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6bf7aab6 | 1 | @c This is part of the Emacs manual. |
259a88ca | 2 | @c Copyright (C) 1985,86,87,93,94,95,97,99, 2000 Free Software Foundation, Inc. |
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3 | @c See file emacs.texi for copying conditions. |
4 | @node Files, Buffers, Fixit, Top | |
5 | @chapter File Handling | |
6 | @cindex files | |
7 | ||
8 | The operating system stores data permanently in named @dfn{files}. So | |
9 | most of the text you edit with Emacs comes from a file and is ultimately | |
10 | stored in a file. | |
11 | ||
12 | To edit a file, you must tell Emacs to read the file and prepare a | |
13 | buffer containing a copy of the file's text. This is called | |
14 | @dfn{visiting} the file. Editing commands apply directly to text in the | |
15 | buffer; that is, to the copy inside Emacs. Your changes appear in the | |
16 | file itself only when you @dfn{save} the buffer back into the file. | |
17 | ||
18 | In addition to visiting and saving files, Emacs can delete, copy, | |
19 | rename, and append to files, keep multiple versions of them, and operate | |
20 | on file directories. | |
21 | ||
22 | @menu | |
23 | * File Names:: How to type and edit file-name arguments. | |
24 | * Visiting:: Visiting a file prepares Emacs to edit the file. | |
25 | * Saving:: Saving makes your changes permanent. | |
26 | * Reverting:: Reverting cancels all the changes not saved. | |
27 | * Auto Save:: Auto Save periodically protects against loss of data. | |
28 | * File Aliases:: Handling multiple names for one file. | |
29 | * Version Control:: Version control systems (RCS, CVS and SCCS). | |
30 | * Directories:: Creating, deleting, and listing file directories. | |
31 | * Comparing Files:: Finding where two files differ. | |
32 | * Misc File Ops:: Other things you can do on files. | |
33 | * Compressed Files:: Accessing compressed files. | |
259a88ca | 34 | * File Archives:: Operating on tar, zip, jar etc. archive files. |
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35 | * Remote Files:: Accessing files on other sites. |
36 | * Quoted File Names:: Quoting special characters in file names. | |
37 | @end menu | |
38 | ||
39 | @node File Names | |
40 | @section File Names | |
41 | @cindex file names | |
42 | ||
43 | Most Emacs commands that operate on a file require you to specify the | |
44 | file name. (Saving and reverting are exceptions; the buffer knows which | |
45 | file name to use for them.) You enter the file name using the | |
46 | minibuffer (@pxref{Minibuffer}). @dfn{Completion} is available, to make | |
47 | it easier to specify long file names. @xref{Completion}. | |
48 | ||
49 | For most operations, there is a @dfn{default file name} which is used | |
50 | if you type just @key{RET} to enter an empty argument. Normally the | |
51 | default file name is the name of the file visited in the current buffer; | |
52 | this makes it easy to operate on that file with any of the Emacs file | |
53 | commands. | |
54 | ||
55 | @vindex default-directory | |
56 | Each buffer has a default directory, normally the same as the | |
57 | directory of the file visited in that buffer. When you enter a file | |
58 | name without a directory, the default directory is used. If you specify | |
59 | a directory in a relative fashion, with a name that does not start with | |
60 | a slash, it is interpreted with respect to the default directory. The | |
61 | default directory is kept in the variable @code{default-directory}, | |
62 | which has a separate value in every buffer. | |
63 | ||
64 | For example, if the default file name is @file{/u/rms/gnu/gnu.tasks} then | |
65 | the default directory is @file{/u/rms/gnu/}. If you type just @samp{foo}, | |
66 | which does not specify a directory, it is short for @file{/u/rms/gnu/foo}. | |
67 | @samp{../.login} would stand for @file{/u/rms/.login}. @samp{new/foo} | |
68 | would stand for the file name @file{/u/rms/gnu/new/foo}. | |
69 | ||
70 | @findex cd | |
71 | @findex pwd | |
72 | The command @kbd{M-x pwd} prints the current buffer's default | |
73 | directory, and the command @kbd{M-x cd} sets it (to a value read using | |
74 | the minibuffer). A buffer's default directory changes only when the | |
75 | @code{cd} command is used. A file-visiting buffer's default directory | |
76 | is initialized to the directory of the file that is visited there. If | |
77 | you create a buffer with @kbd{C-x b}, its default directory is copied | |
78 | from that of the buffer that was current at the time. | |
79 | ||
80 | @vindex insert-default-directory | |
81 | The default directory actually appears in the minibuffer when the | |
82 | minibuffer becomes active to read a file name. This serves two | |
83 | purposes: it @emph{shows} you what the default is, so that you can type | |
84 | a relative file name and know with certainty what it will mean, and it | |
85 | allows you to @emph{edit} the default to specify a different directory. | |
86 | This insertion of the default directory is inhibited if the variable | |
87 | @code{insert-default-directory} is set to @code{nil}. | |
88 | ||
89 | Note that it is legitimate to type an absolute file name after you | |
90 | enter the minibuffer, ignoring the presence of the default directory | |
91 | name as part of the text. The final minibuffer contents may look | |
92 | invalid, but that is not so. For example, if the minibuffer starts out | |
93 | with @samp{/usr/tmp/} and you add @samp{/x1/rms/foo}, you get | |
94 | @samp{/usr/tmp//x1/rms/foo}; but Emacs ignores everything through the | |
95 | first slash in the double slash; the result is @samp{/x1/rms/foo}. | |
96 | @xref{Minibuffer File}. | |
97 | ||
98 | @samp{$} in a file name is used to substitute environment variables. | |
99 | For example, if you have used the shell command @samp{export | |
100 | FOO=rms/hacks} to set up an environment variable named @code{FOO}, then | |
101 | you can use @file{/u/$FOO/test.c} or @file{/u/$@{FOO@}/test.c} as an | |
102 | abbreviation for @file{/u/rms/hacks/test.c}. The environment variable | |
103 | name consists of all the alphanumeric characters after the @samp{$}; | |
104 | alternatively, it may be enclosed in braces after the @samp{$}. Note | |
105 | that shell commands to set environment variables affect Emacs only if | |
106 | done before Emacs is started. | |
107 | ||
108 | To access a file with @samp{$} in its name, type @samp{$$}. This pair | |
109 | is converted to a single @samp{$} at the same time as variable | |
110 | substitution is performed for single @samp{$}. Alternatively, quote the | |
111 | whole file name with @samp{/:} (@pxref{Quoted File Names}). | |
112 | ||
113 | @findex substitute-in-file-name | |
114 | The Lisp function that performs the substitution is called | |
115 | @code{substitute-in-file-name}. The substitution is performed only on | |
116 | file names read as such using the minibuffer. | |
117 | ||
118 | You can include non-ASCII characters in file names if you set the | |
119 | variable @code{file-name-coding-system} to a non-@code{nil} value. | |
120 | @xref{Specify Coding}. | |
121 | ||
122 | @node Visiting | |
123 | @section Visiting Files | |
124 | @cindex visiting files | |
125 | ||
126 | @c WideCommands | |
127 | @table @kbd | |
128 | @item C-x C-f | |
129 | Visit a file (@code{find-file}). | |
130 | @item C-x C-r | |
131 | Visit a file for viewing, without allowing changes to it | |
132 | (@code{find-file-read-only}). | |
133 | @item C-x C-v | |
134 | Visit a different file instead of the one visited last | |
135 | (@code{find-alternate-file}). | |
136 | @item C-x 4 f | |
137 | Visit a file, in another window (@code{find-file-other-window}). Don't | |
138 | alter what is displayed in the selected window. | |
139 | @item C-x 5 f | |
140 | Visit a file, in a new frame (@code{find-file-other-frame}). Don't | |
141 | alter what is displayed in the selected frame. | |
142 | @item M-x find-file-literally | |
143 | Visit a file with no conversion of the contents. | |
144 | @end table | |
145 | ||
146 | @cindex files, visiting and saving | |
147 | @cindex visiting files | |
148 | @cindex saving files | |
149 | @dfn{Visiting} a file means copying its contents into an Emacs buffer | |
150 | so you can edit them. Emacs makes a new buffer for each file that you | |
151 | visit. We say that this buffer is visiting the file that it was created | |
152 | to hold. Emacs constructs the buffer name from the file name by | |
153 | throwing away the directory, keeping just the name proper. For example, | |
154 | a file named @file{/usr/rms/emacs.tex} would get a buffer named | |
155 | @samp{emacs.tex}. If there is already a buffer with that name, a unique | |
156 | name is constructed by appending @samp{<2>}, @samp{<3>}, or so on, using | |
157 | the lowest number that makes a name that is not already in use. | |
158 | ||
159 | Each window's mode line shows the name of the buffer that is being displayed | |
160 | in that window, so you can always tell what buffer you are editing. | |
161 | ||
162 | The changes you make with editing commands are made in the Emacs | |
163 | buffer. They do not take effect in the file that you visited, or any | |
164 | place permanent, until you @dfn{save} the buffer. Saving the buffer | |
165 | means that Emacs writes the current contents of the buffer into its | |
166 | visited file. @xref{Saving}. | |
167 | ||
168 | @cindex modified (buffer) | |
169 | If a buffer contains changes that have not been saved, we say the | |
170 | buffer is @dfn{modified}. This is important because it implies that | |
171 | some changes will be lost if the buffer is not saved. The mode line | |
172 | displays two stars near the left margin to indicate that the buffer is | |
173 | modified. | |
174 | ||
175 | @kindex C-x C-f | |
176 | @findex find-file | |
177 | To visit a file, use the command @kbd{C-x C-f} (@code{find-file}). Follow | |
178 | the command with the name of the file you wish to visit, terminated by a | |
179 | @key{RET}. | |
180 | ||
181 | The file name is read using the minibuffer (@pxref{Minibuffer}), with | |
182 | defaulting and completion in the standard manner (@pxref{File Names}). | |
183 | While in the minibuffer, you can abort @kbd{C-x C-f} by typing @kbd{C-g}. | |
184 | ||
185 | Your confirmation that @kbd{C-x C-f} has completed successfully is the | |
186 | appearance of new text on the screen and a new buffer name in the mode | |
187 | line. If the specified file does not exist and could not be created, or | |
188 | cannot be read, then you get an error, with an error message displayed | |
189 | in the echo area. | |
190 | ||
191 | If you visit a file that is already in Emacs, @kbd{C-x C-f} does not make | |
192 | another copy. It selects the existing buffer containing that file. | |
193 | However, before doing so, it checks that the file itself has not changed | |
194 | since you visited or saved it last. If the file has changed, a warning | |
195 | message is printed. @xref{Interlocking,,Simultaneous Editing}. | |
196 | ||
197 | @cindex creating files | |
198 | What if you want to create a new file? Just visit it. Emacs prints | |
199 | @samp{(New File)} in the echo area, but in other respects behaves as if | |
200 | you had visited an existing empty file. If you make any changes and | |
201 | save them, the file is created. | |
202 | ||
203 | Emacs recognizes from the contents of a file which convention it uses | |
204 | to separate lines---newline (used on GNU/Linux and on Unix), | |
205 | carriage-return linefeed (used on Microsoft systems), or just | |
206 | carriage-return (used on the Macintosh)---and automatically converts the | |
207 | contents to the normal Emacs convention, which is that the newline | |
208 | character separates lines. This is a part of the general feature of | |
209 | coding system conversion (@pxref{Coding Systems}), and makes it possible | |
210 | to edit files imported from various different operating systems with | |
211 | equal convenience. If you change the text and save the file, Emacs | |
212 | performs the inverse conversion, changing newlines back into | |
213 | carriage-return linefeed or just carriage-return if appropriate. | |
214 | ||
215 | @vindex find-file-run-dired | |
216 | If the file you specify is actually a directory, @kbd{C-x C-f} invokes | |
217 | Dired, the Emacs directory browser, so that you can ``edit'' the contents | |
218 | of the directory (@pxref{Dired}). Dired is a convenient way to delete, | |
219 | look at, or operate on the files in the directory. However, if the | |
220 | variable @code{find-file-run-dired} is @code{nil}, then it is an error | |
221 | to try to visit a directory. | |
222 | ||
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223 | @cindex wildcard characters in file names |
224 | @vindex find-file-wildcards | |
225 | If the file name you specify contains @code{sh}-style wildcard | |
226 | characters, Emacs visits all the files that match it. @xref{Quoted File | |
227 | Names}, if you want to visit a file whose name actually contains | |
228 | wildcard characters. Wildcards comprise @samp{?}, @samp{*} and | |
229 | @samp{[@dots{}]} sequences. The wildcard feature can be disabled by | |
230 | customizing @code{find-file-wildcards}. | |
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231 | |
232 | If you visit a file that the operating system won't let you modify, | |
233 | Emacs makes the buffer read-only, so that you won't go ahead and make | |
234 | changes that you'll have trouble saving afterward. You can make the | |
235 | buffer writable with @kbd{C-x C-q} (@code{vc-toggle-read-only}). | |
236 | @xref{Misc Buffer}. | |
237 | ||
238 | @kindex C-x C-r | |
239 | @findex find-file-read-only | |
240 | Occasionally you might want to visit a file as read-only in order to | |
241 | protect yourself from entering changes accidentally; do so by visiting | |
242 | the file with the command @kbd{C-x C-r} (@code{find-file-read-only}). | |
243 | ||
244 | @kindex C-x C-v | |
245 | @findex find-alternate-file | |
246 | If you visit a nonexistent file unintentionally (because you typed the | |
247 | wrong file name), use the @kbd{C-x C-v} command | |
248 | (@code{find-alternate-file}) to visit the file you really wanted. | |
249 | @kbd{C-x C-v} is similar to @kbd{C-x C-f}, but it kills the current | |
250 | buffer (after first offering to save it if it is modified). When it | |
251 | reads the file name to visit, it inserts the entire default file name in | |
252 | the buffer, with point just after the directory part; this is convenient | |
253 | if you made a slight error in typing the name. | |
254 | ||
255 | If you find a file which exists but cannot be read, @kbd{C-x C-f} | |
256 | signals an error. | |
257 | ||
258 | @kindex C-x 4 f | |
259 | @findex find-file-other-window | |
260 | @kbd{C-x 4 f} (@code{find-file-other-window}) is like @kbd{C-x C-f} | |
261 | except that the buffer containing the specified file is selected in another | |
262 | window. The window that was selected before @kbd{C-x 4 f} continues to | |
263 | show the same buffer it was already showing. If this command is used when | |
264 | only one window is being displayed, that window is split in two, with one | |
265 | window showing the same buffer as before, and the other one showing the | |
266 | newly requested file. @xref{Windows}. | |
267 | ||
268 | @kindex C-x 5 f | |
269 | @findex find-file-other-frame | |
270 | @kbd{C-x 5 f} (@code{find-file-other-frame}) is similar, but opens a | |
271 | new frame, or makes visible any existing frame showing the file you | |
272 | seek. This feature is available only when you are using a window | |
273 | system. @xref{Frames}. | |
274 | ||
275 | @findex find-file-literally | |
276 | If you wish to edit a file as a sequence of characters with no special | |
277 | encoding or conversion, use the @kbd{M-x find-file-literally} command. | |
278 | It visits a file, like @kbd{C-x C-f}, but does not do format conversion | |
279 | (@pxref{Formatted Text}), character code conversion (@pxref{Coding | |
280 | Systems}), or automatic uncompression (@pxref{Compressed Files}). | |
281 | If you already have visited the same file in the usual (non-literal) | |
282 | manner, this command asks you whether to visit it literally instead. | |
283 | ||
284 | @vindex find-file-hooks | |
285 | @vindex find-file-not-found-hooks | |
286 | Two special hook variables allow extensions to modify the operation of | |
287 | visiting files. Visiting a file that does not exist runs the functions | |
288 | in the list @code{find-file-not-found-hooks}; this variable holds a list | |
