a new | |
108 | buffer is to use it for making temporary notes. If you try to save | |
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109 | it, Emacs asks for the file name to use, and the buffer's major mode |
110 | is re-established taking that file name into account (@pxref{Choosing | |
111 | Modes}). | |
ea146ed8 | 112 | |
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113 | @kindex C-x @key{LEFT} |
114 | @kindex C-x @key{RIGHT} | |
115 | @findex next-buffer | |
a3700ef7 | 116 | @findex previous-buffer |
7354ca01 | 117 | For conveniently switching between a few buffers, use the commands |
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118 | @kbd{C-x @key{LEFT}} and @kbd{C-x @key{RIGHT}}. @kbd{C-x @key{LEFT}} |
119 | (@code{previous-buffer}) selects the previous buffer (following the | |
120 | order of most recent selection in the current frame), while @kbd{C-x | |
121 | @key{RIGHT}} (@code{next-buffer}) moves through buffers in the reverse | |
122 | direction. | |
7354ca01 | 123 | |
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124 | @kindex C-x 4 b |
125 | @findex switch-to-buffer-other-window | |
8f7cad1f | 126 | To select a buffer in a window other than the current one, type |
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127 | @kbd{C-x 4 b} (@code{switch-to-buffer-other-window}). This prompts |
128 | for a buffer name using the minibuffer, displays that buffer in | |
0a2132ba | 129 | another window, and selects that window. |
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130 | |
131 | @kindex C-x 5 b | |
132 | @findex switch-to-buffer-other-frame | |
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133 | Similarly, @kbd{C-x 5 b} (@code{switch-to-buffer-other-frame}) |
134 | prompts for a buffer name, displays that buffer in another frame, and | |
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135 | selects that frame. If the buffer is already being shown in a window |
136 | on another frame, Emacs selects that window and frame instead of | |
137 | creating a new frame. | |
138 | ||
139 | @xref{Displaying Buffers}, for how the @kbd{C-x 4 b} and @kbd{C-x 5 | |
140 | b} commands get the window and/or frame to display in. | |
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141 | |
142 | In addition, @kbd{C-x C-f}, and any other command for visiting a | |
143 | file, can also be used to switch to an existing file-visiting buffer. | |
144 | @xref{Visiting}. | |
8f7cad1f | 145 | |
dd186936 | 146 | @findex goto-line |
ea146ed8 CY |
147 | @kbd{C-u M-g M-g}, that is @code{goto-line} with a plain prefix |
148 | argument, reads a number @var{n} using the minibuffer, selects the | |
149 | most recently selected buffer other than the current buffer in another | |
150 | window, and then moves point to the beginning of line number @var{n} | |
151 | in that buffer. This is mainly useful in a buffer that refers to line | |
152 | numbers in another buffer: if point is on or just after a number, | |
153 | @code{goto-line} uses that number as the default for @var{n}. Note | |
154 | that prefix arguments other than just @kbd{C-u} behave differently. | |
155 | @kbd{C-u 4 M-g M-g} goes to line 4 in the @emph{current} buffer, | |
156 | without reading a number from the minibuffer. (Remember that @kbd{M-g | |
157 | M-g} without prefix argument reads a number @var{n} and then moves to | |
158 | line number @var{n} in the current buffer. @xref{Moving Point}.) | |
ac2c0786 | 159 | |
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160 | Emacs uses buffer names that start with a space for internal purposes. |
161 | It treats these buffers specially in minor ways---for example, by | |
162 | default they do not record undo information. It is best to avoid using | |
163 | such buffer names yourself. | |
164 | ||
