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6bf7aab6 | 1 | @c This is part of the Emacs manual. |
ee417b73 | 2 | @c Copyright (C) 1985, 1986, 1987, 1993, 1994, 1995, 1997, 1999, 2000, |
8d99e09d | 3 | @c 2001, 2002, 2003, 2004, 2005, 2006 Free Software Foundation, Inc. |
6bf7aab6 | 4 | @c See file emacs.texi for copying conditions. |
f05c7392 | 5 | @node Files, Buffers, Keyboard Macros, Top |
6bf7aab6 DL |
6 | @chapter File Handling |
7 | @cindex files | |
8 | ||
4f09cbeb | 9 | The operating system stores data permanently in named @dfn{files}, so |
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10 | most of the text you edit with Emacs comes from a file and is ultimately |
11 | stored in a file. | |
12 | ||
13 | To edit a file, you must tell Emacs to read the file and prepare a | |
14 | buffer containing a copy of the file's text. This is called | |
15 | @dfn{visiting} the file. Editing commands apply directly to text in the | |
16 | buffer; that is, to the copy inside Emacs. Your changes appear in the | |
17 | file itself only when you @dfn{save} the buffer back into the file. | |
18 | ||
19 | In addition to visiting and saving files, Emacs can delete, copy, | |
20 | rename, and append to files, keep multiple versions of them, and operate | |
21 | on file directories. | |
22 | ||
23 | @menu | |
24 | * File Names:: How to type and edit file-name arguments. | |
25 | * Visiting:: Visiting a file prepares Emacs to edit the file. | |
26 | * Saving:: Saving makes your changes permanent. | |
27 | * Reverting:: Reverting cancels all the changes not saved. | |
28 | * Auto Save:: Auto Save periodically protects against loss of data. | |
29 | * File Aliases:: Handling multiple names for one file. | |
30 | * Version Control:: Version control systems (RCS, CVS and SCCS). | |
31 | * Directories:: Creating, deleting, and listing file directories. | |
32 | * Comparing Files:: Finding where two files differ. | |
33 | * Misc File Ops:: Other things you can do on files. | |
34 | * Compressed Files:: Accessing compressed files. | |
259a88ca | 35 | * File Archives:: Operating on tar, zip, jar etc. archive files. |
6bf7aab6 DL |
36 | * Remote Files:: Accessing files on other sites. |
37 | * Quoted File Names:: Quoting special characters in file names. | |
f02d86a3 | 38 | * File Name Cache:: Completion against a list of files you often use. |
9a98ef18 | 39 | * File Conveniences:: Convenience Features for Finding Files. |
9bc727cd | 40 | * Filesets:: Handling sets of files. |
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41 | @end menu |
42 | ||
43 | @node File Names | |
44 | @section File Names | |
45 | @cindex file names | |
46 | ||
47 | Most Emacs commands that operate on a file require you to specify the | |
48 | file name. (Saving and reverting are exceptions; the buffer knows which | |
49 | file name to use for them.) You enter the file name using the | |
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50 | minibuffer (@pxref{Minibuffer}). @dfn{Completion} is available |
51 | (@pxref{Completion}) to make it easier to specify long file names. When | |
36d6da4e | 52 | completing file names, Emacs ignores those whose file-name extensions |
0cf729ce | 53 | appear in the variable @code{completion-ignored-extensions}; see |
36d6da4e | 54 | @ref{Completion Options}. |
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55 | |
56 | For most operations, there is a @dfn{default file name} which is used | |
57 | if you type just @key{RET} to enter an empty argument. Normally the | |
58 | default file name is the name of the file visited in the current buffer; | |
59 | this makes it easy to operate on that file with any of the Emacs file | |
60 | commands. | |
61 | ||
62 | @vindex default-directory | |
4f09cbeb | 63 | Each buffer has a default directory which is normally the same as the |
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64 | directory of the file visited in that buffer. When you enter a file |
65 | name without a directory, the default directory is used. If you specify | |
66 | a directory in a relative fashion, with a name that does not start with | |
67 | a slash, it is interpreted with respect to the default directory. The | |
68 | default directory is kept in the variable @code{default-directory}, | |
69 | which has a separate value in every buffer. | |
70 | ||
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71 | @findex cd |
72 | @findex pwd | |
1ba2ce68 | 73 | The command @kbd{M-x pwd} displays the current buffer's default |
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74 | directory, and the command @kbd{M-x cd} sets it (to a value read using |
75 | the minibuffer). A buffer's default directory changes only when the | |
76 | @code{cd} command is used. A file-visiting buffer's default directory | |
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77 | is initialized to the directory of the file it visits. If you create |
78 | a buffer with @kbd{C-x b}, its default directory is copied from that | |
79 | of the buffer that was current at the time. | |
80 | ||
81 | For example, if the default file name is @file{/u/rms/gnu/gnu.tasks} | |
82 | then the default directory is normally @file{/u/rms/gnu/}. If you | |
83 | type just @samp{foo}, which does not specify a directory, it is short | |
84 | for @file{/u/rms/gnu/foo}. @samp{../.login} would stand for | |
85 | @file{/u/rms/.login}. @samp{new/foo} would stand for the file name | |
86 | @file{/u/rms/gnu/new/foo}. | |
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87 | |
88 | @vindex insert-default-directory | |
89 | The default directory actually appears in the minibuffer when the | |
90 | minibuffer becomes active to read a file name. This serves two | |
91 | purposes: it @emph{shows} you what the default is, so that you can type | |
92 | a relative file name and know with certainty what it will mean, and it | |
93 | allows you to @emph{edit} the default to specify a different directory. | |
94 | This insertion of the default directory is inhibited if the variable | |
95 | @code{insert-default-directory} is set to @code{nil}. | |
96 | ||
97 | Note that it is legitimate to type an absolute file name after you | |
98 | enter the minibuffer, ignoring the presence of the default directory | |
99 | name as part of the text. The final minibuffer contents may look | |
100 | invalid, but that is not so. For example, if the minibuffer starts out | |
101 | with @samp{/usr/tmp/} and you add @samp{/x1/rms/foo}, you get | |
102 | @samp{/usr/tmp//x1/rms/foo}; but Emacs ignores everything through the | |
103 | first slash in the double slash; the result is @samp{/x1/rms/foo}. | |
104 | @xref{Minibuffer File}. | |
105 | ||
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106 | @cindex home directory shorthand |
107 | You can use @file{~/} in a file name to mean your home directory, | |
108 | or @file{~@var{user-id}/} to mean the home directory of a user whose | |
109 | login name is @code{user-id}. (On DOS and Windows systems, where a user | |
110 | doesn't have a home directory, Emacs substitutes @file{~/} with the | |
111 | value of the environment variable @code{HOME}; see @ref{General | |
112 | Variables}.) | |
113 | ||
3d853351 EZ |
114 | @cindex environment variables in file names |
115 | @cindex expansion of environment variables | |
de508b5f | 116 | @cindex @code{$} in file names |
b3c8fa05 RS |
117 | @anchor{File Names with $}@samp{$} in a file name is used to |
118 | substitute an environment variable. The environment variable name | |
119 | consists of all the alphanumeric characters after the @samp{$}; | |
120 | alternatively, it can be enclosed in braces after the @samp{$}. For | |
121 | example, if you have used the shell command @command{export | |
60a96371 | 122 | FOO=rms/hacks} to set up an environment variable named @env{FOO}, then |
6bf7aab6 | 123 | you can use @file{/u/$FOO/test.c} or @file{/u/$@{FOO@}/test.c} as an |
b3c8fa05 RS |
124 | abbreviation for @file{/u/rms/hacks/test.c}. If the environment |
125 | variable is not defined, no substitution occurs: @file{/u/$notdefined} | |
126 | stands for itself (assuming the environment variable @env{notdefined} | |
127 | is not defined). | |
128 | ||
129 | Note that shell commands to set environment variables affect Emacs | |
130 | only when done before Emacs is started. | |
6bf7aab6 | 131 | |
b3c8fa05 RS |
132 | To access a file with @samp{$} in its name, if the @samp{$} causes |
133 | expansion, type @samp{$$}. This pair is converted to a single | |
134 | @samp{$} at the same time as variable substitution is performed for a | |
135 | single @samp{$}. Alternatively, quote the whole file name with | |
136 | @samp{/:} (@pxref{Quoted File Names}). File names which begin with a | |
137 | literal @samp{~} should also be quoted with @samp{/:}. | |
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138 | |
139 | @findex substitute-in-file-name | |
50a1bd4f | 140 | The Lisp function that performs the @samp{$}-substitution is called |
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141 | @code{substitute-in-file-name}. The substitution is performed only on |
142 | file names read as such using the minibuffer. | |
143 | ||
76dd3692 | 144 | You can include non-@acronym{ASCII} characters in file names if you set the |
6bf7aab6 | 145 | variable @code{file-name-coding-system} to a non-@code{nil} value. |
efa023dd | 146 | @xref{File Name Coding}. |
6bf7aab6 DL |
147 | |
148 | @node Visiting | |
149 | @section Visiting Files | |
150 | @cindex visiting files | |
151 | ||
6bf7aab6 DL |
152 | @table @kbd |
153 | @item C-x C-f | |
154 | Visit a file (@code{find-file}). | |
155 | @item C-x C-r | |
156 | Visit a file for viewing, without allowing changes to it | |
157 | (@code{find-file-read-only}). | |
158 | @item C-x C-v | |
159 | Visit a different file instead of the one visited last | |
160 | (@code{find-alternate-file}). | |
161 | @item C-x 4 f | |
162 | Visit a file, in another window (@code{find-file-other-window}). Don't | |
163 | alter what is displayed in the selected window. | |
164 | @item C-x 5 f | |
165 | Visit a file, in a new frame (@code{find-file-other-frame}). Don't | |
166 | alter what is displayed in the selected frame. | |
167 | @item M-x find-file-literally | |
168 | Visit a file with no conversion of the contents. | |
169 | @end table | |
170 | ||
171 | @cindex files, visiting and saving | |
6bf7aab6 | 172 | @cindex saving files |
0cf729ce RS |
173 | @dfn{Visiting} a file means copying its contents into an Emacs |
174 | buffer so you can edit them. Emacs makes a new buffer for each file | |
175 | that you visit. We often say that this buffer ``is visiting'' that | |
176 | file, or that the buffer's ``visited file'' is that file. Emacs | |
177 | constructs the buffer name from the file name by throwing away the | |
178 | directory, keeping just the name proper. For example, a file named | |
179 | @file{/usr/rms/emacs.tex} would get a buffer named @samp{emacs.tex}. | |
180 | If there is already a buffer with that name, Emacs constructs a unique | |
181 | name---the normal method is to append @samp{<2>}, @samp{<3>}, and so | |
182 | on, but you can select other methods (@pxref{Uniquify}). | |
6bf7aab6 DL |
183 | |
184 | Each window's mode line shows the name of the buffer that is being displayed | |
185 | in that window, so you can always tell what buffer you are editing. | |
186 | ||
187 | The changes you make with editing commands are made in the Emacs | |
188 | buffer. They do not take effect in the file that you visited, or any | |
50a1bd4f | 189 | permanent place, until you @dfn{save} the buffer. Saving the buffer |
6bf7aab6 DL |
190 | means that Emacs writes the current contents of the buffer into its |
191 | visited file. @xref{Saving}. | |
192 | ||
193 | @cindex modified (buffer) | |
194 | If a buffer contains changes that have not been saved, we say the | |
195 | buffer is @dfn{modified}. This is important because it implies that | |
196 | some changes will be lost if the buffer is not saved. The mode line | |
197 | displays two stars near the left margin to indicate that the buffer is | |
198 | modified. | |
199 | ||
200 | @kindex C-x C-f | |
201 | @findex find-file | |
202 | To visit a file, use the command @kbd{C-x C-f} (@code{find-file}). Follow | |
203 | the command with the name of the file you wish to visit, terminated by a | |
204 | @key{RET}. | |
205 | ||
206 | The file name is read using the minibuffer (@pxref{Minibuffer}), with | |
207 | defaulting and completion in the standard manner (@pxref{File Names}). | |
36d6da4e EZ |
208 | While in the minibuffer, you can abort @kbd{C-x C-f} by typing |
209 | @kbd{C-g}. File-name completion ignores certain filenames; for more | |
210 | about this, see @ref{Completion Options}. | |
6bf7aab6 | 211 | |
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212 | Your confirmation that @kbd{C-x C-f} has completed successfully is |
213 | the appearance of new text on the screen and a new buffer name in the | |
214 | mode line. If the specified file does not exist and you could not | |
215 | create it, or exists but you can't read it, then you get an error, | |
216 | with an error message displayed in the echo area. | |
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217 | |
218 | If you visit a file that is already in Emacs, @kbd{C-x C-f} does not make | |
219 | another copy. It selects the existing buffer containing that file. | |
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220 | However, before doing so, it checks whether the file itself has changed |
221 | since you visited or saved it last. If the file has changed, Emacs offers | |
222 | to reread it. | |
6bf7aab6 | 223 | |
3aff69e3 | 224 | @vindex large-file-warning-threshold |
9f2848e4 | 225 | @cindex maximum buffer size exceeded, error message |
3aff69e3 RS |
226 | If you try to visit a file larger than |
227 | @code{large-file-warning-threshold} (the default is 10000000, which is | |
228 | about 10 megabytes), Emacs will ask you for confirmation first. You | |
229 | can answer @kbd{y} to proceed with visiting the file. Note, however, | |
230 | that Emacs cannot visit files that are larger than the maximum Emacs | |
231 | buffer size, which is around 256 megabytes on 32-bit machines | |
232 | (@pxref{Buffers}). If you try, Emacs will display an error message | |
233 | saying that the maximum buffer size has been exceeded. | |
234 | ||
235 | @cindex file selection dialog | |
50a1bd4f | 236 | On graphical displays there are two additional methods for |
3aff69e3 RS |
237 | visiting files. Firstly, when Emacs is built with a suitable GUI |
238 | toolkit, commands invoked with the mouse (by clicking on the menu bar | |
239 | or tool bar) use the toolkit's standard File Selection dialog instead | |
240 | of prompting for the file name in the minibuffer. On Unix and | |
241 | GNU/Linux platforms, Emacs does that when built with GTK, LessTif, and | |
638dab37 | 242 | Motif toolkits; on MS-Windows and Mac, the GUI version does that by default. |
a0554a40 | 243 | For information on how to customize this, see @ref{Dialog Boxes}. |
3aff69e3 | 244 | |
590e3b9e RS |
245 | Secondly, Emacs supports ``drag and drop''; dropping a file into an |
246 | ordinary Emacs window visits the file using that window. However, | |
247 | dropping a file into a window displaying a Dired buffer moves or | |
248 | copies the file into the displayed directory. For details, see | |
249 | @ref{Drag and Drop}, and @ref{Misc Dired Features}. | |
9f2848e4 | 250 | |
6bf7aab6 | 251 | @cindex creating files |
1ba2ce68 | 252 | What if you want to create a new file? Just visit it. Emacs displays |
d3ff0a57 | 253 | @samp{(New file)} in the echo area, but in other respects behaves as if |
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254 | you had visited an existing empty file. If you make any changes and |
255 | save them, the file is created. | |
256 | ||
257 | Emacs recognizes from the contents of a file which convention it uses | |
258 | to separate lines---newline (used on GNU/Linux and on Unix), | |
259 | carriage-return linefeed (used on Microsoft systems), or just | |
260 | carriage-return (used on the Macintosh)---and automatically converts the | |
261 | contents to the normal Emacs convention, which is that the newline | |
262 | character separates lines. This is a part of the general feature of | |
263 | coding system conversion (@pxref{Coding Systems}), and makes it possible | |
4f09cbeb | 264 | to edit files imported from different operating systems with |
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265 | equal convenience. If you change the text and save the file, Emacs |
266 | performs the inverse conversion, changing newlines back into | |
267 | carriage-return linefeed or just carriage-return if appropriate. | |
268 | ||
269 | @vindex find-file-run-dired | |
270 | If the file you specify is actually a directory, @kbd{C-x C-f} invokes | |
271 | Dired, the Emacs directory browser, so that you can ``edit'' the contents | |
4a10556b RS |
272 | of the directory (@pxref{Dired}). Dired is a convenient way to view, delete, |
273 | or operate on the files in the directory. However, if the variable | |
274 | @code{find-file-run-dired} is @code{nil}, then it is an error to try | |
275 | to visit a directory. | |
6bf7aab6 | 276 | |
1b6f26fb EZ |
277 | Files which are actually collections of other files, or @dfn{file |
278 | archives}, are visited in special modes which invoke a Dired-like | |
279 | environment to allow operations on archive members. @xref{File | |
280 | Archives}, for more about these features. | |
281 | ||
7ed32bd8 DL |
282 | @cindex wildcard characters in file names |
283 | @vindex find-file-wildcards | |
092b683a RS |
284 | If the file name you specify contains shell-style wildcard |
285 | characters, Emacs visits all the files that match it. Wildcards | |
286 | include @samp{?}, @samp{*}, and @samp{[@dots{}]} sequences. To enter | |
287 | the wild card @samp{?} in a file name in the minibuffer, you need to | |
288 | type @kbd{C-q ?}. @xref{Quoted File Names}, for information on how to | |
289 | visit a file whose name actually contains wildcard characters. You | |
290 | can disable the wildcard feature by customizing | |
4f09cbeb | 291 | @code{find-file-wildcards}. |
6bf7aab6 DL |
292 | |
293 | If you visit a file that the operating system won't let you modify, | |
867357fb RS |
294 | or that is marked read-only, Emacs makes the buffer read-only too, so |
295 | that you won't go ahead and make changes that you'll have trouble | |
296 | saving afterward. You can make the buffer writable with @kbd{C-x C-q} | |
576c4a0f | 297 | (@code{toggle-read-only}). @xref{Misc Buffer}. |
6bf7aab6 DL |
298 | |
299 | @kindex C-x C-r | |
300 | @findex find-file-read-only | |
867357fb RS |
301 | If you want to visit a file as read-only in order to protect |
302 | yourself from entering changes accidentally, visit it with the command | |
303 | @kbd{C-x C-r} (@code{find-file-read-only}) instead of @kbd{C-x C-f}. | |
6bf7aab6 DL |
304 | |
305 | @kindex C-x C-v | |
306 | @findex find-alternate-file | |
307 | If you visit a nonexistent file unintentionally (because you typed the | |
308 | wrong file name), use the @kbd{C-x C-v} command | |
309 | (@code{find-alternate-file}) to visit the file you really wanted. | |
310 | @kbd{C-x C-v} is similar to @kbd{C-x C-f}, but it kills the current | |
4f09cbeb EZ |
311 | buffer (after first offering to save it if it is modified). When |
312 | @kbd{C-x C-v} reads the file name to visit, it inserts the entire | |
313 | default file name in the buffer, with point just after the directory | |
314 | part; this is convenient if you made a slight error in typing the name. | |
6bf7aab6 | 315 | |
6bf7aab6 DL |
316 | @kindex C-x 4 f |
317 | @findex find-file-other-window | |
318 | @kbd{C-x 4 f} (@code{find-file-other-window}) is like @kbd{C-x C-f} | |
319 | except that the buffer containing the specified file is selected in another | |
320 | window. The window that was selected before @kbd{C-x 4 f} continues to | |
321 | show the same buffer it was already showing. If this command is used when | |
322 | only one window is being displayed, that window is split in two, with one | |
323 | window showing the same buffer as before, and the other one showing the | |
324 | newly requested file. @xref{Windows}. | |
325 | ||
326 | @kindex C-x 5 f | |
327 | @findex find-file-other-frame | |
328 | @kbd{C-x 5 f} (@code{find-file-other-frame}) is similar, but opens a | |
329 | new frame, or makes visible any existing frame showing the file you | |
330 | seek. This feature is available only when you are using a window | |
331 | system. @xref{Frames}. | |
332 | ||
333 | @findex find-file-literally | |
76dd3692 | 334 | If you wish to edit a file as a sequence of @acronym{ASCII} characters with no special |
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335 | encoding or conversion, use the @kbd{M-x find-file-literally} command. |
336 | It visits a file, like @kbd{C-x C-f}, but does not do format conversion | |
337 | (@pxref{Formatted Text}), character code conversion (@pxref{Coding | |
4104194e GM |
338 | Systems}), or automatic uncompression (@pxref{Compressed Files}), and |
339 | does not add a final newline because of @code{require-final-newline}. | |
6bf7aab6 DL |
340 | If you already have visited the same file in the usual (non-literal) |
341 | manner, this command asks you whether to visit it literally instead. | |
342 | ||
f2aa473a SM |
343 | @vindex find-file-hook |
344 | @vindex find-file-not-found-functions | |
6bf7aab6 DL |
345 | Two special hook variables allow extensions to modify the operation of |
346 | visiting files. Visiting a file that does not exist runs the functions | |
f2aa473a | 347 | in the list @code{find-file-not-found-functions}; this variable holds a list |
6bf7aab6 DL |
348 | of functions, and the functions are called one by one (with no |
349 | arguments) until one of them returns non-@code{nil}. This is not a | |
f2aa473a | 350 | normal hook, and the name ends in @samp{-functions} rather than @samp{-hook} |
6bf7aab6 DL |
351 | to indicate that fact. |
352 | ||
0cf729ce | 353 | Successful visiting of any file, whether existing or not, calls the |
f2aa473a SM |
354 | functions in the list @code{find-file-hook}, with no arguments. |
355 | This variable is a normal hook. In the case of a nonexistent file, the | |
356 | @code{find-file-not-found-functions} are run first. @xref{Hooks}. | |
6bf7aab6 DL |
357 | |
358 | There are several ways to specify automatically the major mode for | |
359 | editing the file (@pxref{Choosing Modes}), and to specify local | |
360 | variables defined for that file (@pxref{File Variables}). | |
361 | ||
362 | @node Saving | |
363 | @section Saving Files | |
364 | ||
365 | @dfn{Saving} a buffer in Emacs means writing its contents back into the file | |
366 | that was visited in the buffer. | |
367 | ||
81a35977 RS |
368 | @menu |
369 | * Save Commands:: Commands for saving files. | |
370 | * Backup:: How Emacs saves the old version of your file. | |
371 | * Customize Save:: Customizing the saving of files. | |
372 | * Interlocking:: How Emacs protects against simultaneous editing | |
373 | of one file by two users. | |
374 | * Shadowing: File Shadowing. Copying files to "shadows" automatically. | |
375 | * Time Stamps:: Emacs can update time stamps on saved files. | |
376 | @end menu | |
377 | ||
eef3da72 | 378 | @node Save Commands |
81a35977 RS |
379 | @subsection Commands for Saving Files |
380 | ||
381 | These are the commands that relate to saving and writing files. | |
382 | ||
6bf7aab6 DL |
383 | @table @kbd |
384 | @item C-x C-s | |
0cf729ce | 385 | Save the current buffer in its visited file on disk (@code{save-buffer}). |
6bf7aab6 DL |
386 | @item C-x s |
387 | Save any or all buffers in their visited files (@code{save-some-buffers}). | |
388 | @item M-~ | |
389 | Forget that the current buffer has been changed (@code{not-modified}). | |
db8eeecd | 390 | With prefix argument (@kbd{C-u}), mark the current buffer as changed. |
6bf7aab6 | 391 | @item C-x C-w |
50a1bd4f | 392 | Save the current buffer with a specified file name (@code{write-file}). |
6bf7aab6 | 393 | @item M-x set-visited-file-name |
f65d66f8 | 394 | Change the file name under which the current buffer will be saved. |
6bf7aab6 DL |
395 | @end table |
396 | ||
397 | @kindex C-x C-s | |
398 | @findex save-buffer | |
399 | When you wish to save the file and make your changes permanent, type | |
400 | @kbd{C-x C-s} (@code{save-buffer}). After saving is finished, @kbd{C-x C-s} | |
401 | displays a message like this: | |
