Mercurial > hg > xemacs-beta
annotate man/xemacs/files.texi @ 5797:a1808d52a34a
If the position of a window's cached point is deleted, use buffer point instead
src/ChangeLog addition:
2014-06-17 Aidan Kehoe <kehoea@parhasard.net>
* extents.h:
* window.c:
* window.c (unshow_buffer):
* window.c (Fset_window_buffer):
Use extents, rather than markers, for the window buffer point
cache, so that when the text containing that window buffer point
is deleted, the window display code uses the buffer's actual point
instead of the position that the marker had been moved to.
Fixes Michael Heinrich's problem of
http://mid.gmane.org/6zr42uxtf5.fsf@elektra.science-computing.de ,
introduced by Ben's patch of
https://bitbucket.org/xemacs/xemacs/commits/047d37eb70d70f43803 .
| author | Aidan Kehoe <kehoea@parhasard.net> |
|---|---|
| date | Tue, 17 Jun 2014 20:55:45 +0100 |
| parents | 182d01410b8d |
| children |
| rev | line source |
|---|---|
| 428 | 1 |
| 2 @node Files, Buffers, Fixit, Top | |
| 3 @chapter File Handling | |
| 4 @cindex files | |
| 5 | |
| 6 The basic unit of stored data in Unix is the @dfn{file}. To edit a file, | |
| 7 you must tell Emacs to examine the file and prepare a buffer containing a | |
| 8 copy of the file's text. This is called @dfn{visiting} the file. Editing | |
| 9 commands apply directly to text in the buffer; that is, to the copy inside | |
| 10 Emacs. Your changes appear in the file itself only when you @dfn{save} the | |
| 11 buffer back into the file. | |
| 12 | |
| 741 | 13 @cindex files, remote |
| 14 @cindex remote files | |
| 15 Emacs is also able to handle ``remote files'' which are stored on | |
| 16 other hosts. Not only is Emacs somewhat aware of the special issues | |
| 17 involved with network file systems, but it can also use FTP and ssh (or | |
| 18 rsh) to make local copies of the files, and refresh them on the remote | |
| 19 host automatically when you save the buffer. The FTP interface is | |
| 20 provided by the standard @samp{efs} package @ref{Top, EFS, , efs}. The | |
| 21 ssh/rsh interface is provided by the optional @samp{tramp} package | |
| 22 @ref{Top, TRAMP, , tramp}. These packages attempt to implement all of | |
| 23 the operations described below, making remote file use transparent | |
| 24 (except for unavoidable network delays). | |
| 25 | |
| 428 | 26 In addition to visiting and saving files, Emacs can delete, copy, rename, |
| 27 and append to files, and operate on file directories. | |
| 28 | |
| 29 @menu | |
| 30 * File Names:: How to type and edit file name arguments. | |
| 31 * Visiting:: Visiting a file prepares Emacs to edit the file. | |
| 32 * Saving:: Saving makes your changes permanent. | |
| 33 * Reverting:: Reverting cancels all the changes not saved. | |
| 34 * Auto Save:: Auto Save periodically protects against loss of data. | |
| 35 * Version Control:: Version control systems (RCS and SCCS). | |
| 36 * ListDir:: Listing the contents of a file directory. | |
| 37 * Comparing Files:: Finding where two files differ. | |
| 38 * Dired:: ``Editing'' a directory to delete, rename, etc. | |
| 39 the files in it. | |
| 40 * Misc File Ops:: Other things you can do on files. | |
| 41 @end menu | |
| 42 | |
| 43 @node File Names, Visiting, Files, Files | |
| 44 @section File Names | |
| 45 @cindex file names | |
| 46 | |
| 47 Most Emacs commands that operate on a file require you to specify the | |
| 48 file name. (Saving and reverting are exceptions; the buffer knows which | |
| 49 file name to use for them.) File names are specified in the minibuffer | |
| 50 (@pxref{Minibuffer}). @dfn{Completion} is available, to make it easier to | |
| 51 specify long file names. @xref{Completion}. | |
| 52 | |
| 53 There is always a @dfn{default file name} which is used if you | |
| 54 enter an empty argument by typing just @key{RET}. Normally the default | |
| 55 file name is the name of the file visited in the current buffer; this | |
| 56 makes it easy to operate on that file with any of the Emacs file | |
| 57 commands. | |
| 58 | |
| 741 | 59 The syntax for accessing remote files unfortunately varies depending on |
| 60 the method used. The syntax for using FTP is | |
| 61 @samp{/@var{user}@@@var{remote-host}:@var{path-on-remote-host}}. The | |
| 62 syntax for using ssh is | |
| 63 @samp{/[@var{user}@@@var{remote-host}]@var{path-on-remote-host}}. | |
| 64 | |
| 65 In both cases the @samp{@var{user}@@} portion is optional (it defaults | |
| 66 to your local user name). @var{path-on-remote-host} may use the | |
| 67 @samp{~} notation to indicate @var{user}'s home directory on the remote | |
| 68 host. The default file name will reflect the remote host information. | |
| 69 | |
| 428 | 70 @vindex default-directory |
| 71 Each buffer has a default directory, normally the same as the | |
| 72 directory of the file visited in that buffer. When Emacs reads a file | |
| 73 name, the default directory is used if you do not specify a directory. | |
| 74 If you specify a directory in a relative fashion, with a name that does | |
| 75 not start with a slash, it is interpreted with respect to the default | |
| 76 directory. The default directory of the current buffer is kept in the | |
| 77 variable @code{default-directory}, which has a separate value in every | |
| 78 buffer. The value of the variable should end with a slash. | |
| 79 | |
| 80 For example, if the default file name is @file{/u/rms/gnu/gnu.tasks} then | |
| 81 the default directory is @file{/u/rms/gnu/}. If you type just @samp{foo}, | |
| 82 which does not specify a directory, it is short for @file{/u/rms/gnu/foo}. | |
| 83 @samp{../.login} would stand for @file{/u/rms/.login}. @samp{new/foo} | |
| 84 would stand for the filename @file{/u/rms/gnu/new/foo}. | |
| 85 | |
| 741 | 86 When visiting a remote file via EFS or TRAMP, the remote directory |
| 87 becomes the default directory (@pxref{Visiting}) for that buffer, just | |
| 88 as a local directory would. | |
| 89 | |
| 428 | 90 @vindex default-directory-alist |
| 91 The variable @code{default-directory-alist} takes an alist of major | |
| 92 modes and their opinions on @code{default-directory} as a Lisp | |
| 93 expression to evaluate. A resulting value of @code{nil} is ignored in | |
| 94 favor of @code{default-directory}. | |
| 95 | |
| 96 @findex make-directory | |
| 97 @findex remove-directory | |
| 98 @cindex creating directories | |
| 99 @cindex removing directories | |
| 100 You can create a new directory with the function @code{make-directory}, | |
| 101 which takes as an argument a file name string. The current directory is | |
| 102 displayed in the minibuffer when the function is called; you can delete | |
| 103 the old directory name and supply a new directory name. For example, if | |
| 104 the current directory is @file{/u/rms/gnu}, you can delete @file{gnu} | |
| 105 and type @file{oryx} and @key{RET} to create @file{/u/rms/oryx}. | |
| 106 Removing a directory is similar to creating one. To remove a directory, | |
| 107 use @code{remove-directory}; it takes one argument, a file name string. | |
| 108 | |
| 109 The command @kbd{M-x pwd} prints the current buffer's default directory, | |
| 110 and the command @kbd{M-x cd} sets it (to a value read using the | |
| 111 minibuffer). A buffer's default directory changes only when the @code{cd} | |
| 112 command is used. A file-visiting buffer's default directory is initialized | |
| 113 to the directory of the file that is visited there. If a buffer is created | |
| 114 with @kbd{C-x b}, its default directory is copied from that of the | |
| 115 buffer that was current at the time. | |
| 116 | |
| 117 @vindex insert-default-directory | |
| 118 The default directory name actually appears in the minibuffer when the | |
| 119 minibuffer becomes active to read a file name. This serves two | |
| 120 purposes: it shows you what the default is, so that you can type a | |
| 121 relative file name and know with certainty what it will mean, and it | |
| 122 allows you to edit the default to specify a different directory. To | |
| 123 inhibit the insertion of the default directory, set the variable | |
| 124 @code{insert-default-directory} to @code{nil}. | |
| 125 | |
| 126 Note that it is legitimate to type an absolute file name after you | |
| 127 enter the minibuffer, ignoring the presence of the default directory | |
| 128 name. The final minibuffer contents may look invalid, but that is not | |
| 129 so. @xref{Minibuffer File}. | |
| 130 | |
| 131 @samp{$} in a file name is used to substitute environment variables. For | |
| 132 example, if you have used the shell command @samp{setenv FOO rms/hacks} to | |
| 133 set up an environment variable named @samp{FOO}, then you can use | |
| 134 @file{/u/$FOO/test.c} or @file{/u/$@{FOO@}/test.c} as an abbreviation for | |
| 135 @file{/u/rms/hacks/test.c}. The environment variable name consists of all | |
| 136 the alphanumeric characters after the @samp{$}; alternatively, it may be | |
| 137 enclosed in braces after the @samp{$}. Note that the @samp{setenv} command | |
| 138 affects Emacs only if done before Emacs is started. | |
| 139 | |
| 140 To access a file with @samp{$} in its name, type @samp{$$}. This pair | |
| 141 is converted to a single @samp{$} at the same time variable substitution | |
| 142 is performed for single @samp{$}. The Lisp function that performs the | |
| 143 substitution is called @code{substitute-in-file-name}. The substitution | |
| 144 is performed only on filenames read as such using the minibuffer. | |
| 145 | |
| 146 @node Visiting, Saving, File Names, Files | |
| 147 @section Visiting Files | |
| 148 @cindex visiting files | |
| 149 | |
| 150 @c WideCommands | |
| 151 @table @kbd | |
| 152 @item C-x C-f | |
| 153 Visit a file (@code{find-file}). | |
| 154 @item C-x C-v | |
| 155 Visit a different file instead of the one visited last | |
| 156 (@code{find-alternate-file}). | |