165 | @node List Buffers | |
166 | @section Listing Existing Buffers | |
167 | ||
168 | @table @kbd | |
169 | @item C-x C-b | |
170 | List the existing buffers (@code{list-buffers}). | |
171 | @end table | |
172 | ||
173 | @cindex listing current buffers | |
174 | @kindex C-x C-b | |
175 | @findex list-buffers | |
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176 | To display a list of existing buffers, type @kbd{C-x C-b}. Each |
177 | line in the list shows one buffer's name, major mode and visited file. | |
178 | The buffers are listed in the order that they were current; the | |
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179 | buffers that were current most recently come first. |
180 | ||
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181 | @samp{.} in the first field of a line indicates that the buffer is |
182 | current. @samp{%} indicates a read-only buffer. @samp{*} indicates | |
16152b76 | 183 | that the buffer is ``modified''. If several buffers are modified, it |
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184 | may be time to save some with @kbd{C-x s} (@pxref{Save Commands}). |
185 | Here is an example of a buffer list: | |
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186 | |
187 | @smallexample | |
b1a25f96 | 188 | CRM Buffer Size Mode File |
6105130d MR |
189 | . * .emacs 3294 Emacs-Lisp ~/.emacs |
190 | % *Help* 101 Help | |
517b2c37 JB |
191 | search.c 86055 C ~/cvs/emacs/src/search.c |
192 | % src 20959 Dired by name ~/cvs/emacs/src/ | |
6105130d | 193 | * *mail* 42 Mail |
517b2c37 JB |
194 | % HELLO 1607 Fundamental ~/cvs/emacs/etc/HELLO |
195 | % NEWS 481184 Outline ~/cvs/emacs/etc/NEWS | |
196 | *scratch* 191 Lisp Interaction | |
517b2c37 | 197 | * *Messages* 1554 Fundamental |
6bf7aab6 DL |
198 | @end smallexample |
199 | ||
200 | @noindent | |
1c64e6ed | 201 | The buffer @file{*Help*} was made by a help request (@pxref{Help}); it |
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202 | is not visiting any file. The buffer @code{src} was made by Dired on |
203 | the directory @file{~/cvs/emacs/src/}. You can list only buffers that | |
204 | are visiting files by giving the command a prefix argument, as in | |
564ee37b | 205 | @kbd{C-u C-x C-b}. |
6bf7aab6 | 206 | |
7354ca01 | 207 | @code{list-buffers} omits buffers whose names begin with a space, |
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208 | unless they visit files: such buffers are used internally by Emacs. |
209 | ||
6bf7aab6 DL |
210 | @node Misc Buffer |
211 | @section Miscellaneous Buffer Operations | |
212 | ||
213 | @table @kbd | |
214 | @item C-x C-q | |
8f980b27 | 215 | Toggle read-only status of buffer (@code{toggle-read-only}). |
6bf7aab6 DL |
216 | @item M-x rename-buffer @key{RET} @var{name} @key{RET} |
217 | Change the name of the current buffer. | |
218 | @item M-x rename-uniquely | |
219 | Rename the current buffer by adding @samp{<@var{number}>} to the end. | |
220 | @item M-x view-buffer @key{RET} @var{buffer} @key{RET} | |
2a90dfca | 221 | Scroll through buffer @var{buffer}. @xref{View Mode}. |
6bf7aab6 DL |
222 | @end table |
223 | ||
224 | @kindex C-x C-q | |
6bf7aab6 DL |
225 | @vindex buffer-read-only |
226 | @cindex read-only buffer | |
227 | A buffer can be @dfn{read-only}, which means that commands to change | |
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228 | its contents are not allowed. The mode line indicates read-only |
229 | buffers with @samp{%%} or @samp{%*} near the left margin. Read-only | |
230 | buffers are usually made by subsystems such as Dired and Rmail that | |
231 | have special commands to operate on the text; also by visiting a file | |
232 | whose access control says you cannot write it. | |
6bf7aab6 | 233 | |
8f980b27 | 234 | @findex toggle-read-only |