402 | ||
403 | @example | |
404 | Wrote /u/rms/gnu/gnu.tasks | |
405 | @end example | |
406 | ||
407 | @noindent | |
408 | If the selected buffer is not modified (no changes have been made in it | |
409 | since the buffer was created or last saved), saving is not really done, | |
410 | because it would have no effect. Instead, @kbd{C-x C-s} displays a message | |
411 | like this in the echo area: | |
412 | ||
413 | @example | |
414 | (No changes need to be saved) | |
415 | @end example | |
416 | ||
417 | @kindex C-x s | |
418 | @findex save-some-buffers | |
419 | The command @kbd{C-x s} (@code{save-some-buffers}) offers to save any | |
420 | or all modified buffers. It asks you what to do with each buffer. The | |
421 | possible responses are analogous to those of @code{query-replace}: | |
422 | ||
423 | @table @kbd | |
424 | @item y | |
425 | Save this buffer and ask about the rest of the buffers. | |
426 | @item n | |
427 | Don't save this buffer, but ask about the rest of the buffers. | |
428 | @item ! | |
429 | Save this buffer and all the rest with no more questions. | |
430 | @c following generates acceptable underfull hbox | |
431 | @item @key{RET} | |
432 | Terminate @code{save-some-buffers} without any more saving. | |
433 | @item . | |
434 | Save this buffer, then exit @code{save-some-buffers} without even asking | |
435 | about other buffers. | |
436 | @item C-r | |
437 | View the buffer that you are currently being asked about. When you exit | |
438 | View mode, you get back to @code{save-some-buffers}, which asks the | |
439 | question again. | |
4a10556b RS |
440 | @item d |
441 | Diff the buffer against its corresponding file, so you can see | |
442 | what changes you would be saving. | |
6bf7aab6 DL |
443 | @item C-h |
444 | Display a help message about these options. | |
445 | @end table | |
446 | ||
447 | @kbd{C-x C-c}, the key sequence to exit Emacs, invokes | |
448 | @code{save-some-buffers} and therefore asks the same questions. | |
449 | ||
450 | @kindex M-~ | |
451 | @findex not-modified | |
452 | If you have changed a buffer but you do not want to save the changes, | |
453 | you should take some action to prevent it. Otherwise, each time you use | |
454 | @kbd{C-x s} or @kbd{C-x C-c}, you are liable to save this buffer by | |
455 | mistake. One thing you can do is type @kbd{M-~} (@code{not-modified}), | |
456 | which clears out the indication that the buffer is modified. If you do | |
457 | this, none of the save commands will believe that the buffer needs to be | |
458 | saved. (@samp{~} is often used as a mathematical symbol for `not'; thus | |
459 | @kbd{M-~} is `not', metafied.) You could also use | |
460 | @code{set-visited-file-name} (see below) to mark the buffer as visiting | |
461 | a different file name, one which is not in use for anything important. | |
462 | Alternatively, you can cancel all the changes made since the file was | |
463 | visited or saved, by reading the text from the file again. This is | |
50a1bd4f | 464 | called @dfn{reverting}. @xref{Reverting}. (You could also undo all the |
6bf7aab6 | 465 | changes by repeating the undo command @kbd{C-x u} until you have undone |
50a1bd4f | 466 | all the changes; but reverting is easier.) You can also kill the buffer. |
6bf7aab6 DL |
467 | |
468 | @findex set-visited-file-name | |
469 | @kbd{M-x set-visited-file-name} alters the name of the file that the | |
470 | current buffer is visiting. It reads the new file name using the | |
0cf729ce RS |
471 | minibuffer. Then it marks the buffer as visiting that file name, and |
472 | changes the buffer name correspondingly. @code{set-visited-file-name} | |
473 | does not save the buffer in the newly visited file; it just alters the | |
474 | records inside Emacs in case you do save later. It also marks the | |
475 | buffer as ``modified'' so that @kbd{C-x C-s} in that buffer | |
476 | @emph{will} save. | |
6bf7aab6 DL |
477 | |
478 | @kindex C-x C-w | |
479 | @findex write-file | |
480 | If you wish to mark the buffer as visiting a different file and save it | |
16f56815 RS |
481 | right away, use @kbd{C-x C-w} (@code{write-file}). It is |
482 | equivalent to @code{set-visited-file-name} followed by @kbd{C-x C-s} | |
483 | (except that @kbd{C-x C-w} asks for confirmation if the file exists). | |
6bf7aab6 DL |
484 | @kbd{C-x C-s} used on a buffer that is not visiting a file has the |
485 | same effect as @kbd{C-x C-w}; that is, it reads a file name, marks the | |
486 | buffer as visiting that file, and saves it there. The default file name in | |
487 | a buffer that is not visiting a file is made by combining the buffer name | |
0cf729ce | 488 | with the buffer's default directory (@pxref{File Names}). |
6bf7aab6 DL |
489 | |
490 | If the new file name implies a major mode, then @kbd{C-x C-w} switches | |
491 | to that major mode, in most cases. The command | |
492 | @code{set-visited-file-name} also does this. @xref{Choosing Modes}. | |
493 | ||
494 | If Emacs is about to save a file and sees that the date of the latest | |
495 | version on disk does not match what Emacs last read or wrote, Emacs | |
496 | notifies you of this fact, because it probably indicates a problem caused | |
497 | by simultaneous editing and requires your immediate attention. | |
498 | @xref{Interlocking,, Simultaneous Editing}. | |
499 | ||
6bf7aab6 DL |
500 | @node Backup |
501 | @subsection Backup Files | |
502 | @cindex backup file | |
503 | @vindex make-backup-files | |
504 | @vindex vc-make-backup-files | |
6bf7aab6 DL |
505 | |
506 | On most operating systems, rewriting a file automatically destroys all | |
507 | record of what the file used to contain. Thus, saving a file from Emacs | |
508 | throws away the old contents of the file---or it would, except that | |
509 | Emacs carefully copies the old contents to another file, called the | |
510 | @dfn{backup} file, before actually saving. | |
511 | ||
512 | For most files, the variable @code{make-backup-files} determines | |
513 | whether to make backup files. On most operating systems, its default | |
514 | value is @code{t}, so that Emacs does write backup files. | |
515 | ||
516 | For files managed by a version control system (@pxref{Version | |
517 | Control}), the variable @code{vc-make-backup-files} determines whether | |
4f09cbeb | 518 | to make backup files. By default it is @code{nil}, since backup files |
6bf7aab6 | 519 | are redundant when you store all the previous versions in a version |
ad63cf1d | 520 | control system. @xref{General VC Options}. |
6bf7aab6 | 521 | |
50a1bd4f RS |
522 | At your option, Emacs can keep either a single backup for each file, |
523 | or make a series of numbered backup files for each file that you edit. | |
524 | ||
9a98ef18 DL |
525 | @vindex backup-enable-predicate |
526 | @vindex temporary-file-directory | |
527 | @vindex small-temporary-file-directory | |
6bf7aab6 | 528 | The default value of the @code{backup-enable-predicate} variable |
f02d86a3 RS |
529 | prevents backup files being written for files in the directories used |
530 | for temporary files, specified by @code{temporary-file-directory} or | |
531 | @code{small-temporary-file-directory}. | |
6bf7aab6 | 532 | |
6bf7aab6 DL |
533 | Emacs makes a backup for a file only the first time the file is saved |
534 | from one buffer. No matter how many times you save a file, its backup file | |
535 | continues to contain the contents from before the file was visited. | |
536 | Normally this means that the backup file contains the contents from before | |
537 | the current editing session; however, if you kill the buffer and then visit | |
538 | the file again, a new backup file will be made by the next save. | |
539 | ||
540 | You can also explicitly request making another backup file from a | |
541 | buffer even though it has already been saved at least once. If you save | |
542 | the buffer with @kbd{C-u C-x C-s}, the version thus saved will be made | |
543 | into a backup file if you save the buffer again. @kbd{C-u C-u C-x C-s} | |
544 | saves the buffer, but first makes the previous file contents into a new | |
545 | backup file. @kbd{C-u C-u C-u C-x C-s} does both things: it makes a | |
0cf729ce RS |
546 | backup from the previous contents, and arranges to make another from the |
547 | newly saved contents if you save again. | |
6bf7aab6 DL |
548 | |
549 | @menu | |
1384a610 | 550 | * One or Many: Numbered Backups. Whether to make one backup file or many. |
50a1bd4f | 551 | * Names: Backup Names. How backup files are named. |
6bf7aab6 DL |
552 | * Deletion: Backup Deletion. Emacs deletes excess numbered backups. |
553 | * Copying: Backup Copying. Backups can be made by copying or renaming. | |
554 | @end menu | |
555 | ||
50a1bd4f RS |
556 | @node Numbered Backups |
557 | @subsubsection Numbered Backups | |
558 | ||
559 | @vindex version-control | |
560 | The choice of single backup file or multiple numbered backup files | |
561 | is controlled by the variable @code{version-control}. Its possible | |
562 | values are: | |
563 | ||
564 | @table @code | |
565 | @item t | |
566 | Make numbered backups. | |
567 | @item nil | |
568 | Make numbered backups for files that have numbered backups already. | |
569 | Otherwise, make single backups. | |
570 | @item never | |
571 | Never make numbered backups; always make single backups. | |
572 | @end table | |
573 | ||
574 | @noindent | |
575 | The usual way to set this variable is globally, through your | |
576 | @file{.emacs} file or the customization buffer. However, you can set | |
577 | @code{version-control} locally in an individual buffer to control the | |
578 | making of backups for that buffer's file. For example, Rmail mode | |
579 | locally sets @code{version-control} to @code{never} to make sure that | |
580 | there is only one backup for an Rmail file. @xref{Locals}. | |
581 | ||
582 | @cindex @env{VERSION_CONTROL} environment variable | |
583 | If you set the environment variable @env{VERSION_CONTROL}, to tell | |
584 | various GNU utilities what to do with backup files, Emacs also obeys the | |
585 | environment variable by setting the Lisp variable @code{version-control} | |
586 | accordingly at startup. If the environment variable's value is @samp{t} | |
587 | or @samp{numbered}, then @code{version-control} becomes @code{t}; if the | |
588 | value is @samp{nil} or @samp{existing}, then @code{version-control} | |
589 | becomes @code{nil}; if it is @samp{never} or @samp{simple}, then | |
590 | @code{version-control} becomes @code{never}. | |
591 | ||
6bf7aab6 DL |
592 | @node Backup Names |
593 | @subsubsection Single or Numbered Backups | |
594 | ||
50a1bd4f RS |
595 | When Emacs makes a single backup file, its name is normally |
596 | constructed by appending @samp{~} to the file name being edited; thus, | |
597 | the backup file for @file{eval.c} would be @file{eval.c~}. | |
6bf7aab6 | 598 | |
9a98ef18 DL |
599 | @vindex make-backup-file-name-function |
600 | @vindex backup-directory-alist | |
39cf6a8d | 601 | You can change this behavior by defining the variable |
9a98ef18 DL |
602 | @code{make-backup-file-name-function} to a suitable function. |
603 | Alternatively you can customize the variable | |
9daa0aa0 | 604 | @code{backup-directory-alist} to specify that files matching certain |
f02d86a3 RS |
605 | patterns should be backed up in specific directories. |
606 | ||
607 | A typical use is to add an element @code{("." . @var{dir})} to make | |
608 | all backups in the directory with absolute name @var{dir}; Emacs | |
609 | modifies the backup file names to avoid clashes between files with the | |
610 | same names originating in different directories. Alternatively, | |
83217838 | 611 | adding, say, @code{("." . ".~")} would make backups in the invisible |
f02d86a3 RS |
612 | subdirectory @file{.~} of the original file's directory. Emacs |
613 | creates the directory, if necessary, to make the backup. | |
614 | ||
615 | If access control stops Emacs from writing backup files under the usual | |
616 | names, it writes the backup file as @file{%backup%~} in your home | |
617 | directory. Only one such file can exist, so only the most recently | |
618 | made such backup is available. | |
9a98ef18 | 619 | |
6bf7aab6 | 620 | If you choose to have a series of numbered backup files, backup file |
f02d86a3 RS |
621 | names contain @samp{.~}, the number, and another @samp{~} after the |
622 | original file name. Thus, the backup files of @file{eval.c} would be | |
623 | called @file{eval.c.~1~}, @file{eval.c.~2~}, and so on, all the way | |
624 | through names like @file{eval.c.~259~} and beyond. The variable | |
625 | @code{backup-directory-alist} applies to numbered backups just as | |
626 | usual. | |
6bf7aab6 | 627 | |
6bf7aab6 DL |
628 | @node Backup Deletion |
629 | @subsubsection Automatic Deletion of Backups | |
630 | ||
6b4878ed | 631 | To prevent excessive consumption of disk space, Emacs can delete numbered |
6bf7aab6 DL |
632 | backup versions automatically. Generally Emacs keeps the first few backups |
633 | and the latest few backups, deleting any in between. This happens every | |
634 | time a new backup is made. | |
635 | ||
636 | @vindex kept-old-versions | |
637 | @vindex kept-new-versions | |
638 | The two variables @code{kept-old-versions} and | |
639 | @code{kept-new-versions} control this deletion. Their values are, | |
0cf729ce RS |
640 | respectively, the number of oldest (lowest-numbered) backups to keep |
641 | and the number of newest (highest-numbered) ones to keep, each time a | |
642 | new backup is made. The backups in the middle (excluding those oldest | |
643 | and newest) are the excess middle versions---those backups are | |
644 | deleted. These variables' values are used when it is time to delete | |
645 | excess versions, just after a new backup version is made; the newly | |
646 | made backup is included in the count in @code{kept-new-versions}. By | |
647 | default, both variables are 2. | |
6bf7aab6 DL |
648 | |
649 | @vindex delete-old-versions | |
3f9be7ce LT |
650 | If @code{delete-old-versions} is @code{t}, Emacs deletes the excess |
651 | backup files silently. If it is @code{nil}, the default, Emacs asks | |
652 | you whether it should delete the excess backup versions. If it has | |
653 | any other value, then Emacs never automatically deletes backups. | |
6bf7aab6 DL |
654 | |
655 | Dired's @kbd{.} (Period) command can also be used to delete old versions. | |
656 | @xref{Dired Deletion}. | |
657 | ||
658 | @node Backup Copying | |
659 | @subsubsection Copying vs.@: Renaming | |
660 | ||
0cf729ce RS |
661 | Backup files can be made by copying the old file or by renaming it. |
662 | This makes a difference when the old file has multiple names (hard | |
663 | links). If the old file is renamed into the backup file, then the | |
664 | alternate names become names for the backup file. If the old file is | |
665 | copied instead, then the alternate names remain names for the file | |
666 | that you are editing, and the contents accessed by those names will be | |
667 | the new contents. | |
6bf7aab6 DL |
668 | |
669 | The method of making a backup file may also affect the file's owner | |
670 | and group. If copying is used, these do not change. If renaming is used, | |
671 | you become the file's owner, and the file's group becomes the default | |
672 | (different operating systems have different defaults for the group). | |
673 | ||
674 | Having the owner change is usually a good idea, because then the owner | |
675 | always shows who last edited the file. Also, the owners of the backups | |
676 | show who produced those versions. Occasionally there is a file whose | |
677 | owner should not change; it is a good idea for such files to contain | |
678 | local variable lists to set @code{backup-by-copying-when-mismatch} | |
679 | locally (@pxref{File Variables}). | |
680 | ||
681 | @vindex backup-by-copying | |
682 | @vindex backup-by-copying-when-linked | |
683 | @vindex backup-by-copying-when-mismatch | |
3c8b8db0 EZ |
684 | @vindex backup-by-copying-when-privileged-mismatch |
685 | @cindex file ownership, and backup | |
f02d86a3 | 686 | @cindex backup, and user-id |
3c8b8db0 | 687 | The choice of renaming or copying is controlled by four variables. |
6bf7aab6 DL |
688 | Renaming is the default choice. If the variable |
689 | @code{backup-by-copying} is non-@code{nil}, copying is used. Otherwise, | |
690 | if the variable @code{backup-by-copying-when-linked} is non-@code{nil}, | |
691 | then copying is used for files that have multiple names, but renaming | |
692 | may still be used when the file being edited has only one name. If the | |
693 | variable @code{backup-by-copying-when-mismatch} is non-@code{nil}, then | |
694 | copying is used if renaming would cause the file's owner or group to | |
695 | change. @code{backup-by-copying-when-mismatch} is @code{t} by default | |
3c8b8db0 EZ |
696 | if you start Emacs as the superuser. The fourth variable, |
697 | @code{backup-by-copying-when-privileged-mismatch}, gives the highest | |
f02d86a3 | 698 | numeric user-id for which @code{backup-by-copying-when-mismatch} will be |
4f09cbeb | 699 | forced on. This is useful when low-numbered user-ids are assigned to |
3c8b8db0 EZ |
700 | special system users, such as @code{root}, @code{bin}, @code{daemon}, |
701 | etc., which must maintain ownership of files. | |
6bf7aab6 DL |
702 | |
703 | When a file is managed with a version control system (@pxref{Version | |
704 | Control}), Emacs does not normally make backups in the usual way for | |
705 | that file. But check-in and check-out are similar in some ways to | |
706 | making backups. One unfortunate similarity is that these operations | |
707 | typically break hard links, disconnecting the file name you visited from | |
708 | any alternate names for the same file. This has nothing to do with | |
709 | Emacs---the version control system does it. | |
710 | ||
81a35977 RS |
711 | @node Customize Save |
712 | @subsection Customizing Saving of Files | |
713 | ||
714 | @vindex require-final-newline | |
715 | If the value of the variable @code{require-final-newline} is | |
716 | @code{t}, saving or writing a file silently puts a newline at the end | |
717 | if there isn't already one there. If the value is @code{visit}, Emacs | |
718 | adds a newline at the end of any file that doesn't have one, just | |
719 | after it visits the file. (This marks the buffer as modified, and you | |
720 | can undo it.) If the value is @code{visit-save}, that means to add | |
721 | newlines both on visiting and on saving. If the value is @code{nil}, | |
722 | Emacs leaves the end of the file unchanged; if it's neither @code{nil} | |
723 | nor @code{t}, Emacs asks you whether to add a newline. The default is | |
724 | @code{nil}. | |
725 | ||
726 | @vindex mode-require-final-newline | |
727 | Many major modes are designed for specific kinds of files that are | |
728 | always supposed to end in newlines. These major modes set the | |
729 | variable @code{require-final-newline} according to | |
730 | @code{mode-require-final-newline}. By setting the latter variable, | |
731 | you can control how these modes handle final newlines. | |
732 | ||
733 | @vindex write-region-inhibit-fsync | |
734 | When Emacs saves a file, it invokes the @code{fsync} system call to | |
735 | force the data immediately out to disk. This is important for safety | |
736 | if the system crashes or in case of power outage. However, it can be | |
737 | disruptive on laptops using power saving, because it requires the disk | |
738 | to spin up each time you save a file. Setting | |
739 | @code{write-region-inhibit-fsync} to a non-@code{nil} value disables | |
740 | this synchronization. Be careful---this means increased risk of data | |
741 | loss. | |
742 | ||
6bf7aab6 DL |
743 | @node Interlocking |
744 | @subsection Protection against Simultaneous Editing | |
745 | ||
746 | @cindex file dates | |
747 | @cindex simultaneous editing | |
748 | Simultaneous editing occurs when two users visit the same file, both | |
749 | make changes, and then both save them. If nobody were informed that | |
750 | this was happening, whichever user saved first would later find that his | |
751 | changes were lost. | |
752 | ||
753 | On some systems, Emacs notices immediately when the second user starts | |
754 | to change the file, and issues an immediate warning. On all systems, | |
755 | Emacs checks when you save the file, and warns if you are about to | |
756 | overwrite another user's changes. You can prevent loss of the other | |
757 | user's work by taking the proper corrective action instead of saving the | |
758 | file. | |
759 | ||
760 | @findex ask-user-about-lock | |
761 | @cindex locking files | |
762 | When you make the first modification in an Emacs buffer that is | |
763 | visiting a file, Emacs records that the file is @dfn{locked} by you. | |
764 | (It does this by creating a symbolic link in the same directory with a | |
765 | different name.) Emacs removes the lock when you save the changes. The | |
766 | idea is that the file is locked whenever an Emacs buffer visiting it has | |
767 | unsaved changes. | |
768 | ||
769 | @cindex collision | |
770 | If you begin to modify the buffer while the visited file is locked by | |
771 | someone else, this constitutes a @dfn{collision}. When Emacs detects a | |
772 | collision, it asks you what to do, by calling the Lisp function | |
773 | @code{ask-user-about-lock}. You can redefine this function for the sake | |
774 | of customization. The standard definition of this function asks you a | |
775 | question and accepts three possible answers: | |
776 | ||
777 | @table @kbd | |
778 | @item s | |
779 | Steal the lock. Whoever was already changing the file loses the lock, | |
780 | and you gain the lock. | |
781 | @item p | |
782 | Proceed. Go ahead and edit the file despite its being locked by someone else. | |
783 | @item q | |
0cf729ce RS |
784 | Quit. This causes an error (@code{file-locked}), and the buffer |
785 | contents remain unchanged---the modification you were trying to make | |
786 | does not actually take place. | |
6bf7aab6 DL |
787 | @end table |
788 | ||
789 | Note that locking works on the basis of a file name; if a file has | |
790 | multiple names, Emacs does not realize that the two names are the same file | |
791 | and cannot prevent two users from editing it simultaneously under different | |
792 | names. However, basing locking on names means that Emacs can interlock the | |
793 | editing of new files that will not really exist until they are saved. | |
794 | ||
795 | Some systems are not configured to allow Emacs to make locks, and | |
796 | there are cases where lock files cannot be written. In these cases, | |
797 | Emacs cannot detect trouble in advance, but it still can detect the | |
798 | collision when you try to save a file and overwrite someone else's | |
799 | changes. | |
800 | ||
801 | If Emacs or the operating system crashes, this may leave behind lock | |
066502ab | 802 | files which are stale, so you may occasionally get warnings about |
6bf7aab6 DL |
803 | spurious collisions. When you determine that the collision is spurious, |
804 | just use @kbd{p} to tell Emacs to go ahead anyway. | |
805 | ||
806 | Every time Emacs saves a buffer, it first checks the last-modification | |
807 | date of the existing file on disk to verify that it has not changed since the | |
808 | file was last visited or saved. If the date does not match, it implies | |
809 | that changes were made in the file in some other way, and these changes are | |
810 | about to be lost if Emacs actually does save. To prevent this, Emacs | |
1ba2ce68 | 811 | displays a warning message and asks for confirmation before saving. |
6bf7aab6 DL |
812 | Occasionally you will know why the file was changed and know that it does |
813 | not matter; then you can answer @kbd{yes} and proceed. Otherwise, you should | |
814 | cancel the save with @kbd{C-g} and investigate the situation. | |
815 | ||
816 | The first thing you should do when notified that simultaneous editing | |
817 | has already taken place is to list the directory with @kbd{C-u C-x C-d} | |
818 | (@pxref{Directories}). This shows the file's current author. You | |
819 | should attempt to contact him to warn him not to continue editing. | |
820 | Often the next step is to save the contents of your Emacs buffer under a | |
821 | different name, and use @code{diff} to compare the two files.@refill | |
822 | ||
fa474484 DL |
823 | @node File Shadowing |
824 | @subsection Shadowing Files | |
825 | @cindex shadow files | |
826 | @cindex file shadows | |