289 | of functions, and the functions are called one by one (with no | |
290 | arguments) until one of them returns non-@code{nil}. This is not a | |
291 | normal hook, and the name ends in @samp{-hooks} rather than @samp{-hook} | |
292 | to indicate that fact. | |
293 | ||
294 | Any visiting of a file, whether extant or not, expects | |
295 | @code{find-file-hooks} to contain a list of functions, and calls them | |
296 | all, one by one, with no arguments. This variable is really a normal | |
297 | hook, but it has an abnormal name for historical compatibility. In the | |
298 | case of a nonexistent file, the @code{find-file-not-found-hooks} are run | |
299 | first. @xref{Hooks}. | |
300 | ||
301 | There are several ways to specify automatically the major mode for | |
302 | editing the file (@pxref{Choosing Modes}), and to specify local | |
303 | variables defined for that file (@pxref{File Variables}). | |
304 | ||
305 | @node Saving | |
306 | @section Saving Files | |
307 | ||
308 | @dfn{Saving} a buffer in Emacs means writing its contents back into the file | |
309 | that was visited in the buffer. | |
310 | ||
311 | @table @kbd | |
312 | @item C-x C-s | |
313 | Save the current buffer in its visited file (@code{save-buffer}). | |
314 | @item C-x s | |
315 | Save any or all buffers in their visited files (@code{save-some-buffers}). | |
316 | @item M-~ | |
317 | Forget that the current buffer has been changed (@code{not-modified}). | |
318 | @item C-x C-w | |
319 | Save the current buffer in a specified file (@code{write-file}). | |
320 | @item M-x set-visited-file-name | |
321 | Change file the name under which the current buffer will be saved. | |
322 | @end table | |
323 | ||
324 | @kindex C-x C-s | |
325 | @findex save-buffer | |
326 | When you wish to save the file and make your changes permanent, type | |
327 | @kbd{C-x C-s} (@code{save-buffer}). After saving is finished, @kbd{C-x C-s} | |
328 | displays a message like this: | |
329 | ||
330 | @example | |
331 | Wrote /u/rms/gnu/gnu.tasks | |
332 | @end example | |
333 | ||
334 | @noindent | |
335 | If the selected buffer is not modified (no changes have been made in it | |
336 | since the buffer was created or last saved), saving is not really done, | |
337 | because it would have no effect. Instead, @kbd{C-x C-s} displays a message | |
338 | like this in the echo area: | |
339 | ||
340 | @example | |
341 | (No changes need to be saved) | |
342 | @end example | |
343 | ||
344 | @kindex C-x s | |
345 | @findex save-some-buffers | |
346 | The command @kbd{C-x s} (@code{save-some-buffers}) offers to save any | |
347 | or all modified buffers. It asks you what to do with each buffer. The | |
348 | possible responses are analogous to those of @code{query-replace}: | |
349 | ||
350 | @table @kbd | |
351 | @item y | |
352 | Save this buffer and ask about the rest of the buffers. | |
353 | @item n | |
354 | Don't save this buffer, but ask about the rest of the buffers. | |
355 | @item ! | |
356 | Save this buffer and all the rest with no more questions. | |
357 | @c following generates acceptable underfull hbox | |
358 | @item @key{RET} | |
359 | Terminate @code{save-some-buffers} without any more saving. | |
360 | @item . | |
361 | Save this buffer, then exit @code{save-some-buffers} without even asking | |
362 | about other buffers. | |
363 | @item C-r | |
364 | View the buffer that you are currently being asked about. When you exit | |
365 | View mode, you get back to @code{save-some-buffers}, which asks the | |
366 | question again. | |
367 | @item C-h | |
368 | Display a help message about these options. | |
369 | @end table | |
370 | ||
371 | @kbd{C-x C-c}, the key sequence to exit Emacs, invokes | |
372 | @code{save-some-buffers} and therefore asks the same questions. | |
373 | ||
374 | @kindex M-~ | |
375 | @findex not-modified | |
376 | If you have changed a buffer but you do not want to save the changes, | |
377 | you should take some action to prevent it. Otherwise, each time you use | |
378 | @kbd{C-x s} or @kbd{C-x C-c}, you are liable to save this buffer by | |
379 | mistake. One thing you can do is type @kbd{M-~} (@code{not-modified}), | |
380 | which clears out the indication that the buffer is modified. If you do | |
381 | this, none of the save commands will believe that the buffer needs to be | |
382 | saved. (@samp{~} is often used as a mathematical symbol for `not'; thus | |
383 | @kbd{M-~} is `not', metafied.) You could also use | |
384 | @code{set-visited-file-name} (see below) to mark the buffer as visiting | |
385 | a different file name, one which is not in use for anything important. | |
386 | Alternatively, you can cancel all the changes made since the file was | |
387 | visited or saved, by reading the text from the file again. This is | |
388 | called @dfn{reverting}. @xref{Reverting}. You could also undo all the | |
389 | changes by repeating the undo command @kbd{C-x u} until you have undone | |
390 | all the changes; but reverting is easier. | |
391 | ||
392 | @findex set-visited-file-name | |
393 | @kbd{M-x set-visited-file-name} alters the name of the file that the | |
394 | current buffer is visiting. It reads the new file name using the | |
395 | minibuffer. Then it specifies the visited file name and changes the | |
396 | buffer name correspondingly (as long as the new name is not in use). | |
397 | @code{set-visited-file-name} does not save the buffer in the newly | |
398 | visited file; it just alters the records inside Emacs in case you do | |
399 | save later. It also marks the buffer as ``modified'' so that @kbd{C-x | |
400 | C-s} in that buffer @emph{will} save. | |
401 | ||
402 | @kindex C-x C-w | |
403 | @findex write-file | |
404 | If you wish to mark the buffer as visiting a different file and save it | |
405 | right away, use @kbd{C-x C-w} (@code{write-file}). It is precisely | |
406 | equivalent to @code{set-visited-file-name} followed by @kbd{C-x C-s}. | |
407 | @kbd{C-x C-s} used on a buffer that is not visiting a file has the | |
408 | same effect as @kbd{C-x C-w}; that is, it reads a file name, marks the | |
409 | buffer as visiting that file, and saves it there. The default file name in | |
410 | a buffer that is not visiting a file is made by combining the buffer name | |
411 | with the buffer's default directory. | |
412 | ||
413 | If the new file name implies a major mode, then @kbd{C-x C-w} switches | |
414 | to that major mode, in most cases. The command | |
415 | @code{set-visited-file-name} also does this. @xref{Choosing Modes}. | |
416 | ||
417 | If Emacs is about to save a file and sees that the date of the latest | |
418 | version on disk does not match what Emacs last read or wrote, Emacs | |
419 | notifies you of this fact, because it probably indicates a problem caused | |
420 | by simultaneous editing and requires your immediate attention. | |
421 | @xref{Interlocking,, Simultaneous Editing}. | |
422 | ||
423 | @vindex require-final-newline | |
424 | If the variable @code{require-final-newline} is non-@code{nil}, Emacs | |
425 | puts a newline at the end of any file that doesn't already end in one, | |
426 | every time a file is saved or written. The default is @code{nil}. | |
427 | ||
428 | @menu | |
429 | * Backup:: How Emacs saves the old version of your file. | |
430 | * Interlocking:: How Emacs protects against simultaneous editing | |
431 | of one file by two users. | |
432 | @end menu | |
433 | ||
434 | @node Backup | |
435 | @subsection Backup Files | |
436 | @cindex backup file | |
437 | @vindex make-backup-files | |
438 | @vindex vc-make-backup-files | |
439 | @vindex backup-enable-predicate | |
440 | ||
441 | On most operating systems, rewriting a file automatically destroys all | |
442 | record of what the file used to contain. Thus, saving a file from Emacs | |
443 | throws away the old contents of the file---or it would, except that | |
444 | Emacs carefully copies the old contents to another file, called the | |
445 | @dfn{backup} file, before actually saving. | |
446 | ||
447 | For most files, the variable @code{make-backup-files} determines | |
448 | whether to make backup files. On most operating systems, its default | |
449 | value is @code{t}, so that Emacs does write backup files. | |
450 | ||
451 | For files managed by a version control system (@pxref{Version | |
452 | Control}), the variable @code{vc-make-backup-files} determines whether | |
453 | to make backup files. By default, it is @code{nil}, since backup files | |
454 | are redundant when you store all the previous versions in a version | |
455 | control system. @xref{VC Workfile Handling}. | |
456 | ||
457 | The default value of the @code{backup-enable-predicate} variable | |
458 | prevents backup files being written for files in @file{/tmp}. | |
459 | ||
460 | At your option, Emacs can keep either a single backup file or a series of | |
461 | numbered backup files for each file that you edit. | |
462 | ||
463 | Emacs makes a backup for a file only the first time the file is saved | |
464 | from one buffer. No matter how many times you save a file, its backup file | |
465 | continues to contain the contents from before the file was visited. | |
466 | Normally this means that the backup file contains the contents from before | |
467 | the current editing session; however, if you kill the buffer and then visit | |
468 | the file again, a new backup file will be made by the next save. | |
469 | ||
470 | You can also explicitly request making another backup file from a | |
471 | buffer even though it has already been saved at least once. If you save | |
472 | the buffer with @kbd{C-u C-x C-s}, the version thus saved will be made | |
473 | into a backup file if you save the buffer again. @kbd{C-u C-u C-x C-s} | |
474 | saves the buffer, but first makes the previous file contents into a new | |
475 | backup file. @kbd{C-u C-u C-u C-x C-s} does both things: it makes a | |
476 | backup from the previous contents, and arranges to make another from the | |
477 | newly saved contents, if you save again. | |
478 | ||
479 | @menu | |
480 | * Names: Backup Names. How backup files are named; | |
481 | choosing single or numbered backup files. | |
482 | * Deletion: Backup Deletion. Emacs deletes excess numbered backups. | |
483 | * Copying: Backup Copying. Backups can be made by copying or renaming. | |
484 | @end menu | |
485 | ||
486 | @node Backup Names | |
487 | @subsubsection Single or Numbered Backups | |
488 | ||
489 | If you choose to have a single backup file (this is the default), | |
490 | the backup file's name is constructed by appending @samp{~} to the | |
491 | file name being edited; thus, the backup file for @file{eval.c} would | |
492 | be @file{eval.c~}. | |
493 | ||
494 | If you choose to have a series of numbered backup files, backup file | |
495 | names are made by appending @samp{.~}, the number, and another @samp{~} to | |
496 | the original file name. Thus, the backup files of @file{eval.c} would be | |
497 | called @file{eval.c.~1~}, @file{eval.c.~2~}, and so on, through names | |
498 | like @file{eval.c.~259~} and beyond. | |
499 | ||
500 | If protection stops you from writing backup files under the usual names, | |
501 | the backup file is written as @file{%backup%~} in your home directory. | |
502 | Only one such file can exist, so only the most recently made such backup is | |
503 | available. | |
504 | ||
505 | @vindex version-control | |
506 | The choice of single backup or numbered backups is controlled by the | |
507 | variable @code{version-control}. Its possible values are | |
508 | ||
509 | @table @code | |
510 | @item t | |
511 | Make numbered backups. | |
512 | @item nil | |
513 | Make numbered backups for files that have numbered backups already. | |
514 | Otherwise, make single backups. | |
515 | @item never | |
516 | Do not in any case make numbered backups; always make single backups. | |
517 | @end table | |
518 | ||
519 | @noindent | |
520 | You can set @code{version-control} locally in an individual buffer to | |
521 | control the making of backups for that buffer's file. For example, | |
522 | Rmail mode locally sets @code{version-control} to @code{never} to make sure | |
523 | that there is only one backup for an Rmail file. @xref{Locals}. | |
524 | ||
525 | @cindex @code{VERSION_CONTROL} environment variable | |
526 | If you set the environment variable @code{VERSION_CONTROL}, to tell | |
527 | various GNU utilities what to do with backup files, Emacs also obeys the | |
528 | environment variable by setting the Lisp variable @code{version-control} | |
529 | accordingly at startup. If the environment variable's value is @samp{t} | |
530 | or @samp{numbered}, then @code{version-control} becomes @code{t}; if the | |
531 | value is @samp{nil} or @samp{existing}, then @code{version-control} | |
532 | becomes @code{nil}; if it is @samp{never} or @samp{simple}, then | |
533 | @code{version-control} becomes @code{never}. | |
534 | ||
535 | @node Backup Deletion | |
536 | @subsubsection Automatic Deletion of Backups | |
537 | ||
538 | To prevent unlimited consumption of disk space, Emacs can delete numbered | |
539 | backup versions automatically. Generally Emacs keeps the first few backups | |
540 | and the latest few backups, deleting any in between. This happens every | |
541 | time a new backup is made. | |
542 | ||
543 | @vindex kept-old-versions | |
544 | @vindex kept-new-versions | |
545 | The two variables @code{kept-old-versions} and | |
546 | @code{kept-new-versions} control this deletion. Their values are, | |
547 | respectively the number of oldest (lowest-numbered) backups to keep and | |
548 | the number of newest (highest-numbered) ones to keep, each time a new | |
549 | backup is made. Recall that these values are used just after a new | |
550 | backup version is made; that newly made backup is included in the count | |
551 | in @code{kept-new-versions}. By default, both variables are 2. | |
552 | ||
553 | @vindex delete-old-versions | |
554 | If @code{delete-old-versions} is non-@code{nil}, the excess | |
555 | middle versions are deleted without a murmur. If it is @code{nil}, the | |
556 | default, then you are asked whether the excess middle versions should | |
557 | really be deleted. | |
558 | ||
559 | Dired's @kbd{.} (Period) command can also be used to delete old versions. | |
560 | @xref{Dired Deletion}. | |
561 | ||
562 | @node Backup Copying | |
563 | @subsubsection Copying vs.@: Renaming | |
564 | ||
565 | Backup files can be made by copying the old file or by renaming it. This | |
566 | makes a difference when the old file has multiple names. If the old file | |
567 | is renamed into the backup file, then the alternate names become names for | |
568 | the backup file. If the old file is copied instead, then the alternate | |
569 | names remain names for the file that you are editing, and the contents | |
570 | accessed by those names will be the new contents. | |
571 | ||
572 | The method of making a backup file may also affect the file's owner | |
573 | and group. If copying is used, these do not change. If renaming is used, | |
574 | you become the file's owner, and the file's group becomes the default | |
575 | (different operating systems have different defaults for the group). | |
576 | ||
577 | Having the owner change is usually a good idea, because then the owner | |
578 | always shows who last edited the file. Also, the owners of the backups | |
579 | show who produced those versions. Occasionally there is a file whose | |
580 | owner should not change; it is a good idea for such files to contain | |
581 | local variable lists to set @code{backup-by-copying-when-mismatch} | |
582 | locally (@pxref{File Variables}). | |
583 | ||
584 | @vindex backup-by-copying | |
585 | @vindex backup-by-copying-when-linked | |
586 | @vindex backup-by-copying-when-mismatch | |
587 | The choice of renaming or copying is controlled by three variables. | |
588 | Renaming is the default choice. If the variable | |
589 | @code{backup-by-copying} is non-@code{nil}, copying is used. Otherwise, | |
590 | if the variable @code{backup-by-copying-when-linked} is non-@code{nil}, | |
591 | then copying is used for files that have multiple names, but renaming | |
592 | may still be used when the file being edited has only one name. If the | |
593 | variable @code{backup-by-copying-when-mismatch} is non-@code{nil}, then | |
594 | copying is used if renaming would cause the file's owner or group to | |
595 | change. @code{backup-by-copying-when-mismatch} is @code{t} by default | |
596 | if you start Emacs as the superuser. | |
597 | ||