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235 | The command @kbd{C-x C-q} (@code{toggle-read-only}) makes a read-only |
236 | buffer writable, and makes a writable buffer read-only. This works by | |
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237 | setting the variable @code{buffer-read-only}, which has a local value |
238 | in each buffer and makes the buffer read-only if its value is | |
239 | non-@code{nil}. | |
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240 | |
241 | @findex rename-buffer | |
a3053e27 RS |
242 | @kbd{M-x rename-buffer} changes the name of the current buffer. You |
243 | specify the new name as a minibuffer argument; there is no default. | |
244 | If you specify a name that is in use for some other buffer, an error | |
245 | happens and no renaming is done. | |
6bf7aab6 | 246 | |
0e04ec0b | 247 | @findex rename-uniquely |
eddcfd0e RS |
248 | @kbd{M-x rename-uniquely} renames the current buffer to a similar |
249 | name with a numeric suffix added to make it both different and unique. | |
250 | This command does not need an argument. It is useful for creating | |
1c64e6ed | 251 | multiple shell buffers: if you rename the @file{*shell*} buffer, then |
eddcfd0e | 252 | do @kbd{M-x shell} again, it makes a new shell buffer named |
1c64e6ed | 253 | @file{*shell*}; meanwhile, the old shell buffer continues to exist |
eddcfd0e RS |
254 | under its new name. This method is also good for mail buffers, |
255 | compilation buffers, and most Emacs features that create special | |
256 | buffers with particular names. (With some of these features, such as | |
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257 | @kbd{M-x compile}, @kbd{M-x grep}, you need to switch to some other |
258 | buffer before using the command again, otherwise it will reuse the | |
259 | current buffer despite the name change.) | |
6bf7aab6 | 260 | |
6bf7aab6 | 261 | The commands @kbd{M-x append-to-buffer} and @kbd{M-x insert-buffer} |
2a90dfca DM |
262 | can also be used to copy text from one buffer to another. |
263 | @xref{Accumulating Text}. | |
6bf7aab6 DL |
264 | |
265 | @node Kill Buffer | |
266 | @section Killing Buffers | |
267 | ||
268 | @cindex killing buffers | |
269 | If you continue an Emacs session for a while, you may accumulate a | |
270 | large number of buffers. You may then find it convenient to @dfn{kill} | |
271 | the buffers you no longer need. On most operating systems, killing a | |
272 | buffer releases its space back to the operating system so that other | |
273 | programs can use it. Here are some commands for killing buffers: | |
274 | ||
6bf7aab6 DL |
275 | @table @kbd |
276 | @item C-x k @var{bufname} @key{RET} | |
277 | Kill buffer @var{bufname} (@code{kill-buffer}). | |
278 | @item M-x kill-some-buffers | |
279 | Offer to kill each buffer, one by one. | |
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280 | @item M-x kill-matching-buffers |
281 | Offer to kill all buffers matching a regular expression. | |
6bf7aab6 DL |
282 | @end table |
283 | ||
284 | @findex kill-buffer | |
6bf7aab6 | 285 | @kindex C-x k |
6bf7aab6 | 286 | @kbd{C-x k} (@code{kill-buffer}) kills one buffer, whose name you |
ab25a0c7 RS |
287 | specify in the minibuffer. The default, used if you type just |
288 | @key{RET} in the minibuffer, is to kill the current buffer. If you | |
289 | kill the current buffer, another buffer becomes current: one that was | |
290 | current in the recent past but is not displayed in any window now. If | |
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291 | you ask to kill a file-visiting buffer that is modified, then you must |
292 | confirm with @kbd{yes} before the buffer is killed. | |
6bf7aab6 | 293 | |
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294 | @findex kill-some-buffers |