| 157 @item C-x 4 C-f | |
| 158 Visit a file, in another window (@code{find-file-other-window}). Don't | |
| 159 change this window. | |
| 160 @item C-x 5 C-f | |
| 161 Visit a file, in another frame (@code{find-file-other-frame}). Don't | |
| 162 change this window or frame. | |
| 163 @end table | |
| 164 | |
| 165 @cindex files | |
| 166 @cindex visiting | |
| 167 @cindex saving | |
| 168 @dfn{Visiting} a file means copying its contents into an Emacs buffer | |
| 169 so you can edit it. Emacs creates a new buffer for each file you | |
| 170 visit. We say that the buffer is visiting the file that it was created | |
| 171 to hold. Emacs constructs the buffer name from the file name by | |
| 172 throwing away the directory and keeping just the file name. For example, | |
| 173 a file named @file{/usr/rms/emacs.tex} is displayed in a buffer named | |
| 174 @samp{emacs.tex}. If a buffer with that name exists, a unique | |
| 175 name is constructed by appending @samp{<2>}, @samp{<3>},and so on, using | |
| 176 the lowest number that makes a name that is not already in use. | |
| 177 | |
| 178 Each window's mode line shows the name of the buffer that is being displayed | |
| 179 in that window, so you can always tell what buffer you are editing. | |
| 180 | |
| 181 The changes you make with Emacs are made in the Emacs buffer. They do | |
| 182 not take effect in the file that you visit, or any other permanent | |
| 183 place, until you @dfn{save} the buffer. Saving the buffer means that | |
| 184 Emacs writes the current contents of the buffer into its visited file. | |
| 185 @xref{Saving}. | |
| 186 | |
| 187 @cindex modified (buffer) | |
| 188 If a buffer contains changes that have not been saved, the buffer is said | |
| 189 to be @dfn{modified}. This is important because it implies that some | |
| 190 changes will be lost if the buffer is not saved. The mode line displays | |
| 191 two stars near the left margin if the buffer is modified. | |
| 192 | |
| 193 @kindex C-x 5 C-f | |
| 194 @findex find-file | |
| 195 @findex find-file-other-frame | |
| 196 To visit a file, use the command @kbd{C-x C-f} (@code{find-file}). Follow | |
| 197 the command with the name of the file you wish to visit, terminated by a | |
| 198 @key{RET}. If you are using XEmacs under X, you can also use the | |
| 199 @b{Open...} command from the @b{File} menu bar item. | |
| 200 | |
| 201 The file name is read using the minibuffer (@pxref{Minibuffer}), with | |
| 202 defaulting and completion in the standard manner (@pxref{File Names}). | |
| 203 While in the minibuffer, you can abort @kbd{C-x C-f} by typing @kbd{C-g}. | |
| 204 | |
| 205 @kbd{C-x C-f} has completed successfully when text appears on the | |
| 206 screen and a new buffer name appears in the mode line. If the specified | |
| 207 file does not exist and could not be created or cannot be read, an error | |
| 208 results. The error message is printed in the echo area, and includes | |
| 209 the name of the file that Emacs was trying to visit. | |
| 210 | |
| 211 If you visit a file that is already in Emacs, @kbd{C-x C-f} does not make | |
| 212 another copy. It selects the existing buffer containing that file. | |
| 213 However, before doing so, it checks that the file itself has not changed | |
| 214 since you visited or saved it last. If the file has changed, Emacs | |
| 215 prints a warning message. @xref{Interlocking,,Simultaneous Editing}. | |
| 216 | |
| 217 @findex find-this-file | |
| 218 You can switch to a specific file called out in the current buffer by | |
| 219 calling the function @code{find-this-file}. By providing a prefix | |
| 220 argument, this function calls @code{filename-at-point} and switches to a | |
| 221 buffer visiting the file @var{filename}. It creates one if none already | |
| 222 exists. You can use this function to edit the file mentioned in the | |
| 223 buffer you are working in or to test if the file exists. You can do that | |
| 224 by using the minibuffer completion after snatching the all or part of | |
| 225 the filename. | |
| 226 | |
| 227 @vindex find-file-use-truenames | |
| 228 @vindex buffer-file-name | |
| 229 If the variable @code{find-file-use-truenames}'s value is | |
| 230 non-@code{nil}, a buffer's visited filename will always be traced back | |
| 231 to the real file. The filename will never be a symbolic link, and there | |
| 232 will never be a symbolic link anywhere in its directory path. In other | |
| 233 words, the @code{buffer-file-name} and @code{buffer-file-truename} will | |
| 234 be equal. | |
| 235 | |
| 236 @vindex find-file-compare-truenames | |
| 237 @vindex buffer-file-truename | |
| 238 If the variable @code{find-file-compare-truenames} value is | |
| 239 non-@code{nil}, the @code{find-file} command will check the | |
| 240 @code{buffer-file-truename} of all visited files when deciding whether a | |
| 241 given file is already in a buffer, instead of just | |
| 242 @code{buffer-file-name}. If you attempt to visit another file which is | |
| 444 | 243 a symbolic link to a file that is already in a buffer, the existing |
| 244 buffer will be found instead of a newly created one. This works if any | |
| 245 component of the pathname (including a non-terminal component) is a | |
| 246 symbolic link as well, but doesn't work with hard links (nothing does). | |
| 428 | 247 |
| 248 @cindex creating files | |
| 249 If you want to create a file, just visit it. Emacs prints | |
| 250 @samp{(New File)} in the echo area, but in other respects behaves as if you | |
| 251 had visited an existing empty file. If you make any changes and save them, | |
| 252 the file is created. | |
| 253 | |
| 254 @kindex C-x C-v | |
| 255 @findex find-alternate-file | |
| 256 If you visit a nonexistent file unintentionally (because you typed the | |
| 257 wrong file name), use the @kbd{C-x C-v} (@code{find-alternate-file}) | |
| 258 command to visit the file you wanted. @kbd{C-x C-v} is similar to @kbd{C-x | |
| 259 C-f}, but it kills the current buffer (after first offering to save it if | |
| 260 it is modified). @kbd{C-x C-v} is allowed even if the current buffer | |
| 261 is not visiting a file. | |
| 262 | |
| 263 @vindex find-file-run-dired | |
| 264 If the file you specify is actually a directory, Dired is called on | |
| 265 that directory (@pxref{Dired}). To inhibit this, set the variable | |
| 266 @code{find-file-run-dired} to @code{nil}; then it is an error to try to | |
| 267 visit a directory. | |
| 268 | |
| 269 @kindex C-x 4 f | |
| 270 @findex find-file-other-window | |
| 271 @kbd{C-x 4 f} (@code{find-file-other-window}) is like @kbd{C-x C-f} | |
| 272 except that the buffer containing the specified file is selected in another | |
| 273 window. The window that was selected before @kbd{C-x 4 f} continues to | |
| 274 show the same buffer it was already showing. If you use this command when | |
| 275 only one window is being displayed, that window is split in two, with one | |
| 276 window showing the same buffer as before, and the other one showing the | |
| 277 newly requested file. @xref{Windows}. | |
| 278 | |
| 279 @kindex C-x 5 C-f | |
| 280 @findex find-file-other-frame | |
| 281 @kbd{C-x 5 C-f} (@code{find-file-other-frame}) is like @kbd{C-x C-f} | |
| 282 except that it creates a new frame in which the file is displayed. | |
| 283 | |
| 284 @findex find-this-file-other-window | |
| 285 Use the function @code{find-this-file-other-window} to edit a file | |
| 286 mentioned in the buffer you are editing or to test if that file exists. | |
| 287 To do this, use the minibuffer completion after snatching the part or | |
| 288 all of the filename. By providing a prefix argument, the function calls | |
| 289 @code{filename-at-point} and switches you to a buffer visiting the file | |
| 290 @var{filename} in another window. The function creates a buffer if none | |
| 291 already exists. This function is similar to @code{find-file-other-window}. | |
| 292 | |
| 293 @vindex find-file-hooks | |
| 294 @vindex find-file-not-found-hooks | |
| 295 There are two hook variables that allow extensions to modify the | |
| 296 operation of visiting files. Visiting a file that does not exist runs the | |
| 297 functions in the list @code{find-file-not-found-hooks}; the value of this | |
| 298 variable is expected to be a list of functions which are | |
| 299 called one by one until one of them returns non-@code{nil}. Any visiting | |
| 300 of a file, whether extant or not, expects @code{find-file-hooks} to | |
| 301 contain list of functions and calls them all, one by one. In both cases | |
| 302 the functions receive no arguments. Visiting a nonexistent file | |
| 303 runs the @code{find-file-not-found-hooks} first. | |
| 304 | |
| 305 @node Saving, Reverting, Visiting, Files | |
| 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, and record that file as | |
| 320 the one visited in the buffer (@code{write-file}). | |
| 321 @item M-x set-visited-file-name | |
| 322 Change file the name under which the current buffer will be saved. | |
| 323 @end table | |
| 324 | |
| 325 @kindex C-x C-s | |
| 326 @findex save-buffer | |
| 327 To save a file and make your changes permanent, type | |
| 328 @kbd{C-x C-s} (@code{save-buffer}). After saving is finished, @kbd{C-x C-s} | |
| 329 prints a message such as: | |
| 330 | |
| 331 @example | |
| 332 Wrote /u/rms/gnu/gnu.tasks | |
| 333 @end example | |
| 334 | |
| 335 @noindent | |
| 336 If the selected buffer is not modified (no changes have been made in it | |
| 337 since the buffer was created or last saved), Emacs does not save it | |
| 338 because it would have no effect. Instead, @kbd{C-x C-s} prints a message | |
| 339 in the echo area saying: | |
| 340 | |
| 341 @example | |
| 342 (No changes need to be saved) | |
| 343 @end example | |
| 344 | |
| 345 @kindex C-x s | |
| 346 @findex save-some-buffers | |