598 | When a file is managed with a version control system (@pxref{Version | |
599 | Control}), Emacs does not normally make backups in the usual way for | |
600 | that file. But check-in and check-out are similar in some ways to | |
601 | making backups. One unfortunate similarity is that these operations | |
602 | typically break hard links, disconnecting the file name you visited from | |
603 | any alternate names for the same file. This has nothing to do with | |
604 | Emacs---the version control system does it. | |
605 | ||
606 | @node Interlocking | |
607 | @subsection Protection against Simultaneous Editing | |
608 | ||
609 | @cindex file dates | |
610 | @cindex simultaneous editing | |
611 | Simultaneous editing occurs when two users visit the same file, both | |
612 | make changes, and then both save them. If nobody were informed that | |
613 | this was happening, whichever user saved first would later find that his | |
614 | changes were lost. | |
615 | ||
616 | On some systems, Emacs notices immediately when the second user starts | |
617 | to change the file, and issues an immediate warning. On all systems, | |
618 | Emacs checks when you save the file, and warns if you are about to | |
619 | overwrite another user's changes. You can prevent loss of the other | |
620 | user's work by taking the proper corrective action instead of saving the | |
621 | file. | |
622 | ||
623 | @findex ask-user-about-lock | |
624 | @cindex locking files | |
625 | When you make the first modification in an Emacs buffer that is | |
626 | visiting a file, Emacs records that the file is @dfn{locked} by you. | |
627 | (It does this by creating a symbolic link in the same directory with a | |
628 | different name.) Emacs removes the lock when you save the changes. The | |
629 | idea is that the file is locked whenever an Emacs buffer visiting it has | |
630 | unsaved changes. | |
631 | ||
632 | @cindex collision | |
633 | If you begin to modify the buffer while the visited file is locked by | |
634 | someone else, this constitutes a @dfn{collision}. When Emacs detects a | |
635 | collision, it asks you what to do, by calling the Lisp function | |
636 | @code{ask-user-about-lock}. You can redefine this function for the sake | |
637 | of customization. The standard definition of this function asks you a | |
638 | question and accepts three possible answers: | |
639 | ||
640 | @table @kbd | |
641 | @item s | |
642 | Steal the lock. Whoever was already changing the file loses the lock, | |
643 | and you gain the lock. | |
644 | @item p | |
645 | Proceed. Go ahead and edit the file despite its being locked by someone else. | |
646 | @item q | |
647 | Quit. This causes an error (@code{file-locked}) and the modification you | |
648 | were trying to make in the buffer does not actually take place. | |
649 | @end table | |
650 | ||
651 | Note that locking works on the basis of a file name; if a file has | |
652 | multiple names, Emacs does not realize that the two names are the same file | |
653 | and cannot prevent two users from editing it simultaneously under different | |
654 | names. However, basing locking on names means that Emacs can interlock the | |
655 | editing of new files that will not really exist until they are saved. | |
656 | ||
657 | Some systems are not configured to allow Emacs to make locks, and | |
658 | there are cases where lock files cannot be written. In these cases, | |
659 | Emacs cannot detect trouble in advance, but it still can detect the | |
660 | collision when you try to save a file and overwrite someone else's | |
661 | changes. | |
662 | ||
663 | If Emacs or the operating system crashes, this may leave behind lock | |
664 | files which are stale. So you may occasionally get warnings about | |
665 | spurious collisions. When you determine that the collision is spurious, | |
666 | just use @kbd{p} to tell Emacs to go ahead anyway. | |
667 | ||
668 | Every time Emacs saves a buffer, it first checks the last-modification | |
669 | date of the existing file on disk to verify that it has not changed since the | |
670 | file was last visited or saved. If the date does not match, it implies | |
671 | that changes were made in the file in some other way, and these changes are | |
672 | about to be lost if Emacs actually does save. To prevent this, Emacs | |
673 | prints a warning message and asks for confirmation before saving. | |
674 | Occasionally you will know why the file was changed and know that it does | |
675 | not matter; then you can answer @kbd{yes} and proceed. Otherwise, you should | |
676 | cancel the save with @kbd{C-g} and investigate the situation. | |
677 | ||
678 | The first thing you should do when notified that simultaneous editing | |
679 | has already taken place is to list the directory with @kbd{C-u C-x C-d} | |
680 | (@pxref{Directories}). This shows the file's current author. You | |
681 | should attempt to contact him to warn him not to continue editing. | |
682 | Often the next step is to save the contents of your Emacs buffer under a | |
683 | different name, and use @code{diff} to compare the two files.@refill | |
684 | ||
685 | @node Reverting | |
686 | @section Reverting a Buffer | |
687 | @findex revert-buffer | |
688 | @cindex drastic changes | |
689 | ||
690 | If you have made extensive changes to a file and then change your mind | |
691 | about them, you can get rid of them by reading in the previous version | |
692 | of the file. To do this, use @kbd{M-x revert-buffer}, which operates on | |
693 | the current buffer. Since reverting a buffer unintentionally could lose | |
694 | a lot of work, you must confirm this command with @kbd{yes}. | |
695 | ||
696 | @code{revert-buffer} keeps point at the same distance (measured in | |
697 | characters) from the beginning of the file. If the file was edited only | |
698 | slightly, you will be at approximately the same piece of text after | |
699 | reverting as before. If you have made drastic changes, the same value of | |
700 | point in the old file may address a totally different piece of text. | |
701 | ||
702 | Reverting marks the buffer as ``not modified'' until another change is | |
703 | made. | |
704 | ||
705 | Some kinds of buffers whose contents reflect data bases other than files, | |
706 | such as Dired buffers, can also be reverted. For them, reverting means | |
707 | recalculating their contents from the appropriate data base. Buffers | |
708 | created explicitly with @kbd{C-x b} cannot be reverted; @code{revert-buffer} | |
709 | reports an error when asked to do so. | |
710 | ||
711 | @vindex revert-without-query | |
712 | When you edit a file that changes automatically and frequently---for | |
713 | example, a log of output from a process that continues to run---it may be | |
714 | useful for Emacs to revert the file without querying you, whenever you | |
715 | visit the file again with @kbd{C-x C-f}. | |
716 | ||
717 | To request this behavior, set the variable @code{revert-without-query} | |
718 | to a list of regular expressions. When a file name matches one of these | |
719 | regular expressions, @code{find-file} and @code{revert-buffer} will | |
720 | revert it automatically if it has changed---provided the buffer itself | |
721 | is not modified. (If you have edited the text, it would be wrong to | |
722 | discard your changes.) | |
723 | ||
724 | @node Auto Save | |
725 | @section Auto-Saving: Protection Against Disasters | |
726 | @cindex Auto Save mode | |
727 | @cindex mode, Auto Save | |
728 | @cindex crashes | |
729 | ||
730 | Emacs saves all the visited files from time to time (based on counting | |
731 | your keystrokes) without being asked. This is called @dfn{auto-saving}. | |
732 | It prevents you from losing more than a limited amount of work if the | |
733 | system crashes. | |
734 | ||
735 | When Emacs determines that it is time for auto-saving, each buffer is | |
736 | considered, and is auto-saved if auto-saving is turned on for it and it | |
737 | has been changed since the last time it was auto-saved. The message | |
738 | @samp{Auto-saving...} is displayed in the echo area during auto-saving, | |
739 | if any files are actually auto-saved. Errors occurring during | |
740 | auto-saving are caught so that they do not interfere with the execution | |
741 | of commands you have been typing. | |
742 | ||
743 | @menu | |
744 | * Files: Auto Save Files. The file where auto-saved changes are | |
745 | actually made until you save the file. | |
746 | * Control: Auto Save Control. Controlling when and how often to auto-save. | |
747 | * Recover:: Recovering text from auto-save files. | |
748 | @end menu | |
749 | ||
750 | @node Auto Save Files | |
751 | @subsection Auto-Save Files | |
752 | ||
753 | Auto-saving does not normally save in the files that you visited, because | |
754 | it can be very undesirable to save a program that is in an inconsistent | |
755 | state when you have made half of a planned change. Instead, auto-saving | |
756 | is done in a different file called the @dfn{auto-save file}, and the | |
757 | visited file is changed only when you request saving explicitly (such as | |
758 | with @kbd{C-x C-s}). | |
759 | ||
760 | Normally, the auto-save file name is made by appending @samp{#} to the | |
761 | front and rear of the visited file name. Thus, a buffer visiting file | |
762 | @file{foo.c} is auto-saved in a file @file{#foo.c#}. Most buffers that | |
763 | are not visiting files are auto-saved only if you request it explicitly; | |
764 | when they are auto-saved, the auto-save file name is made by appending | |
765 | @samp{#%} to the front and @samp{#} to the rear of buffer name. For | |
766 | example, the @samp{*mail*} buffer in which you compose messages to be | |
767 | sent is auto-saved in a file named @file{#%*mail*#}. Auto-save file | |
768 | names are made this way unless you reprogram parts of Emacs to do | |
769 | something different (the functions @code{make-auto-save-file-name} and | |
770 | @code{auto-save-file-name-p}). The file name to be used for auto-saving | |
771 | in a buffer is calculated when auto-saving is turned on in that buffer. | |
772 | ||
773 | When you delete a substantial part of the text in a large buffer, auto | |
774 | save turns off temporarily in that buffer. This is because if you | |
775 | deleted the text unintentionally, you might find the auto-save file more | |
776 | useful if it contains the deleted text. To reenable auto-saving after | |
777 | this happens, save the buffer with @kbd{C-x C-s}, or use @kbd{C-u 1 M-x | |
778 | auto-save}. | |
779 | ||
780 | @vindex auto-save-visited-file-name | |
781 | If you want auto-saving to be done in the visited file, set the variable | |
782 | @code{auto-save-visited-file-name} to be non-@code{nil}. In this mode, | |
783 | there is really no difference between auto-saving and explicit saving. | |
784 | ||
785 | @vindex delete-auto-save-files | |
786 | A buffer's auto-save file is deleted when you save the buffer in its | |
787 | visited file. To inhibit this, set the variable @code{delete-auto-save-files} | |
788 | to @code{nil}. Changing the visited file name with @kbd{C-x C-w} or | |
789 | @code{set-visited-file-name} renames any auto-save file to go with | |
790 | the new visited name. | |
791 | ||
792 | @node Auto Save Control | |
793 | @subsection Controlling Auto-Saving | |
794 | ||
795 | @vindex auto-save-default | |
796 | @findex auto-save-mode | |
797 | Each time you visit a file, auto-saving is turned on for that file's | |
798 | buffer if the variable @code{auto-save-default} is non-@code{nil} (but not | |
799 | in batch mode; @pxref{Entering Emacs}). The default for this variable is | |
800 | @code{t}, so auto-saving is the usual practice for file-visiting buffers. | |
801 | Auto-saving can be turned on or off for any existing buffer with the | |
802 | command @kbd{M-x auto-save-mode}. Like other minor mode commands, @kbd{M-x | |
803 | auto-save-mode} turns auto-saving on with a positive argument, off with a | |
804 | zero or negative argument; with no argument, it toggles. | |
805 | ||
806 | @vindex auto-save-interval | |
807 | Emacs does auto-saving periodically based on counting how many characters | |
808 | you have typed since the last time auto-saving was done. The variable | |
809 | @code{auto-save-interval} specifies how many characters there are between | |
810 | auto-saves. By default, it is 300. | |
811 | ||
812 | @vindex auto-save-timeout | |
813 | Auto-saving also takes place when you stop typing for a while. The | |
814 | variable @code{auto-save-timeout} says how many seconds Emacs should | |
815 | wait before it does an auto save (and perhaps also a garbage | |
816 | collection). (The actual time period is longer if the current buffer is | |
817 | long; this is a heuristic which aims to keep out of your way when you | |
818 | are editing long buffers, in which auto-save takes an appreciable amount | |
819 | of time.) Auto-saving during idle periods accomplishes two things: | |
820 | first, it makes sure all your work is saved if you go away from the | |
821 | terminal for a while; second, it may avoid some auto-saving while you | |
822 | are actually typing. | |
823 | ||
824 | Emacs also does auto-saving whenever it gets a fatal error. This | |
825 | includes killing the Emacs job with a shell command such as @samp{kill | |
826 | %emacs}, or disconnecting a phone line or network connection. | |
827 | ||
828 | @findex do-auto-save | |
829 | You can request an auto-save explicitly with the command @kbd{M-x | |
830 | do-auto-save}. | |
831 | ||
832 | @node Recover | |
833 | @subsection Recovering Data from Auto-Saves | |
834 | ||
835 | @findex recover-file | |
836 | You can use the contents of an auto-save file to recover from a loss | |
837 | of data with the command @kbd{M-x recover-file @key{RET} @var{file} | |
838 | @key{RET}}. This visits @var{file} and then (after your confirmation) | |
839 | restores the contents from its auto-save file @file{#@var{file}#}. | |
840 | You can then save with @kbd{C-x C-s} to put the recovered text into | |
841 | @var{file} itself. For example, to recover file @file{foo.c} from its | |
842 | auto-save file @file{#foo.c#}, do:@refill | |
843 | ||
844 | @example | |
845 | M-x recover-file @key{RET} foo.c @key{RET} | |
846 | yes @key{RET} | |
847 | C-x C-s | |
848 | @end example | |
849 | ||
850 | Before asking for confirmation, @kbd{M-x recover-file} displays a | |
851 | directory listing describing the specified file and the auto-save file, | |
852 | so you can compare their sizes and dates. If the auto-save file | |
853 | is older, @kbd{M-x recover-file} does not offer to read it. | |
854 | ||
855 | @findex recover-session | |
856 | If Emacs or the computer crashes, you can recover all the files you | |
857 | were editing from their auto save files with the command @kbd{M-x | |
858 | recover-session}. This first shows you a list of recorded interrupted | |
859 | sessions. Move point to the one you choose, and type @kbd{C-c C-c}. | |
860 | ||
861 | Then @code{recover-session} asks about each of the files that were | |
862 | being edited during that session, asking whether to recover that file. | |
863 | If you answer @kbd{y}, it calls @code{recover-file}, which works in its | |
864 | normal fashion. It shows the dates of the original file and its | |
865 | auto-save file, and asks once again whether to recover that file. | |
866 | ||
867 | When @code{recover-session} is done, the files you've chosen to | |
868 | recover are present in Emacs buffers. You should then save them. Only | |
869 | this---saving them---updates the files themselves. | |
870 | ||
871 | @vindex auto-save-list-file-prefix | |
872 | Interrupted sessions are recorded for later recovery in files named | |
873 | @file{~/.saves-@var{pid}-@var{hostname}}. The @samp{~/.saves} portion of | |
874 | these names comes from the value of @code{auto-save-list-file-prefix}. | |
875 | You can arrange to record sessions in a different place by setting that | |
876 | variable in your @file{.emacs} file, but you'll have to redefine | |
877 | @code{recover-session} as well to make it look in the new place. If you | |
878 | set @code{auto-save-list-file-prefix} to @code{nil} in your | |
879 | @file{.emacs} file, sessions are not recorded for recovery. | |
880 | ||
881 | @node File Aliases | |
882 | @section File Name Aliases | |
883 | ||
884 | Symbolic links and hard links both make it possible for several file | |
885 | names to refer to the same file. Hard links are alternate names that | |
886 | refer directly to the file; all the names are equally valid, and no one | |
887 | of them is preferred. By contrast, a symbolic link is a kind of defined | |