295 | The command @kbd{M-x kill-some-buffers} asks about each buffer, one | |
296 | by one. An answer of @kbd{y} means to kill the buffer, just like | |
297 | @code{kill-buffer}. This command ignores buffers whose names begin | |
298 | with a space, which are used internally by Emacs. | |
299 | ||
300 | @findex kill-matching-buffers | |
301 | The command @kbd{M-x kill-matching-buffers} prompts for a regular | |
302 | expression and kills all buffers whose names match that expression. | |
303 | @xref{Regexps}. Like @code{kill-some-buffers}, it asks for | |
304 | confirmation before each kill. This command normally ignores buffers | |
305 | whose names begin with a space, which are used internally by Emacs. | |
306 | To kill internal buffers as well, call @code{kill-matching-buffers} | |
307 | with a prefix argument. | |
308 | ||
309 | The buffer menu feature is also convenient for killing various | |
310 | buffers. @xref{Several Buffers}. | |
6bf7aab6 DL |
311 | |
312 | @vindex kill-buffer-hook | |
313 | If you want to do something special every time a buffer is killed, you | |
314 | can add hook functions to the hook @code{kill-buffer-hook} (@pxref{Hooks}). | |
315 | ||
316 | @findex clean-buffer-list | |
317 | If you run one Emacs session for a period of days, as many people do, | |
318 | it can fill up with buffers that you used several days ago. The command | |
319 | @kbd{M-x clean-buffer-list} is a convenient way to purge them; it kills | |
320 | all the unmodified buffers that you have not used for a long time. An | |
321 | ordinary buffer is killed if it has not been displayed for three days; | |
322 | however, you can specify certain buffers that should never be killed | |
323 | automatically, and others that should be killed if they have been unused | |
324 | for a mere hour. | |
325 | ||
326 | @cindex Midnight mode | |
327 | @vindex midnight-mode | |
328 | @vindex midnight-hook | |
329 | You can also have this buffer purging done for you, every day at | |
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330 | midnight, by enabling Midnight mode. Midnight mode operates each day |
331 | at midnight; at that time, it runs @code{clean-buffer-list}, or | |
332 | whichever functions you have placed in the normal hook | |
333 | @code{midnight-hook} (@pxref{Hooks}). To enable Midnight mode, use | |
334 | the Customization buffer to set the variable @code{midnight-mode} to | |
335 | @code{t}. @xref{Easy Customization}. | |
6bf7aab6 DL |
336 | |
337 | @node Several Buffers | |
338 | @section Operating on Several Buffers | |
339 | @cindex buffer menu | |
340 | ||
6bf7aab6 DL |
341 | @table @kbd |
342 | @item M-x buffer-menu | |
343 | Begin editing a buffer listing all Emacs buffers. | |
4081af2f EZ |
344 | @item M-x buffer-menu-other-window. |
345 | Similar, but do it in another window. | |
6bf7aab6 DL |
346 | @end table |
347 | ||
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348 | The @dfn{buffer menu} opened by @kbd{C-x C-b} (@pxref{List Buffers}) |
349 | does not merely list buffers. It also allows you to perform various | |
350 | operations on buffers, through an interface similar to Dired | |
351 | (@pxref{Dired}). You can save buffers, kill them (here called | |
352 | @dfn{deleting} them, for consistency with Dired), or display them. | |
353 | ||
6bf7aab6 | 354 | @findex buffer-menu |
4081af2f | 355 | @findex buffer-menu-other-window |
ea146ed8 | 356 | To use the buffer menu, type @kbd{C-x C-b} and switch to the window |
1c64e6ed | 357 | displaying the @file{*Buffer List*} buffer. You can also type |
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358 | @kbd{M-x buffer-menu} to open the buffer menu in the selected window. |
359 | Alternatively, the command @kbd{M-x buffer-menu-other-window} opens | |