| 347 The command @kbd{C-x s} (@code{save-some-buffers}) can save any or all | |
| 348 modified buffers. First it asks, for each modified buffer, whether to | |
| 349 save it. The questions should be answered with @kbd{y} or @kbd{n}. | |
| 350 @kbd{C-x C-c}, the key that kills Emacs, invokes | |
| 351 @code{save-some-buffers} and therefore asks the same questions. | |
| 352 | |
| 353 @kindex M-~ | |
| 354 @findex not-modified | |
| 355 If you have changed a buffer and do not want the changes to be saved, | |
| 356 you should take some action to prevent it. Otherwise, you are liable to | |
| 357 save it by mistake each time you use @code{save-some-buffers} or a | |
| 358 related command. One thing you can do is type @kbd{M-~} | |
| 359 (@code{not-modified}), which removes the indication that the buffer | |
| 360 is modified. If you do this, none of the save commands will believe | |
| 361 that the buffer needs to be saved. (@samp{~} is often used as a | |
| 362 mathematical symbol for `not'; thus @kbd{Meta-~} is `not', metafied.) | |
| 363 You could also use @code{set-visited-file-name} (see below) to mark the | |
| 364 buffer as visiting a different file name, not in use for | |
| 365 anything important. | |
| 366 | |
| 367 You can also undo all the changes made since the file was visited or | |
| 368 saved, by reading the text from the file again. This is called | |
| 369 @dfn{reverting}. @xref{Reverting}. Alternatively, you can undo all the | |
| 370 changes by repeating the undo command @kbd{C-x u}; but this only works | |
| 371 if you have not made more changes than the undo mechanism can remember. | |
| 372 | |
| 373 @findex set-visited-file-name | |
| 374 @kbd{M-x set-visited-file-name} alters the name of the file that the | |
| 375 current buffer is visiting. It prompts you for the new file name in the | |
| 376 minibuffer. You can also use @code{set-visited-file-name} on a buffer | |
| 377 that is not visiting a file. The buffer's name is changed to correspond | |
| 378 to the file it is now visiting unless the new name is already used by a | |
| 379 different buffer; in that case, the buffer name is not changed. | |
| 380 @code{set-visited-file-name} does not save the buffer in the newly | |
| 381 visited file; it just alters the records inside Emacs so that it will | |
| 382 save the buffer in that file. It also marks the buffer as ``modified'' | |
| 383 so that @kbd{C-x C-s} @i{will} save. | |
| 384 | |
| 385 @kindex C-x C-w | |
| 386 @findex write-file | |
| 387 If you wish to mark a buffer as visiting a different file and save it | |
| 388 right away, use @kbd{C-x C-w} (@code{write-file}). It is precisely | |
| 389 equivalent to @code{set-visited-file-name} followed by @kbd{C-x C-s}. | |
| 390 @kbd{C-x C-s} used on a buffer that is not visiting a file has the | |
| 391 same effect as @kbd{C-x C-w}; that is, it reads a file name, marks the | |
| 392 buffer as visiting that file, and saves it there. The default file name in | |
| 393 a buffer that is not visiting a file is made by combining the buffer name | |
| 394 with the buffer's default directory. | |
| 395 | |
| 396 If Emacs is about to save a file and sees that the date of the latest | |
| 397 version on disk does not match what Emacs last read or wrote, Emacs | |
| 398 notifies you of this fact, because it probably indicates a problem caused | |
| 399 by simultaneous editing and requires your immediate attention. | |
| 400 @xref{Interlocking,, Simultaneous Editing}. | |
| 401 | |
| 402 @vindex require-final-newline | |
|
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Add mode-require-final-newline from GNU. Thanks GNU.
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403 If the value of the variable @code{require-final-newline} is |
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Add mode-require-final-newline from GNU. Thanks GNU.
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404 @code{t}, saving or writing a file silently puts a newline at the end |
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Add mode-require-final-newline from GNU. Thanks GNU.
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parents:
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405 if there isn't already one there. If the value is @code{visit}, Emacs |
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Add mode-require-final-newline from GNU. Thanks GNU.
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406 adds a newline at the end of any file that doesn't have one, just |
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Add mode-require-final-newline from GNU. Thanks GNU.
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parents:
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407 after it visits the file. (This marks the buffer as modified, and you |
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408 can undo it.) If the value is @code{visit-save}, Emacs adds such |
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409 newlines both on visiting and on saving. If the value is @code{nil}, |
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410 Emacs leaves the end of the file unchanged; any other non-@code{nil} |
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411 value means to asks you whether to add a newline. The default is |
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412 @code{nil}. |
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413 |
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414 @vindex mode-require-final-newline |
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415 Some major modes are designed for specific kinds of files that are |
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416 always supposed to end in newlines. Such major modes set the variable |
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417 @code{require-final-newline} to the value of |
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418 @code{mode-require-final-newline}, which defaults to @code{t}. By |
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419 setting the latter variable, you can control how these modes handle |
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420 final newlines. |
| 428 | 421 |
| 422 @vindex write-file-hooks | |
| 423 @vindex after-save-hook | |
| 424 Use the hook variable @code{write-file-hooks} to implement other ways | |
| 425 to write files, and specify things to be done before files are written. The | |
| 426 value of this variable should be a list of Lisp functions. When a file | |
| 427 is to be written, the functions in the list are called, one by one, with | |
| 428 no arguments. If one of them returns a non-@code{nil} value, Emacs | |
| 429 takes this to mean that the file has been written in some suitable | |
| 430 fashion; the rest of the functions are not called, and normal writing is | |
| 431 not done. Use the hook variable @code{after-save-hook} to list | |
| 432 all the functions to be called after writing out a buffer to a file. | |
| 433 | |
| 434 @menu | |
| 435 * Backup:: How Emacs saves the old version of your file. | |
| 436 * Interlocking:: How Emacs protects against simultaneous editing | |
| 437 of one file by two users. | |
| 438 @end menu | |
| 439 | |
| 440 @node Backup, Interlocking, Saving, Saving | |
| 441 @subsection Backup Files | |
| 442 @cindex backup file | |
| 443 @vindex make-backup-files | |
| 444 | |
| 445 Because Unix does not provide version numbers in file names, rewriting a | |
| 446 file in Unix automatically destroys all record of what the file used to | |
| 447 contain. Thus, saving a file from Emacs throws away the old contents of | |
| 448 the file---or it would, except that Emacs carefully copies the old contents | |
| 449 to another file, called the @dfn{backup} file, before actually saving. | |
| 450 (Make sure that the variable @code{make-backup-files} is non-@code{nil}. | |
| 451 Backup files are not written if this variable is @code{nil}). | |
| 452 | |
| 453 At your option, Emacs can keep either a single backup file or a series of | |
| 454 numbered backup files for each file you edit. | |
| 455 | |
| 456 Emacs makes a backup for a file only the first time a file is saved | |
| 457 from one buffer. No matter how many times you save a file, its backup file | |
| 458 continues to contain the contents from before the file was visited. | |
| 459 Normally this means that the backup file contains the contents from before | |
| 460 the current editing session; however, if you kill the buffer and then visit | |
| 461 the file again, a new backup file is made by the next save. | |
| 462 | |
| 463 @menu | |
| 464 * Names: Backup Names. How backup files are named; | |
| 465 Choosing single or numbered backup files. | |
| 466 * Deletion: Backup Deletion. Emacs deletes excess numbered backups. | |
| 467 * Copying: Backup Copying. Backups can be made by copying or renaming. | |
| 468 @end menu | |
| 469 | |
| 470 @node Backup Names, Backup Deletion, Backup, Backup | |
| 471 @subsubsection Single or Numbered Backups | |
| 472 | |
| 473 If you choose to have a single backup file (the default), | |
| 474 the backup file's name is constructed by appending @samp{~} to the | |
| 475 file name being edited; thus, the backup file for @file{eval.c} is | |
| 476 @file{eval.c~}. | |
| 477 | |
| 478 If you choose to have a series of numbered backup files, backup file | |
| 479 names are made by appending @samp{.~}, the number, and another @samp{~} to | |
| 480 the original file name. Thus, the backup files of @file{eval.c} would be | |
| 481 called @file{eval.c.~1~}, @file{eval.c.~2~}, and so on, through names | |
| 482 like @file{eval.c.~259~} and beyond. | |
| 483 | |
| 484 If protection stops you from writing backup files under the usual names, | |
| 485 the backup file is written as @file{%backup%~} in your home directory. | |
| 486 Only one such file can exist, so only the most recently made backup is | |