888 | alias: when @file{foo} is a symbolic link to @file{bar}, you can use | |
889 | either name to refer to the file, but @file{bar} is the real name, while | |
890 | @file{foo} is just an alias. More complex cases occur when symbolic | |
891 | links point to directories. | |
892 | ||
893 | If you visit two names for the same file, normally Emacs makes | |
894 | two different buffers, but it warns you about the situation. | |
895 | ||
896 | @vindex find-file-existing-other-name | |
897 | If you wish to avoid visiting the same file in two buffers under | |
898 | different names, set the variable @code{find-file-existing-other-name} | |
899 | to a non-@code{nil} value. Then @code{find-file} uses the existing | |
900 | buffer visiting the file, no matter which of the file's names you | |
901 | specify. | |
902 | ||
903 | @vindex find-file-visit-truename | |
904 | @cindex truenames of files | |
905 | @cindex file truenames | |
906 | If the variable @code{find-file-visit-truename} is non-@code{nil}, | |
907 | then the file name recorded for a buffer is the file's @dfn{truename} | |
908 | (made by replacing all symbolic links with their target names), rather | |
909 | than the name you specify. Setting @code{find-file-visit-truename} also | |
910 | implies the effect of @code{find-file-existing-other-name}. | |
911 | ||
912 | @node Version Control | |
913 | @section Version Control | |
914 | @cindex version control | |
915 | ||
916 | @dfn{Version control systems} are packages that can record multiple | |
917 | versions of a source file, usually storing the unchanged parts of the | |
918 | file just once. Version control systems also record history information | |
919 | such as the creation time of each version, who created it, and a | |
920 | description of what was changed in that version. | |
921 | ||
922 | The Emacs version control interface is called VC. Its commands work | |
923 | with three version control systems---RCS, CVS and SCCS. The GNU project | |
924 | recommends RCS and CVS, which are free software and available from the | |
925 | Free Software Foundation. | |
926 | ||
927 | @menu | |
928 | * Introduction to VC:: How version control works in general. | |
929 | * VC Mode Line:: How the mode line shows version control status. | |
930 | * Basic VC Editing:: How to edit a file under version control. | |
931 | * Old Versions:: Examining and comparing old versions. | |
932 | * Secondary VC Commands:: The commands used a little less frequently. | |
933 | * Branches:: Multiple lines of development. | |
934 | * Snapshots:: Sets of file versions treated as a unit. | |
935 | * Miscellaneous VC:: Various other commands and features of VC. | |
936 | * Customizing VC:: Variables that change VC's behavior. | |
937 | @end menu | |
938 | ||
939 | @node Introduction to VC | |
940 | @subsection Introduction to Version Control | |
941 | ||
942 | VC allows you to use a version control system from within Emacs, | |
943 | integrating the version control operations smoothly with editing. VC | |
944 | provides a uniform interface to version control, so that regardless of | |
945 | which version control system is in use, you can use it the same way. | |
946 | ||
947 | This section provides a general overview of version control, and | |
948 | describes the version control systems that VC supports. You can skip | |
949 | this section if you are already familiar with the version control system | |
950 | you want to use. | |
951 | ||
952 | @menu | |
953 | * Version Systems:: Supported version control back-end systems. | |
954 | * VC Concepts:: Words and concepts related to version control. | |
955 | @end menu | |
956 | ||
957 | @node Version Systems | |
958 | @subsubsection Supported Version Control Systems | |
959 | ||
960 | @cindex RCS | |
961 | @cindex back end (version control) | |
962 | VC currently works with three different version control systems or | |
963 | ``back ends'': RCS, CVS, and SCCS. | |
964 | ||
965 | RCS is a free version control system that is available from the Free | |
966 | Software Foundation. It is perhaps the most mature of the supported | |
967 | back ends, and the VC commands are conceptually closest to RCS. Almost | |
968 | everything you can do with RCS can be done through VC. | |
969 | ||
970 | @cindex CVS | |
971 | CVS is built on top of RCS, and extends the features of RCS, allowing | |
972 | for more sophisticated release management, and concurrent multi-user | |
973 | development. VC supports basic editing operations under CVS, but for | |
974 | some less common tasks you still need to call CVS from the command line. | |
975 | Note also that before using CVS you must set up a repository, which is a | |
976 | subject too complex to treat here. | |
977 | ||
978 | @cindex SCCS | |
979 | SCCS is a proprietary but widely used version control system. In | |
980 | terms of capabilities, it is the weakest of the three that VC | |
981 | supports. VC compensates for certain features missing in SCCS | |
982 | (snapshots, for example) by implementing them itself, but some other VC | |
983 | features, such as multiple branches, are not available with SCCS. You | |
984 | should use SCCS only if for some reason you cannot use RCS. | |
985 | ||
986 | @node VC Concepts | |
987 | @subsubsection Concepts of Version Control | |
988 | ||
989 | @cindex master file | |
990 | @cindex registered file | |
991 | When a file is under version control, we also say that it is | |
992 | @dfn{registered} in the version control system. Each registered file | |
993 | has a corresponding @dfn{master file} which represents the file's | |
994 | present state plus its change history---enough to reconstruct the | |
995 | current version or any earlier version. Usually the master file also | |
996 | records a @dfn{log entry} for each version, describing in words what was | |
997 | changed in that version. | |
998 | ||
999 | @cindex work file | |
1000 | @cindex checking out files | |
1001 | The file that is maintained under version control is sometimes called | |
1002 | the @dfn{work file} corresponding to its master file. You edit the work | |
1003 | file and make changes in it, as you would with an ordinary file. (With | |
1004 | SCCS and RCS, you must @dfn{lock} the file before you start to edit it.) | |
1005 | After you are done with a set of changes, you @dfn{check the file in}, | |
1006 | which records the changes in the master file, along with a log entry for | |
1007 | them. | |
1008 | ||
1009 | With CVS, there are usually multiple work files corresponding to a | |
1010 | single master file---often each user has his own copy. It is also | |
1011 | possible to use RCS in this way, but this is not the usual way to use | |
1012 | RCS. | |
1013 | ||
1014 | @cindex locking and version control | |
1015 | A version control system typically has some mechanism to coordinate | |
1016 | between users who want to change the same file. One method is | |
1017 | @dfn{locking} (analogous to the locking that Emacs uses to detect | |
1018 | simultaneous editing of a file, but distinct from it). The other method | |
1019 | is to merge your changes with other people's changes when you check them | |
1020 | in. | |
1021 | ||
1022 | With version control locking, work files are normally read-only so | |
1023 | that you cannot change them. You ask the version control system to make | |
1024 | a work file writable for you by locking it; only one user can do | |
1025 | this at any given time. When you check in your changes, that unlocks | |
1026 | the file, making the work file read-only again. This allows other users | |
1027 | to lock the file to make further changes. SCCS always uses locking, and | |
1028 | RCS normally does. | |
1029 | ||
1030 | The other alternative for RCS is to let each user modify the work file | |
1031 | at any time. In this mode, locking is not required, but it is | |
1032 | permitted; check-in is still the way to record a new version. | |
1033 | ||
1034 | CVS normally allows each user to modify his own copy of the work file | |
1035 | at any time, but requires merging with changes from other users at | |
1036 | check-in time. However, CVS can also be set up to require locking. | |
1037 | (@pxref{Backend Options}). | |
1038 | ||
1039 | @node VC Mode Line | |
1040 | @subsection Version Control and the Mode Line | |
1041 | ||
1042 | When you visit a file that is under version control, Emacs indicates | |
1043 | this on the mode line. For example, @samp{RCS-1.3} says that RCS is | |
1044 | used for that file, and the current version is 1.3. | |
1045 | ||
1046 | The character between the back-end name and the version number | |
1047 | indicates the version control status of the file. @samp{-} means that | |
1048 | the work file is not locked (if locking is in use), or not modified (if | |
1049 | locking is not in use). @samp{:} indicates that the file is locked, or | |
1050 | that it is modified. If the file is locked by some other user (for | |
1051 | instance, @samp{jim}), that is displayed as @samp{RCS:jim:1.3}. | |
1052 | ||
1053 | @node Basic VC Editing | |
1054 | @subsection Basic Editing under Version Control | |
1055 | ||
1056 | The principal VC command is an all-purpose command that performs | |
1057 | either locking or check-in, depending on the situation. | |
1058 | ||
1059 | @table @kbd | |
1060 | @item C-x C-q | |
1061 | @itemx C-x v v | |
1062 | Perform the next logical version control operation on this file. | |
1063 | @end table | |
1064 | ||
1065 | @findex vc-next-action | |
1066 | @findex vc-toggle-read-only | |
1067 | @kindex C-x v v | |
1068 | @kindex C-x C-q @r{(Version Control)} | |
1069 | Strictly speaking, the command for this job is @code{vc-next-action}, | |
1070 | bound to @kbd{C-x v v}. However, the normal meaning of @kbd{C-x C-q} is | |
1071 | to make a read-only buffer writable, or vice versa; we have extended it | |
1072 | to do the same job properly for files managed by version control, by | |
1073 | performing the appropriate version control operations. When you type | |
1074 | @kbd{C-x C-q} on a registered file, it acts like @kbd{C-x v v}. | |
1075 | ||
1076 | The precise action of this command depends on the state of the file, | |
1077 | and whether the version control system uses locking or not. SCCS and | |
1078 | RCS normally use locking; CVS normally does not use locking. | |
1079 | ||
1080 | @menu | |
1081 | * VC with Locking:: RCS in its default mode, SCCS, and optionally CVS. | |
1082 | * Without Locking:: Without locking: default mode for CVS. | |
1083 | * Log Buffer:: Features available in log entry buffers. | |
1084 | @end menu | |
1085 | ||
1086 | @node VC with Locking | |
1087 | @subsubsection Basic Version Control with Locking | |
1088 | ||
1089 | If locking is used for the file (as with SCCS, and RCS in its default | |
1090 | mode), @kbd{C-x C-q} can either lock a file or check it in: | |
1091 | ||
1092 | @itemize @bullet | |
1093 | @item | |
1094 | If the file is not locked, @kbd{C-x C-q} locks it, and | |
1095 | makes it writable so that you can change it. | |
1096 | ||
1097 | @item | |
1098 | If the file is locked by you, and contains changes, @kbd{C-x C-q} checks | |
1099 | in the changes. In order to do this, it first reads the log entry | |
1100 | for the new version. @xref{Log Buffer}. | |
1101 | ||
1102 | @item | |
1103 | If the file is locked by you, but you have not changed it since you | |
1104 | locked it, @kbd{C-x C-q} releases the lock and makes the file read-only | |
1105 | again. | |
1106 | ||
1107 | @item | |
1108 | If the file is locked by some other user, @kbd{C-x C-q} asks you whether | |
1109 | you want to ``steal the lock'' from that user. If you say yes, the file | |
1110 | becomes locked by you, but a message is sent to the person who had | |
1111 | formerly locked the file, to inform him of what has happened. | |
1112 | @end itemize | |
1113 | ||
1114 | These rules also apply when you use CVS in locking mode, except | |
1115 | that there is no such thing as stealing a lock. | |
1116 | ||
1117 | @node Without Locking | |
1118 | @subsubsection Basic Version Control without Locking | |
1119 | ||
1120 | When there is no locking---the default for CVS---work files are always | |
1121 | writable; you do not need to do anything before you begin to edit a | |
1122 | file. The status indicator on the mode line is @samp{-} if the file is | |
1123 | unmodified; it flips to @samp{:} as soon as you save any changes in the | |
1124 | work file. | |
1125 | ||
1126 | Here is what @kbd{C-x C-q} does when using CVS: | |
1127 | ||
1128 | @itemize @bullet | |
1129 | @item | |
1130 | If some other user has checked in changes into the master file, | |
1131 | Emacs asks you whether you want to merge those changes into your own | |
1132 | work file (@pxref{Merging}). You must do this before you can check in | |
1133 | your own changes. | |
1134 | ||
1135 | @item | |
1136 | If there are no new changes in the master file, but you have made | |
1137 | modifications in your work file, @kbd{C-x C-q} checks in your changes. | |
1138 | In order to do this, it first reads the log entry for the new version. | |
1139 | @xref{Log Buffer}. | |
1140 | ||
1141 | @item | |
1142 | If the file is not modified, the @kbd{C-x C-q} does nothing. | |
1143 | @end itemize | |
1144 | ||
1145 | These rules also apply when you use RCS in the mode that does not | |
1146 | require locking, except that automatic merging of changes from the | |
1147 | master file is not implemented. Unfortunately, this means that nothing | |
1148 | informs you if another user has checked in changes in the same file | |
1149 | since you began editing it, and when this happens, his changes will be | |
1150 | effectively removed when you check in your version (though they will | |
1151 | remain in the master file, so they will not be entirely lost). You must | |
1152 | therefore verify the current version is unchanged, before you check in your | |
1153 | changes. We hope to eliminate this risk and provide automatic merging | |
1154 | with RCS in a future Emacs version. | |
1155 | ||
1156 | In addition, locking is possible with RCS even in this mode, although | |
1157 | it is not required; @kbd{C-x C-q} with an unmodified file locks the | |
1158 | file, just as it does with RCS in its normal (locking) mode. | |
1159 | ||
1160 | @node Log Buffer | |
1161 | @subsubsection Features of the Log Entry Buffer | |
1162 | ||
1163 | When you check in changes, @kbd{C-x C-q} first reads a log entry. It | |
1164 | pops up a buffer called @samp{*VC-Log*} for you to enter the log entry. | |
1165 | When you are finished, type @kbd{C-c C-c} in the @samp{*VC-Log*} buffer. | |
1166 | That is when check-in really happens. | |
1167 | ||
1168 | To abort check-in, just @strong{don't} type @kbd{C-c C-c} in that | |
1169 | buffer. You can switch buffers and do other editing. As long as you | |
1170 | don't try to check in another file, the entry you were editing remains | |
1171 | in the @samp{*VC-Log*} buffer, and you can go back to that buffer at any | |
1172 | time to complete the check-in. | |
1173 | ||
1174 | If you change several source files for the same reason, it is often | |
1175 | convenient to specify the same log entry for many of the files. To do | |
1176 | this, use the history of previous log entries. The commands @kbd{M-n}, | |
1177 | @kbd{M-p}, @kbd{M-s} and @kbd{M-r} for doing this work just like the | |
1178 | minibuffer history commands (except that these versions are used outside | |
1179 | the minibuffer). | |
1180 | ||
1181 | @vindex vc-log-mode-hook | |
1182 | Each time you check in a file, the log entry buffer is put into VC Log | |
1183 | mode, which involves running two hooks: @code{text-mode-hook} and | |
1184 | @code{vc-log-mode-hook}. @xref{Hooks}. | |
1185 | ||
1186 | @node Old Versions | |
1187 | @subsection Examining And Comparing Old Versions | |
1188 | ||
1189 | One of the convenient features of version control is the ability | |
1190 | to examine any version of a file, or compare two versions. | |
1191 | ||
1192 | @table @kbd | |
1193 | @item C-x v ~ @var{version} @key{RET} | |
1194 | Examine version @var{version} of the visited file, in a buffer of its | |
1195 | own. | |
1196 | ||
1197 | @item C-x v = | |
1198 | Compare the current buffer contents with the latest checked-in version | |
1199 | of the file. | |
1200 | ||
1201 | @item C-u C-x v = @var{file} @key{RET} @var{oldvers} @key{RET} @var{newvers} @key{RET} | |
1202 | Compare the specified two versions of @var{file}. | |
1203 | ||
1204 | @item C-x v g | |
1205 | Display the result of the CVS annotate command using colors. | |