50a1bd4f | 827 | @findex shadow-initialize |
fa474484 DL |
828 | |
829 | @table @kbd | |
830 | @item M-x shadow-initialize | |
831 | Set up file shadowing. | |
fa474484 DL |
832 | @item M-x shadow-define-literal-group |
833 | Declare a single file to be shared between sites. | |
f02d86a3 RS |
834 | @item M-x shadow-define-regexp-group |
835 | Make all files that match each of a group of files be shared between hosts. | |
836 | @item M-x shadow-define-cluster @key{RET} @var{name} @key{RET} | |
837 | Define a shadow file cluster @var{name}. | |
fa474484 DL |
838 | @item M-x shadow-copy-files |
839 | Copy all pending shadow files. | |
f02d86a3 RS |
840 | @item M-x shadow-cancel |
841 | Cancel the instruction to shadow some files. | |
fa474484 DL |
842 | @end table |
843 | ||
f02d86a3 RS |
844 | You can arrange to keep identical @dfn{shadow} copies of certain files |
845 | in more than one place---possibly on different machines. To do this, | |
846 | first you must set up a @dfn{shadow file group}, which is a set of | |
847 | identically-named files shared between a list of sites. The file | |
848 | group is permanent and applies to further Emacs sessions as well as | |
849 | the current one. Once the group is set up, every time you exit Emacs, | |
850 | it will copy the file you edited to the other files in its group. You | |
851 | can also do the copying without exiting Emacs, by typing @kbd{M-x | |
852 | shadow-copy-files}. | |
853 | ||
d3ff0a57 RS |
854 | To set up a shadow file group, use @kbd{M-x |
855 | shadow-define-literal-group} or @kbd{M-x shadow-define-regexp-group}. | |
856 | See their documentation strings for further information. | |
f02d86a3 RS |
857 | |
858 | Before copying a file to its shadows, Emacs asks for confirmation. | |
859 | You can answer ``no'' to bypass copying of this file, this time. If | |
860 | you want to cancel the shadowing permanently for a certain file, use | |
861 | @kbd{M-x shadow-cancel} to eliminate or change the shadow file group. | |
862 | ||
863 | A @dfn{shadow cluster} is a group of hosts that share directories, so | |
864 | that copying to or from one of them is sufficient to update the file | |
865 | on all of them. Each shadow cluster has a name, and specifies the | |
866 | network address of a primary host (the one we copy files to), and a | |
d0960fb3 | 867 | regular expression that matches the host names of all the other hosts |
f02d86a3 RS |
868 | in the cluster. You can define a shadow cluster with @kbd{M-x |
869 | shadow-define-cluster}. | |
fa474484 | 870 | |
9575b9ae DL |
871 | @node Time Stamps |
872 | @subsection Updating Time Stamps Automatically | |
9575b9ae DL |
873 | @cindex time stamps |
874 | @cindex modification dates | |
940f14b4 | 875 | @cindex locale, date format |
9575b9ae | 876 | |
4f09cbeb | 877 | You can arrange to put a time stamp in a file, so that it will be updated |
f02d86a3 RS |
878 | automatically each time you edit and save the file. The time stamp |
879 | has to be in the first eight lines of the file, and you should | |
880 | insert it like this: | |
881 | ||
9575b9ae DL |
882 | @example |
883 | Time-stamp: <> | |
884 | @end example | |
f02d86a3 | 885 | |
9575b9ae | 886 | @noindent |
f02d86a3 RS |
887 | or like this: |
888 | ||
9575b9ae | 889 | @example |
51c39777 | 890 | Time-stamp: " " |
9575b9ae | 891 | @end example |
9575b9ae | 892 | |
50a1bd4f | 893 | @findex time-stamp |
f02d86a3 | 894 | Then add the hook function @code{time-stamp} to the hook |
3f9be7ce | 895 | @code{before-save-hook}; that hook function will automatically update |
f02d86a3 RS |
896 | the time stamp, inserting the current date and time when you save the |
897 | file. You can also use the command @kbd{M-x time-stamp} to update the | |
898 | time stamp manually. For other customizations, see the Custom group | |
899 | @code{time-stamp}. Note that non-numeric fields in the time stamp are | |
900 | formatted according to your locale setting (@pxref{Environment}). | |
9575b9ae | 901 | |
6bf7aab6 DL |
902 | @node Reverting |
903 | @section Reverting a Buffer | |
904 | @findex revert-buffer | |
905 | @cindex drastic changes | |
41d39958 | 906 | @cindex reread a file |
6bf7aab6 DL |
907 | |
908 | If you have made extensive changes to a file and then change your mind | |
909 | about them, you can get rid of them by reading in the previous version | |
910 | of the file. To do this, use @kbd{M-x revert-buffer}, which operates on | |
911 | the current buffer. Since reverting a buffer unintentionally could lose | |
912 | a lot of work, you must confirm this command with @kbd{yes}. | |
913 | ||
6deaa218 LT |
914 | @code{revert-buffer} tries to position point in such a way that, if |
915 | the file was edited only slightly, you will be at approximately the | |
916 | same piece of text after reverting as before. However, if you have made | |
917 | drastic changes, point may wind up in a totally different piece of text. | |
6bf7aab6 DL |
918 | |
919 | Reverting marks the buffer as ``not modified'' until another change is | |
920 | made. | |
921 | ||
922 | Some kinds of buffers whose contents reflect data bases other than files, | |
923 | such as Dired buffers, can also be reverted. For them, reverting means | |
924 | recalculating their contents from the appropriate data base. Buffers | |
925 | created explicitly with @kbd{C-x b} cannot be reverted; @code{revert-buffer} | |
926 | reports an error when asked to do so. | |
927 | ||
928 | @vindex revert-without-query | |
929 | When you edit a file that changes automatically and frequently---for | |
930 | example, a log of output from a process that continues to run---it may be | |
931 | useful for Emacs to revert the file without querying you, whenever you | |
932 | visit the file again with @kbd{C-x C-f}. | |
933 | ||
934 | To request this behavior, set the variable @code{revert-without-query} | |
935 | to a list of regular expressions. When a file name matches one of these | |
936 | regular expressions, @code{find-file} and @code{revert-buffer} will | |
937 | revert it automatically if it has changed---provided the buffer itself | |
938 | is not modified. (If you have edited the text, it would be wrong to | |
939 | discard your changes.) | |
940 | ||
9daa0aa0 DL |
941 | @cindex Global Auto-Revert mode |
942 | @cindex mode, Global Auto-Revert | |
943 | @cindex Auto-Revert mode | |
944 | @cindex mode, Auto-Revert | |
945 | @findex global-auto-revert-mode | |
946 | @findex auto-revert-mode | |
3aff69e3 RS |
947 | @findex auto-revert-tail-mode |
948 | ||
949 | You may find it useful to have Emacs revert files automatically when | |
950 | they change. Three minor modes are available to do this. | |
951 | ||
50a1bd4f | 952 | @kbd{M-x global-auto-revert-mode} enables Global Auto-Revert mode, |
3aff69e3 | 953 | which periodically checks all file buffers and reverts when the |
50a1bd4f RS |
954 | corresponding file has changed. @kbd{M-x auto-revert-mode} enables a |
955 | local version, Auto-Revert mode, which applies only to the current | |
956 | buffer. | |
957 | ||
958 | You can use Auto-Revert mode to ``tail'' a file such as a system | |
959 | log, so that changes made to that file by other programs are | |
960 | continuously displayed. To do this, just move the point to the end of | |
961 | the buffer, and it will stay there as the file contents change. | |
962 | However, if you are sure that the file will only change by growing at | |
963 | the end, use Auto-Revert Tail mode instead | |
efa023dd | 964 | (@code{auto-revert-tail-mode}). It is more efficient for this. |
3aff69e3 | 965 | |
9daa0aa0 | 966 | @vindex auto-revert-interval |
3aff69e3 RS |
967 | The variable @code{auto-revert-interval} controls how often to check |
968 | for a changed file. Since checking a remote file is too slow, these | |
969 | modes do not check or revert remote files. | |
9daa0aa0 | 970 | |
50a1bd4f | 971 | @xref{VC Mode Line}, for Auto Revert peculiarities in buffers that |
ea98eb11 | 972 | visit files under version control. |
040d9a64 | 973 | |
6bf7aab6 DL |
974 | @node Auto Save |
975 | @section Auto-Saving: Protection Against Disasters | |
976 | @cindex Auto Save mode | |
977 | @cindex mode, Auto Save | |
978 | @cindex crashes | |
979 | ||
980 | Emacs saves all the visited files from time to time (based on counting | |
981 | your keystrokes) without being asked. This is called @dfn{auto-saving}. | |
982 | It prevents you from losing more than a limited amount of work if the | |
983 | system crashes. | |
984 | ||
50a1bd4f RS |
985 | When Emacs determines that it is time for auto-saving, it considers |
986 | each buffer, and each is auto-saved if auto-saving is enabled for it | |
987 | and it has been changed since the last time it was auto-saved. The | |
988 | message @samp{Auto-saving...} is displayed in the echo area during | |
989 | auto-saving, if any files are actually auto-saved. Errors occurring | |
990 | during auto-saving are caught so that they do not interfere with the | |
991 | execution of commands you have been typing. | |
6bf7aab6 DL |
992 | |
993 | @menu | |
994 | * Files: Auto Save Files. The file where auto-saved changes are | |
995 | actually made until you save the file. | |
996 | * Control: Auto Save Control. Controlling when and how often to auto-save. | |
997 | * Recover:: Recovering text from auto-save files. | |
998 | @end menu | |
999 | ||
1000 | @node Auto Save Files | |
1001 | @subsection Auto-Save Files | |
1002 | ||
1003 | Auto-saving does not normally save in the files that you visited, because | |
1004 | it can be very undesirable to save a program that is in an inconsistent | |
1005 | state when you have made half of a planned change. Instead, auto-saving | |
1006 | is done in a different file called the @dfn{auto-save file}, and the | |
1007 | visited file is changed only when you request saving explicitly (such as | |
1008 | with @kbd{C-x C-s}). | |
1009 | ||
1010 | Normally, the auto-save file name is made by appending @samp{#} to the | |
1011 | front and rear of the visited file name. Thus, a buffer visiting file | |
1012 | @file{foo.c} is auto-saved in a file @file{#foo.c#}. Most buffers that | |
1013 | are not visiting files are auto-saved only if you request it explicitly; | |
1014 | when they are auto-saved, the auto-save file name is made by appending | |
14661c9a RS |
1015 | @samp{#} to the front and rear of buffer name, then |
1016 | adding digits and letters at the end for uniqueness. For | |
6bf7aab6 | 1017 | example, the @samp{*mail*} buffer in which you compose messages to be |
3f9be7ce | 1018 | sent might be auto-saved in a file named @file{#*mail*#704juu}. Auto-save file |
6bf7aab6 DL |
1019 | names are made this way unless you reprogram parts of Emacs to do |
1020 | something different (the functions @code{make-auto-save-file-name} and | |
1021 | @code{auto-save-file-name-p}). The file name to be used for auto-saving | |
1022 | in a buffer is calculated when auto-saving is turned on in that buffer. | |
1023 | ||
5a2ce5f5 GM |
1024 | @cindex auto-save for remote files |
1025 | @vindex auto-save-file-name-transforms | |
b3c8fa05 RS |
1026 | The variable @code{auto-save-file-name-transforms} allows a degree |
1027 | of control over the auto-save file name. It lets you specify a series | |
1028 | of regular expressions and replacements to transform the auto save | |
1029 | file name. The default value puts the auto-save files for remote | |
1030 | files (@pxref{Remote Files}) into the temporary file directory on the | |
1031 | local machine. | |
5a2ce5f5 | 1032 | |
6bf7aab6 DL |
1033 | When you delete a substantial part of the text in a large buffer, auto |
1034 | save turns off temporarily in that buffer. This is because if you | |
1035 | deleted the text unintentionally, you might find the auto-save file more | |
1036 | useful if it contains the deleted text. To reenable auto-saving after | |
1037 | this happens, save the buffer with @kbd{C-x C-s}, or use @kbd{C-u 1 M-x | |
3f9be7ce | 1038 | auto-save-mode}. |
6bf7aab6 DL |
1039 | |
1040 | @vindex auto-save-visited-file-name | |
0cf729ce RS |
1041 | If you want auto-saving to be done in the visited file rather than |
1042 | in a separate auto-save file, set the variable | |
1043 | @code{auto-save-visited-file-name} to a non-@code{nil} value. In this | |
1044 | mode, there is no real difference between auto-saving and explicit | |
1045 | saving. | |
6bf7aab6 DL |
1046 | |
1047 | @vindex delete-auto-save-files | |
1048 | A buffer's auto-save file is deleted when you save the buffer in its | |
50a1bd4f RS |
1049 | visited file. (You can inhibit this by setting the variable |
1050 | @code{delete-auto-save-files} to @code{nil}.) Changing the visited | |
1051 | file name with @kbd{C-x C-w} or @code{set-visited-file-name} renames | |
1052 | any auto-save file to go with the new visited name. | |
6bf7aab6 DL |
1053 | |
1054 | @node Auto Save Control | |
1055 | @subsection Controlling Auto-Saving | |
1056 | ||
1057 | @vindex auto-save-default | |
1058 | @findex auto-save-mode | |
1059 | Each time you visit a file, auto-saving is turned on for that file's | |
1060 | buffer if the variable @code{auto-save-default} is non-@code{nil} (but not | |
1061 | in batch mode; @pxref{Entering Emacs}). The default for this variable is | |
1062 | @code{t}, so auto-saving is the usual practice for file-visiting buffers. | |
1063 | Auto-saving can be turned on or off for any existing buffer with the | |
1064 | command @kbd{M-x auto-save-mode}. Like other minor mode commands, @kbd{M-x | |
1065 | auto-save-mode} turns auto-saving on with a positive argument, off with a | |
1066 | zero or negative argument; with no argument, it toggles. | |
1067 | ||
1068 | @vindex auto-save-interval | |
1069 | Emacs does auto-saving periodically based on counting how many characters | |
1070 | you have typed since the last time auto-saving was done. The variable | |
1071 | @code{auto-save-interval} specifies how many characters there are between | |
dce87f47 EZ |
1072 | auto-saves. By default, it is 300. Emacs doesn't accept values that are |
1073 | too small: if you customize @code{auto-save-interval} to a value less | |
1074 | than 20, Emacs will behave as if the value is 20. | |
6bf7aab6 DL |
1075 | |
1076 | @vindex auto-save-timeout | |
1077 | Auto-saving also takes place when you stop typing for a while. The | |
1078 | variable @code{auto-save-timeout} says how many seconds Emacs should | |
1079 | wait before it does an auto save (and perhaps also a garbage | |
1080 | collection). (The actual time period is longer if the current buffer is | |
1081 | long; this is a heuristic which aims to keep out of your way when you | |
1082 | are editing long buffers, in which auto-save takes an appreciable amount | |
1083 | of time.) Auto-saving during idle periods accomplishes two things: | |
1084 | first, it makes sure all your work is saved if you go away from the | |
1085 | terminal for a while; second, it may avoid some auto-saving while you | |
1086 | are actually typing. | |
1087 | ||
1088 | Emacs also does auto-saving whenever it gets a fatal error. This | |
1089 | includes killing the Emacs job with a shell command such as @samp{kill | |
1090 | %emacs}, or disconnecting a phone line or network connection. | |
1091 | ||
1092 | @findex do-auto-save | |
1093 | You can request an auto-save explicitly with the command @kbd{M-x | |
1094 | do-auto-save}. | |
1095 | ||
1096 | @node Recover | |
1097 | @subsection Recovering Data from Auto-Saves | |
1098 | ||
1099 | @findex recover-file | |
1100 | You can use the contents of an auto-save file to recover from a loss | |
1101 | of data with the command @kbd{M-x recover-file @key{RET} @var{file} | |
1102 | @key{RET}}. This visits @var{file} and then (after your confirmation) | |
1103 | restores the contents from its auto-save file @file{#@var{file}#}. | |
1104 | You can then save with @kbd{C-x C-s} to put the recovered text into | |
1105 | @var{file} itself. For example, to recover file @file{foo.c} from its | |
1106 | auto-save file @file{#foo.c#}, do:@refill | |
1107 | ||
1108 | @example | |
1109 | M-x recover-file @key{RET} foo.c @key{RET} | |
1110 | yes @key{RET} | |
1111 | C-x C-s | |
1112 | @end example | |
1113 | ||
1114 | Before asking for confirmation, @kbd{M-x recover-file} displays a | |
1115 | directory listing describing the specified file and the auto-save file, | |
1116 | so you can compare their sizes and dates. If the auto-save file | |
1117 | is older, @kbd{M-x recover-file} does not offer to read it. | |
1118 | ||
1119 | @findex recover-session | |
1120 | If Emacs or the computer crashes, you can recover all the files you | |
1121 | were editing from their auto save files with the command @kbd{M-x | |
1122 | recover-session}. This first shows you a list of recorded interrupted | |
1123 | sessions. Move point to the one you choose, and type @kbd{C-c C-c}. | |
1124 | ||
1125 | Then @code{recover-session} asks about each of the files that were | |
1126 | being edited during that session, asking whether to recover that file. | |
1127 | If you answer @kbd{y}, it calls @code{recover-file}, which works in its | |
1128 | normal fashion. It shows the dates of the original file and its | |
1129 | auto-save file, and asks once again whether to recover that file. | |
1130 | ||
1131 | When @code{recover-session} is done, the files you've chosen to | |
1132 | recover are present in Emacs buffers. You should then save them. Only | |
1133 | this---saving them---updates the files themselves. | |
1134 | ||
1135 | @vindex auto-save-list-file-prefix | |
f02d86a3 | 1136 | Emacs records interrupted sessions for later recovery in files named |
d41d5dd4 RS |
1137 | @file{~/.emacs.d/auto-save-list/.saves-@var{pid}-@var{hostname}}. All |
1138 | of this name except @file{@var{pid}-@var{hostname}} comes from the | |
1139 | value of @code{auto-save-list-file-prefix}. You can record sessions | |
1140 | in a different place by customizing that variable. If you set | |
1141 | @code{auto-save-list-file-prefix} to @code{nil} in your @file{.emacs} | |
1142 | file, sessions are not recorded for recovery. | |
6bf7aab6 DL |
1143 | |
1144 | @node File Aliases | |
1145 | @section File Name Aliases | |
f0725a6a RS |
1146 | @cindex symbolic links (visiting) |
1147 | @cindex hard links (visiting) | |
6bf7aab6 DL |
1148 | |
1149 | Symbolic links and hard links both make it possible for several file | |
1150 | names to refer to the same file. Hard links are alternate names that | |
1151 | refer directly to the file; all the names are equally valid, and no one | |
1152 | of them is preferred. By contrast, a symbolic link is a kind of defined | |
1153 | alias: when @file{foo} is a symbolic link to @file{bar}, you can use | |
1154 | either name to refer to the file, but @file{bar} is the real name, while | |
1155 | @file{foo} is just an alias. More complex cases occur when symbolic | |
1156 | links point to directories. | |
1157 | ||
177c0ea7 | 1158 | @vindex find-file-existing-other-name |
124c3a1b | 1159 | @vindex find-file-suppress-same-file-warnings |
f70c5e45 | 1160 | |
f02d86a3 RS |
1161 | Normally, if you visit a file which Emacs is already visiting under |
1162 | a different name, Emacs displays a message in the echo area and uses | |
1163 | the existing buffer visiting that file. This can happen on systems | |
f70c5e45 EZ |
1164 | that support hard or symbolic links, or if you use a long file name on |
1165 | a system that truncates long file names, or on a case-insensitive file | |
1166 | system. You can suppress the message by setting the variable | |
1167 | @code{find-file-suppress-same-file-warnings} to a non-@code{nil} | |
1168 | value. You can disable this feature entirely by setting the variable | |
1169 | @code{find-file-existing-other-name} to @code{nil}: then if you visit | |
1170 | the same file under two different names, you get a separate buffer for | |
1171 | each file name. | |
6bf7aab6 DL |
1172 | |
1173 | @vindex find-file-visit-truename | |
1174 | @cindex truenames of files | |
1175 | @cindex file truenames | |
1176 | If the variable @code{find-file-visit-truename} is non-@code{nil}, | |
1177 | then the file name recorded for a buffer is the file's @dfn{truename} | |
1178 | (made by replacing all symbolic links with their target names), rather | |
1179 | than the name you specify. Setting @code{find-file-visit-truename} also | |
1180 | implies the effect of @code{find-file-existing-other-name}. | |
1181 | ||
1182 | @node Version Control | |
1183 | @section Version Control | |
1184 | @cindex version control | |
1185 | ||
1186 | @dfn{Version control systems} are packages that can record multiple | |
1187 | versions of a source file, usually storing the unchanged parts of the | |
1188 | file just once. Version control systems also record history information | |
177c0ea7 | 1189 | such as the creation time of each version, who created it, and a |
6bf7aab6 DL |
1190 | description of what was changed in that version. |
1191 | ||
7d5e745e | 1192 | The Emacs version control interface is called VC. Its commands work |
fa5b6026 AS |
1193 | with different version control systems---currently, it supports CVS, |
1194 | GNU Arch, RCS, Meta-CVS, Subversion, and SCCS. Of these, the GNU | |
1195 | project distributes CVS, GNU Arch, and RCS; we recommend that you use | |
1196 | either CVS or GNU Arch for your projects, and RCS for individual | |
1197 | files. We also have free software to replace SCCS, known as CSSC; if | |
1198 | you are using SCCS and don't want to make the incompatible change to | |
1199 | RCS or CVS, you can switch to CSSC. | |
6bf7aab6 | 1200 | |
bbf7e41b AS |
1201 | VC is enabled by default in Emacs. To disable it, set the |
1202 | customizable variable @code{vc-handled-backends} to @code{nil} | |
1203 | (@pxref{Customizing VC}). | |
1204 | ||
6bf7aab6 DL |
1205 | @menu |
1206 | * Introduction to VC:: How version control works in general. | |
30068267 | 1207 | * VC Mode Line:: How the mode line shows version control status. |
6bf7aab6 DL |
1208 | * Basic VC Editing:: How to edit a file under version control. |
1209 | * Old Versions:: Examining and comparing old versions. | |
1210 | * Secondary VC Commands:: The commands used a little less frequently. | |
1211 | * Branches:: Multiple lines of development. | |
ad63cf1d | 1212 | * Remote Repositories:: Efficient access to remote CVS servers. |
6bf7aab6 DL |
1213 | * Snapshots:: Sets of file versions treated as a unit. |
1214 | * Miscellaneous VC:: Various other commands and features of VC. | |
1215 | * Customizing VC:: Variables that change VC's behavior. | |
1216 | @end menu | |
1217 | ||
1218 | @node Introduction to VC | |
1219 | @subsection Introduction to Version Control | |
1220 | ||
1221 | VC allows you to use a version control system from within Emacs, | |
1222 | integrating the version control operations smoothly with editing. VC | |
1223 | provides a uniform interface to version control, so that regardless of | |
1224 | which version control system is in use, you can use it the same way. | |
1225 | ||
1226 | This section provides a general overview of version control, and | |
1227 | describes the version control systems that VC supports. You can skip | |
1228 | this section if you are already familiar with the version control system | |
1229 | you want to use. | |
1230 | ||
1231 | @menu | |
1232 | * Version Systems:: Supported version control back-end systems. | |
1233 | * VC Concepts:: Words and concepts related to version control. | |
d4bb5888 | 1234 | * Types of Log File:: The per-file VC log in contrast to the ChangeLog. |
6bf7aab6 DL |
1235 | @end menu |
1236 | ||
1237 | @node Version Systems | |
1238 | @subsubsection Supported Version Control Systems | |
1239 | ||
6bf7aab6 | 1240 | @cindex back end (version control) |
fa5b6026 AS |
1241 | VC currently works with six different version control systems or |
1242 | ``back ends'': CVS, GNU Arch, RCS, Meta-CVS, Subversion, and SCCS. | |
6bf7aab6 DL |
1243 | |
1244 | @cindex CVS | |
fa5b6026 AS |
1245 | CVS is a free version control system that is used for the majority |
1246 | of free software projects today. It allows concurrent multi-user | |
1247 | development either locally or over the network. Some of its | |
1248 | shortcomings, corrected by newer systems such as GNU Arch, are that it | |
1249 | lacks atomic commits or support for renaming files. VC supports all | |
1250 | basic editing operations under CVS, but for some less common tasks you | |
1251 | still need to call CVS from the command line. Note also that before | |
1252 | using CVS you must set up a repository, which is a subject too complex | |
1253 | to treat here. | |
1254 | ||