| 487 available. | |
| 488 | |
| 489 @vindex version-control | |
| 490 The choice of single backup or numbered backups is controlled by the | |
| 491 variable @code{version-control}. Its possible values are: | |
| 492 | |
| 493 @table @code | |
| 494 @item t | |
| 495 Make numbered backups. | |
| 496 @item nil | |
| 497 Make numbered backups for files that have numbered backups already. | |
| 498 Otherwise, make single backups. | |
| 499 @item never | |
| 500 Never make numbered backups; always make single backups. | |
| 501 @end table | |
| 502 | |
| 503 @noindent | |
| 504 @code{version-control} may be set locally in an individual buffer to | |
| 505 control the making of backups for that buffer's file. For example, | |
| 506 Rmail mode locally sets @code{version-control} to @code{never} to make sure | |
| 507 that there is only one backup for an Rmail file. @xref{Locals}. | |
| 508 | |
| 509 @node Backup Deletion, Backup Copying, Backup Names, Backup | |
| 510 @subsubsection Automatic Deletion of Backups | |
| 511 | |
| 512 @vindex kept-old-versions | |
| 513 @vindex kept-new-versions | |
| 514 To prevent unlimited consumption of disk space, Emacs can delete numbered | |
| 515 backup versions automatically. Generally Emacs keeps the first few backups | |
| 516 and the latest few backups, deleting any in between. This happens every | |
| 517 time a new backup is made. The two variables that control the deletion are | |
| 518 @code{kept-old-versions} and @code{kept-new-versions}. Their values are, respectively | |
| 519 the number of oldest (lowest-numbered) backups to keep and the number of | |
| 520 newest (highest-numbered) ones to keep, each time a new backup is made. | |
| 521 The values are used just after a new backup version is made; | |
| 522 that newly made backup is included in the count in @code{kept-new-versions}. | |
| 523 By default, both variables are 2. | |
| 524 | |
| 442 | 525 @vindex delete-old-versions |
| 526 If @code{delete-old-versions} is non-@code{nil}, excess | |
| 428 | 527 middle versions are deleted without notification. If it is @code{nil}, the |
| 528 default, you are asked whether the excess middle versions should | |
| 529 really be deleted. | |
| 530 | |
| 531 You can also use Dired's @kbd{.} (Period) command to delete old versions. | |
| 532 @xref{Dired}. | |
| 533 | |
| 534 @node Backup Copying, , Backup Deletion, Backup | |
| 535 @subsubsection Copying vs.@: Renaming | |
| 536 | |
| 537 You can make backup files by copying the old file or by renaming it. | |
| 538 This makes a difference when the old file has multiple names. If you | |
| 539 rename the old file into the backup file, the alternate names | |
| 540 become names for the backup file. If you copy the old file instead, | |
| 541 the alternate names remain names for the file that you are editing, | |
| 542 and the contents accessed by those names will be the new contents. | |
| 543 | |
| 544 How you make a backup file may also affect the file's owner | |
| 545 and group. If you use copying, they do not change. If renaming is used, | |
| 546 you become the file's owner, and the file's group becomes the default | |
| 547 (different operating systems have different defaults for the group). | |
| 548 | |
| 549 Having the owner change is usually a good idea, because then the owner | |
| 550 is always the person who last edited the file. Occasionally there is a | |
| 551 file whose owner should not change. Since most files should change | |
| 552 owners, it is a good idea to use local variable lists to set | |
| 553 @code{backup-by-copying-when-mismatch} for the special cases where the | |
| 554 owner should not change (@pxref{File Variables}). | |
| 555 | |
| 556 @vindex backup-by-copying | |
| 557 @vindex backup-by-copying-when-linked | |
| 558 @vindex backup-by-copying-when-mismatch | |
| 559 Three variables control the choice of renaming or copying. | |
| 560 Normally, renaming is done. If the variable @code{backup-by-copying} is | |
| 561 non-@code{nil}, copying is used. Otherwise, if the variable | |
| 562 @code{backup-by-copying-when-linked} is non-@code{nil}, copying is | |
| 563 done for files that have multiple names, but renaming may still be done when | |
| 564 the file being edited has only one name. If the variable | |
| 565 @code{backup-by-copying-when-mismatch} is non-@code{nil}, copying is | |
| 566 done if renaming would cause the file's owner or group to change. @refill | |
| 567 | |
| 568 @node Interlocking, , Backup, Saving | |
| 569 @subsection Protection Against Simultaneous Editing | |
| 570 | |
| 571 @cindex file dates | |
| 572 @cindex simultaneous editing | |
| 573 Simultaneous editing occurs when two users visit the same file, both | |
| 574 make changes, and both save their changes. If no one was informed that | |
| 575 this was happening, and you saved first, you would later find that your | |
| 576 changes were lost. On some systems, Emacs notices immediately when the | |
| 577 second user starts to change a file already being edited, and issues a | |
| 578 warning. When this is not possible, or if the second user has started | |
| 579 to change the file despite the warning, Emacs checks when the file is | |
| 580 saved, and issues a second warning when a user is about to overwrite a | |
| 581 file containing another user's changes. If you are the user editing the | |
| 582 file, you can take corrective action at this point and prevent actual | |
| 583 loss of work. | |
| 584 | |
| 585 @findex ask-user-about-lock | |
| 586 When you make the first modification in an Emacs buffer that is visiting | |
| 587 a file, Emacs records that you have locked the file. (It does this by | |
| 588 writing another file in a directory reserved for this purpose.) The lock | |
| 589 is removed when you save the changes. The idea is that the file is locked | |
| 590 whenever the buffer is modified. If you begin to modify the buffer while | |
| 591 the visited file is locked by someone else, this constitutes a collision, | |
| 592 and Emacs asks you what to do. It does this by calling the Lisp function | |
| 593 @code{ask-user-about-lock}, which you can redefine to customize what it | |
| 594 does. The standard definition of this function asks you a | |
| 595 question and accepts three possible answers: | |
| 596 | |
| 597 @table @kbd | |
| 598 @item s | |
| 599 Steal the lock. Whoever was already changing the file loses the lock, | |
| 600 and you get the lock. | |
| 601 @item p | |
| 602 Proceed. Go ahead and edit the file despite its being locked by someone else. | |
| 603 @item q | |
| 604 Quit. This causes an error (@code{file-locked}) and the modification you | |
| 605 were trying to make in the buffer does not actually take place. | |
| 606 @end table | |
| 607 | |
| 608 Note that locking works on the basis of a file name; if a file has | |
| 609 multiple names, Emacs does not realize that the two names are the same file | |
| 610 and cannot prevent two users from editing it simultaneously under different | |
| 611 names. However, basing locking on names means that Emacs can interlock the | |
| 612 editing of new files that do not really exist until they are saved. | |
| 613 | |
| 614 Some systems are not configured to allow Emacs to make locks. On | |
| 615 these systems, Emacs cannot detect trouble in advance, but it can still | |
| 616 detect it in time to prevent you from overwriting someone else's changes. | |
| 617 | |
| 618 Every time Emacs saves a buffer, it first checks the last-modification | |
| 619 date of the existing file on disk to see that it has not changed since the | |
| 620 file was last visited or saved. If the date does not match, it implies | |
| 621 that changes were made in the file in some other way, and these changes are | |
| 622 about to be lost if Emacs actually does save. To prevent this, Emacs | |
| 623 prints a warning message and asks for confirmation before saving. | |
| 624 Occasionally you will know why the file was changed and know that it does | |
| 625 not matter; then you can answer @kbd{yes} and proceed. Otherwise, you should | |
| 626 cancel the save with @kbd{C-g} and investigate the situation. | |
| 627 | |
| 628 The first thing you should do when notified that simultaneous editing | |
| 629 has already taken place is to list the directory with @kbd{C-u C-x C-d} | |
| 630 (@pxref{ListDir,,Directory Listing}). This will show the file's current | |
| 631 author. You should attempt to contact that person and ask him not to | |
| 632 continue editing. Often the next step is to save the contents of your | |
| 633 Emacs buffer under a different name, and use @code{diff} to compare the | |
| 634 two files.@refill | |
| 635 | |
| 636 Simultaneous editing checks are also made when you visit a file that | |
| 637 is already visited with @kbd{C-x C-f} and when you start to modify a | |
| 638 file. This is not strictly necessary, but it is useful to find out | |
| 639 about such a problem as early as possible, when corrective action takes | |
| 640 less work. | |
| 641 | |
| 642 @findex set-default-file-modes | |
| 643 @cindex file protection | |
| 644 Another way to protect your file is to set the read, write, and | |
| 645 executable permissions for the file. Use the function | |
| 646 @code{set-default-file-modes} to set the UNIX @code{umask} value to the | |
| 647 @var{nmask} argument. The @code{umask} value is the default protection | |
| 648 mode for new files. | |
| 649 | |
| 650 @node Reverting, Auto Save, Saving, Files | |
| 651 @section Reverting a Buffer | |
| 652 @findex revert-buffer | |
| 653 @cindex drastic changes | |
| 654 | |
| 655 If you have made extensive changes to a file and then change your mind | |
| 656 about them, you can get rid of all changes by reading in the previous | |
| 657 version of the file. To do this, use @kbd{M-x revert-buffer}, which | |