1206 | @end table | |
1207 | ||
1208 | @findex vc-version-other-window | |
1209 | @kindex C-x v ~ | |
1210 | To examine an old version in toto, visit the file and then type | |
1211 | @kbd{C-x v ~ @var{version} @key{RET}} (@code{vc-version-other-window}). | |
1212 | This puts the text of version @var{version} in a file named | |
1213 | @file{@var{filename}.~@var{version}~}, and visits it in its own buffer | |
1214 | in a separate window. (In RCS, you can also select an old version | |
1215 | and create a branch from it. @xref{Branches}.) | |
1216 | ||
1217 | @findex vc-diff | |
1218 | @kindex C-x v = | |
1219 | But usually it is more convenient to compare two versions of the file, | |
1220 | with the command @kbd{C-x v =} (@code{vc-diff}). Plain @kbd{C-x v =} | |
1221 | compares the current buffer contents (saving them in the file if | |
1222 | necessary) with the last checked-in version of the file. @kbd{C-u C-x v | |
1223 | =}, with a numeric argument, reads a file name and two version numbers, | |
1224 | then compares those versions of the specified file. | |
1225 | ||
1226 | If you supply a directory name instead of the name of a registered | |
1227 | file, this command compares the two specified versions of all registered | |
1228 | files in that directory and its subdirectories. | |
1229 | ||
1230 | You can specify a checked-in version by its number; an empty input | |
1231 | specifies the current contents of the work file (which may be different | |
1232 | from all the checked-in versions). You can also specify a snapshot name | |
1233 | (@pxref{Snapshots}) instead of one or both version numbers. | |
1234 | ||
1235 | This command works by running the @code{diff} utility, getting the | |
1236 | options from the variable @code{diff-switches}. It displays the output | |
1237 | in a special buffer in another window. Unlike the @kbd{M-x diff} | |
1238 | command, @kbd{C-x v =} does not try to locate the changes in the old and | |
1239 | new versions. This is because normally one or both versions do not | |
1240 | exist as files when you compare them; they exist only in the records of | |
1241 | the master file. @xref{Comparing Files}, for more information about | |
1242 | @kbd{M-x diff}. | |
1243 | ||
1244 | @findex vc-annotate | |
1245 | @kindex C-x v g | |
1246 | For CVS-controlled files, you can display the result of the CVS | |
1247 | annotate command, using colors to enhance the visual appearance. Use | |
1248 | the command @kbd{M-x vc-annotate} to do this. Red means new, blue means | |
1249 | old, and intermediate colors indicate intermediate ages. A prefix | |
1250 | argument @var{n} specifies a stretch factor for the time scale; it makes | |
1251 | each color cover a period @var{n} times as long. | |
1252 | ||
1253 | @node Secondary VC Commands | |
1254 | @subsection The Secondary Commands of VC | |
1255 | ||
1256 | This section explains the secondary commands of VC; those that you might | |
1257 | use once a day. | |
1258 | ||
1259 | @menu | |
1260 | * Registering:: Putting a file under version control. | |
1261 | * VC Status:: Viewing the VC status of files. | |
1262 | * VC Undo:: Cancelling changes before or after check-in. | |
1263 | * VC Dired Mode:: Listing files managed by version control. | |
1264 | * VC Dired Commands:: Commands to use in a VC Dired buffer. | |
1265 | @end menu | |
1266 | ||
1267 | @node Registering | |
1268 | @subsubsection Registering a File for Version Control | |
1269 | ||
1270 | @kindex C-x v i | |
1271 | @findex vc-register | |
1272 | You can put any file under version control by simply visiting it, and | |
1273 | then typing @w{@kbd{C-x v i}} (@code{vc-register}). | |
1274 | ||
1275 | @table @kbd | |
1276 | @item C-x v i | |
1277 | Register the visited file for version control. | |
1278 | @end table | |
1279 | ||
1280 | @vindex vc-default-back-end | |
1281 | To register the file, Emacs must choose which version control system | |
1282 | to use for it. You can specify your choice explicitly by setting | |
1283 | @code{vc-default-back-end} to @code{RCS}, @code{CVS} or @code{SCCS}. | |
1284 | Otherwise, if there is a subdirectory named @file{RCS}, @file{SCCS}, or | |
1285 | @file{CVS}, Emacs uses the corresponding version control system. In the | |
1286 | absence of any specification, the default choice is RCS if RCS is | |
1287 | installed, otherwise SCCS. | |
1288 | ||
1289 | If locking is in use, @kbd{C-x v i} leaves the file unlocked and | |
1290 | read-only. Type @kbd{C-x C-q} if you wish to start editing it. After | |
1291 | registering a file with CVS, you must subsequently commit the initial | |
1292 | version by typing @kbd{C-x C-q}. | |
1293 | ||
1294 | @vindex vc-default-init-version | |
1295 | The initial version number for a newly registered file is 1.1, by | |
1296 | default. You can specify a different default by setting the variable | |
1297 | @code{vc-default-init-version}, or you can give @kbd{C-x v i} a numeric | |
1298 | argument; then it reads the initial version number for this particular | |
1299 | file using the minibuffer. | |
1300 | ||
1301 | @vindex vc-initial-comment | |
1302 | If @code{vc-initial-comment} is non-@code{nil}, @kbd{C-x v i} reads an | |
1303 | initial comment to describe the purpose of this source file. Reading | |
1304 | the initial comment works like reading a log entry (@pxref{Log Buffer}). | |
1305 | ||
1306 | @node VC Status | |
1307 | @subsubsection VC Status Commands | |
1308 | ||
1309 | @table @kbd | |
1310 | @item C-x v l | |
1311 | Display version control state and change history. | |
1312 | @end table | |
1313 | ||
1314 | @kindex C-x v l | |
1315 | @findex vc-print-log | |
1316 | To view the detailed version control status and history of a file, | |
1317 | type @kbd{C-x v l} (@code{vc-print-log}). It displays the history of | |
1318 | changes to the current file, including the text of the log entries. The | |
1319 | output appears in a separate window. | |
1320 | ||
1321 | @node VC Undo | |
1322 | @subsubsection Undoing Version Control Actions | |
1323 | ||
1324 | @table @kbd | |
1325 | @item C-x v u | |
1326 | Revert the buffer and the file to the last checked-in version. | |
1327 | ||
1328 | @item C-x v c | |
1329 | Remove the last-entered change from the master for the visited file. | |
1330 | This undoes your last check-in. | |
1331 | @end table | |
1332 | ||
1333 | @kindex C-x v u | |
1334 | @findex vc-revert-buffer | |
1335 | If you want to discard your current set of changes and revert to the | |
1336 | last version checked in, use @kbd{C-x v u} (@code{vc-revert-buffer}). | |
1337 | This leaves the file unlocked; if locking is in use, you must first lock | |
1338 | the file again before you change it again. @kbd{C-x v u} requires | |
1339 | confirmation, unless it sees that you haven't made any changes since the | |
1340 | last checked-in version. | |
1341 | ||
1342 | @kbd{C-x v u} is also the command to unlock a file if you lock it and | |
1343 | then decide not to change it. | |
1344 | ||
1345 | @kindex C-x v c | |
1346 | @findex vc-cancel-version | |
1347 | To cancel a change that you already checked in, use @kbd{C-x v c} | |
1348 | (@code{vc-cancel-version}). This command discards all record of the | |
1349 | most recent checked-in version. @kbd{C-x v c} also offers to revert | |
1350 | your work file and buffer to the previous version (the one that precedes | |
1351 | the version that is deleted). | |
1352 | ||
1353 | If you answer @kbd{no}, VC keeps your changes in the buffer, and locks | |
1354 | the file. The no-revert option is useful when you have checked in a | |
1355 | change and then discover a trivial error in it; you can cancel the | |
1356 | erroneous check-in, fix the error, and check the file in again. | |
1357 | ||
1358 | When @kbd{C-x v c} does not revert the buffer, it unexpands all | |
1359 | version control headers in the buffer instead (@pxref{Version Headers}). | |
1360 | This is because the buffer no longer corresponds to any existing | |
1361 | version. If you check it in again, the check-in process will expand the | |
1362 | headers properly for the new version number. | |
1363 | ||
1364 | However, it is impossible to unexpand the RCS @samp{@w{$}Log$} header | |
1365 | automatically. If you use that header feature, you have to unexpand it | |
1366 | by hand---by deleting the entry for the version that you just canceled. | |
1367 | ||
1368 | Be careful when invoking @kbd{C-x v c}, as it is easy to lose a lot of | |
1369 | work with it. To help you be careful, this command always requires | |
1370 | confirmation with @kbd{yes}. Note also that this command is disabled | |
1371 | under CVS, because canceling versions is very dangerous and discouraged | |
1372 | with CVS. | |
1373 | ||
1374 | @node VC Dired Mode | |
1375 | @subsubsection Dired under VC | |
1376 | ||
1377 | @kindex C-x v d | |
1378 | @findex vc-directory | |
1379 | When you are working on a large program, it is often useful to find | |
1380 | out which files have changed within an entire directory tree, or to view | |
1381 | the status of all files under version control at once, and to perform | |
1382 | version control operations on collections of files. You can use the | |
1383 | command @kbd{C-x v d} (@code{vc-directory}) to make a directory listing | |
1384 | that includes only files relevant for version control. | |
1385 | ||
1386 | @vindex vc-dired-terse-display | |
1387 | @kbd{C-x v d} creates a buffer which uses VC Dired Mode. This looks | |
1388 | much like an ordinary Dired buffer (@pxref{Dired}); however, normally it | |
1389 | shows only the noteworthy files (those locked or not up-to-date). This | |
1390 | is called @dfn{terse display}. If you set the variable | |
1391 | @code{vc-dired-terse-display} to @code{nil}, then VC Dired shows all | |
1392 | relevant files---those managed under version control, plus all | |
1393 | subdirectories (@dfn{full display}). The command @kbd{v t} in a VC | |
1394 | Dired buffer toggles between terse display and full display (@pxref{VC | |
1395 | Dired Commands}). | |
1396 | ||
1397 | @vindex vc-dired-recurse | |
1398 | By default, VC Dired produces a recursive listing of noteworthy or | |
1399 | relevant files at or below the given directory. You can change this by | |
1400 | setting the variable @code{vc-dired-recurse} to @code{nil}; then VC | |
1401 | Dired shows only the files in the given directory. | |
1402 | ||
1403 | The line for an individual file shows the version control state in the | |
1404 | place of the hard link count, owner, group, and size of the file. If | |
1405 | the file is unmodified, in sync with the master file, the version | |
1406 | control state shown is blank. Otherwise it consists of text in | |
1407 | parentheses. Under RCS and SCCS, the name of the user locking the file | |
1408 | is shown; under CVS, an abbreviated version of the @samp{cvs status} | |
1409 | output is used. Here is an example using RCS: | |
1410 | ||
1411 | @smallexample | |
1412 | @group | |
1413 | /home/jim/project: | |
1414 | ||
1415 | -rw-r--r-- (jim) Apr 2 23:39 file1 | |
1416 | -r--r--r-- Apr 5 20:21 file2 | |
1417 | @end group | |
1418 | @end smallexample | |
1419 | ||
1420 | @noindent | |
1421 | The files @samp{file1} and @samp{file2} are under version control, | |
1422 | @samp{file1} is locked by user jim, and @samp{file2} is unlocked. | |
1423 | ||
1424 | Here is an example using CVS: | |
1425 | ||
1426 | @smallexample | |
1427 | @group | |
1428 | /home/joe/develop: | |
1429 | ||
1430 | -rw-r--r-- (modified) Aug 2 1997 file1.c | |
1431 | -rw-r--r-- Apr 4 20:09 file2.c | |
1432 | -rw-r--r-- (merge) Sep 13 1996 file3.c | |
1433 | @end group | |
1434 | @end smallexample | |
1435 | ||
1436 | Here @samp{file1.c} is modified with respect to the repository, and | |
1437 | @samp{file2.c} is not. @samp{file3.c} is modified, but other changes | |
1438 | have also been checked in to the repository---you need to merge them | |
1439 | with the work file before you can check it in. | |
1440 | ||
1441 | @vindex vc-directory-exclusion-list | |
1442 | When VC Dired displays subdirectories (in the ``full'' display mode), | |
1443 | it omits some that should never contain any files under version control. | |
1444 | By default, this includes Version Control subdirectories such as | |
1445 | @samp{RCS} and @samp{CVS}; you can customize this by setting the | |
1446 | variable @code{vc-directory-exclusion-list}. | |
1447 | ||
1448 | You can fine-tune VC Dired's format by typing @kbd{C-u C-x v d}---as in | |
1449 | ordinary Dired, that allows you to specify additional switches for the | |
1450 | @samp{ls} command. | |
1451 | ||
1452 | @node VC Dired Commands | |
1453 | @subsubsection VC Dired Commands | |
1454 | ||
1455 | All the usual Dired commands work normally in VC Dired mode, except | |
1456 | for @kbd{v}, which is redefined as the version control prefix. You can | |
1457 | invoke VC commands such as @code{vc-diff} and @code{vc-print-log} by | |
1458 | typing @kbd{v =}, or @kbd{v l}, and so on. Most of these commands apply | |
1459 | to the file name on the current line. | |
1460 | ||
1461 | The command @kbd{v v} (@code{vc-next-action}) operates on all the | |
1462 | marked files, so that you can lock or check in several files at once. | |
1463 | If it operates on more than one file, it handles each file according to | |
1464 | its current state; thus, it might lock one file, but check in another | |
1465 | file. This could be confusing; it is up to you to avoid confusing | |
1466 | behavior by marking a set of files that are in a similar state. | |
1467 | ||
1468 | If any files call for check-in, @kbd{v v} reads a single log entry, | |
1469 | then uses it for all the files being checked in. This is convenient for | |
1470 | registering or checking in several files at once, as part of the same | |
1471 | change. | |
1472 | ||
1473 | @findex vc-dired-toggle-terse-mode | |
1474 | @findex vc-dired-mark-locked | |
1475 | You can toggle between terse display (only locked files, or files not | |
1476 | up-to-date) and full display at any time by typing @kbd{v t} | |
1477 | @code{vc-dired-toggle-terse-mode}. There is also a special command | |
1478 | @kbd{* l} (@code{vc-dired-mark-locked}), which marks all files currently | |
1479 | locked (or, with CVS, all files not up-to-date). Thus, typing @kbd{* l | |
1480 | t k} is another way to delete from the buffer all files except those | |
1481 | currently locked. | |
1482 | ||
1483 | @node Branches | |
1484 | @subsection Multiple Branches of a File | |
1485 | @cindex branch (version control) | |
1486 | @cindex trunk (version control) | |
1487 | ||
1488 | One use of version control is to maintain multiple ``current'' | |
1489 | versions of a file. For example, you might have different versions of a | |
1490 | program in which you are gradually adding various unfinished new | |
1491 | features. Each such independent line of development is called a | |
1492 | @dfn{branch}. VC allows you to create branches, switch between | |
1493 | different branches, and merge changes from one branch to another. | |
1494 | Please note, however, that branches are only supported for RCS at the | |
1495 | moment. | |
1496 | ||
1497 | A file's main line of development is usually called the @dfn{trunk}. | |
1498 | The versions on the trunk are normally numbered 1.1, 1.2, 1.3, etc. At | |
1499 | any such version, you can start an independent branch. A branch | |
1500 | starting at version 1.2 would have version number 1.2.1.1, and consecutive | |
1501 | versions on this branch would have numbers 1.2.1.2, 1.2.1.3, 1.2.1.4, | |
1502 | and so on. If there is a second branch also starting at version 1.2, it | |
1503 | would consist of versions 1.2.2.1, 1.2.2.2, 1.2.2.3, etc. | |
1504 | ||
1505 | @cindex head version | |
1506 | If you omit the final component of a version number, that is called a | |
1507 | @dfn{branch number}. It refers to the highest existing version on that | |
1508 | branch---the @dfn{head version} of that branch. The branches in the | |
1509 | example above have branch numbers 1.2.1 and 1.2.2. | |
1510 | ||
1511 | @menu | |
1512 | * Switching Branches:: How to get to another existing branch. | |
1513 | * Creating Branches:: How to start a new branch. | |
1514 | * Merging:: Transferring changes between branches. | |
1515 | * Multi-User Branching:: Multiple users working at multiple branches | |
1516 | in parallel. | |
1517 | @end menu | |
1518 | ||
1519 | @node Switching Branches | |
1520 | @subsubsection Switching between Branches | |
1521 | ||
1522 | To switch between branches, type @kbd{C-u C-x C-q} and specify the | |
1523 | version number you want to select. This version is then visited | |