360 | the buffer menu in another window, and selects that window. | |
361 | ||
362 | The buffer menu is a read-only buffer, and can be changed only | |
363 | through the special commands described in this section. The usual | |
364 | Emacs cursor motion commands can be used in this buffer. The | |
365 | following commands apply to the buffer described on the current line: | |
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366 | |
367 | @table @kbd | |
368 | @item d | |
369 | Request to delete (kill) the buffer, then move down. The request | |
370 | shows as a @samp{D} on the line, before the buffer name. Requested | |
371 | deletions take place when you type the @kbd{x} command. | |
372 | @item C-d | |
373 | Like @kbd{d} but move up afterwards instead of down. | |
374 | @item s | |
375 | Request to save the buffer. The request shows as an @samp{S} on the | |
376 | line. Requested saves take place when you type the @kbd{x} command. | |
377 | You may request both saving and deletion for the same buffer. | |
378 | @item x | |
379 | Perform previously requested deletions and saves. | |
380 | @item u | |
381 | Remove any request made for the current line, and move down. | |
382 | @item @key{DEL} | |
383 | Move to previous line and remove any request made for that line. | |
384 | @end table | |
385 | ||
386 | The @kbd{d}, @kbd{C-d}, @kbd{s} and @kbd{u} commands to add or remove | |
387 | flags also move down (or up) one line. They accept a numeric argument | |
388 | as a repeat count. | |
389 | ||
390 | These commands operate immediately on the buffer listed on the current | |
391 | line: | |
392 | ||
393 | @table @kbd | |
394 | @item ~ | |
16152b76 | 395 | Mark the buffer ``unmodified''. The command @kbd{~} does this |
6bf7aab6 DL |
396 | immediately when you type it. |
397 | @item % | |
398 | Toggle the buffer's read-only flag. The command @kbd{%} does | |
399 | this immediately when you type it. | |
400 | @item t | |
401 | Visit the buffer as a tags table. @xref{Select Tags Table}. | |
402 | @end table | |
403 | ||
404 | There are also commands to select another buffer or buffers: | |
405 | ||
406 | @table @kbd | |
407 | @item q | |
408 | Quit the buffer menu---immediately display the most recent formerly | |
409 | visible buffer in its place. | |
410 | @item @key{RET} | |
411 | @itemx f | |
1c64e6ed | 412 | Immediately select this line's buffer in place of the @file{*Buffer |
6bf7aab6 DL |
413 | List*} buffer. |
414 | @item o | |
415 | Immediately select this line's buffer in another window as if by | |
1c64e6ed | 416 | @kbd{C-x 4 b}, leaving @file{*Buffer List*} visible. |
6bf7aab6 DL |
417 | @item C-o |
418 | Immediately display this line's buffer in another window, but don't | |
419 | select the window. | |
420 | @item 1 | |
421 | Immediately select this line's buffer in a full-screen window. | |
422 | @item 2 | |
041aabd8 LT |
423 | Immediately set up two windows, with this line's buffer selected in |
424 | one, and the previously current buffer (aside from the buffer | |
1c64e6ed | 425 | @file{*Buffer List*}) displayed in the other. |
6bf7aab6 DL |
426 | @item b |
427 | Bury the buffer listed on this line. | |
428 | @item m | |
429 | Mark this line's buffer to be displayed in another window if you exit | |
430 | with the @kbd{v} command. The request shows as a @samp{>} at the | |
431 | beginning of the line. (A single buffer may not have both a delete | |
432 | request and a display request.) | |
433 | @item v | |
434 | Immediately select this line's buffer, and also display in other windows | |
435 | any buffers previously marked with the @kbd{m} command. If you have not | |
436 | marked any buffers, this command is equivalent to @kbd{1}. | |
437 | @end table | |
438 | ||
7354ca01 RS |
439 | There is also a command that affects the entire buffer list: |
440 | ||