| 658 operates on the current buffer. Since reverting a buffer can result in | |
| 659 very extensive changes, you must confirm it with @kbd{yes}. | |
| 660 | |
| 661 If the current buffer has been auto-saved more recently than it has been | |
| 662 saved explicitly, @code{revert-buffer} offers to read the auto save file | |
| 663 instead of the visited file (@pxref{Auto Save}). Emacs asks you about | |
| 664 the auto-save file before the request for confirmation of the | |
| 665 @kbd{revert-buffer} operation, and demands @kbd{y} or @kbd{n} | |
| 666 as an answer. If you have started to type @kbd{yes} for confirmation | |
| 667 without realizing that the auto-save question was going to be asked, the | |
| 668 @kbd{y} will answer that question, but the @kbd{es} will not be valid | |
| 669 confirmation. This gives you a chance to cancel the operation with | |
| 670 @kbd{C-g} and try again with the answers you really intend. | |
| 671 | |
| 672 @code{revert-buffer} keeps point at the same distance (measured in | |
| 673 characters) from the beginning of the file. If the file was edited only | |
| 674 slightly, you will be at approximately the same piece of text after | |
| 675 reverting as before. If you have made more extensive changes, the value of | |
| 676 point in the old file may bring you to a totally different piece of text | |
| 677 than your last editing point. | |
| 678 | |
| 679 A buffer reverted from its visited file is marked ``not modified'' until | |
| 680 you make a change. | |
| 681 | |
| 682 Some kinds of buffers whose contents reflect data bases other than files, | |
| 683 such as Dired buffers, can also be reverted. For them, reverting means | |
| 684 recalculating their contents from the appropriate data. Buffers | |
| 685 created randomly with @kbd{C-x b} cannot be reverted; @code{revert-buffer} | |
| 686 reports an error when asked to do so. | |
| 687 | |
| 688 @node Auto Save, Version Control, Reverting, Files | |
| 689 @section Auto-Saving: Protection Against Disasters | |
| 690 @cindex Auto-Save mode | |
| 691 @cindex crashes | |
| 692 | |
| 693 Emacs saves all the visited files from time to time (based on counting | |
| 694 your keystrokes) without being asked. This is called @dfn{auto-saving}. | |
| 695 It prevents you from losing more than a limited amount of work if the | |
| 696 system crashes. | |
| 697 | |
| 698 When Emacs determines it is time for auto-saving, each buffer is | |
| 699 considered and is auto-saved if auto-saving is turned on for it and it has | |
| 700 changed since the last time it was auto-saved. If any auto-saving is | |
| 701 done, the message @samp{Auto-saving...} is displayed in the echo area until | |
| 702 auto-saving is finished. Errors occurring during auto-saving are caught | |
| 703 so that they do not interfere with the execution of commands you have been | |
| 704 typing. | |
| 705 | |
| 706 @menu | |
| 707 * Files: Auto Save Files. | |
| 708 * Control: Auto Save Control. | |
| 709 * Recover:: Recovering text from auto-save files. | |
| 710 @end menu | |
| 711 | |
| 712 @node Auto Save Files, Auto Save Control, Auto Save, Auto Save | |
| 713 @subsection Auto-Save Files | |
| 714 | |
| 715 Auto-saving does not normally write to the files you visited, because | |
| 716 it can be undesirable to save a program that is in an inconsistent | |
| 717 state when you have made only half of a planned change. Instead, auto-saving | |
| 718 is done in a different file called the @dfn{auto-save file}, and the | |
| 719 visited file is changed only when you save explicitly, for example, | |
| 720 with @kbd{C-x C-s}. | |
| 721 | |
| 722 Normally, the name of the auto-save file is generated by appending | |
| 723 @samp{#} to the front and back of the visited file name. Thus, a buffer | |
| 724 visiting file @file{foo.c} would be auto-saved in a file @file{#foo.c#}. | |
| 725 Most buffers that are not visiting files are auto-saved only if you | |
| 726 request it explicitly; when they are auto-saved, the auto-save file name | |
| 727 is generated by appending @samp{#%} to the front and @samp{#} to the | |
| 728 back of buffer name. For example, the @samp{*mail*} buffer in which you | |
| 729 compose messages to be sent is auto-saved in a file named | |
| 730 @file{#%*mail*#}. Names of auto-save files are generated this way | |
| 731 unless you customize the functions @code{make-auto-save-file-name} and | |
| 732 @code{auto-save-file-name-p} to do something different. The file name | |
| 733 to be used for auto-saving a buffer is calculated at the time auto-saving is | |
| 734 turned on in that buffer. | |
| 735 | |
| 736 @vindex auto-save-visited-file-name | |
| 737 If you want auto-saving to be done in the visited file, set the variable | |
| 738 @code{auto-save-visited-file-name} to be non-@code{nil}. In this mode, | |
| 739 there is really no difference between auto-saving and explicit saving. | |
| 740 | |
| 741 @vindex delete-auto-save-files | |
| 742 Emacs deletes a buffer's auto-save file when you explicitly save the | |
| 743 buffer. To inhibit the deletion, set the variable | |
| 744 @code{delete-auto-save-files} to @code{nil}. Changing the visited file | |
| 745 name with @kbd{C-x C-w} or @code{set-visited-file-name} renames any | |
| 746 auto-save file to correspond to the new visited name. | |
| 747 | |
| 748 @node Auto Save Control, Recover, Auto Save Files, Auto Save | |
| 749 @subsection Controlling Auto-Saving | |
| 750 | |
| 751 @vindex auto-save-default | |
| 752 @findex auto-save-mode | |
| 753 Each time you visit a file, auto-saving is turned on for that file's | |
| 754 buffer if the variable @code{auto-save-default} is non-@code{nil} (but | |
| 755 not in batch mode; @pxref{Entering Emacs}). The default for this | |
| 756 variable is @code{t}, so Emacs auto-saves buffers that visit files by | |
| 757 default. You can use the command @kbd{M-x auto-save-mode} to turn | |
| 758 auto-saving for a buffer on or off. Like other minor mode commands, | |
| 759 @kbd{M-x auto-save-mode} turns auto-saving on with a positive argument, | |
| 760 off with a zero or negative argument; with no argument, it toggles. | |
| 761 | |
| 762 @vindex auto-save-interval | |
| 763 @findex do-auto-save | |
| 764 Emacs performs auto-saving periodically based on counting how many | |
| 765 characters you have typed since the last time auto-saving happened. The | |
| 766 variable @code{auto-save-interval} specifies the number of characters | |
| 767 between auto-saves. By default, it is 300. Emacs also auto-saves | |
| 768 whenever you call the function @code{do-auto-save}. | |
| 769 | |
| 770 Emacs also does auto-saving whenever it gets a fatal error. This | |
| 771 includes killing the Emacs job with a shell command such as @code{kill | |
| 772 -emacs}, or disconnecting a phone line or network connection. | |
| 773 | |
| 774 @vindex auto-save-timeout | |
| 775 You can set the number of seconds of idle time before an auto-save is | |
| 776 done. Setting the value of the variable @code{auto-save-timeout} to zero or | |
| 777 @code{nil} will disable auto-saving due to idleness. | |
| 778 | |
| 779 The actual amount of idle time between auto-saves is logarithmically | |
| 780 related to the size of the current buffer. This variable is the number | |
| 781 of seconds after which an auto-save will happen when the current buffer | |
| 782 is 50k or less; the timeout will be 2 1/4 times this in a 200k buffer, 3 | |
| 783 3/4 times this in a 1000k buffer, and 4 1/2 times this in a 2000k | |
| 784 buffer. | |
| 785 | |
| 786 For this variable to have any effect, you must do @code{(require 'timer)}. | |
| 787 | |
| 788 @node Recover, , Auto Save Control, Auto Save | |
| 789 @subsection Recovering Data from Auto-Saves | |
| 790 | |
| 791 @findex recover-file | |
| 792 If you want to use the contents of an auto-save file to recover from a | |
| 793 loss of data, use the command @kbd{M-x recover-file @key{RET} @var{file} | |
| 794 @key{RET}}. Emacs visits @var{file} and then (after your confirmation) | |
| 795 restores the contents from the auto-save file @file{#@var{file}#}. You | |
| 796 can then save the file with @kbd{C-x C-s} to put the recovered text into | |
| 797 @var{file} itself. For example, to recover file @file{foo.c} from its | |
| 798 auto-save file @file{#foo.c#}, do:@refill | |
| 799 | |
| 800 @example | |
| 801 M-x recover-file @key{RET} foo.c @key{RET} | |
| 802 C-x C-s | |
| 803 @end example | |
| 804 | |
| 805 Before asking for confirmation, @kbd{M-x recover-file} displays a | |
| 806 directory listing describing the specified file and the auto-save file, | |
| 807 so you can compare their sizes and dates. If the auto-save file | |
| 808 is older, @kbd{M-x recover-file} does not offer to read it. | |
| 809 | |
| 810 Auto-saving is disabled by @kbd{M-x recover-file} because using | |
| 811 this command implies that the auto-save file contains valuable data | |
| 812 from a past session. If you save the data in the visited file and | |
| 813 then go on to make new changes, turn auto-saving back on | |
| 814 with @kbd{M-x auto-save-mode}. | |
| 815 | |
| 816 @node Version Control, ListDir, Auto Save, Files | |
| 817 @section Version Control | |
| 818 @cindex version control | |
| 819 | |
| 820 @dfn{Version control systems} are packages that can record multiple | |
| 821 versions of a source file, usually storing the unchanged parts of the | |
| 822 file just once. Version control systems also record history information | |
| 823 such as the creation time of each version, who created it, and a | |
| 824 description of what was changed in that version. | |
| 825 | |
| 826 The GNU project recommends the version control system known as RCS, | |
| 827 which is free software and available from the Free Software Foundation. | |
| 828 Emacs supports use of either RCS or SCCS (a proprietary, but widely | |
| 829 used, version control system that is not quite as powerful as RCS) | |