1524 | @emph{unlocked} (write-protected), so you can examine it before locking | |
1525 | it. Switching branches in this way is allowed only when the file is not | |
1526 | locked. | |
1527 | ||
1528 | You can omit the minor version number, thus giving only the branch | |
1529 | number; this takes you to the head version on the chosen branch. If you | |
1530 | only type @key{RET}, Emacs goes to the highest version on the trunk. | |
1531 | ||
1532 | After you have switched to any branch (including the main branch), you | |
1533 | stay on it for subsequent VC commands, until you explicitly select some | |
1534 | other branch. | |
1535 | ||
1536 | @node Creating Branches | |
1537 | @subsubsection Creating New Branches | |
1538 | ||
1539 | To create a new branch from a head version (one that is the latest in | |
1540 | the branch that contains it), first select that version if necessary, | |
1541 | lock it with @kbd{C-x C-q}, and make whatever changes you want. Then, | |
1542 | when you check in the changes, use @kbd{C-u C-x C-q}. This lets you | |
1543 | specify the version number for the new version. You should specify a | |
1544 | suitable branch number for a branch starting at the current version. | |
1545 | For example, if the current version is 2.5, the branch number should be | |
1546 | 2.5.1, 2.5.2, and so on, depending on the number of existing branches at | |
1547 | that point. | |
1548 | ||
1549 | To create a new branch at an older version (one that is no longer the | |
1550 | head of a branch), first select that version (@pxref{Switching | |
1551 | Branches}), then lock it with @kbd{C-x C-q}. You'll be asked to | |
1552 | confirm, when you lock the old version, that you really mean to create a | |
1553 | new branch---if you say no, you'll be offered a chance to lock the | |
1554 | latest version instead. | |
1555 | ||
1556 | Then make your changes and type @kbd{C-x C-q} again to check in a new | |
1557 | version. This automatically creates a new branch starting from the | |
1558 | selected version. You need not specially request a new branch, because | |
1559 | that's the only way to add a new version at a point that is not the head | |
1560 | of a branch. | |
1561 | ||
1562 | After the branch is created, you ``stay'' on it. That means that | |
1563 | subsequent check-ins create new versions on that branch. To leave the | |
1564 | branch, you must explicitly select a different version with @kbd{C-u C-x | |
1565 | C-q}. To transfer changes from one branch to another, use the merge | |
1566 | command, described in the next section. | |
1567 | ||
1568 | @node Merging | |
1569 | @subsubsection Merging Branches | |
1570 | ||
1571 | @cindex merging changes | |
1572 | When you have finished the changes on a certain branch, you will | |
1573 | often want to incorporate them into the file's main line of development | |
1574 | (the trunk). This is not a trivial operation, because development might | |
1575 | also have proceeded on the trunk, so that you must @dfn{merge} the | |
1576 | changes into a file that has already been changed otherwise. VC allows | |
1577 | you to do this (and other things) with the @code{vc-merge} command. | |
1578 | ||
1579 | @table @kbd | |
1580 | @item C-x v m (vc-merge) | |
1581 | Merge changes into the work file. | |
1582 | @end table | |
1583 | ||
1584 | @kindex C-x v m | |
1585 | @findex vc-merge | |
1586 | @kbd{C-x v m} (@code{vc-merge}) takes a set of changes and merges it | |
1587 | into the current version of the work file. It first asks you for a | |
1588 | branch number or a pair of version numbers in the minibuffer. Then it | |
1589 | finds the changes from that branch, or between the two versions you | |
1590 | specified, and merges them into the current version of the current file. | |
1591 | ||
1592 | As an example, suppose that you have finished a certain feature on | |
1593 | branch 1.3.1. In the meantime, development on the trunk has proceeded | |
1594 | to version 1.5. To merge the changes from the branch to the trunk, | |
1595 | first go to the head version of the trunk, by typing @kbd{C-u C-x C-q | |
1596 | RET}. Version 1.5 is now current. If locking is used for the file, | |
1597 | type @kbd{C-x C-q} to lock version 1.5 so that you can change it. Next, | |
1598 | type @kbd{C-x v m 1.3.1 RET}. This takes the entire set of changes on | |
1599 | branch 1.3.1 (relative to version 1.3, where the branch started, up to | |
1600 | the last version on the branch) and merges it into the current version | |
1601 | of the work file. You can now check in the changed file, thus creating | |
1602 | version 1.6 containing the changes from the branch. | |
1603 | ||
1604 | It is possible to do further editing after merging the branch, before | |
1605 | the next check-in. But it is usually wiser to check in the merged | |
1606 | version, then lock it and make the further changes. This will keep | |
1607 | a better record of the history of changes. | |
1608 | ||
1609 | @cindex conflicts | |
1610 | @cindex resolving conflicts | |
1611 | When you merge changes into a file that has itself been modified, the | |
1612 | changes might overlap. We call this situation a @dfn{conflict}, and | |
1613 | reconciling the conflicting changes is called @dfn{resolving a | |
1614 | conflict}. | |
1615 | ||
1616 | Whenever conflicts occur during merging, VC detects them, tells you | |
1617 | about them in the echo area, and asks whether you want help in merging. | |
1618 | If you say yes, it starts an Ediff session (@pxref{Top, | |
1619 | Ediff, Ediff, ediff, The Ediff Manual}). | |
1620 | ||
1621 | If you say no, the conflicting changes are both inserted into the | |
1622 | file, surrounded by @dfn{conflict markers}. The example below shows how | |
1623 | a conflict region looks; the file is called @samp{name} and the current | |
1624 | master file version with user B's changes in it is 1.11. | |
1625 | ||
1626 | @c @w here is so CVS won't think this is a conflict. | |
1627 | @smallexample | |
1628 | @group | |
1629 | @w{<}<<<<<< name | |
1630 | @var{User A's version} | |
1631 | ======= | |
1632 | @var{User B's version} | |
1633 | @w{>}>>>>>> 1.11 | |
1634 | @end group | |
1635 | @end smallexample | |
1636 | ||
1637 | @cindex vc-resolve-conflicts | |
1638 | Then you can resolve the conflicts by editing the file manually. Or | |
1639 | you can type @code{M-x vc-resolve-conflicts} after visiting the file. | |
1640 | This starts an Ediff session, as described above. | |
1641 | ||
1642 | @node Multi-User Branching | |
1643 | @subsubsection Multi-User Branching | |
1644 | ||
1645 | It is often useful for multiple developers to work simultaneously on | |
1646 | different branches of a file. CVS allows this by default; for RCS, it | |
1647 | is possible if you create multiple source directories. Each source | |
1648 | directory should have a link named @file{RCS} which points to a common | |
1649 | directory of RCS master files. Then each source directory can have its | |
1650 | own choice of selected versions, but all share the same common RCS | |
1651 | records. | |
1652 | ||
1653 | This technique works reliably and automatically, provided that the | |
1654 | source files contain RCS version headers (@pxref{Version Headers}). The | |
1655 | headers enable Emacs to be sure, at all times, which version number is | |
1656 | present in the work file. | |
1657 | ||
1658 | If the files do not have version headers, you must instead tell Emacs | |
1659 | explicitly in each session which branch you are working on. To do this, | |
1660 | first find the file, then type @kbd{C-u C-x C-q} and specify the correct | |
1661 | branch number. This ensures that Emacs knows which branch it is using | |
1662 | during this particular editing session. | |
1663 | ||
1664 | @node Snapshots | |
1665 | @subsection Snapshots | |
1666 | @cindex snapshots and version control | |
1667 | ||
1668 | A @dfn{snapshot} is a named set of file versions (one for each | |
1669 | registered file) that you can treat as a unit. One important kind of | |
1670 | snapshot is a @dfn{release}, a (theoretically) stable version of the | |
1671 | system that is ready for distribution to users. | |
1672 | ||
1673 | @menu | |
1674 | * Making Snapshots:: The snapshot facilities. | |
1675 | * Snapshot Caveats:: Things to be careful of when using snapshots. | |
1676 | @end menu | |
1677 | ||
1678 | @node Making Snapshots | |
1679 | @subsubsection Making and Using Snapshots | |
1680 | ||
1681 | There are two basic commands for snapshots; one makes a | |
1682 | snapshot with a given name, the other retrieves a named snapshot. | |
1683 | ||
1684 | @table @code | |
1685 | @kindex C-x v s | |
1686 | @findex vc-create-snapshot | |
1687 | @item C-x v s @var{name} @key{RET} | |
1688 | Define the last saved versions of every registered file in or under the | |
1689 | current directory as a snapshot named @var{name} | |
1690 | (@code{vc-create-snapshot}). | |
1691 | ||
1692 | @kindex C-x v r | |
1693 | @findex vc-retrieve-snapshot | |
1694 | @item C-x v r @var{name} @key{RET} | |
1695 | For all registered files at or below the current directory level, select | |
1696 | whatever versions correspond to the snapshot @var{name} | |
1697 | (@code{vc-retrieve-snapshot}). | |
1698 | ||
1699 | This command reports an error if any files are locked at or below the | |
1700 | current directory, without changing anything; this is to avoid | |
1701 | overwriting work in progress. | |
1702 | @end table | |
1703 | ||
1704 | A snapshot uses a very small amount of resources---just enough to record | |
1705 | the list of file names and which version belongs to the snapshot. Thus, | |
1706 | you need not hesitate to create snapshots whenever they are useful. | |
1707 | ||
1708 | You can give a snapshot name as an argument to @kbd{C-x v =} or | |
1709 | @kbd{C-x v ~} (@pxref{Old Versions}). Thus, you can use it to compare a | |
1710 | snapshot against the current files, or two snapshots against each other, | |
1711 | or a snapshot against a named version. | |
1712 | ||
1713 | @node Snapshot Caveats | |
1714 | @subsubsection Snapshot Caveats | |
1715 | ||
1716 | @cindex named configurations (RCS) | |
1717 | VC's snapshot facilities are modeled on RCS's named-configuration | |
1718 | support. They use RCS's native facilities for this, so under VC | |
1719 | snapshots made using RCS are visible even when you bypass VC. | |
1720 | ||
1721 | @c worded verbosely to avoid overfull hbox. | |
1722 | For SCCS, VC implements snapshots itself. The files it uses contain | |
1723 | name/file/version-number triples. These snapshots are visible only | |
1724 | through VC. | |
1725 | ||
1726 | A snapshot is a set of checked-in versions. So make sure that all the | |
1727 | files are checked in and not locked when you make a snapshot. | |
1728 | ||
1729 | File renaming and deletion can create some difficulties with snapshots. | |
1730 | This is not a VC-specific problem, but a general design issue in version | |
1731 | control systems that no one has solved very well yet. | |
1732 | ||
1733 | If you rename a registered file, you need to rename its master along | |
1734 | with it (the command @code{vc-rename-file} does this automatically). If | |
1735 | you are using SCCS, you must also update the records of the snapshot, to | |
1736 | mention the file by its new name (@code{vc-rename-file} does this, | |
1737 | too). An old snapshot that refers to a master file that no longer | |
1738 | exists under the recorded name is invalid; VC can no longer retrieve | |
1739 | it. It would be beyond the scope of this manual to explain enough about | |
1740 | RCS and SCCS to explain how to update the snapshots by hand. | |
1741 | ||
1742 | Using @code{vc-rename-file} makes the snapshot remain valid for | |
1743 | retrieval, but it does not solve all problems. For example, some of the | |
1744 | files in the program probably refer to others by name. At the very | |
1745 | least, the makefile probably mentions the file that you renamed. If you | |
1746 | retrieve an old snapshot, the renamed file is retrieved under its new | |
1747 | name, which is not the name that the makefile expects. So the program | |
1748 | won't really work as retrieved. | |
1749 | ||
1750 | @node Miscellaneous VC | |
1751 | @subsection Miscellaneous Commands and Features of VC | |
1752 | ||
1753 | This section explains the less-frequently-used features of VC. | |
1754 | ||
1755 | @menu | |
1756 | * Change Logs and VC:: Generating a change log file from log entries. | |
1757 | * Renaming and VC:: A command to rename both the source and master | |
1758 | file correctly. | |
1759 | * Version Headers:: Inserting version control headers into working files. | |
1760 | @end menu | |
1761 | ||
1762 | @node Change Logs and VC | |
1763 | @subsubsection Change Logs and VC | |
1764 | ||
1765 | If you use RCS or CVS for a program and also maintain a change log | |
1766 | file for it (@pxref{Change Log}), you can generate change log entries | |
1767 | automatically from the version control log entries: | |
1768 | ||
1769 | @table @kbd | |
1770 | @item C-x v a | |
1771 | @kindex C-x v a | |
1772 | @findex vc-update-change-log | |
1773 | Visit the current directory's change log file and, for registered files | |
1774 | in that directory, create new entries for versions checked in since the | |
1775 | most recent entry in the change log file. | |
1776 | (@code{vc-update-change-log}). | |
1777 | ||
1778 | This command works with RCS or CVS only, not with SCCS. | |
1779 | ||
1780 | @item C-u C-x v a | |
1781 | As above, but only find entries for the current buffer's file. | |
1782 | ||
1783 | @item M-1 C-x v a | |
1784 | As above, but find entries for all the currently visited files that are | |
1785 | maintained with version control. This works only with RCS, and it puts | |
1786 | all entries in the log for the default directory, which may not be | |
1787 | appropriate. | |
1788 | @end table | |
1789 | ||
1790 | For example, suppose the first line of @file{ChangeLog} is dated | |
1791 | 1999-04-10, and that the only check-in since then was by Nathaniel | |
1792 | Bowditch to @file{rcs2log} on 1999-05-22 with log text @samp{Ignore log | |
1793 | messages that start with `#'.}. Then @kbd{C-x v a} visits | |
1794 | @file{ChangeLog} and inserts text like this: | |
1795 | ||
1796 | @iftex | |
1797 | @medbreak | |
1798 | @end iftex | |
1799 | @smallexample | |
1800 | @group | |
1801 | 1999-05-22 Nathaniel Bowditch <nat@@apn.org> | |
1802 | ||
1803 | * rcs2log: Ignore log messages that start with `#'. | |
1804 | @end group | |
1805 | @end smallexample | |
1806 | @iftex | |
1807 | @medbreak | |
1808 | @end iftex | |
1809 | ||
1810 | @noindent | |
1811 | You can then edit the new change log entry further as you wish. | |
1812 | ||
1813 | Unfortunately, timestamps in ChangeLog files are only dates, so some | |
1814 | of the new change log entry may duplicate what's already in ChangeLog. | |
1815 | You will have to remove these duplicates by hand. | |
1816 | ||
1817 | Normally, the log entry for file @file{foo} is displayed as @samp{* | |
1818 | foo: @var{text of log entry}}. The @samp{:} after @file{foo} is omitted | |
1819 | if the text of the log entry starts with @w{@samp{(@var{functionname}): | |
1820 | }}. For example, if the log entry for @file{vc.el} is | |
1821 | @samp{(vc-do-command): Check call-process status.}, then the text in | |
1822 | @file{ChangeLog} looks like this: | |
1823 | ||
1824 | @iftex | |
1825 | @medbreak | |
1826 | @end iftex | |
1827 | @smallexample | |
1828 | @group | |
1829 | 1999-05-06 Nathaniel Bowditch <nat@@apn.org> | |
1830 | ||
1831 | * vc.el (vc-do-command): Check call-process status. | |
1832 | @end group | |
1833 | @end smallexample | |
1834 | @iftex | |
1835 | @medbreak | |
1836 | @end iftex | |
1837 | ||
1838 | When @kbd{C-x v a} adds several change log entries at once, it groups | |
1839 | related log entries together if they all are checked in by the same | |
1840 | author at nearly the same time. If the log entries for several such | |
1841 | files all have the same text, it coalesces them into a single entry. | |
1842 | For example, suppose the most recent check-ins have the following log | |
1843 | entries: | |
1844 | ||
1845 | @flushleft | |
1846 | @bullet{} For @file{vc.texinfo}: @samp{Fix expansion typos.} | |
1847 | @bullet{} For @file{vc.el}: @samp{Don't call expand-file-name.} | |
1848 | @bullet{} For @file{vc-hooks.el}: @samp{Don't call expand-file-name.} | |
1849 | @end flushleft | |
1850 | ||
1851 | @noindent | |
1852 | They appear like this in @file{ChangeLog}: | |
1853 | ||
1854 | @iftex | |