441 | @table @kbd | |
442 | @item T | |
443 | Delete, or reinsert, lines for non-file buffers. This command toggles | |
444 | the inclusion of such buffers in the buffer list. | |
445 | @end table | |
446 | ||
447 | What @code{buffer-menu} actually does is create and switch to a | |
448 | suitable buffer, and turn on Buffer Menu mode in it. Everything else | |
6bf7aab6 DL |
449 | described above is implemented by the special commands provided in |
450 | Buffer Menu mode. One consequence of this is that you can switch from | |
1c64e6ed GM |
451 | the @file{*Buffer List*} buffer to another Emacs buffer, and edit |
452 | there. You can reselect the @file{*Buffer List*} buffer later, to | |
7354ca01 RS |
453 | perform the operations already requested, or you can kill it, or pay |
454 | no further attention to it. | |
455 | ||
1c64e6ed | 456 | Normally, the buffer @file{*Buffer List*} is not updated |
a3053e27 RS |
457 | automatically when buffers are created and killed; its contents are |
458 | just text. If you have created, deleted or renamed buffers, the way | |
1c64e6ed | 459 | to update @file{*Buffer List*} to show what you have done is to type |
a3053e27 RS |
460 | @kbd{g} (@code{revert-buffer}). You can make this happen regularly |
461 | every @code{auto-revert-interval} seconds if you enable Auto Revert | |
462 | mode in this buffer, as long as it is not marked modified. Global | |
1c64e6ed | 463 | Auto Revert mode applies to the @file{*Buffer List*} buffer only if |
a3053e27 | 464 | @code{global-auto-revert-non-file-buffers} is non-@code{nil}. |
bbe9cbb8 | 465 | @iftex |
eca2d6cd | 466 | @inforef{Autorevert,, emacs-xtra}, for details. |
bbe9cbb8 EZ |
467 | @end iftex |
468 | @ifnottex | |
469 | @xref{Autorevert, global-auto-revert-non-file-buffers}, for details. | |
470 | @end ifnottex | |
471 | ||
6bf7aab6 DL |
472 | @node Indirect Buffers |
473 | @section Indirect Buffers | |
474 | @cindex indirect buffer | |
475 | @cindex base buffer | |
476 | ||
477 | An @dfn{indirect buffer} shares the text of some other buffer, which | |
478 | is called the @dfn{base buffer} of the indirect buffer. In some ways it | |
479 | is the analogue, for buffers, of a symbolic link between files. | |
480 | ||
481 | @table @kbd | |
482 | @findex make-indirect-buffer | |
52ec6cdc | 483 | @item M-x make-indirect-buffer @key{RET} @var{base-buffer} @key{RET} @var{indirect-name} @key{RET} |
6bf7aab6 DL |
484 | Create an indirect buffer named @var{indirect-name} whose base buffer |
485 | is @var{base-buffer}. | |
f16874ce EZ |
486 | @findex clone-indirect-buffer |
487 | @item M-x clone-indirect-buffer @key{RET} | |
488 | Create an indirect buffer that is a twin copy of the current buffer. | |
112c140f | 489 | @item C-x 4 c |
f16874ce EZ |
490 | @kindex C-x 4 c |
491 | @findex clone-indirect-buffer-other-window | |
492 | Create an indirect buffer that is a twin copy of the current buffer, and | |
493 | select it in another window (@code{clone-indirect-buffer-other-window}). | |
6bf7aab6 DL |
494 | @end table |
495 | ||
496 | The text of the indirect buffer is always identical to the text of its | |
497 | base buffer; changes made by editing either one are visible immediately | |
498 | in the other. But in all other respects, the indirect buffer and its | |
ea146ed8 | 499 | base buffer are completely separate. They can have different names, |
6bf7aab6 DL |
500 | different values of point, different narrowing, different markers, |
501 | different major modes, and different local variables. | |
502 | ||
503 | An indirect buffer cannot visit a file, but its base buffer can. If | |
504 | you try to save the indirect buffer, that actually works by saving the | |
505 | base buffer. Killing the base buffer effectively kills the indirect | |