| 830 through a facility called VC. The same Emacs commands work with either | |
| 831 RCS or SCCS, so you hardly have to know which one of them you are | |
| 832 using. | |
| 833 | |
| 834 @menu | |
| 835 * Concepts of VC:: Basic version control information; | |
| 836 checking files in and out. | |
| 837 * Editing with VC:: Commands for editing a file maintained | |
| 838 with version control. | |
| 839 * Variables for Check-in/out:: Variables that affect the commands used | |
| 840 to check files in or out. | |
| 841 * Log Entries:: Logging your changes. | |
| 842 * Change Logs and VC:: Generating a change log file from log | |
| 843 entries. | |
| 844 * Old Versions:: Examining and comparing old versions. | |
| 845 * VC Status:: Commands to view the VC status of files and | |
| 846 look at log entries. | |
| 847 * Renaming and VC:: A command to rename both the source and | |
| 848 master file correctly. | |
| 849 * Snapshots:: How to make and use snapshots, a set of | |
| 850 file versions that can be treated as a unit. | |
| 851 * Version Headers:: Inserting version control headers into | |
| 852 working files. | |
| 853 @end menu | |
| 854 | |
| 855 @node Concepts of VC, Editing with VC, Version Control, Version Control | |
| 856 @subsection Concepts of Version Control | |
| 857 | |
| 858 @cindex RCS | |
| 859 @cindex SCCS | |
| 860 @cindex master file | |
| 861 @cindex registered file | |
| 862 @cindex work file | |
| 863 When a file is under version control, we also say that it is | |
| 864 @dfn{registered} in the version control system. Each registered file | |
| 865 has a corresponding @dfn{master file} which represents the file's | |
| 866 present state plus its change history, so that you can reconstruct from | |
| 867 it either the current version or any specified earlier version. Usually | |
| 868 the master file also records a @dfn{log entry} for each version describing | |
| 869 what was changed in that version. | |
| 870 | |
| 871 The file that is maintained under version control is sometimes called | |
| 872 the @dfn{work file} corresponding to its master file. | |
| 873 | |
| 874 @cindex checking out files | |
| 875 @cindex checking in files | |
| 876 @cindex locking and version control | |
| 877 To examine a file, you @dfn{check it out}. This extracts a version | |
| 878 of the source file (typically, the most recent) from the master file. | |
| 879 If you want to edit the file, you must check it out @dfn{locked}. Only | |
| 880 one user can do this at a time for any given source file. (This kind | |
| 881 of locking is completely unrelated to the locking that Emacs uses to | |
| 882 detect simultaneous editing of a file.) | |
| 883 | |
| 884 When you are done with your editing, you must @dfn{check in} the new | |
| 885 version. This records the new version in the master file, and unlocks | |
| 886 the source file so that other people can lock it and thus modify it. | |
| 887 | |
| 888 Checkin and checkout are the basic operations of version control. You | |
| 889 can do both of them with a single Emacs command: @w{@kbd{C-x C-q}} | |
| 890 (@code{vc-toggle-read-only}). | |
| 891 | |
| 892 A @dfn{snapshot} is a coherent collection of versions of the various | |
| 893 files that make up a program. @xref{Snapshots}. | |
| 894 | |
| 895 @node Editing with VC, Variables for Check-in/out, Concepts of VC, Version Control | |
| 896 @subsection Editing with Version Control | |
| 897 | |
| 898 When you visit a file that is maintained using version control, the | |
| 899 mode line displays @samp{RCS} or @samp{SCCS} to inform you that version | |
| 900 control is in use, and also (in case you care) which low-level system | |
| 901 the file is actually stored in. Normally, such a source file is | |
| 902 read-only, and the mode line indicates this with @samp{%%}. With RCS, | |
| 903 the mode line also indicates the number of the head version, which is | |
| 904 normally also the version you are looking at. | |
| 905 | |
| 906 These are the commands for editing a file maintained with | |
| 907 version control: | |
| 908 | |
| 909 @table @kbd | |
| 910 @item C-x C-q | |
| 911 Check the visited file in or out. | |
| 912 | |
| 913 @item C-x v u | |
| 914 Revert the buffer and the file to the last checked in version. | |
| 915 | |
| 916 @item C-x v c | |
| 917 Remove the last-entered change from the master for the visited file. | |
| 918 This undoes your last check-in. | |
| 919 | |
| 920 @item C-x v i | |
| 921 Register the visited file in version control. | |
| 922 @end table | |
| 923 | |
| 924 @noindent | |
| 925 (@kbd{C-x v} is the prefix key for version control commands; all of these | |
| 926 commands except for @kbd{C-x C-q} start with @kbd{C-x v}.) | |
| 927 | |
| 928 @kindex C-x C-q @r{(version control)} | |
| 929 When you want to modify a file maintained with version control, type | |
| 930 @kbd{C-x C-q} (@code{vc-toggle-read-only}). This @dfn{checks out} the | |
| 931 file, and tells RCS or SCCS to lock the file. This means making the | |
| 932 file writable for you (but not for anyone else). | |
| 933 | |
| 934 @cindex log entry | |
| 935 When you are finished editing the file, type @kbd{C-x C-q} again. | |
| 936 When used on a file that is checked out, this command checks the file | |
| 937 in. But check-in does not start immediately; first, you must enter the | |
| 938 @dfn{log entry}---a description of the changes in the new version. | |
| 939 @kbd{C-x C-q} pops up a buffer for you to enter this in. When you are | |
| 940 finished typing in the log entry, type @kbd{C-c C-c} to terminate it; this is | |
| 941 when actual check-in takes place. | |
| 942 | |
| 943 Once you have checked in your changes, the file is unlocked, so that | |
| 944 other users can lock it and modify it. | |
| 945 | |
| 946 @vindex vc-make-backup-files | |
| 947 Emacs does not save backup files for source files that are maintained | |
| 948 with version control. If you want to make backup files despite version | |
| 949 control, set the variable @code{vc-make-backup-files} to a | |
| 950 non-@code{nil} value. | |
| 951 | |
| 952 @vindex vc-keep-workfiles | |
| 953 Normally the work file exists all the time, whether it is locked or | |
| 954 not. If you set @code{vc-keep-workfiles} to @code{nil}, then checking | |
| 955 in a new version with @kbd{C-x C-q} deletes the work file; but any | |
| 956 attempt to visit the file with Emacs creates it again. | |
| 957 | |
| 958 It is not impossible to lock a file that someone else has locked. If | |
| 959 you try to check out a file that is locked, @kbd{C-x C-q} asks you | |
| 960 whether you want to ``steal the lock.'' If you say yes, the file | |
| 961 becomes locked by you, but a message is sent to the person who had | |
| 962 formerly locked the file, to inform him of what has happened. The mode | |
| 963 line indicates that a file is locked by someone else by displaying the | |
| 964 login name of that person, before the version number. | |
| 965 | |
| 966 @kindex C-x v u | |
| 967 @findex vc-revert-buffer | |
| 968 If you want to discard your current set of changes and revert to the | |
| 969 last version checked in, use @kbd{C-x v u} (@code{vc-revert-buffer}). | |
| 970 This cancels your last check-out, leaving the file unlocked. If you want | |
| 971 to make a different set of changes, you must first check the file out | |
| 972 again. @kbd{C-x v u} requires confirmation, unless it sees that | |
| 973 you haven't made any changes since the last checked-in version. | |
| 974 | |
| 975 @kbd{C-x v u} is also the command to use if you lock a file and then | |
| 976 don't actually change it. | |
| 977 | |
| 978 @kindex C-x v c | |
| 979 @findex vc-cancel-version | |
| 980 You can cancel a change after checking it in, with @kbd{C-x v c} | |
| 981 (@code{vc-cancel-version}). This command discards all record of the | |
| 982 most recent checked in version, so be careful about using it. It | |
| 983 requires confirmation with @kbd{yes}. By default, @kbd{C-x v c} reverts | |
| 984 your workfile and buffer to the previous version (the one that precedes | |
| 985 the version that is deleted), but you can prevent the reversion by | |
| 986 giving the command a prefix argument. Then the buffer does not change. | |
| 987 | |
| 988 This command with a prefix argument is useful when you have checked in | |
| 989 a change and then discover a trivial error in it; you can cancel the | |
| 990 erroneous check-in, fix the error, and repeat the check-in. | |
| 991 | |
| 992 Be careful when invoking @kbd{C-x v c}, as it is easy to throw away a | |
| 993 lot of work with it. To help you be careful, this command always | |
| 994 requires confirmation with @samp{yes}. | |
| 995 | |
| 996 @kindex C-x v i | |
| 997 @findex vc-register | |
| 998 @vindex vc-default-back-end | |
| 999 You can register the visited file for version control using | |
| 1000 @w{@kbd{C-x v i}} (@code{vc-register}). If the variable | |
| 1001 @code{vc-default-back-end} is non-@code{nil}, it specifies which | |
| 1002 version control system to use; otherwise, this uses RCS if it is | |
| 1003 installed on your system and SCCS if not. After @kbd{C-x v i}, | |
| 1004 the file is unlocked and read-only. Type @kbd{C-x C-q} if you wish to | |
| 1005 edit it. | |
| 1006 | |
| 1007 By default, the initial version number is 1.1. If you want to use a | |
| 1008 different number, give @kbd{C-x v i} a prefix argument; then it reads | |
| 1009 the initial version number using the minibuffer. | |
| 1010 | |
| 1011 @vindex vc-initial-comment | |
| 1012 If @code{vc-initial-comment} is non-@code{nil}, @kbd{C-x v i} reads | |
| 1013 an initial comment (much like a log entry) to describe the purpose of | |
| 1014 this source file. | |
| 1015 | |
| 1016 @kindex C-u C-x v v | |
| 1017 @findex vc-next-action | |
| 1018 To specify the version number for a subsequent checkin, use the | |