1255 | @cindex GNU Arch | |
1256 | @cindex Arch | |
1257 | GNU Arch is a new version control system that is designed for | |
1258 | distributed work. It differs in many ways from old well-known | |
1259 | systems, such as CVS and RCS. It supports different transports for | |
1260 | interoperating between users, offline operations, and it has good | |
1261 | branching and merging features. It also supports atomic commits, and | |
1262 | history of file renaming and moving. VC does not support all | |
1263 | operations provided by GNU Arch, so you must sometimes invoke it from | |
1264 | the command line, or use a specialized module. | |
1265 | ||
1266 | @cindex RCS | |
1267 | RCS is the free version control system around which VC was initially | |
1268 | built. The VC commands are therefore conceptually closest to RCS. | |
1269 | Almost everything you can do with RCS can be done through VC. You | |
1270 | cannot use RCS over the network though, and it only works at the level | |
1271 | of individual files, rather than projects. You should use it if you | |
1272 | want a simple, yet reliable tool for handling individual files. | |
1273 | ||
1274 | @cindex SVN | |
1275 | @cindex Subversion | |
1276 | Subversion is a free version control system designed to be similar | |
1277 | to CVS but without CVS's problems. Subversion supports atomic commits, | |
1278 | and versions directories, symbolic links, meta-data, renames, copies, | |
1279 | and deletes. It can be used via http or via its own protocol. | |
1280 | ||
1281 | @cindex MCVS | |
1282 | @cindex Meta-CVS | |
3aff69e3 | 1283 | Meta-CVS is another attempt to solve problems arising in CVS. It |
fa5b6026 AS |
1284 | supports directory structure versioning, improved branching and |
1285 | merging, and use of symbolic links and meta-data in repositories. | |
6bf7aab6 DL |
1286 | |
1287 | @cindex SCCS | |
1288 | SCCS is a proprietary but widely used version control system. In | |
fa5b6026 AS |
1289 | terms of capabilities, it is the weakest of the six that VC supports. |
1290 | VC compensates for certain features missing in SCCS (snapshots, for | |
1291 | example) by implementing them itself, but some other VC features, such | |
50a1bd4f RS |
1292 | as multiple branches, are not available with SCCS. Since SCCS is |
1293 | non-free, not respecting its users freedom,d, you should not use it; | |
1294 | use its free replacement CSSC instead. But you should use CSSC only | |
1295 | if for some reason you cannot use RCS, or one of the higher-level | |
1296 | systems such as CVS or GNU Arch. | |
6bf7aab6 | 1297 | |
a0554a40 | 1298 | In the following, we discuss mainly RCS, SCCS and CVS. Nearly |
be245005 | 1299 | everything said about CVS applies to GNU Arch, Subversion and Meta-CVS |
a0554a40 LT |
1300 | as well. |
1301 | ||
6bf7aab6 DL |
1302 | @node VC Concepts |
1303 | @subsubsection Concepts of Version Control | |
1304 | ||
1305 | @cindex master file | |
1306 | @cindex registered file | |
1307 | When a file is under version control, we also say that it is | |
1308 | @dfn{registered} in the version control system. Each registered file | |
1309 | has a corresponding @dfn{master file} which represents the file's | |
1310 | present state plus its change history---enough to reconstruct the | |
1311 | current version or any earlier version. Usually the master file also | |
1312 | records a @dfn{log entry} for each version, describing in words what was | |
1313 | changed in that version. | |
1314 | ||
1315 | @cindex work file | |
1316 | @cindex checking out files | |
1317 | The file that is maintained under version control is sometimes called | |
1318 | the @dfn{work file} corresponding to its master file. You edit the work | |
1319 | file and make changes in it, as you would with an ordinary file. (With | |
1320 | SCCS and RCS, you must @dfn{lock} the file before you start to edit it.) | |
1321 | After you are done with a set of changes, you @dfn{check the file in}, | |
1322 | which records the changes in the master file, along with a log entry for | |
1323 | them. | |
1324 | ||
1325 | With CVS, there are usually multiple work files corresponding to a | |
1326 | single master file---often each user has his own copy. It is also | |
1327 | possible to use RCS in this way, but this is not the usual way to use | |
1328 | RCS. | |
1329 | ||
1330 | @cindex locking and version control | |
1331 | A version control system typically has some mechanism to coordinate | |
1332 | between users who want to change the same file. One method is | |
1333 | @dfn{locking} (analogous to the locking that Emacs uses to detect | |
1334 | simultaneous editing of a file, but distinct from it). The other method | |
1335 | is to merge your changes with other people's changes when you check them | |
1336 | in. | |
1337 | ||
1338 | With version control locking, work files are normally read-only so | |
1339 | that you cannot change them. You ask the version control system to make | |
1340 | a work file writable for you by locking it; only one user can do | |
1341 | this at any given time. When you check in your changes, that unlocks | |
1342 | the file, making the work file read-only again. This allows other users | |
1343 | to lock the file to make further changes. SCCS always uses locking, and | |
1344 | RCS normally does. | |
1345 | ||
1346 | The other alternative for RCS is to let each user modify the work file | |
1347 | at any time. In this mode, locking is not required, but it is | |
1348 | permitted; check-in is still the way to record a new version. | |
1349 | ||
1350 | CVS normally allows each user to modify his own copy of the work file | |
1351 | at any time, but requires merging with changes from other users at | |
1352 | check-in time. However, CVS can also be set up to require locking. | |
ad63cf1d | 1353 | (@pxref{CVS Options}). |
6bf7aab6 | 1354 | |
d4bb5888 RC |
1355 | @node Types of Log File |
1356 | @subsubsection Types of Log File | |
30068267 | 1357 | @cindex types of log file |
177c0ea7 | 1358 | @cindex log File, types of |
30068267 | 1359 | @cindex version control log |
d4bb5888 | 1360 | |
bf96cde1 RS |
1361 | Projects that use a revision control system can have @emph{two} |
1362 | types of log for changes. One is the per-file log maintained by the | |
1363 | revision control system: each time you check in a change, you must | |
1364 | fill out a @dfn{log entry} for the change (@pxref{Log Buffer}). This | |
1365 | kind of log is called the @dfn{version control log}, also the | |
1366 | @dfn{revision control log}, @dfn{RCS log}, or @dfn{CVS log}. | |
1367 | ||
1368 | The other kind of log is the file @file{ChangeLog} (@pxref{Change | |
1369 | Log}). It provides a chronological record of all changes to a large | |
1370 | portion of a program---typically one directory and its subdirectories. | |
1371 | A small program would use one @file{ChangeLog} file; a large program | |
1372 | may well merit a @file{ChangeLog} file in each major directory. | |
1373 | @xref{Change Log}. | |
1374 | ||
1375 | A project maintained with version control can use just the per-file | |
1376 | log, or it can use both kinds of logs. It can handle some files one | |
1377 | way and some files the other way. Each project has its policy, which | |
1378 | you should follow. | |
1379 | ||
1380 | When the policy is to use both, you typically want to write an entry | |
1381 | for each change just once, then put it into both logs. You can write | |
30068267 RS |
1382 | the entry in @file{ChangeLog}, then copy it to the log buffer when you |
1383 | check in the change. Or you can write the entry in the log buffer | |
1384 | while checking in the change, and later use the @kbd{C-x v a} command | |
1385 | to copy it to @file{ChangeLog} (@pxref{Change Logs and VC}). | |
d4bb5888 | 1386 | |
6bf7aab6 DL |
1387 | @node VC Mode Line |
1388 | @subsection Version Control and the Mode Line | |
1389 | ||
1390 | When you visit a file that is under version control, Emacs indicates | |
1391 | this on the mode line. For example, @samp{RCS-1.3} says that RCS is | |
1392 | used for that file, and the current version is 1.3. | |
1393 | ||
1394 | The character between the back-end name and the version number | |
1395 | indicates the version control status of the file. @samp{-} means that | |
1396 | the work file is not locked (if locking is in use), or not modified (if | |
1397 | locking is not in use). @samp{:} indicates that the file is locked, or | |
1398 | that it is modified. If the file is locked by some other user (for | |
1399 | instance, @samp{jim}), that is displayed as @samp{RCS:jim:1.3}. | |
1400 | ||
ea98eb11 LT |
1401 | @vindex auto-revert-check-vc-info |
1402 | When Auto Revert mode (@pxref{Reverting}) reverts a buffer that is | |
1403 | under version control, it updates the version control information in | |
1404 | the mode line. However, Auto Revert mode may not properly update this | |
1405 | information if the version control status changes without changes to | |
1406 | the work file, from outside the current Emacs session. If you set | |
1407 | @code{auto-revert-check-vc-info} to @code{t}, Auto Revert mode updates | |
1408 | the version control status information every | |
1409 | @code{auto-revert-interval} seconds, even if the work file itself is | |
1410 | unchanged. The resulting CPU usage depends on the version control | |
1411 | system, but is usually not excessive. | |
1412 | ||
6bf7aab6 DL |
1413 | @node Basic VC Editing |
1414 | @subsection Basic Editing under Version Control | |
1415 | ||
1416 | The principal VC command is an all-purpose command that performs | |
1417 | either locking or check-in, depending on the situation. | |
1418 | ||
1419 | @table @kbd | |
6bf7aab6 DL |
1420 | @itemx C-x v v |
1421 | Perform the next logical version control operation on this file. | |
1422 | @end table | |
1423 | ||
1424 | @findex vc-next-action | |
6bf7aab6 | 1425 | @kindex C-x v v |
6bf7aab6 DL |
1426 | The precise action of this command depends on the state of the file, |
1427 | and whether the version control system uses locking or not. SCCS and | |
1428 | RCS normally use locking; CVS normally does not use locking. | |
1429 | ||
576c4a0f AS |
1430 | @findex vc-toggle-read-only |
1431 | @kindex C-x C-q @r{(Version Control)} | |
1432 | As a special convenience that is particularly useful for files with | |
1433 | locking, you can let Emacs check a file in or out whenever you change | |
1434 | its read-only flag. This means, for example, that you cannot | |
1435 | accidentally edit a file without properly checking it out first. To | |
1436 | achieve this, bind the key @kbd{C-x C-q} to @kbd{vc-toggle-read-only} | |
1437 | in your @file{~/.emacs} file. (@xref{Init Rebinding}.) | |
1438 | ||
6bf7aab6 DL |
1439 | @menu |
1440 | * VC with Locking:: RCS in its default mode, SCCS, and optionally CVS. | |
1441 | * Without Locking:: Without locking: default mode for CVS. | |
576c4a0f | 1442 | * Advanced C-x v v:: Advanced features available with a prefix argument. |
6bf7aab6 DL |
1443 | * Log Buffer:: Features available in log entry buffers. |
1444 | @end menu | |
177c0ea7 JB |
1445 | |
1446 | @node VC with Locking | |
6bf7aab6 DL |
1447 | @subsubsection Basic Version Control with Locking |
1448 | ||
1449 | If locking is used for the file (as with SCCS, and RCS in its default | |
576c4a0f | 1450 | mode), @kbd{C-x v v} can either lock a file or check it in: |
6bf7aab6 DL |
1451 | |
1452 | @itemize @bullet | |
1453 | @item | |
576c4a0f | 1454 | If the file is not locked, @kbd{C-x v v} locks it, and |
6bf7aab6 DL |
1455 | makes it writable so that you can change it. |
1456 | ||
1457 | @item | |
576c4a0f | 1458 | If the file is locked by you, and contains changes, @kbd{C-x v v} checks |
6bf7aab6 DL |
1459 | in the changes. In order to do this, it first reads the log entry |
1460 | for the new version. @xref{Log Buffer}. | |
1461 | ||
1462 | @item | |
1463 | If the file is locked by you, but you have not changed it since you | |
576c4a0f | 1464 | locked it, @kbd{C-x v v} releases the lock and makes the file read-only |
6bf7aab6 DL |
1465 | again. |
1466 | ||
1467 | @item | |
576c4a0f | 1468 | If the file is locked by some other user, @kbd{C-x v v} asks you whether |
6bf7aab6 DL |
1469 | you want to ``steal the lock'' from that user. If you say yes, the file |
1470 | becomes locked by you, but a message is sent to the person who had | |
1471 | formerly locked the file, to inform him of what has happened. | |
1472 | @end itemize | |
1473 | ||
1474 | These rules also apply when you use CVS in locking mode, except | |
1475 | that there is no such thing as stealing a lock. | |
1476 | ||
1477 | @node Without Locking | |
1478 | @subsubsection Basic Version Control without Locking | |
1479 | ||
1480 | When there is no locking---the default for CVS---work files are always | |
1481 | writable; you do not need to do anything before you begin to edit a | |
1482 | file. The status indicator on the mode line is @samp{-} if the file is | |
1483 | unmodified; it flips to @samp{:} as soon as you save any changes in the | |
1484 | work file. | |
1485 | ||
576c4a0f | 1486 | Here is what @kbd{C-x v v} does when using CVS: |
6bf7aab6 DL |
1487 | |
1488 | @itemize @bullet | |
1489 | @item | |
7d5e745e RS |
1490 | If some other user has checked in changes into the master file, Emacs |
1491 | asks you whether you want to merge those changes into your own work | |
1492 | file. You must do this before you can check in your own changes. (To | |
1493 | pick up any recent changes from the master file @emph{without} trying | |
1494 | to commit your own changes, type @kbd{C-x v m @key{RET}}.) | |
ad63cf1d | 1495 | @xref{Merging}. |
6bf7aab6 DL |
1496 | |
1497 | @item | |
1498 | If there are no new changes in the master file, but you have made | |
576c4a0f | 1499 | modifications in your work file, @kbd{C-x v v} checks in your changes. |
6bf7aab6 DL |
1500 | In order to do this, it first reads the log entry for the new version. |
1501 | @xref{Log Buffer}. | |
1502 | ||
1503 | @item | |
576c4a0f | 1504 | If the file is not modified, the @kbd{C-x v v} does nothing. |
6bf7aab6 DL |
1505 | @end itemize |
1506 | ||
1507 | These rules also apply when you use RCS in the mode that does not | |
1508 | require locking, except that automatic merging of changes from the | |
1509 | master file is not implemented. Unfortunately, this means that nothing | |
1510 | informs you if another user has checked in changes in the same file | |
1511 | since you began editing it, and when this happens, his changes will be | |
1512 | effectively removed when you check in your version (though they will | |
1513 | remain in the master file, so they will not be entirely lost). You must | |
a0554a40 LT |
1514 | therefore verify that the current version is unchanged, before you |
1515 | check in your changes. We hope to eliminate this risk and provide | |
1516 | automatic merging with RCS in a future Emacs version. | |
6bf7aab6 DL |
1517 | |
1518 | In addition, locking is possible with RCS even in this mode, although | |
576c4a0f | 1519 | it is not required; @kbd{C-x v v} with an unmodified file locks the |
6bf7aab6 DL |
1520 | file, just as it does with RCS in its normal (locking) mode. |
1521 | ||
576c4a0f AS |
1522 | @node Advanced C-x v v |
1523 | @subsubsection Advanced Control in @kbd{C-x v v} | |
ad63cf1d | 1524 | |
37b844b9 | 1525 | @cindex version number to check in/out |
7d5e745e | 1526 | When you give a prefix argument to @code{vc-next-action} (@kbd{C-u |
576c4a0f | 1527 | C-x v v}), it still performs the next logical version control |
7d5e745e RS |
1528 | operation, but accepts additional arguments to specify precisely how |
1529 | to do the operation. | |
ad63cf1d AS |
1530 | |
1531 | @itemize @bullet | |
7d5e745e RS |
1532 | @item |
1533 | If the file is modified (or locked), you can specify the version | |
0cf729ce | 1534 | number to use for the new version that you check in. This is one way |
7d5e745e RS |
1535 | to create a new branch (@pxref{Branches}). |
1536 | ||
1537 | @item | |
1538 | If the file is not modified (and unlocked), you can specify the | |
1539 | version to select; this lets you start working from an older version, | |
1540 | or on another branch. If you do not enter any version, that takes you | |
1541 | to the highest version on the current branch; therefore @kbd{C-u C-x | |
576c4a0f | 1542 | v v @key{RET}} is a convenient way to get the latest version of a file from |
7d5e745e RS |
1543 | the repository. |
1544 | ||
1545 | @item | |
37b844b9 | 1546 | @cindex specific version control system |
7d5e745e RS |
1547 | Instead of the version number, you can also specify the name of a |
1548 | version control system. This is useful when one file is being managed | |
0cf729ce | 1549 | with two version control systems at the same time (@pxref{Local |
7d5e745e | 1550 | Version Control}). |
ad63cf1d AS |
1551 | @end itemize |
1552 | ||
6bf7aab6 DL |
1553 | @node Log Buffer |
1554 | @subsubsection Features of the Log Entry Buffer | |
1555 | ||
576c4a0f | 1556 | When you check in changes, @kbd{C-x v v} first reads a log entry. It |
6bf7aab6 | 1557 | pops up a buffer called @samp{*VC-Log*} for you to enter the log entry. |
e07ddddb | 1558 | |
50a1bd4f | 1559 | Sometimes the @samp{*VC-Log*} buffer contains default text when you enter it, |
e07ddddb NR |
1560 | typically the last log message entered. If it does, mark and point |
1561 | are set around the entire contents of the buffer so that it is easy to | |
1562 | kill the contents of the buffer with @kbd{C-w}. | |
1563 | ||
1564 | @findex log-edit-insert-changelog | |
50a1bd4f | 1565 | If you work by writing entries in the @file{ChangeLog} |
e07ddddb NR |
1566 | (@pxref{Change Log}) and then commit the change under revision |
1567 | control, you can generate the Log Edit text from the ChangeLog using | |
1568 | @kbd{C-c C-a} (@kbd{log-edit-insert-changelog}). This looks for | |
1569 | entries for the file(s) concerned in the top entry in the ChangeLog | |
1570 | and uses those paragraphs as the log text. This text is only inserted | |
1571 | if the top entry was made under your user name on the current date. | |
1572 | @xref{Change Logs and VC}, for the opposite way of | |
1573 | working---generating ChangeLog entries from the revision control log. | |
1574 | ||
50a1bd4f | 1575 | In the @samp{*VC-Log*} buffer, @kbd{C-c C-f} (@kbd{M-x log-edit-show-files}) |
e07ddddb | 1576 | shows the list of files to be committed in case you need to check |
7df73b0d LT |
1577 | that. (This can be a list of more than one file if you use VC Dired |
1578 | mode or PCL-CVS. @xref{VC Dired Mode}, and @ref{Top, , About PCL-CVS, | |
1579 | pcl-cvs, PCL-CVS --- The Emacs Front-End to CVS}.) | |
e07ddddb | 1580 | |
50a1bd4f | 1581 | When you have finished editing the log message, type @kbd{C-c C-c} to |
e07ddddb | 1582 | exit the buffer and commit the change. |
6bf7aab6 DL |
1583 | |
1584 | To abort check-in, just @strong{don't} type @kbd{C-c C-c} in that | |
1585 | buffer. You can switch buffers and do other editing. As long as you | |
1586 | don't try to check in another file, the entry you were editing remains | |
1587 | in the @samp{*VC-Log*} buffer, and you can go back to that buffer at any | |
1588 | time to complete the check-in. | |
1589 | ||
1590 | If you change several source files for the same reason, it is often | |
1591 | convenient to specify the same log entry for many of the files. To do | |
1592 | this, use the history of previous log entries. The commands @kbd{M-n}, | |
1593 | @kbd{M-p}, @kbd{M-s} and @kbd{M-r} for doing this work just like the | |
1594 | minibuffer history commands (except that these versions are used outside | |
1595 | the minibuffer). | |
1596 | ||
1597 | @vindex vc-log-mode-hook | |
1598 | Each time you check in a file, the log entry buffer is put into VC Log | |
1599 | mode, which involves running two hooks: @code{text-mode-hook} and | |
1600 | @code{vc-log-mode-hook}. @xref{Hooks}. | |
1601 | ||
1602 | @node Old Versions | |
1603 | @subsection Examining And Comparing Old Versions | |
1604 | ||
1605 | One of the convenient features of version control is the ability | |
1606 | to examine any version of a file, or compare two versions. | |
1607 | ||
1608 | @table @kbd | |
1609 | @item C-x v ~ @var{version} @key{RET} | |
1610 | Examine version @var{version} of the visited file, in a buffer of its | |
1611 | own. | |
1612 | ||
1613 | @item C-x v = | |
1614 | Compare the current buffer contents with the latest checked-in version | |
1615 | of the file. | |
1616 | ||
1617 | @item C-u C-x v = @var{file} @key{RET} @var{oldvers} @key{RET} @var{newvers} @key{RET} | |
1618 | Compare the specified two versions of @var{file}. | |
1619 | ||
1620 | @item C-x v g | |
7bba6c37 | 1621 | Display the file with per-line version information and using colors. |
6bf7aab6 DL |
1622 | @end table |
1623 | ||
1624 | @findex vc-version-other-window | |
1625 | @kindex C-x v ~ | |
0cf729ce | 1626 | To examine an old version in its entirety, visit the file and then type |
6bf7aab6 DL |
1627 | @kbd{C-x v ~ @var{version} @key{RET}} (@code{vc-version-other-window}). |
1628 | This puts the text of version @var{version} in a file named | |
1629 | @file{@var{filename}.~@var{version}~}, and visits it in its own buffer | |
1630 | in a separate window. (In RCS, you can also select an old version | |
1631 | and create a branch from it. @xref{Branches}.) | |
1632 | ||
1633 | @findex vc-diff | |
1634 | @kindex C-x v = | |
ae529c64 | 1635 | It is usually more convenient to compare two versions of the file, |
6bf7aab6 DL |
1636 | with the command @kbd{C-x v =} (@code{vc-diff}). Plain @kbd{C-x v =} |
1637 | compares the current buffer contents (saving them in the file if | |
7d5e745e RS |
1638 | necessary) with the last checked-in version of the file. @kbd{C-u C-x |
1639 | v =}, with a numeric argument, reads a file name and two version | |
1640 | numbers, then compares those versions of the specified file. Both | |
1641 | forms display the output in a special buffer in another window. | |
6bf7aab6 DL |
1642 | |
1643 | You can specify a checked-in version by its number; an empty input | |
1644 | specifies the current contents of the work file (which may be different | |
1645 | from all the checked-in versions). You can also specify a snapshot name | |
1646 | (@pxref{Snapshots}) instead of one or both version numbers. | |
1647 | ||
7d5e745e RS |
1648 | If you supply a directory name instead of the name of a registered |
1649 | file, this command compares the two specified versions of all registered | |
1650 | files in that directory and its subdirectories. | |
1651 | ||
ad63cf1d | 1652 | @vindex vc-diff-switches |
0cf729ce | 1653 | @vindex vc-rcs-diff-switches |
7d5e745e | 1654 | @kbd{C-x v =} works by running a variant of the @code{diff} utility |
0cf729ce RS |
1655 | designed to work with the version control system in use. When you |
1656 | invoke @code{diff} this way, in addition to the options specified by | |
36d36f35 | 1657 | @code{diff-switches} (@pxref{Comparing Files}), it receives those |
0cf729ce RS |
1658 | specified by @code{vc-diff-switches}, plus those specified for the |
1659 | specific back end by @code{vc-@var{backend}-diff-switches}. For | |
1660 | instance, when the version control back end is RCS, @code{diff} uses | |
1661 | the options in @code{vc-rcs-diff-switches}. The | |
1662 | @samp{vc@dots{}diff-switches} variables are @code{nil} by default. | |
7d5e745e | 1663 | |
97f5d067 AS |
1664 | The buffer produced by @kbd{C-x v =} supports the commands of |
1665 | Compilation mode (@pxref{Compilation Mode}), such as @kbd{C-x `} and | |
1666 | @kbd{C-c C-c}, in both the ``old'' and ``new'' text, and they always | |
1667 | find the corresponding locations in the current work file. (Older | |
1668 | versions are not, in general, present as files on your disk.) | |
6bf7aab6 DL |
1669 | |
1670 | @findex vc-annotate | |
1671 | @kindex C-x v g | |
7bba6c37 TTN |
1672 | For some backends, you can display the file @dfn{annotated} with |
1673 | per-line version information and using colors to enhance the visual | |
559d82bf | 1674 | appearance, with the command @kbd{M-x vc-annotate}. |
50a1bd4f RS |
1675 | It creates a new buffer (the ``annotate buffer'') displaying the |
1676 | file's text, with each part colored to show how old it is. Text | |
67696322 RS |
1677 | colored red is new, blue means old, and intermediate colors indicate |
1678 | intermediate ages. By default, the time scale is 360 days, so that | |
1679 | everything more than one year old is shown in blue. | |
1680 | ||
1681 | When you give a prefix argument to this command, it uses the | |