506 | buffer, but killing an indirect buffer has no effect on its base buffer. | |
507 | ||
508 | One way to use indirect buffers is to display multiple views of an | |
509 | outline. @xref{Outline Views}. | |
b54346bc | 510 | |
ea146ed8 | 511 | @vindex clone-indirect-buffer-hook |
564ee37b RS |
512 | A quick and handy way to make an indirect buffer is with the command |
513 | @kbd{M-x clone-indirect-buffer}. It creates and selects an indirect | |
514 | buffer whose base buffer is the current buffer. With a numeric | |
515 | argument, it prompts for the name of the indirect buffer; otherwise it | |
160bde9c LT |
516 | uses the name of the current buffer, with a @samp{<@var{n}>} suffix |
517 | added. @kbd{C-x 4 c} (@code{clone-indirect-buffer-other-window}) | |
518 | works like @kbd{M-x clone-indirect-buffer}, but it selects the new | |
ea146ed8 CY |
519 | buffer in another window. These functions run the hook |
520 | @code{clone-indirect-buffer-hook} after creating the indirect buffer. | |
eddcfd0e RS |
521 | |
522 | The more general way to make an indirect buffer is with the command | |
523 | @kbd{M-x make-indirect-buffer}. It creates an indirect buffer from | |
524 | buffer @var{base-buffer}, under the name @var{indirect-name}. It | |
525 | prompts for both @var{base-buffer} and @var{indirect-name} using the | |
526 | minibuffer. | |
f16874ce | 527 | |
b54346bc DL |
528 | @node Buffer Convenience |
529 | @section Convenience Features and Customization of Buffer Handling | |
530 | ||
85d6c6e7 RS |
531 | This section describes several modes and features that make it more |
532 | convenient to switch between buffers. | |
533 | ||
b54346bc | 534 | @menu |
7354ca01 | 535 | * Uniquify:: Making buffer names unique with directory parts. |
d04efc64 | 536 | * Iswitchb:: Switching between buffers with substrings. |
177c0ea7 | 537 | * Buffer Menus:: Configurable buffer menu. |
b54346bc DL |
538 | @end menu |
539 | ||
540 | @node Uniquify | |
564ee37b | 541 | @subsection Making Buffer Names Unique |
b54346bc | 542 | |
b54346bc DL |
543 | @cindex unique buffer names |
544 | @cindex directories in buffer names | |
564ee37b RS |
545 | When several buffers visit identically-named files, Emacs must give |
546 | the buffers distinct names. The usual method for making buffer names | |
547 | unique adds @samp{<2>}, @samp{<3>}, etc. to the end of the buffer | |
548 | names (all but one of them). | |
549 | ||
550 | @vindex uniquify-buffer-name-style | |
551 | Other methods work by adding parts of each file's directory to the | |
5dbbdd33 | 552 | buffer name. To select one, load the library @file{uniquify} (e.g. |
64f3bde2 | 553 | using @code{(require 'uniquify)}), and customize the variable |
564ee37b RS |
554 | @code{uniquify-buffer-name-style} (@pxref{Easy Customization}). |
555 | ||
df7593dd KB |
556 | To begin with, the @code{forward} naming method includes part of the |
557 | file's directory name at the beginning of the buffer name; using this | |
558 | method, buffers visiting the files @file{/u/rms/tmp/Makefile} and | |
564ee37b RS |
559 | @file{/usr/projects/zaphod/Makefile} would be named |
560 | @samp{tmp/Makefile} and @samp{zaphod/Makefile}, respectively (instead | |
561 | of @samp{Makefile} and @samp{Makefile<2>}). | |
562 | ||
df7593dd | 563 | In contrast, the @code{post-forward} naming method would call the |
564ee37b RS |
564 | buffers @samp{Makefile|tmp} and @samp{Makefile|zaphod}, and the |
565 | @code{reverse} naming method would call them @samp{Makefile\tmp} and | |
566 | @samp{Makefile\zaphod}. The nontrivial difference between | |
567 | @code{post-forward} and @code{reverse} occurs when just one directory | |
568 | name is not enough to distinguish two files; then @code{reverse} puts | |
569 | the directory names in reverse order, so that @file{/top/middle/file} | |