1855 | @medbreak | |
1856 | @end iftex | |
1857 | @smallexample | |
1858 | @group | |
1859 | 1999-04-01 Nathaniel Bowditch <nat@@apn.org> | |
1860 | ||
1861 | * vc.texinfo: Fix expansion typos. | |
1862 | ||
1863 | * vc.el, vc-hooks.el: Don't call expand-file-name. | |
1864 | @end group | |
1865 | @end smallexample | |
1866 | @iftex | |
1867 | @medbreak | |
1868 | @end iftex | |
1869 | ||
1870 | Normally, @kbd{C-x v a} separates log entries by a blank line, but you | |
1871 | can mark several related log entries to be clumped together (without an | |
1872 | intervening blank line) by starting the text of each related log entry | |
1873 | with a label of the form @w{@samp{@{@var{clumpname}@} }}. The label | |
1874 | itself is not copied to @file{ChangeLog}. For example, suppose the log | |
1875 | entries are: | |
1876 | ||
1877 | @flushleft | |
1878 | @bullet{} For @file{vc.texinfo}: @samp{@{expand@} Fix expansion typos.} | |
1879 | @bullet{} For @file{vc.el}: @samp{@{expand@} Don't call expand-file-name.} | |
1880 | @bullet{} For @file{vc-hooks.el}: @samp{@{expand@} Don't call expand-file-name.} | |
1881 | @end flushleft | |
1882 | ||
1883 | @noindent | |
1884 | Then the text in @file{ChangeLog} looks like this: | |
1885 | ||
1886 | @iftex | |
1887 | @medbreak | |
1888 | @end iftex | |
1889 | @smallexample | |
1890 | @group | |
1891 | 1999-04-01 Nathaniel Bowditch <nat@@apn.org> | |
1892 | ||
1893 | * vc.texinfo: Fix expansion typos. | |
1894 | * vc.el, vc-hooks.el: Don't call expand-file-name. | |
1895 | @end group | |
1896 | @end smallexample | |
1897 | @iftex | |
1898 | @medbreak | |
1899 | @end iftex | |
1900 | ||
1901 | A log entry whose text begins with @samp{#} is not copied to | |
1902 | @file{ChangeLog}. For example, if you merely fix some misspellings in | |
1903 | comments, you can log the change with an entry beginning with @samp{#} | |
1904 | to avoid putting such trivia into @file{ChangeLog}. | |
1905 | ||
1906 | @node Renaming and VC | |
1907 | @subsubsection Renaming VC Work Files and Master Files | |
1908 | ||
1909 | @findex vc-rename-file | |
1910 | When you rename a registered file, you must also rename its master | |
1911 | file correspondingly to get proper results. Use @code{vc-rename-file} | |
1912 | to rename the source file as you specify, and rename its master file | |
1913 | accordingly. It also updates any snapshots (@pxref{Snapshots}) that | |
1914 | mention the file, so that they use the new name; despite this, the | |
1915 | snapshot thus modified may not completely work (@pxref{Snapshot | |
1916 | Caveats}). | |
1917 | ||
1918 | You cannot use @code{vc-rename-file} on a file that is locked by | |
1919 | someone else. | |
1920 | ||
1921 | @node Version Headers | |
1922 | @subsubsection Inserting Version Control Headers | |
1923 | ||
1924 | Sometimes it is convenient to put version identification strings | |
1925 | directly into working files. Certain special strings called | |
1926 | @dfn{version headers} are replaced in each successive version by the | |
1927 | number of that version. | |
1928 | ||
1929 | If you are using RCS, and version headers are present in your working | |
1930 | files, Emacs can use them to determine the current version and the | |
1931 | locking state of the files. This is more reliable than referring to the | |
1932 | master files, which is done when there are no version headers. Note | |
1933 | that in a multi-branch environment, version headers are necessary to | |
1934 | make VC behave correctly (@pxref{Multi-User Branching}). | |
1935 | ||
1936 | Searching for version headers is controlled by the variable | |
1937 | @code{vc-consult-headers}. If it is non-@code{nil}, Emacs searches for | |
1938 | headers to determine the version number you are editing. Setting it to | |
1939 | @code{nil} disables this feature. | |
1940 | ||
1941 | @kindex C-x v h | |
1942 | @findex vc-insert-headers | |
1943 | You can use the @kbd{C-x v h} command (@code{vc-insert-headers}) to | |
1944 | insert a suitable header string. | |
1945 | ||
1946 | @table @kbd | |
1947 | @item C-x v h | |
1948 | Insert headers in a file for use with your version-control system. | |
1949 | @end table | |
1950 | ||
1951 | @vindex vc-header-alist | |
1952 | The default header string is @samp{@w{$}Id$} for RCS and | |
1953 | @samp{@w{%}W%} for SCCS. You can specify other headers to insert by | |
1954 | setting the variable @code{vc-header-alist}. Its value is a list of | |
1955 | elements of the form @code{(@var{program} . @var{string})} where | |
1956 | @var{program} is @code{RCS} or @code{SCCS} and @var{string} is the | |
1957 | string to use. | |
1958 | ||
1959 | Instead of a single string, you can specify a list of strings; then | |
1960 | each string in the list is inserted as a separate header on a line of | |
1961 | its own. | |
1962 | ||
1963 | It is often necessary to use ``superfluous'' backslashes when writing | |
1964 | the strings that you put in this variable. This is to prevent the | |
1965 | string in the constant from being interpreted as a header itself if the | |
1966 | Emacs Lisp file containing it is maintained with version control. | |
1967 | ||
1968 | @vindex vc-comment-alist | |
1969 | Each header is inserted surrounded by tabs, inside comment delimiters, | |
1970 | on a new line at point. Normally the ordinary comment | |
1971 | start and comment end strings of the current mode are used, but for | |
1972 | certain modes, there are special comment delimiters for this purpose; | |
1973 | the variable @code{vc-comment-alist} specifies them. Each element of | |
1974 | this list has the form @code{(@var{mode} @var{starter} @var{ender})}. | |
1975 | ||
1976 | @vindex vc-static-header-alist | |
1977 | The variable @code{vc-static-header-alist} specifies further strings | |
1978 | to add based on the name of the buffer. Its value should be a list of | |
1979 | elements of the form @code{(@var{regexp} . @var{format})}. Whenever | |
1980 | @var{regexp} matches the buffer name, @var{format} is inserted as part | |
1981 | of the header. A header line is inserted for each element that matches | |
1982 | the buffer name, and for each string specified by | |
1983 | @code{vc-header-alist}. The header line is made by processing the | |
1984 | string from @code{vc-header-alist} with the format taken from the | |
1985 | element. The default value for @code{vc-static-header-alist} is as follows: | |
1986 | ||
1987 | @example | |
1988 | @group | |
1989 | (("\\.c$" . | |
1990 | "\n#ifndef lint\nstatic char vcid[] = \"\%s\";\n\ | |
1991 | #endif /* lint */\n")) | |
1992 | @end group | |
1993 | @end example | |
1994 | ||
1995 | @noindent | |
1996 | It specifies insertion of text of this form: | |
1997 | ||
1998 | @example | |
1999 | @group | |
2000 | ||
2001 | #ifndef lint | |
2002 | static char vcid[] = "@var{string}"; | |
2003 | #endif /* lint */ | |
2004 | @end group | |
2005 | @end example | |
2006 | ||
2007 | @noindent | |
2008 | Note that the text above starts with a blank line. | |
2009 | ||
2010 | If you use more than one version header in a file, put them close | |
2011 | together in the file. The mechanism in @code{revert-buffer} that | |
2012 | preserves markers may not handle markers positioned between two version | |
2013 | headers. | |
2014 | ||
2015 | @node Customizing VC | |
2016 | @subsection Customizing VC | |
2017 | ||
2018 | There are many ways of customizing VC. The options you can set fall | |
2019 | into four categories, described in the following sections. | |
2020 | ||
4f36dd62 DL |
2021 | @vindex vc-ignore-vc-files |
2022 | @cindex Version control, deactivating | |
2023 | In addition, it is possible to turn VC on and off generally by setting | |
2024 | the variable @code{vc-ignore-vc-files}. Normally VC will notice the | |
2025 | presence of version control on a file you visit and automatically invoke | |
2026 | the relevant program to check the file's state. Change | |
2027 | @code{vc-ignore-vc-files} if this isn't the right thing, for instance, | |
2028 | if you edit files under version control but don't have the relevant | |
2029 | version control programs available. | |
2030 | ||
6bf7aab6 DL |
2031 | @menu |
2032 | * Backend Options:: Customizing the back-end to your needs. | |
2033 | * VC Workfile Handling:: Various options concerning working files. | |
2034 | * VC Status Retrieval:: How VC finds the version control status of a file, | |
2035 | and how to customize this. | |
2036 | * VC Command Execution:: Which commands VC should run, and how. | |
2037 | @end menu | |
2038 | ||
2039 | @node Backend Options | |
2040 | @subsubsection Options for VC Backends | |
2041 | ||
2042 | @cindex backend options (VC) | |
2043 | @cindex locking under version control | |
2044 | You can tell RCS and CVS whether to use locking for a file or not | |
2045 | (@pxref{VC Concepts}, for a description of locking). VC automatically | |
2046 | recognizes what you have chosen, and behaves accordingly. | |
2047 | ||
2048 | @cindex non-strict locking (RCS) | |
2049 | @cindex locking, non-strict (RCS) | |
2050 | For RCS, the default is to use locking, but there is a mode called | |
2051 | @dfn{non-strict locking} in which you can check-in changes without | |
2052 | locking the file first. Use @samp{rcs -U} to switch to non-strict | |
2053 | locking for a particular file, see the @samp{rcs} manpage for details. | |
2054 | ||
2055 | @cindex locking (CVS) | |
2056 | Under CVS, the default is not to use locking; anyone can change a work | |
2057 | file at any time. However, there are ways to restrict this, resulting | |
2058 | in behavior that resembles locking. | |
2059 | ||
2060 | @cindex CVSREAD environment variable (CVS) | |
2061 | For one thing, you can set the @code{CVSREAD} environment variable to | |
2062 | an arbitrary value. If this variable is defined, CVS makes your work | |
2063 | files read-only by default. In Emacs, you must type @kbd{C-x C-q} to | |
2064 | make the file writeable, so that editing works in fact similar as if | |
2065 | locking was used. Note however, that no actual locking is performed, so | |
2066 | several users can make their files writeable at the same time. When | |
2067 | setting @code{CVSREAD} for the first time, make sure to check out all | |
2068 | your modules anew, so that the file protections are set correctly. | |
2069 | ||
2070 | @cindex cvs watch feature | |
2071 | @cindex watching files (CVS) | |
2072 | Another way to achieve something similar to locking is to use the | |
2073 | @dfn{watch} feature of CVS. If a file is being watched, CVS makes it | |
2074 | read-only by default, and you must also use @kbd{C-x C-q} in Emacs to | |
2075 | make it writable. VC calls @code{cvs edit} to make the file writeable, | |
2076 | and CVS takes care to notify other developers of the fact that you | |
2077 | intend to change the file. See the CVS documentation for details on | |
2078 | using the watch feature. | |
2079 | ||
2080 | @vindex vc-handle-cvs | |
2081 | You can turn off use of VC for CVS-managed files by setting the | |
2082 | variable @code{vc-handle-cvs} to @code{nil}. If you do this, Emacs | |
2083 | treats these files as if they were not registered, and the VC commands | |
2084 | are not available for them. You must do all CVS operations manually. | |
2085 | ||
2086 | @node VC Workfile Handling | |
2087 | @subsubsection VC Workfile Handling | |
2088 | ||
2089 | @vindex vc-make-backup-files | |
2090 | Emacs normally does not save backup files for source files that are | |
2091 | maintained with version control. If you want to make backup files even | |
2092 | for files that use version control, set the variable | |
2093 | @code{vc-make-backup-files} to a non-@code{nil} value. | |
2094 | ||
2095 | @vindex vc-keep-workfiles | |
2096 | Normally the work file exists all the time, whether it is locked or | |
2097 | not. If you set @code{vc-keep-workfiles} to @code{nil}, then checking | |
2098 | in a new version with @kbd{C-x C-q} deletes the work file; but any | |
2099 | attempt to visit the file with Emacs creates it again. (With CVS, work | |
2100 | files are always kept.) | |
2101 | ||
2102 | @vindex vc-follow-symlinks | |
2103 | Editing a version-controlled file through a symbolic link can be | |
2104 | dangerous. It bypasses the version control system---you can edit the | |
2105 | file without locking it, and fail to check your changes in. Also, | |
2106 | your changes might overwrite those of another user. To protect against | |
2107 | this, VC checks each symbolic link that you visit, to see if it points | |
2108 | to a file under version control. | |
2109 | ||
2110 | The variable @code{vc-follow-symlinks} controls what to do when a | |
2111 | symbolic link points to a version-controlled file. If it is @code{nil}, | |
2112 | VC only displays a warning message. If it is @code{t}, VC automatically | |
2113 | follows the link, and visits the real file instead, telling you about | |
2114 | this in the echo area. If the value is @code{ask} (the default), VC | |
2115 | asks you each time whether to follow the link. | |
2116 | ||
2117 | @node VC Status Retrieval | |
2118 | @subsubsection VC Status Retrieval | |
2119 | @c There is no need to tell users about vc-master-templates. | |
2120 | ||
2121 | When deducing the locked/unlocked state of a file, VC first looks for | |
2122 | an RCS version header string in the file (@pxref{Version Headers}). If | |
2123 | there is no header string, or if you are using SCCS, VC normally looks | |
2124 | at the file permissions of the work file; this is fast. But there might | |
2125 | be situations when the file permissions cannot be trusted. In this case | |
2126 | the master file has to be consulted, which is rather expensive. Also | |
2127 | the master file can only tell you @emph{if} there's any lock on the | |
2128 | file, but not whether your work file really contains that locked | |
2129 | version. | |
2130 | ||
2131 | @vindex vc-consult-headers | |
2132 | You can tell VC not to use version headers to determine lock status by | |
2133 | setting @code{vc-consult-headers} to @code{nil}. VC then always uses | |
2134 | the file permissions (if it can trust them), or else checks the master | |
2135 | file. | |
2136 | ||
2137 | @vindex vc-mistrust-permissions | |
2138 | You can specify the criterion for whether to trust the file | |
2139 | permissions by setting the variable @code{vc-mistrust-permissions}. Its | |
2140 | value can be @code{t} (always mistrust the file permissions and check | |
2141 | the master file), @code{nil} (always trust the file permissions), or a | |
2142 | function of one argument which makes the decision. The argument is the | |
2143 | directory name of the @file{RCS}, @file{CVS} or @file{SCCS} | |
2144 | subdirectory. A non-@code{nil} value from the function says to mistrust | |
2145 | the file permissions. If you find that the file permissions of work | |
2146 | files are changed erroneously, set @code{vc-mistrust-permissions} to | |
2147 | @code{t}. Then VC always checks the master file to determine the file's | |
2148 | status. | |
2149 | ||
2150 | @node VC Command Execution | |
2151 | @subsubsection VC Command Execution | |
2152 | ||
2153 | @vindex vc-suppress-confirm | |
2154 | If @code{vc-suppress-confirm} is non-@code{nil}, then @kbd{C-x C-q} | |
2155 | and @kbd{C-x v i} can save the current buffer without asking, and | |
2156 | @kbd{C-x v u} also operates without asking for confirmation. (This | |
2157 | variable does not affect @kbd{C-x v c}; that operation is so drastic | |
2158 | that it should always ask for confirmation.) | |
2159 | ||
2160 | @vindex vc-command-messages | |
2161 | VC mode does much of its work by running the shell commands for RCS, | |
2162 | CVS and SCCS. If @code{vc-command-messages} is non-@code{nil}, VC | |
2163 | displays messages to indicate which shell commands it runs, and | |
2164 | additional messages when the commands finish. | |
2165 | ||
2166 | @vindex vc-path | |
2167 | You can specify additional directories to search for version control | |
2168 | programs by setting the variable @code{vc-path}. These directories are | |
2169 | searched before the usual search path. But the proper files are usually | |
2170 | found automatically. | |
2171 | ||
2172 | @node Directories | |
2173 | @section File Directories | |
2174 | ||
2175 | @cindex file directory | |
2176 | @cindex directory listing | |
2177 | The file system groups files into @dfn{directories}. A @dfn{directory | |
2178 | listing} is a list of all the files in a directory. Emacs provides | |
2179 | commands to create and delete directories, and to make directory | |