1682 | minibuffer to read two arguments: which version number to display and | |
1683 | annotate (instead of the current file contents), and a stretch factor | |
1684 | for the time scale. A stretch factor of 0.1 means that the color | |
1685 | range from red to blue spans the past 36 days instead of 360 days. A | |
1686 | stretch factor greater than 1 means the color range spans more than a | |
1687 | year. | |
6bf7aab6 | 1688 | |
e8d8cb3e | 1689 | From the annotate buffer, you can use the following keys to browse the |
2a7790cf AS |
1690 | annotations of past revisions, view diffs, or view log entries: |
1691 | ||
e8d8cb3e RS |
1692 | @table @kbd |
1693 | @item P | |
1694 | Annotate the previous revision, that is to say, the revision before | |
1695 | the one currently annotated. A numeric prefix argument is a repeat | |
1696 | count, so @kbd{C-u 10 P} would take you back 10 revisions. | |
1697 | ||
1698 | @item N | |
1699 | Annotate the next revision---the one after the revision currently | |
1700 | annotated. A numeric prefix argument is a repeat count. | |
1701 | ||
1702 | @item J | |
1703 | Annotate the revision indicated by the current line. | |
1704 | ||
1705 | @item A | |
1706 | Annotate the revision before the one indicated by the current line. | |
1707 | This is useful to see the state the file was in before the change on | |
1708 | the current line was made. | |
1709 | ||
1710 | @item D | |
1711 | Display the diff between the current line's revision and the previous | |
1712 | revision. This is useful to see what the current line's revision | |
1713 | actually changed in the file. | |
1714 | ||
1715 | @item L | |
1716 | Show the log of the current line's revision. This is useful to see | |
1717 | the author's description of the changes in the revision on the current | |
1718 | line. | |
1719 | ||
1720 | @item W | |
1721 | Annotate the workfile version--the one you are editing. If you used | |
1722 | @kbd{P} and @kbd{N} to browse to other revisions, use this key to | |
1723 | return to the latest version. | |
1724 | @end table | |
2a7790cf | 1725 | |
6bf7aab6 DL |
1726 | @node Secondary VC Commands |
1727 | @subsection The Secondary Commands of VC | |
1728 | ||
1729 | This section explains the secondary commands of VC; those that you might | |
1730 | use once a day. | |
1731 | ||
1732 | @menu | |
1733 | * Registering:: Putting a file under version control. | |
1734 | * VC Status:: Viewing the VC status of files. | |
3f9be7ce | 1735 | * VC Undo:: Canceling changes before or after check-in. |
177c0ea7 | 1736 | * VC Dired Mode:: Listing files managed by version control. |
6bf7aab6 DL |
1737 | * VC Dired Commands:: Commands to use in a VC Dired buffer. |
1738 | @end menu | |
1739 | ||
1740 | @node Registering | |
1741 | @subsubsection Registering a File for Version Control | |
1742 | ||
1743 | @kindex C-x v i | |
1744 | @findex vc-register | |
1745 | You can put any file under version control by simply visiting it, and | |
1746 | then typing @w{@kbd{C-x v i}} (@code{vc-register}). | |
1747 | ||
1748 | @table @kbd | |
1749 | @item C-x v i | |
1750 | Register the visited file for version control. | |
1751 | @end table | |
1752 | ||
6bf7aab6 | 1753 | To register the file, Emacs must choose which version control system |
ad63cf1d AS |
1754 | to use for it. If the file's directory already contains files |
1755 | registered in a version control system, Emacs uses that system. If | |
1756 | there is more than one system in use for a directory, Emacs uses the one | |
d3ff0a57 | 1757 | that appears first in @code{vc-handled-backends} (@pxref{Customizing VC}). |
ad63cf1d | 1758 | On the other hand, if there are no files already registered, |
d3ff0a57 | 1759 | Emacs uses the first system from @code{vc-handled-backends} that could |
a0554a40 LT |
1760 | register the file (for example, you cannot register a file under CVS if |
1761 | its directory is not already part of a CVS tree); with the default | |
1762 | value of @code{vc-handled-backends}, this means that Emacs uses RCS in | |
1763 | this situation. | |
6bf7aab6 DL |
1764 | |
1765 | If locking is in use, @kbd{C-x v i} leaves the file unlocked and | |
576c4a0f | 1766 | read-only. Type @kbd{C-x v v} if you wish to start editing it. After |
6bf7aab6 | 1767 | registering a file with CVS, you must subsequently commit the initial |
c5d36b03 RS |
1768 | version by typing @kbd{C-x v v}. Until you do that, the version |
1769 | appears as @samp{@@@@} in the mode line. | |
6bf7aab6 DL |
1770 | |
1771 | @vindex vc-default-init-version | |
37b844b9 | 1772 | @cindex initial version number to register |
6bf7aab6 DL |
1773 | The initial version number for a newly registered file is 1.1, by |
1774 | default. You can specify a different default by setting the variable | |
1775 | @code{vc-default-init-version}, or you can give @kbd{C-x v i} a numeric | |
1776 | argument; then it reads the initial version number for this particular | |
1777 | file using the minibuffer. | |
1778 | ||
1779 | @vindex vc-initial-comment | |
1780 | If @code{vc-initial-comment} is non-@code{nil}, @kbd{C-x v i} reads an | |
1781 | initial comment to describe the purpose of this source file. Reading | |
1782 | the initial comment works like reading a log entry (@pxref{Log Buffer}). | |
1783 | ||
1784 | @node VC Status | |
1785 | @subsubsection VC Status Commands | |
1786 | ||
1787 | @table @kbd | |
1788 | @item C-x v l | |
1789 | Display version control state and change history. | |
1790 | @end table | |
1791 | ||
1792 | @kindex C-x v l | |
1793 | @findex vc-print-log | |
1794 | To view the detailed version control status and history of a file, | |
1795 | type @kbd{C-x v l} (@code{vc-print-log}). It displays the history of | |
1796 | changes to the current file, including the text of the log entries. The | |
7436d3ff RS |
1797 | output appears in a separate window. The point is centered at the |
1798 | revision of the file that is currently being visited. | |
1799 | ||
50a1bd4f RS |
1800 | In the change log buffer, you can use the following keys to move |
1801 | between the logs of revisions and of files, to view past revisions, and | |
7436d3ff RS |
1802 | to view diffs: |
1803 | ||
1804 | @table @kbd | |
1805 | @item p | |
1806 | Move to the previous revision-item in the buffer. (Revision entries in the log | |
1807 | buffer are usually in reverse-chronological order, so the previous | |
1808 | revision-item usually corresponds to a newer revision.) A numeric | |
1809 | prefix argument is a repeat count. | |
1810 | ||
1811 | @item n | |
1812 | Move to the next revision-item (which most often corresponds to the | |
1813 | previous revision of the file). A numeric prefix argument is a repeat | |
1814 | count. | |
1815 | ||
7436d3ff RS |
1816 | @item P |
1817 | Move to the log of the previous file, when the logs of multiple files | |
1818 | are in the log buffer (@pxref{VC Dired Mode}). Otherwise, just move | |
1819 | to the beginning of the log. A numeric prefix argument is a repeat | |
1820 | count, so @kbd{C-u 10 P} would move backward 10 files. | |
1821 | ||
1822 | @item N | |
1823 | Move to the log of the next file, when the logs of multiple files are | |
1824 | in the log buffer (@pxref{VC Dired Mode}). It also takes a numeric | |
1825 | prefix argument as a repeat count. | |
11cfab98 JL |
1826 | |
1827 | @item f | |
1828 | Visit the revision indicated at the current line, like typing @kbd{C-x | |
1829 | v ~} and specifying this revision's number (@pxref{Old Versions}). | |
1830 | ||
1831 | @item d | |
1832 | Display the diff (@pxref{Comparing Files}) between the revision | |
1833 | indicated at the current line and the next earlier revision. This is | |
1834 | useful to see what actually changed when the revision indicated on the | |
1835 | current line was committed. | |
7436d3ff | 1836 | @end table |
6bf7aab6 DL |
1837 | |
1838 | @node VC Undo | |
1839 | @subsubsection Undoing Version Control Actions | |
1840 | ||
1841 | @table @kbd | |
1842 | @item C-x v u | |
1843 | Revert the buffer and the file to the last checked-in version. | |
1844 | ||
1845 | @item C-x v c | |
1846 | Remove the last-entered change from the master for the visited file. | |
1847 | This undoes your last check-in. | |
1848 | @end table | |
1849 | ||
1850 | @kindex C-x v u | |
1851 | @findex vc-revert-buffer | |
1852 | If you want to discard your current set of changes and revert to the | |
1853 | last version checked in, use @kbd{C-x v u} (@code{vc-revert-buffer}). | |
1854 | This leaves the file unlocked; if locking is in use, you must first lock | |
1855 | the file again before you change it again. @kbd{C-x v u} requires | |
1856 | confirmation, unless it sees that you haven't made any changes since the | |
1857 | last checked-in version. | |
1858 | ||
1859 | @kbd{C-x v u} is also the command to unlock a file if you lock it and | |
1860 | then decide not to change it. | |
1861 | ||
1862 | @kindex C-x v c | |
1863 | @findex vc-cancel-version | |
1864 | To cancel a change that you already checked in, use @kbd{C-x v c} | |
1865 | (@code{vc-cancel-version}). This command discards all record of the | |
1866 | most recent checked-in version. @kbd{C-x v c} also offers to revert | |
1867 | your work file and buffer to the previous version (the one that precedes | |
1868 | the version that is deleted). | |
1869 | ||
1870 | If you answer @kbd{no}, VC keeps your changes in the buffer, and locks | |
1871 | the file. The no-revert option is useful when you have checked in a | |
1872 | change and then discover a trivial error in it; you can cancel the | |
1873 | erroneous check-in, fix the error, and check the file in again. | |
1874 | ||
1875 | When @kbd{C-x v c} does not revert the buffer, it unexpands all | |
1876 | version control headers in the buffer instead (@pxref{Version Headers}). | |
1877 | This is because the buffer no longer corresponds to any existing | |
1878 | version. If you check it in again, the check-in process will expand the | |
1879 | headers properly for the new version number. | |
1880 | ||
1881 | However, it is impossible to unexpand the RCS @samp{@w{$}Log$} header | |
1882 | automatically. If you use that header feature, you have to unexpand it | |
1883 | by hand---by deleting the entry for the version that you just canceled. | |
1884 | ||
1885 | Be careful when invoking @kbd{C-x v c}, as it is easy to lose a lot of | |
1886 | work with it. To help you be careful, this command always requires | |
1887 | confirmation with @kbd{yes}. Note also that this command is disabled | |
1888 | under CVS, because canceling versions is very dangerous and discouraged | |
1889 | with CVS. | |
1890 | ||
1891 | @node VC Dired Mode | |
1892 | @subsubsection Dired under VC | |
1893 | ||
fa474484 DL |
1894 | @cindex PCL-CVS |
1895 | @pindex cvs | |
1896 | @cindex CVS Dired Mode | |
f02d86a3 RS |
1897 | The VC Dired Mode described here works with all the version control |
1898 | systems that VC supports. Another more powerful facility, designed | |
1899 | specifically for CVS, is called PCL-CVS. @xref{Top, , About PCL-CVS, | |
1900 | pcl-cvs, PCL-CVS --- The Emacs Front-End to CVS}. | |
fa474484 | 1901 | |
6bf7aab6 DL |
1902 | @kindex C-x v d |
1903 | @findex vc-directory | |
1904 | When you are working on a large program, it is often useful to find | |
1905 | out which files have changed within an entire directory tree, or to view | |
1906 | the status of all files under version control at once, and to perform | |
1907 | version control operations on collections of files. You can use the | |
1908 | command @kbd{C-x v d} (@code{vc-directory}) to make a directory listing | |
1909 | that includes only files relevant for version control. | |
1910 | ||
1911 | @vindex vc-dired-terse-display | |
1912 | @kbd{C-x v d} creates a buffer which uses VC Dired Mode. This looks | |
1913 | much like an ordinary Dired buffer (@pxref{Dired}); however, normally it | |
1914 | shows only the noteworthy files (those locked or not up-to-date). This | |
1915 | is called @dfn{terse display}. If you set the variable | |
1916 | @code{vc-dired-terse-display} to @code{nil}, then VC Dired shows all | |
1917 | relevant files---those managed under version control, plus all | |
1918 | subdirectories (@dfn{full display}). The command @kbd{v t} in a VC | |
1919 | Dired buffer toggles between terse display and full display (@pxref{VC | |
1920 | Dired Commands}). | |
1921 | ||
1922 | @vindex vc-dired-recurse | |
1923 | By default, VC Dired produces a recursive listing of noteworthy or | |
1924 | relevant files at or below the given directory. You can change this by | |
1925 | setting the variable @code{vc-dired-recurse} to @code{nil}; then VC | |
1926 | Dired shows only the files in the given directory. | |
1927 | ||
1928 | The line for an individual file shows the version control state in the | |
1929 | place of the hard link count, owner, group, and size of the file. If | |
1930 | the file is unmodified, in sync with the master file, the version | |
1931 | control state shown is blank. Otherwise it consists of text in | |
1932 | parentheses. Under RCS and SCCS, the name of the user locking the file | |
1933 | is shown; under CVS, an abbreviated version of the @samp{cvs status} | |
1934 | output is used. Here is an example using RCS: | |
1935 | ||
1936 | @smallexample | |
1937 | @group | |
1938 | /home/jim/project: | |
1939 | ||
1940 | -rw-r--r-- (jim) Apr 2 23:39 file1 | |
1941 | -r--r--r-- Apr 5 20:21 file2 | |
1942 | @end group | |
1943 | @end smallexample | |
1944 | ||
1945 | @noindent | |
1946 | The files @samp{file1} and @samp{file2} are under version control, | |
1947 | @samp{file1} is locked by user jim, and @samp{file2} is unlocked. | |
1948 | ||
1949 | Here is an example using CVS: | |
1950 | ||
1951 | @smallexample | |
1952 | @group | |
1953 | /home/joe/develop: | |
1954 | ||
1955 | -rw-r--r-- (modified) Aug 2 1997 file1.c | |
1956 | -rw-r--r-- Apr 4 20:09 file2.c | |
1957 | -rw-r--r-- (merge) Sep 13 1996 file3.c | |
1958 | @end group | |
1959 | @end smallexample | |
1960 | ||
1961 | Here @samp{file1.c} is modified with respect to the repository, and | |
1962 | @samp{file2.c} is not. @samp{file3.c} is modified, but other changes | |
1963 | have also been checked in to the repository---you need to merge them | |
1964 | with the work file before you can check it in. | |
1965 | ||
1966 | @vindex vc-directory-exclusion-list | |
1967 | When VC Dired displays subdirectories (in the ``full'' display mode), | |
1968 | it omits some that should never contain any files under version control. | |
1969 | By default, this includes Version Control subdirectories such as | |
1970 | @samp{RCS} and @samp{CVS}; you can customize this by setting the | |
1971 | variable @code{vc-directory-exclusion-list}. | |
1972 | ||
1973 | You can fine-tune VC Dired's format by typing @kbd{C-u C-x v d}---as in | |
1974 | ordinary Dired, that allows you to specify additional switches for the | |
1975 | @samp{ls} command. | |
1976 | ||
1977 | @node VC Dired Commands | |
1978 | @subsubsection VC Dired Commands | |
1979 | ||
1980 | All the usual Dired commands work normally in VC Dired mode, except | |
1981 | for @kbd{v}, which is redefined as the version control prefix. You can | |
1982 | invoke VC commands such as @code{vc-diff} and @code{vc-print-log} by | |
1983 | typing @kbd{v =}, or @kbd{v l}, and so on. Most of these commands apply | |
1984 | to the file name on the current line. | |
1985 | ||
1986 | The command @kbd{v v} (@code{vc-next-action}) operates on all the | |
1987 | marked files, so that you can lock or check in several files at once. | |
1988 | If it operates on more than one file, it handles each file according to | |
1989 | its current state; thus, it might lock one file, but check in another | |
1990 | file. This could be confusing; it is up to you to avoid confusing | |
a0554a40 LT |
1991 | behavior by marking a set of files that are in a similar state. If no |
1992 | files are marked, @kbd{v v} operates on the file in the current line. | |
6bf7aab6 DL |
1993 | |
1994 | If any files call for check-in, @kbd{v v} reads a single log entry, | |
1995 | then uses it for all the files being checked in. This is convenient for | |
1996 | registering or checking in several files at once, as part of the same | |
1997 | change. | |
1998 | ||
1999 | @findex vc-dired-toggle-terse-mode | |
2000 | @findex vc-dired-mark-locked | |
2001 | You can toggle between terse display (only locked files, or files not | |
2002 | up-to-date) and full display at any time by typing @kbd{v t} | |
d3ff0a57 | 2003 | (@code{vc-dired-toggle-terse-mode}). There is also a special command |
6bf7aab6 DL |
2004 | @kbd{* l} (@code{vc-dired-mark-locked}), which marks all files currently |
2005 | locked (or, with CVS, all files not up-to-date). Thus, typing @kbd{* l | |
2006 | t k} is another way to delete from the buffer all files except those | |
2007 | currently locked. | |
2008 | ||
2009 | @node Branches | |
2010 | @subsection Multiple Branches of a File | |
2011 | @cindex branch (version control) | |
2012 | @cindex trunk (version control) | |
2013 | ||
2014 | One use of version control is to maintain multiple ``current'' | |
2015 | versions of a file. For example, you might have different versions of a | |
2016 | program in which you are gradually adding various unfinished new | |
2017 | features. Each such independent line of development is called a | |
2018 | @dfn{branch}. VC allows you to create branches, switch between | |
2019 | different branches, and merge changes from one branch to another. | |
a0554a40 | 2020 | Please note, however, that branches are not supported for SCCS. |
6bf7aab6 DL |
2021 | |
2022 | A file's main line of development is usually called the @dfn{trunk}. | |
2023 | The versions on the trunk are normally numbered 1.1, 1.2, 1.3, etc. At | |
2024 | any such version, you can start an independent branch. A branch | |
2025 | starting at version 1.2 would have version number 1.2.1.1, and consecutive | |
2026 | versions on this branch would have numbers 1.2.1.2, 1.2.1.3, 1.2.1.4, | |
2027 | and so on. If there is a second branch also starting at version 1.2, it | |
2028 | would consist of versions 1.2.2.1, 1.2.2.2, 1.2.2.3, etc. | |
2029 | ||
2030 | @cindex head version | |
2031 | If you omit the final component of a version number, that is called a | |
2032 | @dfn{branch number}. It refers to the highest existing version on that | |
2033 | branch---the @dfn{head version} of that branch. The branches in the | |
2034 | example above have branch numbers 1.2.1 and 1.2.2. | |
2035 | ||
2036 | @menu | |
2037 | * Switching Branches:: How to get to another existing branch. | |
2038 | * Creating Branches:: How to start a new branch. | |
2039 | * Merging:: Transferring changes between branches. | |
177c0ea7 | 2040 | * Multi-User Branching:: Multiple users working at multiple branches |
6bf7aab6 DL |
2041 | in parallel. |
2042 | @end menu | |
2043 | ||
2044 | @node Switching Branches | |
2045 | @subsubsection Switching between Branches | |
2046 | ||
576c4a0f | 2047 | To switch between branches, type @kbd{C-u C-x v v} and specify the |
6bf7aab6 DL |
2048 | version number you want to select. This version is then visited |
2049 | @emph{unlocked} (write-protected), so you can examine it before locking | |
2050 | it. Switching branches in this way is allowed only when the file is not | |
2051 | locked. | |
2052 | ||
2053 | You can omit the minor version number, thus giving only the branch | |
2054 | number; this takes you to the head version on the chosen branch. If you | |
7d5e745e | 2055 | only type @key{RET}, Emacs goes to the highest version on the trunk. |
6bf7aab6 DL |
2056 | |
2057 | After you have switched to any branch (including the main branch), you | |
2058 | stay on it for subsequent VC commands, until you explicitly select some | |
2059 | other branch. | |
2060 | ||
2061 | @node Creating Branches | |
2062 | @subsubsection Creating New Branches | |
2063 | ||
2064 | To create a new branch from a head version (one that is the latest in | |
2065 | the branch that contains it), first select that version if necessary, | |
576c4a0f AS |
2066 | lock it with @kbd{C-x v v}, and make whatever changes you want. Then, |
2067 | when you check in the changes, use @kbd{C-u C-x v v}. This lets you | |
6bf7aab6 DL |
2068 | specify the version number for the new version. You should specify a |
2069 | suitable branch number for a branch starting at the current version. | |
2070 | For example, if the current version is 2.5, the branch number should be | |
2071 | 2.5.1, 2.5.2, and so on, depending on the number of existing branches at | |
2072 | that point. | |
2073 | ||
2074 | To create a new branch at an older version (one that is no longer the | |
2075 | head of a branch), first select that version (@pxref{Switching | |
576c4a0f | 2076 | Branches}), then lock it with @kbd{C-x v v}. You'll be asked to |
6bf7aab6 DL |
2077 | confirm, when you lock the old version, that you really mean to create a |
2078 | new branch---if you say no, you'll be offered a chance to lock the | |
2079 | latest version instead. | |
2080 | ||
576c4a0f | 2081 | Then make your changes and type @kbd{C-x v v} again to check in a new |
6bf7aab6 DL |
2082 | version. This automatically creates a new branch starting from the |
2083 | selected version. You need not specially request a new branch, because | |
2084 | that's the only way to add a new version at a point that is not the head | |
2085 | of a branch. | |
2086 | ||
2087 | After the branch is created, you ``stay'' on it. That means that | |
2088 | subsequent check-ins create new versions on that branch. To leave the | |
2089 | branch, you must explicitly select a different version with @kbd{C-u C-x | |
576c4a0f | 2090 | v v}. To transfer changes from one branch to another, use the merge |
6bf7aab6 DL |
2091 | command, described in the next section. |
2092 | ||
2093 | @node Merging | |
2094 | @subsubsection Merging Branches | |
2095 | ||
2096 | @cindex merging changes | |
2097 | When you have finished the changes on a certain branch, you will | |
2098 | often want to incorporate them into the file's main line of development | |
2099 | (the trunk). This is not a trivial operation, because development might | |
2100 | also have proceeded on the trunk, so that you must @dfn{merge} the | |
2101 | changes into a file that has already been changed otherwise. VC allows | |
2102 | you to do this (and other things) with the @code{vc-merge} command. | |
2103 | ||
2104 | @table @kbd | |
2105 | @item C-x v m (vc-merge) | |
2106 | Merge changes into the work file. | |
2107 | @end table | |
2108 | ||
2109 | @kindex C-x v m | |
2110 | @findex vc-merge | |
2111 | @kbd{C-x v m} (@code{vc-merge}) takes a set of changes and merges it | |
ad63cf1d AS |
2112 | into the current version of the work file. It firsts asks you in the |
2113 | minibuffer where the changes should come from. If you just type | |
7d5e745e | 2114 | @key{RET}, Emacs merges any changes that were made on the same branch |
ad63cf1d AS |
2115 | since you checked the file out (we call this @dfn{merging the news}). |
2116 | This is the common way to pick up recent changes from the repository, | |
2117 | regardless of whether you have already changed the file yourself. | |
2118 | ||
2119 | You can also enter a branch number or a pair of version numbers in | |
0cf729ce RS |
2120 | the minibuffer. Then @kbd{C-x v m} finds the changes from that |
2121 | branch, or the differences between the two versions you specified, and | |
2122 | merges them into the current version of the current file. | |
6bf7aab6 DL |
2123 | |
2124 | As an example, suppose that you have finished a certain feature on | |
2125 | branch 1.3.1. In the meantime, development on the trunk has proceeded | |
2126 | to version 1.5. To merge the changes from the branch to the trunk, | |
576c4a0f | 2127 | first go to the head version of the trunk, by typing @kbd{C-u C-x v v |
7d5e745e | 2128 | @key{RET}}. Version 1.5 is now current. If locking is used for the file, |
576c4a0f | 2129 | type @kbd{C-x v v} to lock version 1.5 so that you can change it. Next, |
7d5e745e | 2130 | type @kbd{C-x v m 1.3.1 @key{RET}}. This takes the entire set of changes on |
6bf7aab6 DL |
2131 | branch 1.3.1 (relative to version 1.3, where the branch started, up to |
2132 | the last version on the branch) and merges it into the current version | |
2133 | of the work file. You can now check in the changed file, thus creating | |
2134 | version 1.6 containing the changes from the branch. | |
2135 | ||
2136 | It is possible to do further editing after merging the branch, before | |