570 | becomes @samp{file\middle\top}, while @code{post-forward} puts them in | |
571 | forward order after the file name, as in @samp{file|top/middle}. | |
572 | ||
573 | Which rule to follow for putting the directory names in the buffer | |
574 | name is not very important if you are going to @emph{look} at the | |
575 | buffer names before you type one. But as an experienced user, if you | |
576 | know the rule, you won't have to look. And then you may find that one | |
a3053e27 | 577 | rule or another is easier for you to remember and apply quickly. |
b54346bc | 578 | |
1ea14188 DL |
579 | @node Iswitchb |
580 | @subsection Switching Between Buffers using Substrings | |
581 | ||
582 | @findex iswitchb-mode | |
583 | @cindex Iswitchb mode | |
584 | @cindex mode, Iswitchb | |
585 | @kindex C-x b @r{(Iswitchb mode)} | |
586 | @kindex C-x 4 b @r{(Iswitchb mode)} | |
587 | @kindex C-x 5 b @r{(Iswitchb mode)} | |
588 | @kindex C-x 4 C-o @r{(Iswitchb mode)} | |
589 | ||
564ee37b RS |
590 | Iswitchb global minor mode provides convenient switching between |
591 | buffers using substrings of their names. It replaces the normal | |
592 | definitions of @kbd{C-x b}, @kbd{C-x 4 b}, @kbd{C-x 5 b}, and @kbd{C-x | |
16152b76 | 593 | 4 C-o} with alternative commands that are somewhat ``smarter''. |
1ea14188 | 594 | |
564ee37b RS |
595 | When one of these commands prompts you for a buffer name, you can |
596 | type in just a substring of the name you want to choose. As you enter | |
597 | the substring, Iswitchb mode continuously displays a list of buffers | |
598 | that match the substring you have typed. | |
1ea14188 | 599 | |
564ee37b RS |
600 | At any time, you can type @key{RET} to select the first buffer in |
601 | the list. So the way to select a particular buffer is to make it the | |
602 | first in the list. There are two ways to do this. You can type more | |
603 | of the buffer name and thus narrow down the list, excluding unwanted | |
604 | buffers above the desired one. Alternatively, you can use @kbd{C-s} | |
605 | and @kbd{C-r} to rotate the list until the desired buffer is first. | |
606 | ||
607 | @key{TAB} while entering the buffer name performs completion on the | |
608 | string you have entered, based on the displayed list of buffers. | |
609 | ||
85d6c6e7 RS |
610 | To enable Iswitchb mode, type @kbd{M-x iswitchb-mode}, or customize |
611 | the variable @code{iswitchb-mode} to @code{t} (@pxref{Easy | |
612 | Customization}). | |
613 | ||
564ee37b RS |
614 | @node Buffer Menus |
615 | @subsection Customizing Buffer Menus | |
b54346bc | 616 | |
d04efc64 | 617 | @findex bs-show |
d04efc64 DL |
618 | @cindex buffer list, customizable |
619 | @table @kbd | |
620 | @item M-x bs-show | |
621 | Make a list of buffers similarly to @kbd{M-x list-buffers} but | |
622 | customizable. | |
d04efc64 DL |
623 | @end table |
624 | ||
564ee37b RS |
625 | @kbd{M-x bs-show} pops up a buffer list similar to the one normally |
626 | displayed by @kbd{C-x C-b} but which you can customize. If you prefer | |
627 | this to the usual buffer list, you can bind this command to @kbd{C-x | |
628 | C-b}. To customize this buffer list, use the @code{bs} Custom group | |
629 | (@pxref{Easy Customization}). | |
1ea14188 DL |
630 | |
631 | @findex msb-mode | |
632 | @cindex mode, MSB | |
633 | @cindex MSB mode | |
634 | @cindex buffer menu | |
635 | @findex mouse-buffer-menu | |
564ee37b RS |
636 | @kindex C-Down-Mouse-1 |
637 | MSB global minor mode (``MSB'' stands for ``mouse select buffer'') | |
638 | provides a different and customizable mouse buffer menu which you may | |
639 | prefer. It replaces the bindings of @code{mouse-buffer-menu}, | |
640 | normally on @kbd{C-Down-Mouse-1}, and the menu bar buffer menu. You | |
641 | can customize the menu in the @code{msb} Custom group. |