| 1019 command @kbd{C-u C-x v v}. @kbd{C-x v v} (@code{vc-next-action}) is the | |
| 1020 command that @kbd{C-x C-q} uses to do the ``real work'' when the visited | |
| 1021 file uses version control. When used for checkin, and given a prefix | |
| 1022 argument, it reads the version number with the minibuffer. | |
| 1023 | |
| 1024 @node Variables for Check-in/out, Log Entries, Editing with VC, Version Control | |
| 1025 @subsection Variables Affecting Check-in and Check-out | |
| 1026 @c There is no need to tell users about vc-master-templates. | |
| 1027 | |
| 1028 @vindex vc-suppress-confirm | |
| 1029 If @code{vc-suppress-confirm} is non-@code{nil}, then @kbd{C-x C-q} | |
| 1030 and @kbd{C-x v i} can save the current buffer without asking, and | |
| 1031 @kbd{C-x v u} also operates without asking for confirmation. | |
| 1032 (This variable does not affect @kbd{C-x v c}; that is so drastic | |
| 1033 that it should always ask for confirmation.) | |
| 1034 | |
| 1035 @vindex vc-command-messages | |
| 1036 VC mode does much of its work by running the shell commands for RCS | |
| 1037 and SCCS. If @code{vc-command-messages} is non-@code{nil}, VC displays | |
| 1038 messages to indicate which shell commands it runs, and additional | |
| 1039 messages when the commands finish. | |
| 1040 | |
| 1041 Normally, VC assumes that it can deduce the locked/unlocked state of | |
| 1042 files by looking at the file permissions of the work file; this is | |
| 1043 fast. However, if the @file{RCS} or @file{SCCS} subdirectory is | |
| 1044 actually a symbolic link, then VC does not trust the file permissions to | |
| 1045 reflect this status. | |
| 1046 | |
| 1047 @vindex vc-mistrust-permissions | |
| 1048 You can specify the criterion for whether to trust the file permissions | |
| 1049 by setting the variable @code{vc-mistrust-permissions}. Its value may | |
| 1050 be @code{t} (always mistrust the file permissions and check the master | |
| 1051 file), @code{nil} (always trust the file permissions), or a function of | |
| 1052 one argument which makes the decision. The argument is the directory | |
| 1053 name of the @file{RCS} or @file{SCCS} subdirectory. A non-@code{nil} | |
| 1054 value from the function says to mistrust the file permissions. | |
| 1055 | |
| 1056 If you find that the file permissions of work files are changed | |
| 1057 erroneously, set @code{vc-mistrust-permissions} to @code{t}. Then VC | |
| 1058 always checks the master file to determine the file's status. | |
| 1059 | |
| 1060 @vindex vc-path | |
| 1061 You can specify additional directories to search for version control | |
| 1062 programs by setting the variable @code{vc-path}. These directories | |
| 1063 are searched before the usual search path. The proper result usually | |
| 1064 happens automatically. | |
| 1065 | |
| 1066 @node Log Entries, Change Logs and VC, Variables for Check-in/out, Version Control | |
| 1067 @subsection Log Entries | |
| 1068 | |
| 1069 When you're editing an initial comment or log entry for inclusion in a | |
| 1070 master file, finish your entry by typing @kbd{C-c C-c}. | |
| 1071 | |
| 1072 @table @kbd | |
| 1073 @item C-c C-c | |
| 1074 Finish the comment edit normally (@code{vc-finish-logentry}). | |
| 1075 This finishes check-in. | |
| 1076 @end table | |
| 1077 | |
| 1078 To abort check-in, just don't type @kbd{C-c C-c} in that buffer. You | |
| 1079 can switch buffers and do other editing. As long as you don't try to | |
| 1080 check in another file, the entry you were editing remains in its | |
| 1081 buffer, and you can go back to that buffer at any time to complete the | |
| 1082 check-in. | |
| 1083 | |
| 1084 If you change several source files for the same reason, it is often | |
| 1085 convenient to specify the same log entry for many of the files. To do | |
| 1086 this, use the history of previous log entries. The commands @kbd{M-n}, | |
| 1087 @kbd{M-p}, @kbd{M-s} and @kbd{M-r} for doing this work just like the | |
| 1088 minibuffer history commands (except that these versions are used outside | |
| 1089 the minibuffer). | |
| 1090 | |
| 1091 @vindex vc-log-mode-hook | |
| 1092 Each time you check in a file, the log entry buffer is put into VC Log | |
| 1093 mode, which involves running two hooks: @code{text-mode-hook} and | |
| 1094 @code{vc-log-mode-hook}. | |
| 1095 | |
| 1096 @node Change Logs and VC, Old Versions, Log Entries, Version Control | |
| 1097 @subsection Change Logs and VC | |
| 1098 | |
| 1099 If you use RCS for a program and also maintain a change log file for | |
| 1100 it (@pxref{Change Log}), you can generate change log entries | |
| 1101 automatically from the version control log entries: | |
| 1102 | |
| 1103 @table @kbd | |
| 1104 @item C-x v a | |
| 1105 @kindex C-x v a | |
| 1106 @findex vc-update-change-log | |
| 1107 Visit the current directory's change log file and create new entries for | |
| 1108 versions checked in since the most recent entry in the change log file | |
| 1109 (@code{vc-update-change-log}). | |
| 1110 | |
| 1111 This command works with RCS only; it does not work with SCCS. | |
| 1112 @end table | |
| 1113 | |
| 1114 For example, suppose the first line of @file{ChangeLog} is dated 10 | |
| 1115 April 1992, and that the only check-in since then was by Nathaniel | |
| 1116 Bowditch to @file{rcs2log} on 8 May 1992 with log text @samp{Ignore log | |
| 1117 messages that start with `#'.}. Then @kbd{C-x v a} visits | |
| 1118 @file{ChangeLog} and inserts text like this: | |
| 1119 | |
| 1120 @smallexample | |
| 1121 @group | |
| 1122 Fri May 8 21:45:00 1992 Nathaniel Bowditch (nat@@apn.org) | |
| 1123 | |
| 1124 * rcs2log: Ignore log messages that start with `#'. | |
| 1125 @end group | |
| 1126 @end smallexample | |
| 1127 | |
| 1128 @noindent | |
| 1129 You can then edit the new change log entry further as you wish. | |
| 1130 | |
| 1131 Normally, the log entry for file @file{foo} is displayed as @samp{* | |
| 1132 foo: @var{text of log entry}}. The @samp{:} after @file{foo} is omitted | |
| 1133 if the text of the log entry starts with @w{@samp{(@var{functionname}): | |
| 1134 }}. For example, if the log entry for @file{vc.el} is | |
| 1135 @samp{(vc-do-command): Check call-process status.}, then the text in | |
| 1136 @file{ChangeLog} looks like this: | |
| 1137 | |
| 1138 @smallexample | |
| 1139 @group | |
| 1140 Wed May 6 10:53:00 1992 Nathaniel Bowditch (nat@@apn.org) | |
| 1141 | |
| 1142 * vc.el (vc-do-command): Check call-process status. | |
| 1143 @end group | |
| 1144 @end smallexample | |
| 1145 | |
| 1146 When @kbd{C-x v a} adds several change log entries at once, it groups | |
| 1147 related log entries together if they all are checked in by the same | |
| 1148 author at nearly the same time. If the log entries for several such | |
| 1149 files all have the same text, it coalesces them into a single entry. | |
| 1150 For example, suppose the most recent checkins have the following log | |
| 1151 entries: | |
| 1152 | |
| 1153 @example | |
| 1154 @exdent For @file{vc.texinfo}: | |
| 1155 Fix expansion typos. | |
| 1156 @exdent For @file{vc.el}: | |
| 1157 Don't call expand-file-name. | |
| 1158 @exdent For @file{vc-hooks.el}: | |
| 1159 Don't call expand-file-name. | |
| 1160 @end example | |
| 1161 | |
| 1162 They appear like this in @file{ChangeLog}: | |
| 1163 | |
| 1164 @smallexample | |
| 1165 @group | |
| 1166 Wed Apr 1 08:57:59 1992 Nathaniel Bowditch (nat@@apn.org) | |
| 1167 | |
| 1168 * vc.texinfo: Fix expansion typos. | |
| 1169 | |
| 1170 * vc.el, vc-hooks.el: Don't call expand-file-name. | |
| 1171 @end group | |
| 1172 @end smallexample | |
| 1173 | |
| 1174 Normally, @kbd{C-x v a} separates log entries by a blank line, but you | |
| 1175 can mark several related log entries to be clumped together (without an | |
| 1176 intervening blank line) by starting the text of each related log entry | |
| 1177 with a label of the form @w{@samp{@{@var{clumpname}@} }}. The label | |
| 1178 itself is not copied to @file{ChangeLog}. For example, suppose the log | |
| 1179 entries are: | |
| 1180 | |
| 1181 @example | |
| 1182 @exdent For @file{vc.texinfo}: | |
| 1183 @{expand@} Fix expansion typos. | |
| 1184 @exdent For @file{vc.el}: | |
| 1185 @{expand@} Don't call expand-file-name. | |
| 1186 @exdent For @file{vc-hooks.el}: | |
| 1187 @{expand@} Don't call expand-file-name. | |
| 1188 @end example | |
| 1189 | |
| 1190 @noindent | |
| 1191 Then the text in @file{ChangeLog} looks like this: | |
| 1192 | |
| 1193 @smallexample | |
| 1194 @group | |
| 1195 Wed Apr 1 08:57:59 1992 Nathaniel Bowditch (nat@@apn.org) | |
| 1196 | |
| 1197 * vc.texinfo: Fix expansion typos. | |
| 1198 * vc.el, vc-hooks.el: Don't call expand-file-name. | |
| 1199 @end group | |
| 1200 @end smallexample | |
| 1201 | |
| 1202 A log entry whose text begins with @samp{#} is not copied to | |
| 1203 @file{ChangeLog}. For example, if you merely fix some misspellings in | |
| 1204 comments, you can log the change with an entry beginning with @samp{#} | |
| 1205 to avoid putting such trivia into @file{ChangeLog}. | |
| 1206 | |
| 1207 @node Old Versions, VC Status, Change Logs and VC, Version Control | |
| 1208 @subsection Examining And Comparing Old Versions | |
| 1209 | |
| 1210 @table @kbd | |
| 1211 @item C-x v ~ @var{version} @key{RET} | |
| 1212 Examine version @var{version} of the visited file, in a buffer of its | |
| 1213 own (@code{vc-version-other-window}). | |
| 1214 | |
| 1215 @item C-x v = | |
| 1216 Compare the current buffer contents with the latest checked-in version | |
| 1217 of the file. | |
| 1218 | |
| 1219 @item C-u C-x v = @var{file} @key{RET} @var{oldvers} @key{RET} @var{newvers} @key{RET} | |
| 1220 Compare the specified two versions of @var{file}. | |
| 1221 @end table | |
| 1222 | |
| 1223 @findex vc-version-other-window | |
| 1224 @kindex C-x v ~ | |