2137 | the next check-in. But it is usually wiser to check in the merged | |
2138 | version, then lock it and make the further changes. This will keep | |
2139 | a better record of the history of changes. | |
2140 | ||
2141 | @cindex conflicts | |
2142 | @cindex resolving conflicts | |
2143 | When you merge changes into a file that has itself been modified, the | |
2144 | changes might overlap. We call this situation a @dfn{conflict}, and | |
2145 | reconciling the conflicting changes is called @dfn{resolving a | |
2146 | conflict}. | |
2147 | ||
2148 | Whenever conflicts occur during merging, VC detects them, tells you | |
2149 | about them in the echo area, and asks whether you want help in merging. | |
2150 | If you say yes, it starts an Ediff session (@pxref{Top, | |
2151 | Ediff, Ediff, ediff, The Ediff Manual}). | |
2152 | ||
2153 | If you say no, the conflicting changes are both inserted into the | |
2154 | file, surrounded by @dfn{conflict markers}. The example below shows how | |
2155 | a conflict region looks; the file is called @samp{name} and the current | |
2156 | master file version with user B's changes in it is 1.11. | |
2157 | ||
2158 | @c @w here is so CVS won't think this is a conflict. | |
2159 | @smallexample | |
2160 | @group | |
2161 | @w{<}<<<<<< name | |
2162 | @var{User A's version} | |
2163 | ======= | |
2164 | @var{User B's version} | |
2165 | @w{>}>>>>>> 1.11 | |
2166 | @end group | |
2167 | @end smallexample | |
2168 | ||
2169 | @cindex vc-resolve-conflicts | |
2170 | Then you can resolve the conflicts by editing the file manually. Or | |
2171 | you can type @code{M-x vc-resolve-conflicts} after visiting the file. | |
0cf729ce RS |
2172 | This starts an Ediff session, as described above. Don't forget to |
2173 | check in the merged version afterwards. | |
6bf7aab6 DL |
2174 | |
2175 | @node Multi-User Branching | |
2176 | @subsubsection Multi-User Branching | |
2177 | ||
2178 | It is often useful for multiple developers to work simultaneously on | |
2179 | different branches of a file. CVS allows this by default; for RCS, it | |
2180 | is possible if you create multiple source directories. Each source | |
2181 | directory should have a link named @file{RCS} which points to a common | |
2182 | directory of RCS master files. Then each source directory can have its | |
2183 | own choice of selected versions, but all share the same common RCS | |
2184 | records. | |
2185 | ||
2186 | This technique works reliably and automatically, provided that the | |
2187 | source files contain RCS version headers (@pxref{Version Headers}). The | |
2188 | headers enable Emacs to be sure, at all times, which version number is | |
2189 | present in the work file. | |
2190 | ||
2191 | If the files do not have version headers, you must instead tell Emacs | |
2192 | explicitly in each session which branch you are working on. To do this, | |
576c4a0f | 2193 | first find the file, then type @kbd{C-u C-x v v} and specify the correct |
6bf7aab6 DL |
2194 | branch number. This ensures that Emacs knows which branch it is using |
2195 | during this particular editing session. | |
2196 | ||
ad63cf1d AS |
2197 | @node Remote Repositories |
2198 | @subsection Remote Repositories | |
2199 | @cindex remote repositories (CVS) | |
2200 | ||
7d5e745e RS |
2201 | A common way of using CVS is to set up a central CVS repository on |
2202 | some Internet host, then have each developer check out a personal | |
2203 | working copy of the files on his local machine. Committing changes to | |
2204 | the repository, and picking up changes from other users into one's own | |
2205 | working area, then works by direct interactions with the CVS server. | |
ad63cf1d | 2206 | |
7d5e745e | 2207 | One difficulty is that access to the CVS server is often slow, and |
d0960fb3 | 2208 | that developers might need to work off-line as well. VC is designed |
7d5e745e | 2209 | to reduce the amount of network interaction necessary. |
ad63cf1d AS |
2210 | |
2211 | @menu | |
2212 | * Version Backups:: Keeping local copies of repository versions. | |
2213 | * Local Version Control:: Using another version system for local editing. | |
2214 | @end menu | |
2215 | ||
2216 | @node Version Backups | |
2217 | @subsubsection Version Backups | |
2218 | @cindex version backups | |
2219 | ||
ad63cf1d | 2220 | @cindex automatic version backups |
7d5e745e RS |
2221 | When VC sees that the CVS repository for a file is on a remote |
2222 | machine, it automatically makes local backups of unmodified versions | |
2223 | of the file---@dfn{automatic version backups}. This means that you | |
2224 | can compare the file to the repository version (@kbd{C-x v =}), or | |
2225 | revert to that version (@kbd{C-x v u}), without any network | |
2226 | interactions. | |
2227 | ||
2228 | The local copy of the unmodified file is called a @dfn{version | |
2229 | backup} to indicate that it corresponds exactly to a version that is | |
2230 | stored in the repository. Note that version backups are not the same | |
2231 | as ordinary Emacs backup files (@pxref{Backup}). But they follow a | |
2232 | similar naming convention. | |
2233 | ||
2234 | For a file that comes from a remote CVS repository, VC makes a | |
2235 | version backup whenever you save the first changes to the file, and | |
2236 | removes it after you have committed your modified version to the | |
2237 | repository. You can disable the making of automatic version backups by | |
2238 | setting @code{vc-cvs-stay-local} to @code{nil} (@pxref{CVS Options}). | |
2239 | ||
ad63cf1d | 2240 | @cindex manual version backups |
7d5e745e RS |
2241 | The name of the automatic version backup for version @var{version} |
2242 | of file @var{file} is @code{@var{file}.~@var{version}.~}. This is | |
2243 | almost the same as the name used by @kbd{C-x v ~} (@pxref{Old | |
2244 | Versions}), the only difference being the additional dot (@samp{.}) | |
2245 | after the version number. This similarity is intentional, because | |
2246 | both kinds of files store the same kind of information. The file made | |
2247 | by @kbd{C-x v ~} acts as a @dfn{manual version backup}. | |
2248 | ||
2249 | All the VC commands that operate on old versions of a file can use | |
2250 | both kinds of version backups. For instance, @kbd{C-x v ~} uses | |
2251 | either an automatic or a manual version backup, if possible, to get | |
2252 | the contents of the version you request. Likewise, @kbd{C-x v =} and | |
2253 | @kbd{C-x v u} use either an automatic or a manual version backup, if | |
2254 | one of them exists, to get the contents of a version to compare or | |
2255 | revert to. If you changed a file outside of Emacs, so that no | |
2256 | automatic version backup was created for the previous text, you can | |
2257 | create a manual backup of that version using @kbd{C-x v ~}, and thus | |
2258 | obtain the benefit of the local copy for Emacs commands. | |
2259 | ||
2260 | The only difference in Emacs's handling of manual and automatic | |
2261 | version backups, once they exist, is that Emacs deletes automatic | |
2262 | version backups when you commit to the repository. By contrast, | |
2263 | manual version backups remain until you delete them. | |
ad63cf1d AS |
2264 | |
2265 | @node Local Version Control | |
2266 | @subsubsection Local Version Control | |
2267 | @cindex local version control | |
2268 | @cindex local back end (version control) | |
2269 | ||
2270 | When you make many changes to a file that comes from a remote | |
2271 | repository, it can be convenient to have version control on your local | |
2272 | machine as well. You can then record intermediate versions, revert to | |
2273 | a previous state, etc., before you actually commit your changes to the | |
2274 | remote server. | |
2275 | ||
2276 | VC lets you do this by putting a file under a second, local version | |
2277 | control system, so that the file is effectively registered in two | |
2278 | systems at the same time. For the description here, we will assume | |
2279 | that the remote system is CVS, and you use RCS locally, although the | |
2280 | mechanism works with any combination of version control systems | |
2281 | (@dfn{back ends}). | |
2282 | ||
7d5e745e RS |
2283 | To make it work with other back ends, you must make sure that the |
2284 | ``more local'' back end comes before the ``more remote'' back end in | |
d3ff0a57 | 2285 | the setting of @code{vc-handled-backends} (@pxref{Customizing VC}). By |
7d5e745e RS |
2286 | default, this variable is set up so that you can use remote CVS and |
2287 | local RCS as described here. | |
ad63cf1d | 2288 | |
7d5e745e RS |
2289 | To start using local RCS for a file that comes from a remote CVS |
2290 | server, you must @emph{register the file in RCS}, by typing @kbd{C-u | |
2291 | C-x v v rcs @key{RET}}. (In other words, use @code{vc-next-action} with a | |
2292 | prefix argument, and specify RCS as the back end.) | |
ad63cf1d | 2293 | |
7d5e745e | 2294 | You can do this at any time; it does not matter whether you have |
ad63cf1d AS |
2295 | already modified the file with respect to the version in the CVS |
2296 | repository. If possible, VC tries to make the RCS master start with | |
4f09cbeb | 2297 | the unmodified repository version, then checks in any local changes |
7d5e745e RS |
2298 | as a new version. This works if you have not made any changes yet, or |
2299 | if the unmodified repository version exists locally as a version | |
ad63cf1d AS |
2300 | backup (@pxref{Version Backups}). If the unmodified version is not |
2301 | available locally, the RCS master starts with the modified version; | |
4f09cbeb | 2302 | the only drawback to this is that you cannot compare your changes |
ad63cf1d AS |
2303 | locally to what is stored in the repository. |
2304 | ||
2305 | The version number of the RCS master is derived from the current CVS | |
2306 | version, starting a branch from it. For example, if the current CVS | |
2307 | version is 1.23, the local RCS branch will be 1.23.1. Version 1.23 in | |
2308 | the RCS master will be identical to version 1.23 under CVS; your first | |
2309 | changes are checked in as 1.23.1.1. (If the unmodified file is not | |
7d5e745e | 2310 | available locally, VC will check in the modified file twice, both as |
ad63cf1d AS |
2311 | 1.23 and 1.23.1.1, to make the revision numbers consistent.) |
2312 | ||
2313 | If you do not use locking under CVS (the default), locking is also | |
7d5e745e RS |
2314 | disabled for RCS, so that editing under RCS works exactly as under |
2315 | CVS. | |
2316 | ||
41be8731 RS |
2317 | When you are done with local editing, you can commit the final version |
2318 | back to the CVS repository by typing @kbd{C-u C-x v v cvs @key{RET}}. | |
2319 | This initializes the log entry buffer (@pxref{Log Buffer}) to contain | |
2320 | all the log entries you have recorded in the RCS master; you can edit | |
2321 | them as you wish, and then commit in CVS by typing @kbd{C-c C-c}. If | |
2322 | the commit is successful, VC removes the RCS master, so that the file | |
2323 | is once again registered under CVS only. (The RCS master is not | |
2324 | actually deleted, just renamed by appending @samp{~} to the name, so | |
2325 | that you can refer to it later if you wish.) | |
2326 | ||
2327 | While using local RCS, you can pick up recent changes from the CVS | |
2328 | repository into your local file, or commit some of your changes back | |
2329 | to CVS, without terminating local RCS version control. To do this, | |
d0960fb3 | 2330 | switch to the CVS back end temporarily, with the @kbd{C-x v b} command: |
ad63cf1d AS |
2331 | |
2332 | @table @kbd | |
2333 | @item C-x v b | |
7d5e745e | 2334 | Switch to another back end that the current file is registered |
ad63cf1d | 2335 | under (@code{vc-switch-backend}). |
7d5e745e RS |
2336 | |
2337 | @item C-u C-x v b @var{backend} @key{RET} | |
2338 | Switch to @var{backend} for the current file. | |
ad63cf1d AS |
2339 | @end table |
2340 | ||
b4d063bf | 2341 | @kindex C-x v b |
ad63cf1d | 2342 | @findex vc-switch-backend |
7d5e745e RS |
2343 | @kbd{C-x v b} does not change the buffer contents, or any files; it |
2344 | only changes VC's perspective on how to handle the file. Any | |
2345 | subsequent VC commands for that file will operate on the back end that | |
2346 | is currently selected. | |
2347 | ||
ad63cf1d | 2348 | If the current file is registered in more than one back end, typing |
7d5e745e RS |
2349 | @kbd{C-x v b} ``cycles'' through all of these back ends. With a |
2350 | prefix argument, it asks for the back end to use in the minibuffer. | |
ad63cf1d | 2351 | |
41be8731 RS |
2352 | Thus, if you are using local RCS, and you want to pick up some recent |
2353 | changes in the file from remote CVS, first visit the file, then type | |
2354 | @kbd{C-x v b} to switch to CVS, and finally use @kbd{C-x v m | |
2355 | @key{RET}} to merge the news (@pxref{Merging}). You can then switch | |
2356 | back to RCS by typing @kbd{C-x v b} again, and continue to edit | |
2357 | locally. | |
2358 | ||
2359 | But if you do this, the revision numbers in the RCS master no longer | |
2360 | correspond to those of CVS. Technically, this is not a problem, but | |
2361 | it can become difficult to keep track of what is in the CVS repository | |
2362 | and what is not. So we suggest that you return from time to time to | |
a0554a40 LT |
2363 | CVS-only operation, by committing your local changes back to the |
2364 | repository using @kbd{C-u C-x v v cvs @key{RET}}. | |
ad63cf1d | 2365 | |
6bf7aab6 DL |
2366 | @node Snapshots |
2367 | @subsection Snapshots | |
2368 | @cindex snapshots and version control | |
2369 | ||
2370 | A @dfn{snapshot} is a named set of file versions (one for each | |
2371 | registered file) that you can treat as a unit. One important kind of | |
2372 | snapshot is a @dfn{release}, a (theoretically) stable version of the | |
2373 | system that is ready for distribution to users. | |
2374 | ||
2375 | @menu | |
2376 | * Making Snapshots:: The snapshot facilities. | |
2377 | * Snapshot Caveats:: Things to be careful of when using snapshots. | |
2378 | @end menu | |
2379 | ||
2380 | @node Making Snapshots | |
2381 | @subsubsection Making and Using Snapshots | |
2382 | ||
2383 | There are two basic commands for snapshots; one makes a | |
2384 | snapshot with a given name, the other retrieves a named snapshot. | |
2385 | ||
2386 | @table @code | |
2387 | @kindex C-x v s | |
2388 | @findex vc-create-snapshot | |
2389 | @item C-x v s @var{name} @key{RET} | |
2390 | Define the last saved versions of every registered file in or under the | |
2391 | current directory as a snapshot named @var{name} | |
2392 | (@code{vc-create-snapshot}). | |
2393 | ||
2394 | @kindex C-x v r | |
2395 | @findex vc-retrieve-snapshot | |
2396 | @item C-x v r @var{name} @key{RET} | |
2397 | For all registered files at or below the current directory level, select | |
2398 | whatever versions correspond to the snapshot @var{name} | |
2399 | (@code{vc-retrieve-snapshot}). | |
2400 | ||
2401 | This command reports an error if any files are locked at or below the | |
2402 | current directory, without changing anything; this is to avoid | |
2403 | overwriting work in progress. | |
2404 | @end table | |
2405 | ||
2406 | A snapshot uses a very small amount of resources---just enough to record | |
2407 | the list of file names and which version belongs to the snapshot. Thus, | |
2408 | you need not hesitate to create snapshots whenever they are useful. | |
2409 | ||
2410 | You can give a snapshot name as an argument to @kbd{C-x v =} or | |
2411 | @kbd{C-x v ~} (@pxref{Old Versions}). Thus, you can use it to compare a | |
2412 | snapshot against the current files, or two snapshots against each other, | |
2413 | or a snapshot against a named version. | |
2414 | ||
2415 | @node Snapshot Caveats | |
2416 | @subsubsection Snapshot Caveats | |
2417 | ||
2418 | @cindex named configurations (RCS) | |
2419 | VC's snapshot facilities are modeled on RCS's named-configuration | |
50a1bd4f RS |
2420 | support. They use RCS's native facilities for this, so |
2421 | snapshots made using RCS through VC are visible even when you bypass VC. | |
6bf7aab6 DL |
2422 | |
2423 | @c worded verbosely to avoid overfull hbox. | |
2424 | For SCCS, VC implements snapshots itself. The files it uses contain | |
2425 | name/file/version-number triples. These snapshots are visible only | |
2426 | through VC. | |
2427 | ||
50a1bd4f RS |
2428 | @c ??? What about CVS? |
2429 | ||
6bf7aab6 DL |
2430 | A snapshot is a set of checked-in versions. So make sure that all the |
2431 | files are checked in and not locked when you make a snapshot. | |
2432 | ||
2433 | File renaming and deletion can create some difficulties with snapshots. | |
2434 | This is not a VC-specific problem, but a general design issue in version | |
2435 | control systems that no one has solved very well yet. | |
2436 | ||
2437 | If you rename a registered file, you need to rename its master along | |
2438 | with it (the command @code{vc-rename-file} does this automatically). If | |
2439 | you are using SCCS, you must also update the records of the snapshot, to | |
2440 | mention the file by its new name (@code{vc-rename-file} does this, | |
2441 | too). An old snapshot that refers to a master file that no longer | |
2442 | exists under the recorded name is invalid; VC can no longer retrieve | |
2443 | it. It would be beyond the scope of this manual to explain enough about | |
2444 | RCS and SCCS to explain how to update the snapshots by hand. | |
2445 | ||
2446 | Using @code{vc-rename-file} makes the snapshot remain valid for | |
2447 | retrieval, but it does not solve all problems. For example, some of the | |
4f09cbeb | 2448 | files in your program probably refer to others by name. At the very |
6bf7aab6 DL |
2449 | least, the makefile probably mentions the file that you renamed. If you |
2450 | retrieve an old snapshot, the renamed file is retrieved under its new | |
2451 | name, which is not the name that the makefile expects. So the program | |
2452 | won't really work as retrieved. | |
2453 | ||
2454 | @node Miscellaneous VC | |
2455 | @subsection Miscellaneous Commands and Features of VC | |
2456 | ||
2457 | This section explains the less-frequently-used features of VC. | |
2458 | ||
2459 | @menu | |
2460 | * Change Logs and VC:: Generating a change log file from log entries. | |
177c0ea7 | 2461 | * Renaming and VC:: A command to rename both the source and master |
6bf7aab6 DL |
2462 | file correctly. |
2463 | * Version Headers:: Inserting version control headers into working files. | |
2464 | @end menu | |
2465 | ||
2466 | @node Change Logs and VC | |
2467 | @subsubsection Change Logs and VC | |
2468 | ||
2469 | If you use RCS or CVS for a program and also maintain a change log | |
2470 | file for it (@pxref{Change Log}), you can generate change log entries | |
2471 | automatically from the version control log entries: | |
2472 | ||
2473 | @table @kbd | |
2474 | @item C-x v a | |
2475 | @kindex C-x v a | |
2476 | @findex vc-update-change-log | |
2477 | Visit the current directory's change log file and, for registered files | |
2478 | in that directory, create new entries for versions checked in since the | |
2479 | most recent entry in the change log file. | |
2480 | (@code{vc-update-change-log}). | |
2481 | ||
2482 | This command works with RCS or CVS only, not with SCCS. | |
2483 | ||
50a1bd4f RS |
2484 | @c ??? What about other back ends? |
2485 | ||
6bf7aab6 DL |
2486 | @item C-u C-x v a |
2487 | As above, but only find entries for the current buffer's file. | |
2488 | ||
2489 | @item M-1 C-x v a | |
2490 | As above, but find entries for all the currently visited files that are | |
2491 | maintained with version control. This works only with RCS, and it puts | |
2492 | all entries in the log for the default directory, which may not be | |
2493 | appropriate. | |
2494 | @end table | |
2495 | ||
2496 | For example, suppose the first line of @file{ChangeLog} is dated | |
2497 | 1999-04-10, and that the only check-in since then was by Nathaniel | |
2498 | Bowditch to @file{rcs2log} on 1999-05-22 with log text @samp{Ignore log | |
2499 | messages that start with `#'.}. Then @kbd{C-x v a} visits | |
2500 | @file{ChangeLog} and inserts text like this: | |
2501 | ||
2502 | @iftex | |
2503 | @medbreak | |
2504 | @end iftex | |
2505 | @smallexample | |
2506 | @group | |
2507 | 1999-05-22 Nathaniel Bowditch <nat@@apn.org> | |
2508 | ||
2509 | * rcs2log: Ignore log messages that start with `#'. | |
2510 | @end group | |
2511 | @end smallexample | |
2512 | @iftex | |
2513 | @medbreak | |
2514 | @end iftex | |
2515 | ||
2516 | @noindent | |
2517 | You can then edit the new change log entry further as you wish. | |
2518 | ||
4f09cbeb | 2519 | Some of the new change log entries may duplicate what's already in |
7d5e745e | 2520 | ChangeLog. You will have to remove these duplicates by hand. |
6bf7aab6 DL |
2521 | |
2522 | Normally, the log entry for file @file{foo} is displayed as @samp{* | |
2523 | foo: @var{text of log entry}}. The @samp{:} after @file{foo} is omitted | |
2524 | if the text of the log entry starts with @w{@samp{(@var{functionname}): | |
2525 | }}. For example, if the log entry for @file{vc.el} is | |
2526 | @samp{(vc-do-command): Check call-process status.}, then the text in | |
2527 | @file{ChangeLog} looks like this: | |
2528 | ||
2529 | @iftex | |
2530 | @medbreak | |
2531 | @end iftex | |
2532 | @smallexample | |
2533 | @group | |
2534 | 1999-05-06 Nathaniel Bowditch <nat@@apn.org> | |
2535 | ||
2536 | * vc.el (vc-do-command): Check call-process status. | |
2537 | @end group | |
2538 | @end smallexample | |
2539 | @iftex | |
2540 | @medbreak | |
2541 | @end iftex | |
2542 | ||
2543 | When @kbd{C-x v a} adds several change log entries at once, it groups | |
2544 | related log entries together if they all are checked in by the same | |
2545 | author at nearly the same time. If the log entries for several such | |
2546 | files all have the same text, it coalesces them into a single entry. | |
2547 | For example, suppose the most recent check-ins have the following log | |
2548 | entries: | |
2549 | ||
2550 | @flushleft | |
2551 | @bullet{} For @file{vc.texinfo}: @samp{Fix expansion typos.} | |
2552 | @bullet{} For @file{vc.el}: @samp{Don't call expand-file-name.} | |
2553 | @bullet{} For @file{vc-hooks.el}: @samp{Don't call expand-file-name.} | |
2554 | @end flushleft | |
2555 | ||
2556 | @noindent | |
2557 | They appear like this in @file{ChangeLog}: | |
2558 | ||
2559 | @iftex | |
2560 | @medbreak | |
2561 | @end iftex | |
2562 | @smallexample | |
2563 | @group | |
2564 | 1999-04-01 Nathaniel Bowditch <nat@@apn.org> | |
2565 | ||
2566 | * vc.texinfo: Fix expansion typos. | |
2567 | ||
2568 | * vc.el, vc-hooks.el: Don't call expand-file-name. | |
2569 | @end group | |
2570 | @end smallexample | |
2571 | @iftex | |
2572 | @medbreak | |
2573 | @end iftex | |
2574 | ||
2575 | Normally, @kbd{C-x v a} separates log entries by a blank line, but you | |
2576 | can mark several related log entries to be clumped together (without an | |
2577 | intervening blank line) by starting the text of each related log entry | |
2578 | with a label of the form @w{@samp{@{@var{clumpname}@} }}. The label | |
2579 | itself is not copied to @file{ChangeLog}. For example, suppose the log | |
2580 | entries are: | |
2581 | ||
2582 | @flushleft | |
2583 | @bullet{} For @file{vc.texinfo}: @samp{@{expand@} Fix expansion typos.} | |
2584 | @bullet{} For @file{vc.el}: @samp{@{expand@} Don't call expand-file-name.} | |
2585 | @bullet{} For @file{vc-hooks.el}: @samp{@{expand@} Don't call expand-file-name.} | |
2586 | @end flushleft | |
2587 | ||
2588 | @noindent | |
2589 | Then the text in @file{ChangeLog} looks like this: | |
2590 | ||
2591 | @iftex | |
2592 | @medbreak | |
2593 | @end iftex | |
2594 | @smallexample | |
2595 | @group | |
2596 | 1999-04-01 Nathaniel Bowditch <nat@@apn.org> | |
2597 | ||
2598 | * vc.texinfo: Fix expansion typos. | |
2599 | * vc.el, vc-hooks.el: Don't call expand-file-name. | |
2600 | @end group | |
2601 | @end smallexample | |
2602 | @iftex | |
2603 | @medbreak | |
2604 | @end iftex | |
2605 | ||
2606 | A log entry whose text begins with @samp{#} is not copied to | |
2607 | @file{ChangeLog}. For example, if you merely fix some misspellings in | |
2608 | comments, you can log the change with an entry beginning with @samp{#} | |
2609 | to avoid putting such trivia into @file{ChangeLog}. | |
2610 | ||
2611 | @node Renaming and VC | |
2612 | @subsubsection Renaming VC Work Files and Master Files | |
2613 | ||
2614 | @findex vc-rename-file | |