2180 | listings in brief format (file names only) and verbose format (sizes, | |
2181 | dates, and authors included). There is also a directory browser called | |
2182 | Dired; see @ref{Dired}. | |
2183 | ||
2184 | @table @kbd | |
2185 | @item C-x C-d @var{dir-or-pattern} @key{RET} | |
2186 | Display a brief directory listing (@code{list-directory}). | |
2187 | @item C-u C-x C-d @var{dir-or-pattern} @key{RET} | |
2188 | Display a verbose directory listing. | |
2189 | @item M-x make-directory @key{RET} @var{dirname} @key{RET} | |
2190 | Create a new directory named @var{dirname}. | |
2191 | @item M-x delete-directory @key{RET} @var{dirname} @key{RET} | |
2192 | Delete the directory named @var{dirname}. It must be empty, | |
2193 | or you get an error. | |
2194 | @end table | |
2195 | ||
2196 | @findex list-directory | |
2197 | @kindex C-x C-d | |
2198 | The command to display a directory listing is @kbd{C-x C-d} | |
2199 | (@code{list-directory}). It reads using the minibuffer a file name | |
2200 | which is either a directory to be listed or a wildcard-containing | |
2201 | pattern for the files to be listed. For example, | |
2202 | ||
2203 | @example | |
2204 | C-x C-d /u2/emacs/etc @key{RET} | |
2205 | @end example | |
2206 | ||
2207 | @noindent | |
2208 | lists all the files in directory @file{/u2/emacs/etc}. Here is an | |
2209 | example of specifying a file name pattern: | |
2210 | ||
2211 | @example | |
2212 | C-x C-d /u2/emacs/src/*.c @key{RET} | |
2213 | @end example | |
2214 | ||
2215 | Normally, @kbd{C-x C-d} prints a brief directory listing containing | |
2216 | just file names. A numeric argument (regardless of value) tells it to | |
2217 | make a verbose listing including sizes, dates, and authors (like | |
2218 | @samp{ls -l}). | |
2219 | ||
2220 | @vindex list-directory-brief-switches | |
2221 | @vindex list-directory-verbose-switches | |
2222 | The text of a directory listing is obtained by running @code{ls} in an | |
2223 | inferior process. Two Emacs variables control the switches passed to | |
2224 | @code{ls}: @code{list-directory-brief-switches} is a string giving the | |
2225 | switches to use in brief listings (@code{"-CF"} by default), and | |
2226 | @code{list-directory-verbose-switches} is a string giving the switches to | |
2227 | use in a verbose listing (@code{"-l"} by default). | |
2228 | ||
2229 | @node Comparing Files | |
2230 | @section Comparing Files | |
2231 | @cindex comparing files | |
2232 | ||
2233 | @findex diff | |
2234 | @vindex diff-switches | |
2235 | The command @kbd{M-x diff} compares two files, displaying the | |
2236 | differences in an Emacs buffer named @samp{*Diff*}. It works by running | |
2237 | the @code{diff} program, using options taken from the variable | |
2238 | @code{diff-switches}, whose value should be a string. | |
2239 | ||
2240 | The buffer @samp{*Diff*} has Compilation mode as its major mode, so | |
2241 | you can use @kbd{C-x `} to visit successive changed locations in the two | |
2242 | source files. You can also move to a particular hunk of changes and | |
2243 | type @key{RET} or @kbd{C-c C-c}, or click @kbd{Mouse-2} on it, to move | |
2244 | to the corresponding source location. You can also use the other | |
2245 | special commands of Compilation mode: @key{SPC} and @key{DEL} for | |
2246 | scrolling, and @kbd{M-p} and @kbd{M-n} for cursor motion. | |
2247 | @xref{Compilation}. | |
2248 | ||
2249 | @findex diff-backup | |
2250 | The command @kbd{M-x diff-backup} compares a specified file with its most | |
2251 | recent backup. If you specify the name of a backup file, | |
2252 | @code{diff-backup} compares it with the source file that it is a backup | |
2253 | of. | |
2254 | ||
2255 | @findex compare-windows | |
2256 | The command @kbd{M-x compare-windows} compares the text in the current | |
2257 | window with that in the next window. Comparison starts at point in each | |
2258 | window, and each starting position is pushed on the mark ring in its | |
2259 | respective buffer. Then point moves forward in each window, a character | |
2260 | at a time, until a mismatch between the two windows is reached. Then | |
2261 | the command is finished. For more information about windows in Emacs, | |
2262 | @ref{Windows}. | |
2263 | ||
2264 | @vindex compare-ignore-case | |
2265 | With a numeric argument, @code{compare-windows} ignores changes in | |
2266 | whitespace. If the variable @code{compare-ignore-case} is | |
2267 | non-@code{nil}, it ignores differences in case as well. | |
2268 | ||
2269 | See also @ref{Emerge}, for convenient facilities for merging two | |
2270 | similar files. | |
2271 | ||
2272 | @node Misc File Ops | |
2273 | @section Miscellaneous File Operations | |
2274 | ||
2275 | Emacs has commands for performing many other operations on files. | |
2276 | All operate on one file; they do not accept wildcard file names. | |
2277 | ||
2278 | @findex view-file | |
2279 | @cindex viewing | |
2280 | @cindex View mode | |
2281 | @cindex mode, View | |
2282 | @kbd{M-x view-file} allows you to scan or read a file by sequential | |
2283 | screenfuls. It reads a file name argument using the minibuffer. After | |
2284 | reading the file into an Emacs buffer, @code{view-file} displays the | |
2285 | beginning. You can then type @key{SPC} to scroll forward one windowful, | |
2286 | or @key{DEL} to scroll backward. Various other commands are provided | |
2287 | for moving around in the file, but none for changing it; type @kbd{?} | |
2288 | while viewing for a list of them. They are mostly the same as normal | |
2289 | Emacs cursor motion commands. To exit from viewing, type @kbd{q}. | |
2290 | The commands for viewing are defined by a special major mode called View | |
2291 | mode. | |
2292 | ||
2293 | A related command, @kbd{M-x view-buffer}, views a buffer already present | |
2294 | in Emacs. @xref{Misc Buffer}. | |
2295 | ||
2296 | @findex insert-file | |
2297 | @kbd{M-x insert-file} inserts a copy of the contents of the specified | |
2298 | file into the current buffer at point, leaving point unchanged before the | |
2299 | contents and the mark after them. | |
2300 | ||
2301 | @findex write-region | |
2302 | @kbd{M-x write-region} is the inverse of @kbd{M-x insert-file}; it | |
2303 | copies the contents of the region into the specified file. @kbd{M-x | |
2304 | append-to-file} adds the text of the region to the end of the specified | |
2305 | file. @xref{Accumulating Text}. | |
2306 | ||
2307 | @findex delete-file | |
2308 | @cindex deletion (of files) | |
2309 | @kbd{M-x delete-file} deletes the specified file, like the @code{rm} | |
2310 | command in the shell. If you are deleting many files in one directory, it | |
2311 | may be more convenient to use Dired (@pxref{Dired}). | |
2312 | ||
2313 | @findex rename-file | |
2314 | @kbd{M-x rename-file} reads two file names @var{old} and @var{new} using | |
2315 | the minibuffer, then renames file @var{old} as @var{new}. If a file named | |
2316 | @var{new} already exists, you must confirm with @kbd{yes} or renaming is not | |
2317 | done; this is because renaming causes the old meaning of the name @var{new} | |
2318 | to be lost. If @var{old} and @var{new} are on different file systems, the | |
2319 | file @var{old} is copied and deleted. | |
2320 | ||
2321 | @findex add-name-to-file | |
2322 | The similar command @kbd{M-x add-name-to-file} is used to add an | |
2323 | additional name to an existing file without removing its old name. | |
2324 | The new name must belong on the same file system that the file is on. | |
2325 | ||
2326 | @findex copy-file | |
2327 | @cindex copying files | |
2328 | @kbd{M-x copy-file} reads the file @var{old} and writes a new file named | |
2329 | @var{new} with the same contents. Confirmation is required if a file named | |
2330 | @var{new} already exists, because copying has the consequence of overwriting | |
2331 | the old contents of the file @var{new}. | |
2332 | ||
2333 | @findex make-symbolic-link | |
2334 | @kbd{M-x make-symbolic-link} reads two file names @var{target} and | |
2335 | @var{linkname}, then creates a symbolic link named @var{linkname} and | |
2336 | pointing at @var{target}. The effect is that future attempts to open file | |
2337 | @var{linkname} will refer to whatever file is named @var{target} at the | |
2338 | time the opening is done, or will get an error if the name @var{target} is | |
2339 | not in use at that time. This command does not expand the argument | |
2340 | @var{target}, so that it allows you to specify a relative name | |
2341 | as the target of the link. | |
2342 | ||
2343 | Confirmation is required when creating the link if @var{linkname} is | |
2344 | in use. Note that not all systems support symbolic links. | |
2345 | ||
2346 | @node Compressed Files | |
2347 | @section Accessing Compressed Files | |
2348 | @cindex compression | |
2349 | @cindex uncompression | |
2350 | @cindex Auto Compression mode | |
2351 | @cindex mode, Auto Compression | |
2352 | @pindex gzip | |
2353 | ||
2354 | @findex auto-compression-mode | |
259a88ca | 2355 | @vindex auto-compression-mode |
6bf7aab6 DL |
2356 | Emacs comes with a library that can automatically uncompress |
2357 | compressed files when you visit them, and automatically recompress them | |
2358 | if you alter them and save them. To enable this feature, type the | |
259a88ca DL |
2359 | command @kbd{M-x auto-compression-mode}. You can enable it permanently |
2360 | by customizing the option @var{auto-compression-mode}. | |
6bf7aab6 DL |
2361 | |
2362 | When automatic compression (which implies automatic uncompression as | |
2363 | well) is enabled, Emacs recognizes compressed files by their file names. | |
2364 | File names ending in @samp{.gz} indicate a file compressed with | |
2365 | @code{gzip}. Other endings indicate other compression programs. | |
2366 | ||
2367 | Automatic uncompression and compression apply to all the operations in | |
2368 | which Emacs uses the contents of a file. This includes visiting it, | |
2369 | saving it, inserting its contents into a buffer, loading it, and byte | |
2370 | compiling it. | |
2371 | ||
259a88ca DL |
2372 | @node File Archives |
2373 | @section File Archives | |
2374 | @cindex mode, tar | |
2375 | @cindex Tar mode | |
2376 | @cindex Archive mode | |
2377 | @cindex mode, archive | |
2378 | @cindex @code{arc} | |
2379 | @cindex @code{jar} | |
2380 | @cindex @code{zip} | |
2381 | @cindex @code{lzh} | |
2382 | @cindex @code{zoo} | |
2383 | @pindex tar | |
2384 | @pindex arc | |
2385 | @pindex jar | |
2386 | @pindex zip | |
2387 | @pindex lzh | |
2388 | @pindex zoo | |
2389 | ||
2390 | If you visit a file with extension @samp{.tar}, it is assumed to be an | |
2391 | `archive' made by the @code{tar} program and it is viewed in a Tar mode | |
2392 | buffer. This provides a Dired-like listing of the contents. | |
2393 | @xref{Dired}. You can move around the component files as in Dired to | |
2394 | visit and manipulate them. | |
2395 | ||
2396 | The keys @kbd{e}, @kbd{f} and @kbd{RET} all extract a component file | |
2397 | into its own buffer. You can edit it there and when you save the buffer | |
2398 | the edited version will replace the version in the Tar buffer. @var{v} | |
2399 | extracts a file into a buffer in View mode. @kbd{d} marks a file for | |
2400 | deletion when you later use @kbd{x}, as in Dired. @kbd{C} copies a file | |
2401 | from the archive to disk and @kbd{R} renames a file. | |
2402 | ||
2403 | Saving the Tar buffer writes a new version of the archive to disk with | |
2404 | the changes you made to the components. | |
2405 | ||
2406 | If you enable Auto Compression mode (@pxref{Compressed Files}), then Tar | |
2407 | mode will be used also for compressed archives in files with extensions | |
2408 | @samp{.tgz}, @code{.tar.Z} and @code{.tar.gz}. | |
2409 | ||
7ed32bd8 DL |
2410 | It is not necessary to have the @code{tar} program available to use Tar |
2411 | mode or Archive mode---Emacs reads the archives directly. | |
2412 | ||
259a88ca DL |
2413 | @cindex @code{arc} |
2414 | @cindex @code{jar} | |
2415 | @cindex @code{zip} | |
2416 | @cindex @code{lzh} | |
2417 | @cindex @code{zoo} | |
2418 | @pindex tar | |
2419 | @pindex arc | |
2420 | @pindex jar | |
2421 | @pindex zip | |
2422 | @pindex lzh | |
2423 | @pindex zoo | |
2424 | @cindex Java class archives | |
2425 | A separate but similar Archive mode, is used for archives produced by | |
2426 | the programs @code{arc}, @code{zip}, @code{lzh} and @code{zoo} which | |
2427 | have extensions corresponding to the program names. These archiving | |
2428 | programs are typically used on MS-DOS and MS-Windows systems. Java | |
2429 | class archives with extension @samp{.jar} are also recognized. The | |
2430 | keybindings in Archive mode are similar to those in Tar mode. | |
2431 | ||
7ed32bd8 DL |
2432 | Unlike Tar mode, Archive mode runs the appropriate program to unpack and |
2433 | repack archives. Details of the program names and their options can be | |
2434 | set in the `Archive' Customize group. | |
259a88ca | 2435 | |
6bf7aab6 DL |
2436 | @node Remote Files |
2437 | @section Remote Files | |
2438 | ||
2439 | @cindex FTP | |
2440 | @cindex remote file access | |
2441 | You can refer to files on other machines using a special file name syntax: | |
2442 | ||
2443 | @example | |
2444 | @group | |
2445 | /@var{host}:@var{filename} | |
2446 | /@var{user}@@@var{host}:@var{filename} | |
4f36dd62 | 2447 | /@var{user}@@@var{host}#@var{port}:@var{filename} |
6bf7aab6 DL |
2448 | @end group |
2449 | @end example | |
2450 | ||
2451 | @noindent | |
2452 | When you do this, Emacs uses the FTP program to read and write files on | |
2453 | the specified host. It logs in through FTP using your user name or the | |
2454 | name @var{user}. It may ask you for a password from time to time; this | |
4f36dd62 DL |
2455 | is used for logging in on @var{host}. The form using @var{port} allows |
2456 | you to access servers running on a non-default TCP port. | |
6bf7aab6 DL |
2457 | |
2458 | @cindex ange-ftp | |
2459 | @vindex ange-ftp-default-user | |
2460 | Normally, if you do not specify a user name in a remote file name, | |
2461 | that means to use your own user name. But if you set the variable | |
2462 | @code{ange-ftp-default-user} to a string, that string is used instead. | |
2463 | (The Emacs package that implements FTP file access is called | |
2464 | @code{ange-ftp}.) | |
2465 | ||
2466 | @vindex file-name-handler-alist | |
4f36dd62 DL |
2467 | You can entirely turn off the FTP file name feature by removing the |
2468 | entries @var{ange-ftp-completion-hook-function} and | |
2469 | @var{ange-ftp-hook-function} from the variable | |
7ed32bd8 DL |
2470 | @code{file-name-handler-alist}. You can turn off the feature in |
2471 | individual cases by quoting the file name with @samp{/:} (@pxref{Quoted | |
2472 | File Names}). | |
6bf7aab6 DL |
2473 | |
2474 | @node Quoted File Names | |
2475 | @section Quoted File Names | |
2476 | ||
2477 | @cindex quoting file names | |
2478 | You can @dfn{quote} an absolute file name to prevent special | |
2479 | characters and syntax in it from having their special effects. | |
2480 | The way to do this is to add @samp{/:} at the beginning. | |
2481 | ||
2482 | For example, you can quote a local file name which appears remote, to | |
2483 | prevent it from being treated as a remote file name. Thus, if you have | |
2484 | a directory named @file{/foo:} and a file named @file{bar} in it, you | |
2485 | can refer to that file in Emacs as @samp{/:/foo:/bar}. | |
2486 | ||
2487 | @samp{/:} can also prevent @samp{~} from being treated as a special | |
2488 | character for a user's home directory. For example, @file{/:/tmp/~hack} | |
2489 | refers to a file whose name is @file{~hack} in directory @file{/tmp}. | |
2490 | ||
2491 | Likewise, quoting with @samp{/:} is one way to enter in the minibuffer | |
2492 | a file name that contains @samp{$}. However, the @samp{/:} must be at | |
2493 | the beginning of the buffer in order to quote @samp{$}. | |
2494 | ||
7ed32bd8 | 2495 | @cindex wildcard characters in file names |
6bf7aab6 DL |
2496 | You can also quote wildcard characters with @samp{/:}, for visiting. |
2497 | For example, @file{/:/tmp/foo*bar} visits the file @file{/tmp/foo*bar}. | |
2498 | However, in most cases you can simply type the wildcard characters for | |
2499 | themselves. For example, if the only file name in @file{/tmp} that | |
2500 | starts with @samp{foo} and ends with @samp{bar} is @file{foo*bar}, then | |
2501 | specifying @file{/tmp/foo*bar} will visit just @file{/tmp/foo*bar}. | |
7ed32bd8 | 2502 | Another way is to specify @file{/tmp/foo[*]bar}. |