2615 | When you rename a registered file, you must also rename its master | |
2616 | file correspondingly to get proper results. Use @code{vc-rename-file} | |
2617 | to rename the source file as you specify, and rename its master file | |
2618 | accordingly. It also updates any snapshots (@pxref{Snapshots}) that | |
2619 | mention the file, so that they use the new name; despite this, the | |
2620 | snapshot thus modified may not completely work (@pxref{Snapshot | |
2621 | Caveats}). | |
2622 | ||
c5d36b03 RS |
2623 | Some backends do not provide an explicit rename operation to their |
2624 | repositories. After issuing @code{vc-rename-file}, use @kbd{C-x v v} | |
2625 | on the original and renamed buffers and provide the necessary edit | |
2626 | log. | |
2627 | ||
6bf7aab6 DL |
2628 | You cannot use @code{vc-rename-file} on a file that is locked by |
2629 | someone else. | |
2630 | ||
2631 | @node Version Headers | |
2632 | @subsubsection Inserting Version Control Headers | |
2633 | ||
2634 | Sometimes it is convenient to put version identification strings | |
2635 | directly into working files. Certain special strings called | |
2636 | @dfn{version headers} are replaced in each successive version by the | |
2637 | number of that version. | |
2638 | ||
50a1bd4f RS |
2639 | @c ??? How does this relate to CVS? |
2640 | ||
6bf7aab6 DL |
2641 | If you are using RCS, and version headers are present in your working |
2642 | files, Emacs can use them to determine the current version and the | |
2643 | locking state of the files. This is more reliable than referring to the | |
2644 | master files, which is done when there are no version headers. Note | |
2645 | that in a multi-branch environment, version headers are necessary to | |
2646 | make VC behave correctly (@pxref{Multi-User Branching}). | |
2647 | ||
2648 | Searching for version headers is controlled by the variable | |
0cf729ce RS |
2649 | @code{vc-consult-headers}. If it is non-@code{nil} (the default), |
2650 | Emacs searches for headers to determine the version number you are | |
2651 | editing. Setting it to @code{nil} disables this feature. | |
6bf7aab6 DL |
2652 | |
2653 | @kindex C-x v h | |
2654 | @findex vc-insert-headers | |
2655 | You can use the @kbd{C-x v h} command (@code{vc-insert-headers}) to | |
2656 | insert a suitable header string. | |
2657 | ||
2658 | @table @kbd | |
2659 | @item C-x v h | |
2660 | Insert headers in a file for use with your version-control system. | |
2661 | @end table | |
2662 | ||
a0554a40 | 2663 | @vindex vc-@var{backend}-header |
6bf7aab6 DL |
2664 | The default header string is @samp{@w{$}Id$} for RCS and |
2665 | @samp{@w{%}W%} for SCCS. You can specify other headers to insert by | |
a0554a40 LT |
2666 | setting the variables @code{vc-@var{backend}-header} where |
2667 | @var{backend} is @code{rcs} or @code{sccs}. | |
6bf7aab6 DL |
2668 | |
2669 | Instead of a single string, you can specify a list of strings; then | |
2670 | each string in the list is inserted as a separate header on a line of | |
2671 | its own. | |
2672 | ||
50a1bd4f | 2673 | It may be necessary to use apparently-superfluous backslashes when |
0cf729ce RS |
2674 | writing the strings that you put in this variable. For instance, you |
2675 | might write @code{"$Id\$"} rather than @code{"$Id@w{$}"}. The extra | |
2676 | backslash prevents the string constant from being interpreted as a | |
2677 | header, if the Emacs Lisp file containing it is maintained with | |
2678 | version control. | |
6bf7aab6 DL |
2679 | |
2680 | @vindex vc-comment-alist | |
2681 | Each header is inserted surrounded by tabs, inside comment delimiters, | |
2682 | on a new line at point. Normally the ordinary comment | |
2683 | start and comment end strings of the current mode are used, but for | |
2684 | certain modes, there are special comment delimiters for this purpose; | |
2685 | the variable @code{vc-comment-alist} specifies them. Each element of | |
2686 | this list has the form @code{(@var{mode} @var{starter} @var{ender})}. | |
2687 | ||
2688 | @vindex vc-static-header-alist | |
2689 | The variable @code{vc-static-header-alist} specifies further strings | |
2690 | to add based on the name of the buffer. Its value should be a list of | |
2691 | elements of the form @code{(@var{regexp} . @var{format})}. Whenever | |
2692 | @var{regexp} matches the buffer name, @var{format} is inserted as part | |
2693 | of the header. A header line is inserted for each element that matches | |
2694 | the buffer name, and for each string specified by | |
a0554a40 LT |
2695 | @code{vc-@var{backend}-header}. The header line is made by processing the |
2696 | string from @code{vc-@var{backend}-header} with the format taken from the | |
6bf7aab6 DL |
2697 | element. The default value for @code{vc-static-header-alist} is as follows: |
2698 | ||
2699 | @example | |
2700 | @group | |
2701 | (("\\.c$" . | |
2702 | "\n#ifndef lint\nstatic char vcid[] = \"\%s\";\n\ | |
2703 | #endif /* lint */\n")) | |
2704 | @end group | |
2705 | @end example | |
2706 | ||
2707 | @noindent | |
2708 | It specifies insertion of text of this form: | |
2709 | ||
2710 | @example | |
2711 | @group | |
2712 | ||
2713 | #ifndef lint | |
2714 | static char vcid[] = "@var{string}"; | |
2715 | #endif /* lint */ | |
2716 | @end group | |
2717 | @end example | |
2718 | ||
2719 | @noindent | |
2720 | Note that the text above starts with a blank line. | |
2721 | ||
2722 | If you use more than one version header in a file, put them close | |
2723 | together in the file. The mechanism in @code{revert-buffer} that | |
2724 | preserves markers may not handle markers positioned between two version | |
2725 | headers. | |
2726 | ||
2727 | @node Customizing VC | |
2728 | @subsection Customizing VC | |
2729 | ||
ad63cf1d | 2730 | @vindex vc-handled-backends |
d3ff0a57 | 2731 | The variable @code{vc-handled-backends} determines which version |
ad63cf1d | 2732 | control systems VC should handle. The default value is @code{(RCS CVS |
a0554a40 LT |
2733 | SVN SCCS Arch MCVS)}, so it contains all six version systems that are |
2734 | currently supported. If you want VC to ignore one or more of these | |
2735 | systems, exclude its name from the list. To disable VC entirely, set | |
2736 | this variable to @code{nil}. | |
ad63cf1d AS |
2737 | |
2738 | The order of systems in the list is significant: when you visit a file | |
d3ff0a57 RS |
2739 | registered in more than one system (@pxref{Local Version Control}), |
2740 | VC uses the system that comes first in @code{vc-handled-backends} by | |
ad63cf1d AS |
2741 | default. The order is also significant when you register a file for |
2742 | the first time, @pxref{Registering} for details. | |
6bf7aab6 DL |
2743 | |
2744 | @menu | |
7d5e745e RS |
2745 | * General VC Options:: Options that apply to multiple back ends. |
2746 | * RCS and SCCS:: Options for RCS and SCCS. | |
ad63cf1d | 2747 | * CVS Options:: Options for CVS. |
6bf7aab6 DL |
2748 | @end menu |
2749 | ||
ad63cf1d AS |
2750 | @node General VC Options |
2751 | @subsubsection General Options | |
6bf7aab6 DL |
2752 | |
2753 | @vindex vc-make-backup-files | |
2754 | Emacs normally does not save backup files for source files that are | |
2755 | maintained with version control. If you want to make backup files even | |
2756 | for files that use version control, set the variable | |
2757 | @code{vc-make-backup-files} to a non-@code{nil} value. | |
2758 | ||
2759 | @vindex vc-keep-workfiles | |
2760 | Normally the work file exists all the time, whether it is locked or | |
2761 | not. If you set @code{vc-keep-workfiles} to @code{nil}, then checking | |
576c4a0f | 2762 | in a new version with @kbd{C-x v v} deletes the work file; but any |
6bf7aab6 DL |
2763 | attempt to visit the file with Emacs creates it again. (With CVS, work |
2764 | files are always kept.) | |
2765 | ||
2766 | @vindex vc-follow-symlinks | |
2767 | Editing a version-controlled file through a symbolic link can be | |
2768 | dangerous. It bypasses the version control system---you can edit the | |
2769 | file without locking it, and fail to check your changes in. Also, | |
2770 | your changes might overwrite those of another user. To protect against | |
2771 | this, VC checks each symbolic link that you visit, to see if it points | |
2772 | to a file under version control. | |
2773 | ||
2774 | The variable @code{vc-follow-symlinks} controls what to do when a | |
2775 | symbolic link points to a version-controlled file. If it is @code{nil}, | |
2776 | VC only displays a warning message. If it is @code{t}, VC automatically | |
2777 | follows the link, and visits the real file instead, telling you about | |
2778 | this in the echo area. If the value is @code{ask} (the default), VC | |
2779 | asks you each time whether to follow the link. | |
2780 | ||
6bf7aab6 | 2781 | @vindex vc-suppress-confirm |
576c4a0f | 2782 | If @code{vc-suppress-confirm} is non-@code{nil}, then @kbd{C-x v v} |
6bf7aab6 DL |
2783 | and @kbd{C-x v i} can save the current buffer without asking, and |
2784 | @kbd{C-x v u} also operates without asking for confirmation. (This | |
2785 | variable does not affect @kbd{C-x v c}; that operation is so drastic | |
2786 | that it should always ask for confirmation.) | |
2787 | ||
2788 | @vindex vc-command-messages | |
2789 | VC mode does much of its work by running the shell commands for RCS, | |
2790 | CVS and SCCS. If @code{vc-command-messages} is non-@code{nil}, VC | |
2791 | displays messages to indicate which shell commands it runs, and | |
2792 | additional messages when the commands finish. | |
2793 | ||
2794 | @vindex vc-path | |
2795 | You can specify additional directories to search for version control | |
7d5e745e RS |
2796 | programs by setting the variable @code{vc-path}. These directories |
2797 | are searched before the usual search path. It is rarely necessary to | |
2798 | set this variable, because VC normally finds the proper files | |
2799 | automatically. | |
6bf7aab6 | 2800 | |
7d5e745e RS |
2801 | @node RCS and SCCS |
2802 | @subsubsection Options for RCS and SCCS | |
ad63cf1d AS |
2803 | |
2804 | @cindex non-strict locking (RCS) | |
2805 | @cindex locking, non-strict (RCS) | |
2806 | By default, RCS uses locking to coordinate the activities of several | |
2807 | users, but there is a mode called @dfn{non-strict locking} in which | |
2808 | you can check-in changes without locking the file first. Use | |
2809 | @samp{rcs -U} to switch to non-strict locking for a particular file, | |
d0960fb3 | 2810 | see the @code{rcs} manual page for details. |
ad63cf1d | 2811 | |
7d5e745e RS |
2812 | When deducing the version control state of an RCS file, VC first |
2813 | looks for an RCS version header string in the file (@pxref{Version | |
ad63cf1d AS |
2814 | Headers}). If there is no header string, VC normally looks at the |
2815 | file permissions of the work file; this is fast. But there might be | |
2816 | situations when the file permissions cannot be trusted. In this case | |
2817 | the master file has to be consulted, which is rather expensive. Also | |
2818 | the master file can only tell you @emph{if} there's any lock on the | |
2819 | file, but not whether your work file really contains that locked | |
2820 | version. | |
2821 | ||
2822 | @vindex vc-consult-headers | |
2823 | You can tell VC not to use version headers to determine the file | |
2824 | status by setting @code{vc-consult-headers} to @code{nil}. VC then | |
7d5e745e RS |
2825 | always uses the file permissions (if it is supposed to trust them), or |
2826 | else checks the master file. | |
ad63cf1d AS |
2827 | |
2828 | @vindex vc-mistrust-permissions | |
2829 | You can specify the criterion for whether to trust the file | |
2830 | permissions by setting the variable @code{vc-mistrust-permissions}. | |
2831 | Its value can be @code{t} (always mistrust the file permissions and | |
2832 | check the master file), @code{nil} (always trust the file | |
2833 | permissions), or a function of one argument which makes the decision. | |
2834 | The argument is the directory name of the @file{RCS} subdirectory. A | |
2835 | non-@code{nil} value from the function says to mistrust the file | |
2836 | permissions. If you find that the file permissions of work files are | |
2837 | changed erroneously, set @code{vc-mistrust-permissions} to @code{t}. | |
2838 | Then VC always checks the master file to determine the file's status. | |
2839 | ||
7d5e745e RS |
2840 | VC determines the version control state of files under SCCS much as |
2841 | with RCS. It does not consider SCCS version headers, though. Thus, | |
d3ff0a57 RS |
2842 | the variable @code{vc-mistrust-permissions} affects SCCS use, but |
2843 | @code{vc-consult-headers} does not. | |
7d5e745e | 2844 | |
ad63cf1d AS |
2845 | @node CVS Options |
2846 | @subsubsection Options specific for CVS | |
2847 | ||
2848 | @cindex locking (CVS) | |
2849 | By default, CVS does not use locking to coordinate the activities of | |
2850 | several users; anyone can change a work file at any time. However, | |
2851 | there are ways to restrict this, resulting in behavior that resembles | |
2852 | locking. | |
2853 | ||
2854 | @cindex CVSREAD environment variable (CVS) | |
7d5e745e RS |
2855 | For one thing, you can set the @env{CVSREAD} environment variable |
2856 | (the value you use makes no difference). If this variable is defined, | |
2857 | CVS makes your work files read-only by default. In Emacs, you must | |
576c4a0f | 2858 | type @kbd{C-x v v} to make the file writable, so that editing works |
7d5e745e | 2859 | in fact similar as if locking was used. Note however, that no actual |
d0960fb3 | 2860 | locking is performed, so several users can make their files writable |
7d5e745e RS |
2861 | at the same time. When setting @env{CVSREAD} for the first time, make |
2862 | sure to check out all your modules anew, so that the file protections | |
2863 | are set correctly. | |
ad63cf1d AS |
2864 | |
2865 | @cindex cvs watch feature | |
2866 | @cindex watching files (CVS) | |
2867 | Another way to achieve something similar to locking is to use the | |
2868 | @dfn{watch} feature of CVS. If a file is being watched, CVS makes it | |
576c4a0f | 2869 | read-only by default, and you must also use @kbd{C-x v v} in Emacs to |
d0960fb3 | 2870 | make it writable. VC calls @code{cvs edit} to make the file writable, |
ad63cf1d AS |
2871 | and CVS takes care to notify other developers of the fact that you |
2872 | intend to change the file. See the CVS documentation for details on | |
2873 | using the watch feature. | |
2874 | ||
2875 | @vindex vc-cvs-stay-local | |
2876 | @cindex remote repositories (CVS) | |
2877 | When a file's repository is on a remote machine, VC tries to keep | |
2878 | network interactions to a minimum. This is controlled by the variable | |
d3ff0a57 | 2879 | @code{vc-cvs-stay-local}. If it is @code{t} (the default), then VC uses |
033ae89c AS |
2880 | only the entry in the local CVS subdirectory to determine the file's |
2881 | state (and possibly information returned by previous CVS commands). One | |
2882 | consequence of this is that when you have modified a file, and somebody | |
2883 | else has already checked in other changes to the file, you are not | |
2884 | notified of it until you actually try to commit. (But you can try to | |
2885 | pick up any recent changes from the repository first, using @kbd{C-x v m | |
7d5e745e | 2886 | @key{RET}}, @pxref{Merging}). |
ad63cf1d | 2887 | |
b3c8fa05 | 2888 | @vindex vc-cvs-global-switches |
a0554a40 LT |
2889 | The variable @code{vc-cvs-global-switches}, if non-@code{nil}, |
2890 | should be a string specifying switches to pass to CVS for all CVS | |
2891 | operations. | |
b3c8fa05 | 2892 | |
d3ff0a57 | 2893 | When @code{vc-cvs-stay-local} is @code{t}, VC also makes local |
ad63cf1d AS |
2894 | version backups, so that simple diff and revert operations are |
2895 | completely local (@pxref{Version Backups}). | |
2896 | ||
d3ff0a57 | 2897 | On the other hand, if you set @code{vc-cvs-stay-local} to @code{nil}, |
ad63cf1d AS |
2898 | then VC queries the remote repository @emph{before} it decides what to |
2899 | do in @code{vc-next-action} (@kbd{C-x v v}), just as it does for local | |
2900 | repositories. It also does not make any version backups. | |
2901 | ||
d3ff0a57 | 2902 | You can also set @code{vc-cvs-stay-local} to a regular expression |
d0960fb3 | 2903 | that is matched against the repository host name; VC then stays local |
7d5e745e | 2904 | only for repositories from hosts that match the pattern. |
ad63cf1d | 2905 | |
6bf7aab6 DL |
2906 | @node Directories |
2907 | @section File Directories | |
2908 | ||
2909 | @cindex file directory | |
2910 | @cindex directory listing | |
2911 | The file system groups files into @dfn{directories}. A @dfn{directory | |
2912 | listing} is a list of all the files in a directory. Emacs provides | |
2913 | commands to create and delete directories, and to make directory | |
2914 | listings in brief format (file names only) and verbose format (sizes, | |
50a1bd4f RS |
2915 | dates, and authors included). Emacs also includes a directory browser |
2916 | feature called Dired; see @ref{Dired}. | |
6bf7aab6 DL |
2917 | |
2918 | @table @kbd | |
2919 | @item C-x C-d @var{dir-or-pattern} @key{RET} | |
2920 | Display a brief directory listing (@code{list-directory}). | |
2921 | @item C-u C-x C-d @var{dir-or-pattern} @key{RET} | |
2922 | Display a verbose directory listing. | |
2923 | @item M-x make-directory @key{RET} @var{dirname} @key{RET} | |
2924 | Create a new directory named @var{dirname}. | |
2925 | @item M-x delete-directory @key{RET} @var{dirname} @key{RET} | |
2926 | Delete the directory named @var{dirname}. It must be empty, | |
2927 | or you get an error. | |
2928 | @end table | |
2929 | ||
2930 | @findex list-directory | |
2931 | @kindex C-x C-d | |
2932 | The command to display a directory listing is @kbd{C-x C-d} | |
2933 | (@code{list-directory}). It reads using the minibuffer a file name | |
2934 | which is either a directory to be listed or a wildcard-containing | |
2935 | pattern for the files to be listed. For example, | |
2936 | ||
2937 | @example | |
2938 | C-x C-d /u2/emacs/etc @key{RET} | |
2939 | @end example | |
2940 | ||
2941 | @noindent | |
2942 | lists all the files in directory @file{/u2/emacs/etc}. Here is an | |
2943 | example of specifying a file name pattern: | |
2944 | ||
2945 | @example | |
2946 | C-x C-d /u2/emacs/src/*.c @key{RET} | |
2947 | @end example | |
2948 | ||
1ba2ce68 | 2949 | Normally, @kbd{C-x C-d} displays a brief directory listing containing |
6bf7aab6 | 2950 | just file names. A numeric argument (regardless of value) tells it to |
d3ff0a57 | 2951 | make a verbose listing including sizes, dates, and owners (like |
6bf7aab6 DL |
2952 | @samp{ls -l}). |
2953 | ||
2954 | @vindex list-directory-brief-switches | |
2955 | @vindex list-directory-verbose-switches | |
b3c8fa05 RS |
2956 | The text of a directory listing is mostly obtained by running |
2957 | @code{ls} in an inferior process. Two Emacs variables control the | |
2958 | switches passed to @code{ls}: @code{list-directory-brief-switches} is | |
2959 | a string giving the switches to use in brief listings (@code{"-CF"} by | |
2960 | default), and @code{list-directory-verbose-switches} is a string | |
2961 | giving the switches to use in a verbose listing (@code{"-l"} by | |
2962 | default). | |
2963 | ||
2964 | @vindex directory-free-space-program | |
2965 | @vindex directory-free-space-args | |
50a1bd4f RS |
2966 | In verbose directory listings, Emacs adds information about the |
2967 | amount of free space on the disk that contains the directory. To do | |
2968 | this, it runs the program specified by | |
2969 | @code{directory-free-space-program} with arguments | |
b3c8fa05 | 2970 | @code{directory-free-space-args}. |
6bf7aab6 DL |
2971 | |
2972 | @node Comparing Files | |
2973 | @section Comparing Files | |
2974 | @cindex comparing files | |
2975 | ||
2976 | @findex diff | |
2977 | @vindex diff-switches | |
2978 | The command @kbd{M-x diff} compares two files, displaying the | |
0cf729ce RS |
2979 | differences in an Emacs buffer named @samp{*diff*}. It works by |
2980 | running the @code{diff} program, using options taken from the variable | |
2981 | @code{diff-switches}. The value of @code{diff-switches} should be a | |
2982 | string; the default is @code{"-c"} to specify a context diff. | |
6bf7aab6 | 2983 | |
6bf7aab6 DL |
2984 | @findex diff-backup |
2985 | The command @kbd{M-x diff-backup} compares a specified file with its most | |
2986 | recent backup. If you specify the name of a backup file, | |
2987 | @code{diff-backup} compares it with the source file that it is a backup | |
2988 | of. | |
2989 | ||
50a1bd4f RS |
2990 | @findex diff-goto-source |
2991 | @findex diff-mode | |
2992 | @cindex Diff mode | |
2993 | The @samp{*diff*} buffer uses Diff mode, which enables you to use | |
2994 | @kbd{C-x `} to visit successive changed locations in the two source | |
2995 | files, as in Compilation mode (@pxref{Compilation Mode}.) You can | |
2996 | also move to a particular hunk of changes and type @kbd{C-c C-c} | |
2997 | (@code{diff-goto-source}) to visit the corresponding source location. | |
2998 | ||
2999 | @cindex patches | |
3000 | Differences between versions of files are often distributed as | |
3001 | patches, which are the output from the @command{diff} program. You | |
3002 | can use Diff mode to operate on a patch by typing @kbd{M-x diff-mode}. | |
3003 | ||
6bf7aab6 | 3004 | @findex compare-windows |
ce08e7d4 RS |
3005 | The command @kbd{M-x compare-windows} compares the text in the |
3006 | current window with that in the next window. (For more information | |
3007 | about windows in Emacs, @ref{Windows}.) Comparison starts at point in | |
3008 | each window, after pushing each initial point value on the mark ring | |
3009 | in its respective buffer. Then it moves point forward in each window, | |
3010 | one character at a time, until it reaches characters that don't match. | |
3011 | Then the command exits. | |
3012 | ||
3013 | If point in the two windows is followed by non-matching text when | |
50a1bd4f RS |
3014 | the command starts, @kbd{M-x compare-windows} tries heuristically to |
3015 | advance up to matching text in the two windows, and then exits. So if | |
3016 | you use @kbd{M-x compare-windows} repeatedly, each time it either | |
3017 | skips one matching range or finds the start of another. | |
6bf7aab6 DL |
3018 | |
3019 | @vindex compare-ignore-case | |
3aff69e3 | 3020 | @vindex compare-ignore-whitespace |
6bf7aab6 DL |
3021 | With a numeric argument, @code{compare-windows} ignores changes in |
3022 | whitespace. If the variable @code{compare-ignore-case} is | |
3aff69e3 | 3023 | non-@code{nil}, the comparison ignores differences in case as well. |
a0554a40 | 3024 | If the variable @code{compare-ignore-whitespace} is non-@code{nil}, |
3aff69e3 RS |
3025 | @code{compare-windows} normally ignores changes in whitespace, and a |
3026 | prefix argument turns that off. | |
6bf7aab6 | 3027 | |
fa474484 DL |
3028 | @cindex Smerge mode |
3029 | @findex smerge-mode | |
3030 | @cindex failed merges | |
3031 | @cindex merges, failed | |
089d639f | 3032 | @cindex comparing 3 files (@code{diff3}) |
f02d86a3 RS |
3033 | You can use @kbd{M-x smerge-mode} to turn on Smerge mode, a minor |
3034 | mode for editing output from the @command{diff3} program. This is | |
3035 | typically the result of a failed merge from a version control system | |
3036 | ``update'' outside VC, due to conflicting changes to a file. Smerge | |
3037 | mode provides commands to resolve conflicts by selecting specific | |
3038 | changes. | |
3039 | ||
3040 | See also @ref{Emerge}, and @ref{Top,,, ediff, The Ediff Manual}, for | |
3041 | convenient facilities for merging two similar files. | |
6bf7aab6 DL |
3042 | |
3043 | @node Misc File Ops | |
3044 | @section Miscellaneous File Operations | |
3045 | ||
3046 | Emacs has commands for performing many other operations on files. | |
3047 | All operate on one file; they do not accept wildcard file names. | |
3048 | ||
3049 | @findex view-file | |
3050 | @cindex viewing | |
3051 | @cindex View mode | |
3052 | @cindex mode, View | |
3053 | @kbd{M-x view-file} allows you to scan or read a file by sequential | |
3054 | screenfuls. It reads a file name argument using the minibuffer. After | |
3055 | reading the file into an Emacs buffer, @code{view-file} displays the | |
3056 | beginning. You can then type @key{SPC} to scroll forward one windowful, | |
3057 | or @key{DEL} to scroll backward. Various other commands are provided | |
3058 | for moving around in the file, but none for changing it; type @kbd{?} | |
3059 | while viewing for a list of them. They are mostly the same as normal | |
3060 | Emacs cursor motion commands. To exit from viewing, type @kbd{q}. | |
2e3c33de | 3061 | The commands for viewing are defined by a special minor mode called View |
6bf7aab6 DL |
3062 | mode. |
3063 | ||
3064 | A related command, @kbd{M-x view-buffer}, views a buffer already present | |
3065 | in Emacs. @xref{Misc Buffer}. | |
3066 | ||
0cf729ce | 3067 | @kindex C-x i |
6bf7aab6 | 3068 | @findex insert-file |
0cf729ce RS |
3069 | @kbd{M-x insert-file} (also @kbd{C-x i}) inserts a copy of the |
3070 | contents of the specified file into the current buffer at point, | |
3071 | leaving point unchanged before the contents and the mark after them. | |
6bf7aab6 DL |
3072 | |
3073 | @findex write-region | |
3074 | @kbd{M-x write-region} is the inverse of @kbd{M-x insert-file}; it | |
3075 | copies the contents of the region into the specified file. @kbd{M-x | |
81a35977 RS |
3076 | append-to-file} adds the text of the region to the end of the |
3077 | specified file. @xref{Accumulating Text}. The variable | |
3078 | @code{write-region-inhibit-fsync} applies to these commands, as well | |
3079 | as saving files; see @ref{Customize Save}. | |
6bf7aab6 DL |
3080 | |
3081 | @findex delete-file | |
3082 | @cindex deletion (of files) | |
3083 | @kbd{M-x delete-file} deletes the specified file, like the @code{rm} | |
3084 | command in the shell. If you are deleting many files in one directory, it | |
3085 | may be more convenient to use Dired (@pxref{Dired}). | |
3086 | ||
3087 | @findex rename-file | |
3088 | @kbd{M-x rename-file} reads two file names @var{old} and @var{new} using | |
0cf729ce | 3089 | the minibuffer, then renames file @var{old} as @var{new}. If the file name |
6bf7aab6 DL |
3090 | @var{new} already exists, you must confirm with @kbd{yes} or renaming is not |
3091 | done; this is because renaming causes the old meaning of the name @var{new} | |
3092 | to be lost. If @var{old} and @var{new} are on different file systems, the | |
3093 | file @var{old} is copied and deleted. | |
3094 | ||
3aff69e3 RS |
3095 | If the argument @var{new} is just a directory name, the real new |
3096 | name is in that directory, with the same non-directory component as | |
3097 | @var{old}. For example, @kbd{M-x rename-file RET ~/foo RET /tmp RET} | |
3098 | renames @file{~/foo} to @file{/tmp/foo}. The same rule applies to all | |
3099 | the remaining commands in this section. All of them ask for | |
3100 | confirmation when the new file name already exists, too. | |
3101 | ||
6bf7aab6 | 3102 | @findex add-name-to-file |
0cf729ce | 3103 | @cindex hard links (creation) |
6bf7aab6 DL |
3104 | The similar command @kbd{M-x add-name-to-file} is used to add an |
3105 | additional name to an existing file without removing its old name. | |
0cf729ce | 3106 | The new name is created as a ``hard link'' to the existing file. |
6bf7aab6 | 3107 | The new name must belong on the same file system that the file is on. |
3aff69e3 | 3108 | On MS-Windows, this command works only if the file resides in an NTFS |
40c56a36 | 3109 | file system. On MS-DOS, it works by copying the file. |
6bf7aab6 DL |
3110 | |
3111 | @findex copy-file | |
3112 | @cindex copying files | |
3aff69e3 RS |
3113 | @kbd{M-x copy-file} reads the file @var{old} and writes a new file |
3114 | named @var{new} with the same contents. | |
6bf7aab6 DL |
3115 | |
3116 | @findex make-symbolic-link | |
f0725a6a | 3117 | @cindex symbolic links (creation) |
6bf7aab6 | 3118 | @kbd{M-x make-symbolic-link} reads two file names @var{target} and |
3aff69e3 RS |
3119 | @var{linkname}, then creates a symbolic link named @var{linkname}, |
3120 | which points at @var{target}. The effect is that future attempts to | |
3121 | open file @var{linkname} will refer to whatever file is named | |
3122 | @var{target} at the time the opening is done, or will get an error if | |
3123 | the name @var{target} is nonexistent at that time. This command does | |
3124 | not expand the argument @var{target}, so that it allows you to specify | |
3125 | a relative name as the target of the link. | |
3126 | ||
3127 | Not all systems support symbolic links; on systems that don't | |
3128 | support them, this command is not defined. | |
6bf7aab6 DL |
3129 | |
3130 | @node Compressed Files | |
3131 | @section Accessing Compressed Files | |
3132 | @cindex compression | |
3133 | @cindex uncompression | |
3134 | @cindex Auto Compression mode | |
3135 | @cindex mode, Auto Compression | |
3136 | @pindex gzip | |
3137 | ||
2bdeaecc | 3138 | Emacs automatically uncompresses compressed files when you visit |
158a07a8 | 3139 | them, and automatically recompresses them if you alter them and save |
2bdeaecc RS |
3140 | them. Emacs recognizes compressed files by their file names. File |
3141 | names ending in @samp{.gz} indicate a file compressed with | |
6bf7aab6 DL |
3142 | @code{gzip}. Other endings indicate other compression programs. |
3143 | ||
3144 | Automatic uncompression and compression apply to all the operations in | |
3145 | which Emacs uses the contents of a file. This includes visiting it, | |
3146 | saving it, inserting its contents into a buffer, loading it, and byte | |
3147 | compiling it. | |
3148 | ||
2bdeaecc RS |
3149 | @findex auto-compression-mode |
3150 | @vindex auto-compression-mode | |
3151 | To disable this feature, type the command @kbd{M-x | |
3152 | auto-compression-mode}. You can disenable it permanently by | |
3153 | customizing the variable @code{auto-compression-mode}. | |
3154 | ||
259a88ca DL |
3155 | @node File Archives |
3156 | @section File Archives | |
3157 | @cindex mode, tar | |
3158 | @cindex Tar mode | |
089d639f | 3159 | @cindex file archives |
259a88ca | 3160 | |
f02d86a3 RS |
3161 | A file whose name ends in @samp{.tar} is normally an @dfn{archive} |
3162 | made by the @code{tar} program. Emacs views these files in a special | |
3163 | mode called Tar mode which provides a Dired-like list of the contents | |
3164 | (@pxref{Dired}). You can move around through the list just as you | |
3165 | would in Dired, and visit the subfiles contained in the archive. | |
3166 | However, not all Dired commands are available in Tar mode. | |
3167 | ||
50a1bd4f | 3168 | If Auto Compression mode is enabled (@pxref{Compressed Files}), then |
f02d86a3 RS |
3169 | Tar mode is used also for compressed archives---files with extensions |
3170 | @samp{.tgz}, @code{.tar.Z} and @code{.tar.gz}. | |
259a88ca | 3171 | |
7d5e745e | 3172 | The keys @kbd{e}, @kbd{f} and @key{RET} all extract a component file |
50a1bd4f RS |
3173 | into its own buffer. You can edit it there, and if you save the |
3174 | buffer, the edited version will replace the version in the Tar buffer. | |
3175 | @kbd{v} extracts a file into a buffer in View mode. @kbd{o} extracts | |
3176 | the file and displays it in another window, so you could edit the file | |
3177 | and operate on the archive simultaneously. @kbd{d} marks a file for | |
366f22ff EZ |
3178 | deletion when you later use @kbd{x}, and @kbd{u} unmarks a file, as in |
3179 | Dired. @kbd{C} copies a file from the archive to disk and @kbd{R} | |
50a1bd4f RS |
3180 | renames a file within the archive. @kbd{g} reverts the buffer from |
3181 | the archive on disk. | |
366f22ff EZ |
3182 | |
3183 | The keys @kbd{M}, @kbd{G}, and @kbd{O} change the file's permission | |
3184 | bits, group, and owner, respectively. | |
3185 | ||
3186 | If your display supports colors and the mouse, moving the mouse | |
3187 | pointer across a file name highlights that file name, indicating that | |
3188 | you can click on it. Clicking @kbd{Mouse-2} on the highlighted file | |
3189 | name extracts the file into a buffer and displays that buffer. | |
3190 | ||
3191 | Saving the Tar buffer writes a new version of the archive to disk with | |
259a88ca DL |
3192 | the changes you made to the components. |
3193 | ||
f02d86a3 RS |
3194 | You don't need the @code{tar} program to use Tar mode---Emacs reads |
3195 | the archives directly. However, accessing compressed archives | |
3196 | requires the appropriate uncompression program. | |
fa474484 | 3197 | |
366f22ff EZ |
3198 | @cindex Archive mode |
3199 | @cindex mode, archive | |
259a88ca DL |
3200 | @cindex @code{arc} |
3201 | @cindex @code{jar} | |
3202 | @cindex @code{zip} | |
3203 | @cindex @code{lzh} | |
3204 | @cindex @code{zoo} | |
259a88ca DL |
3205 | @pindex arc |
3206 | @pindex jar | |
3207 | @pindex zip | |
3208 | @pindex lzh | |
3209 | @pindex zoo | |
3210 | @cindex Java class archives | |
366f22ff EZ |
3211 | @cindex unzip archives |
3212 | A separate but similar Archive mode is used for archives produced by | |
f02d86a3 RS |
3213 | the programs @code{arc}, @code{jar}, @code{lzh}, @code{zip}, and |
3214 | @code{zoo}, which have extensions corresponding to the program names. | |
366f22ff | 3215 | |
d0960fb3 | 3216 | The key bindings of Archive mode are similar to those in Tar mode, |
f02d86a3 | 3217 | with the addition of the @kbd{m} key which marks a file for subsequent |
366f22ff | 3218 | operations, and @kbd{M-@key{DEL}} which unmarks all the marked files. |
f02d86a3 RS |
3219 | Also, the @kbd{a} key toggles the display of detailed file |
3220 | information, for those archive types where it won't fit in a single | |
3221 | line. Operations such as renaming a subfile, or changing its mode or | |
3222 | owner, are supported only for some of the archive formats. | |
366f22ff | 3223 | |
f02d86a3 RS |
3224 | Unlike Tar mode, Archive mode runs the archiving program to unpack |
3225 | and repack archives. Details of the program names and their options | |
3226 | can be set in the @samp{Archive} Customize group. However, you don't | |
d3ff0a57 RS |
3227 | need these programs to look at the archive table of contents, only to |
3228 | extract or manipulate the subfiles in the archive. | |
259a88ca | 3229 | |
6bf7aab6 DL |
3230 | @node Remote Files |
3231 | @section Remote Files | |
3232 | ||
63e889df | 3233 | @cindex Tramp |
6bf7aab6 DL |
3234 | @cindex FTP |
3235 | @cindex remote file access | |
83fa16cf KG |
3236 | You can refer to files on other machines using a special file name |
3237 | syntax: | |
6bf7aab6 DL |
3238 | |
3239 | @example | |
3240 | @group | |
3241 | /@var{host}:@var{filename} | |
3242 | /@var{user}@@@var{host}:@var{filename} | |
4f36dd62 | 3243 | /@var{user}@@@var{host}#@var{port}:@var{filename} |
83fa16cf KG |
3244 | /@var{method}:@var{user}@@@var{host}:@var{filename} |
3245 | /@var{method}:@var{user}@@@var{host}#@var{port}:@var{filename} | |
6bf7aab6 DL |
3246 | @end group |
3247 | @end example | |
3248 | ||
3249 | @noindent | |
4a10556b RS |
3250 | To carry out this request, Emacs uses either the FTP program or a |
3251 | remote-login program such as @command{ssh}, @command{rlogin}, or | |
3252 | @command{telnet}. You can always specify in the file name which | |
3253 | method to use---for example, | |
ec6a646a | 3254 | @file{/ftp:@var{user}@@@var{host}:@var{filename}} uses FTP, whereas |
30f75e62 | 3255 | @file{/ssh:@var{user}@@@var{host}:@var{filename}} uses @command{ssh}. |
4a10556b RS |
3256 | When you don't specify a method in the file name, Emacs chooses |
3257 | the method as follows: | |
83fa16cf KG |
3258 | |
3259 | @enumerate | |
3260 | @item | |
4a10556b RS |
3261 | If the host name starts with @samp{ftp.} (with dot), then Emacs uses |
3262 | FTP. | |
83fa16cf | 3263 | @item |
4a10556b RS |
3264 | If the user name is @samp{ftp} or @samp{anonymous}, then Emacs uses |
3265 | FTP. | |
83fa16cf | 3266 | @item |
4a10556b | 3267 | Otherwise, Emacs uses @command{ssh}. |
83fa16cf | 3268 | @end enumerate |
63e889df KG |
3269 | |
3270 | @noindent | |
83fa16cf KG |
3271 | Remote file access through FTP is handled by the Ange-FTP package, which |
3272 | is documented in the following. Remote file access through the other | |
3273 | methods is handled by the Tramp package, which has its own manual. | |
3274 | @xref{Top, The Tramp Manual,, tramp, The Tramp Manual}. | |
3275 | ||
3276 | When the Ange-FTP package is used, Emacs logs in through FTP using your | |
3277 | user name or the name @var{user}. It may ask you for a password from | |
3278 | time to time; this is used for logging in on @var{host}. The form using | |
3279 | @var{port} allows you to access servers running on a non-default TCP | |
3280 | port. | |
63e889df | 3281 | |
436b2c06 EZ |
3282 | @cindex backups for remote files |
3283 | @vindex ange-ftp-make-backup-files | |
3284 | If you want to disable backups for remote files, set the variable | |
3285 | @code{ange-ftp-make-backup-files} to @code{nil}. | |
3286 | ||
5a2ce5f5 GM |
3287 | By default, the auto-save files (@pxref{Auto Save Files}) for remote |
3288 | files are made in the temporary file directory on the local machine. | |
3289 | This is achieved using the variable @code{auto-save-file-name-transforms}. | |
3290 | ||
6bf7aab6 DL |
3291 | @cindex ange-ftp |
3292 | @vindex ange-ftp-default-user | |
436b2c06 | 3293 | @cindex user name for remote file access |
6bf7aab6 DL |
3294 | Normally, if you do not specify a user name in a remote file name, |
3295 | that means to use your own user name. But if you set the variable | |
3296 | @code{ange-ftp-default-user} to a string, that string is used instead. | |
6bf7aab6 | 3297 | |
436b2c06 EZ |
3298 | @cindex anonymous FTP |
3299 | @vindex ange-ftp-generate-anonymous-password | |
3300 | To visit files accessible by anonymous FTP, you use special user | |
697e2b99 RS |
3301 | names @samp{anonymous} or @samp{ftp}. Passwords for these user names |
3302 | are handled specially. The variable | |
436b2c06 EZ |
3303 | @code{ange-ftp-generate-anonymous-password} controls what happens: if |
3304 | the value of this variable is a string, then that string is used as | |
3305 | the password; if non-@code{nil} (the default), then the value of | |
50a1bd4f RS |
3306 | @code{user-mail-address} is used; if @code{nil}, then Emacs prompts |
3307 | you for a password as usual. | |
436b2c06 EZ |
3308 | |
3309 | @cindex firewall, and accessing remote files | |
3310 | @cindex gateway, and remote file access with @code{ange-ftp} | |
3311 | @vindex ange-ftp-smart-gateway | |
3312 | @vindex ange-ftp-gateway-host | |
3313 | Sometimes you may be unable to access files on a remote machine | |
f02d86a3 RS |
3314 | because a @dfn{firewall} in between blocks the connection for security |
3315 | reasons. If you can log in on a @dfn{gateway} machine from which the | |
3316 | target files @emph{are} accessible, and whose FTP server supports | |
3317 | gatewaying features, you can still use remote file names; all you have | |
3318 | to do is specify the name of the gateway machine by setting the | |
3319 | variable @code{ange-ftp-gateway-host}, and set | |
3320 | @code{ange-ftp-smart-gateway} to @code{t}. Otherwise you may be able | |
3321 | to make remote file names work, but the procedure is complex. You can | |
3322 | read the instructions by typing @kbd{M-x finder-commentary @key{RET} | |
3323 | ange-ftp @key{RET}}. | |
436b2c06 | 3324 | |
6bf7aab6 | 3325 | @vindex file-name-handler-alist |
f02d86a3 | 3326 | @cindex disabling remote files |
4f36dd62 | 3327 | You can entirely turn off the FTP file name feature by removing the |
d3ff0a57 RS |
3328 | entries @code{ange-ftp-completion-hook-function} and |
3329 | @code{ange-ftp-hook-function} from the variable | |
7ed32bd8 DL |
3330 | @code{file-name-handler-alist}. You can turn off the feature in |
3331 | individual cases by quoting the file name with @samp{/:} (@pxref{Quoted | |
3332 | File Names}). | |
6bf7aab6 DL |
3333 | |
3334 | @node Quoted File Names | |
3335 | @section Quoted File Names | |
3336 | ||
3337 | @cindex quoting file names | |
7dc24a36 | 3338 | @cindex file names, quote special characters |
6bf7aab6 DL |
3339 | You can @dfn{quote} an absolute file name to prevent special |
3340 | characters and syntax in it from having their special effects. | |
3341 | The way to do this is to add @samp{/:} at the beginning. | |
3342 | ||
3343 | For example, you can quote a local file name which appears remote, to | |
3344 | prevent it from being treated as a remote file name. Thus, if you have | |
3345 | a directory named @file{/foo:} and a file named @file{bar} in it, you | |
3346 | can refer to that file in Emacs as @samp{/:/foo:/bar}. | |
3347 | ||
3348 | @samp{/:} can also prevent @samp{~} from being treated as a special | |
3349 | character for a user's home directory. For example, @file{/:/tmp/~hack} | |
3350 | refers to a file whose name is @file{~hack} in directory @file{/tmp}. | |
3351 | ||
e643ceae RS |
3352 | Quoting with @samp{/:} is also a way to enter in the minibuffer a |
3353 | file name that contains @samp{$}. In order for this to work, the | |
3354 | @samp{/:} must be at the beginning of the minibuffer contents. (You | |
d41d5dd4 | 3355 | can also double each @samp{$}; see @ref{File Names with $}.) |
6bf7aab6 DL |
3356 | |
3357 | You can also quote wildcard characters with @samp{/:}, for visiting. | |
e643ceae RS |
3358 | For example, @file{/:/tmp/foo*bar} visits the file |
3359 | @file{/tmp/foo*bar}. | |
3360 | ||
3361 | Another method of getting the same result is to enter | |
3362 | @file{/tmp/foo[*]bar}, which is a wildcard specification that matches | |
3363 | only @file{/tmp/foo*bar}. However, in many cases there is no need to | |
3364 | quote the wildcard characters because even unquoted they give the | |
3365 | right result. For example, if the only file name in @file{/tmp} that | |
3366 | starts with @samp{foo} and ends with @samp{bar} is @file{foo*bar}, | |
3367 | then specifying @file{/tmp/foo*bar} will visit only | |
3368 | @file{/tmp/foo*bar}. | |
9a98ef18 | 3369 | |
f02d86a3 RS |
3370 | @node File Name Cache |
3371 | @section File Name Cache | |
3372 | ||
3373 | @cindex file name caching | |
3374 | @cindex cache of file names | |
3375 | @pindex find | |
3376 | @kindex C-@key{TAB} | |
3377 | @findex file-cache-minibuffer-complete | |
3378 | You can use the @dfn{file name cache} to make it easy to locate a | |
3379 | file by name, without having to remember exactly where it is located. | |
3380 | When typing a file name in the minibuffer, @kbd{C-@key{tab}} | |
3381 | (@code{file-cache-minibuffer-complete}) completes it using the file | |
3382 | name cache. If you repeat @kbd{C-@key{tab}}, that cycles through the | |
3383 | possible completions of what you had originally typed. Note that the | |
3384 | @kbd{C-@key{tab}} character cannot be typed on most text-only | |
3385 | terminals. | |
3386 | ||
3387 | The file name cache does not fill up automatically. Instead, you | |
3388 | load file names into the cache using these commands: | |
9a98ef18 | 3389 | |
f02d86a3 | 3390 | @findex file-cache-add-directory |
fa474484 | 3391 | @table @kbd |
fa474484 | 3392 | @item M-x file-cache-add-directory @key{RET} @var{directory} @key{RET} |
f02d86a3 RS |
3393 | Add each file name in @var{directory} to the file name cache. |
3394 | @item M-x file-cache-add-directory-using-find @key{RET} @var{directory} @key{RET} | |
3395 | Add each file name in @var{directory} and all of its nested | |
3396 | subdirectories to the file name cache. | |
3397 | @item M-x file-cache-add-directory-using-locate @key{RET} @var{directory} @key{RET} | |
3398 | Add each file name in @var{directory} and all of its nested | |
3399 | subdirectories to the file name cache, using @command{locate} to find | |
3400 | them all. | |
3401 | @item M-x file-cache-add-directory-list @key{RET} @var{variable} @key{RET} | |
3402 | Add each file name in each directory listed in @var{variable} | |
3403 | to the file name cache. @var{variable} should be a Lisp variable | |
3404 | such as @code{load-path} or @code{exec-path}, whose value is a list | |
3405 | of directory names. | |
3406 | @item M-x file-cache-clear-cache @key{RET} | |
3407 | Clear the cache; that is, remove all file names from it. | |
fa474484 | 3408 | @end table |
9a98ef18 | 3409 | |
f02d86a3 RS |
3410 | @node File Conveniences |
3411 | @section Convenience Features for Finding Files | |
fa474484 | 3412 | |
30b1dff1 RS |
3413 | In this section, we introduce some convenient facilities for finding |
3414 | recently-opened files, reading file names from a buffer, and viewing | |
3415 | image files. | |
3416 | ||
fa474484 DL |
3417 | @findex recentf-mode |
3418 | @vindex recentf-mode | |
3419 | @findex recentf-save-list | |
3420 | @findex recentf-edit-list | |
f02d86a3 | 3421 | If you enable Recentf mode, with @kbd{M-x recentf-mode}, the |
d3ff0a57 | 3422 | @samp{File} menu includes a submenu containing a list of recently |
f02d86a3 | 3423 | opened files. @kbd{M-x recentf-save-list} saves the current |
d3ff0a57 RS |
3424 | @code{recent-file-list} to a file, and @kbd{M-x recentf-edit-list} |
3425 | edits it. | |
0d7a07f3 | 3426 | |
f02d86a3 RS |
3427 | The @kbd{M-x ffap} command generalizes @code{find-file} with more |
3428 | powerful heuristic defaults (@pxref{FFAP}), often based on the text at | |
3429 | point. Partial Completion mode offers other features extending | |
3430 | @code{find-file}, which can be used with @code{ffap}. | |
3431 | @xref{Completion Options}. | |
ab5796a9 | 3432 | |
9bc727cd RS |
3433 | @findex image-mode |
3434 | @findex image-toggle-display | |
3435 | @cindex images, viewing | |
3436 | Visiting image files automatically selects Image mode. This major | |
3437 | mode allows you to toggle between displaying the file as an image in | |
3438 | the Emacs buffer, and displaying its underlying text representation, | |
3439 | using the command @kbd{C-c C-c} (@code{image-toggle-display}). This | |
3440 | works only when Emacs can display the specific image type. | |
3441 | ||
30b1dff1 RS |
3442 | @findex thumbs-mode |
3443 | @findex mode, thumbs | |
3444 | Thumbs mode is a major mode for viewing directories containing many | |
3445 | image files. To use it, type @kbd{M-x thumbs} and specify the | |
3446 | directory to view. The images in that directory will be displayed in | |
3447 | a @samp{Thumbs} buffer as @dfn{thumbnails}; type @kbd{RET} on a | |
3448 | thumbnail to view the full-size image. Thumbs mode requires the | |
3449 | @file{convert} program, which is part of the ImageMagick software | |
3450 | package. | |
3451 | ||
9bc727cd RS |
3452 | @node Filesets |
3453 | @section Filesets | |
3454 | @cindex filesets | |
3455 | ||
3456 | @findex filesets-init | |
3457 | If you regularly edit a certain group of files, you can define them | |
3458 | as a @dfn{fileset}. This lets you perform certain operations, such as | |
3459 | visiting, @code{query-replace}, and shell commands on all the files | |
3460 | at once. To make use of filesets, you must first add the expression | |
3461 | @code{(filesets-init)} to your @file{.emacs} file (@pxref{Init File}). | |
3462 | This adds a @samp{Filesets} menu to the menu bar. | |
3463 | ||
3464 | @findex filesets-add-buffer | |
3465 | @findex filesets-remove-buffer | |
50a1bd4f | 3466 | The simplest way to define a fileset is by adding files to it one |
9bc727cd RS |
3467 | at a time. To add a file to fileset @var{name}, visit the file and |
3468 | type @kbd{M-x filesets-add-buffer @kbd{RET} @var{name} @kbd{RET}}. If | |
3469 | there is no fileset @var{name}, this creates a new one, which | |
3470 | initially creates only the current file. The command @kbd{M-x | |
3471 | filesets-remove-buffer} removes the current file from a fileset. | |
3472 | ||
3473 | You can also edit the list of filesets directly, with @kbd{M-x | |
3474 | filesets-edit} (or by choosing @samp{Edit Filesets} from the | |
3475 | @samp{Filesets} menu). The editing is performed in a Customize buffer | |
3476 | (@pxref{Easy Customization}). Filesets need not be a simple list of | |
3477 | files---you can also define filesets using regular expression matching | |
3478 | file names. Some examples of these more complicated filesets are | |
3479 | shown in the Customize buffer. Remember to select @samp{Save for | |
3480 | future sessions} if you want to use the same filesets in future Emacs | |
3481 | sessions. | |
3482 | ||
3483 | You can use the command @kbd{M-x filesets-open} to visit all the | |
3484 | files in a fileset, and @kbd{M-x filesets-close} to close them. Use | |
3485 | @kbd{M-x filesets-run-cmd} to run a shell command on all the files in | |
3486 | a fileset. These commands are also available from the @samp{Filesets} | |
3487 | menu, where each existing fileset is represented by a submenu. | |
3488 | ||
ab5796a9 MB |
3489 | @ignore |
3490 | arch-tag: 768d32cb-e15a-4cc1-b7bf-62c00ee12250 | |
3491 | @end ignore |