| 1225 You can examine any version of a file by first visiting it, and then | |
| 1226 using @kbd{C-x v ~ @var{version} @key{RET}} | |
| 1227 (@code{vc-version-other-window}). This puts the text of version | |
| 1228 @var{version} in a file named @file{@var{filename}.~@var{version}~}, | |
| 1229 then visits it in a separate window. | |
| 1230 | |
| 1231 @findex vc-diff | |
| 1232 @kindex C-x v = | |
| 1233 To compare two versions of a file, use the command @kbd{C-x v =} | |
| 1234 (@code{vc-diff}). | |
| 1235 | |
| 1236 Plain @kbd{C-x v =} compares the current buffer contents (saving them | |
| 1237 in the file if necessary) with the last checked-in version of the file. | |
| 1238 With a prefix argument, @kbd{C-x v =} reads a file name and two version | |
| 1239 numbers, then compares those versions of the specified file. | |
| 1240 | |
| 1241 If you supply a directory name instead of the name of a work file, | |
| 1242 this command compares the two specified versions of all registered files | |
| 1243 in that directory and its subdirectories. You can also specify a | |
| 1244 snapshot name (@pxref{Snapshots}) instead of one or both version | |
| 1245 numbers. | |
| 1246 | |
| 1247 You can specify a checked-in version by its number; you can specify | |
| 1248 the most recent checked-in version with an empty version number. | |
| 1249 | |
| 1250 This command works by running the @code{vcdiff} utility, getting the | |
| 1251 options from the variable @code{diff-switches}. It displays the output | |
| 1252 in a special buffer in another window. Unlike the @kbd{M-x diff} | |
| 1253 command, @kbd{C-x v =} does not try to find the changes in the old and | |
| 1254 new versions. This is because one or both versions normally do not | |
| 1255 exist as files. They exist only in the records of the master file. | |
| 1256 @xref{Comparing Files}, for more information about @kbd{M-x diff}. | |
| 1257 | |
| 1258 @node VC Status, Renaming and VC, Old Versions, Version Control | |
| 1259 @subsection VC Status Commands | |
| 1260 | |
| 1261 @kindex C-x v l | |
| 1262 @findex vc-print-log | |
| 1263 To view the detailed version control status and history of a file, | |
| 1264 type @kbd{C-x v l} (@code{vc-print-log}). It displays the history of | |
| 1265 changes to the current file, including the text of the log entries. The | |
| 1266 output appears in a separate window. | |
| 1267 | |
| 1268 @kindex C-x v d | |
| 1269 @findex vc-directory | |
| 1270 When you are working on a large program, it's often useful to find all | |
| 1271 the files that are currently locked, or all the files maintained in | |
| 1272 version control at all. You can use @kbd{C-x v d} (@code{vc-directory}) | |
| 1273 to show all the locked files in or beneath the current directory. This | |
| 1274 includes all files that are locked by any user. @kbd{C-u C-x v d} lists | |
| 1275 all files in or beneath the current directory that are maintained with | |
| 1276 version control. | |
| 1277 | |
| 1278 The list of files is displayed as a buffer that uses an augmented | |
| 1279 Dired mode. The names of the users locking various files are shown (in | |
| 1280 parentheses) in place of the owner and group. All the normal Dired | |
| 1281 commands work in this buffer. Most interactive VC commands work also, | |
| 1282 and apply to the file name on the current line. | |
| 1283 | |
| 1284 The @kbd{C-x v v} command (@code{vc-next-action}), when used in the | |
| 1285 augmented Dired buffer, operates on all the marked files (or the file on | |
| 1286 the current line). If it operates on more than one file, it handles | |
| 1287 each file according to its current state; thus, it may check out one | |
| 1288 file and check in another (because it is already checked out). If it | |
| 1289 has to check in any files, it reads a single log entry, then uses that | |
| 1290 text for all the files being checked in. This can be convenient for | |
| 1291 registering or checking in several files at once, as part of the same | |
| 1292 change. | |
| 1293 | |
| 1294 @node Renaming and VC, Snapshots, VC Status, Version Control | |
| 1295 @subsection Renaming VC Work Files and Master Files | |
| 1296 | |
| 1297 @findex vc-rename-file | |
| 1298 When you rename a registered file, you must also rename its master | |
| 1299 file correspondingly to get proper results. Use @code{vc-rename-file} | |
| 1300 to rename the source file as you specify, and rename its master file | |
| 1301 accordingly. It also updates any snapshots (@pxref{Snapshots}) that | |
| 1302 mention the file, so that they use the new name; despite this, the | |
| 1303 snapshot thus modified may not completely work (@pxref{Snapshot | |
| 1304 Caveats}). | |
| 1305 | |
| 1306 You cannot use @code{vc-rename-file} on a file that is locked by | |
| 1307 someone else. | |
| 1308 | |
| 1309 @node Snapshots, Version Headers, Renaming and VC, Version Control | |
| 1310 @subsection Snapshots | |
| 1311 @cindex snapshots and version control | |
| 1312 | |
| 1313 A @dfn{snapshot} is a named set of file versions (one for each | |
| 1314 registered file) that you can treat as a unit. One important kind of | |
| 1315 snapshot is a @dfn{release}, a (theoretically) stable version of the | |
| 1316 system that is ready for distribution to users. | |
| 1317 | |
| 1318 @menu | |
| 1319 * Making Snapshots:: The snapshot facilities. | |
| 1320 * Snapshot Caveats:: Things to be careful of when using snapshots. | |
| 1321 @end menu | |
| 1322 | |
| 1323 @node Making Snapshots, Snapshot Caveats, Snapshots, Snapshots | |
| 1324 @subsubsection Making and Using Snapshots | |
| 1325 | |
| 1326 There are two basic commands for snapshots; one makes a | |
| 1327 snapshot with a given name, the other retrieves a named snapshot. | |
| 1328 | |
| 1329 @table @code | |
| 1330 @kindex C-x v s | |
| 1331 @findex vc-create-snapshot | |
| 1332 @item C-x v s @var{name} @key{RET} | |
| 1333 Define the last saved versions of every registered file in or under the | |
| 1334 current directory as a snapshot named @var{name} | |
| 1335 (@code{vc-create-snapshot}). | |
| 1336 | |
| 1337 @kindex C-x v r | |
| 1338 @findex vc-retrieve-snapshot | |
| 1339 @item C-x v r @var{name} @key{RET} | |
| 1340 Check out all registered files at or below the current directory level | |
| 1341 using whatever versions correspond to the snapshot @var{name} | |
| 1342 (@code{vc-retrieve-snapshot}). | |
| 1343 | |
| 1344 This command reports an error if any files are locked at or below the | |
| 1345 current directory, without changing anything; this is to avoid | |
| 1346 overwriting work in progress. | |
| 1347 @end table | |
| 1348 | |
| 1349 A snapshot uses a very small amount of resources---just enough to record | |
| 1350 the list of file names and which version belongs to the snapshot. Thus, | |
| 1351 you need not hesitate to create snapshots whenever they are useful. | |
| 1352 | |
| 1353 You can give a snapshot name as an argument to @kbd{C-x v =} or | |
| 1354 @kbd{C-x v ~} (@pxref{Old Versions}). Thus, you can use it to compare a | |
| 1355 snapshot against the current files, or two snapshots against each other, | |
| 1356 or a snapshot against a named version. | |
| 1357 | |
| 1358 @node Snapshot Caveats, , Making Snapshots, Snapshots | |
| 1359 @subsubsection Snapshot Caveats | |
| 1360 | |
| 1361 @cindex named configurations (RCS) | |
| 1362 VC's snapshot facilities are modeled on RCS's named-configuration | |
| 1363 support. They use RCS's native facilities for this, so under VC | |
| 1364 snapshots made using RCS are visible even when you bypass VC. | |
| 1365 | |
| 1366 @c worded verbosely to avoid overfull hbox. | |
| 1367 For SCCS, VC implements snapshots itself. The files it uses contain | |
| 1368 name/file/version-number triples. These snapshots are visible only | |
| 1369 through VC. | |
| 1370 | |
| 1371 A snapshot is a set of checked-in versions. So make sure that all the | |
| 1372 files are checked in and not locked when you make a snapshot. | |
| 1373 | |
| 1374 File renaming and deletion can create some difficulties with snapshots. | |
| 1375 This is not a VC-specific problem, but a general design issue in version | |
| 1376 control systems that no one has solved very well yet. | |
| 1377 | |
| 1378 If you rename a registered file, you need to rename its master along | |
| 1379 with it (the command @code{vc-rename-file} does this automatically). If | |
| 1380 you are using SCCS, you must also update the records of the snapshot, to | |
| 1381 mention the file by its new name (@code{vc-rename-file} does this, | |
| 1382 too). An old snapshot that refers to a master file that no longer | |
| 1383 exists under the recorded name is invalid; VC can no longer retrieve | |
| 1384 it. It would be beyond the scope of this manual to explain enough about | |
| 1385 RCS and SCCS to explain how to update the snapshots by hand. | |
| 1386 | |
| 1387 Using @code{vc-rename-file} makes the snapshot remain valid for | |
| 1388 retrieval, but it does not solve all problems. For example, some of the | |
| 1389 files in the program probably refer to others by name. At the very | |
| 1390 least, the makefile probably mentions the file that you renamed. If you | |
| 1391 retrieve an old snapshot, the renamed file is retrieved under its new | |
| 1392 name, which is not the name that the makefile expects. So the program | |
| 1393 won't really work as retrieved. | |
| 1394 | |
| 1395 @node Version Headers, , Snapshots, Version Control | |
| 1396 @subsection Inserting Version Control Headers | |
| 1397 | |
| 1398 Sometimes it is convenient to put version identification strings | |
| 1399 directly into working files. Certain special strings called | |
| 1400 @dfn{version headers} are replaced in each successive version by the | |
| 1401 number of that version. | |
| 1402 | |
| 1403 @kindex C-x v h | |
| 1404 @findex vc-insert-headers | |
| 1405 You can use the @kbd{C-x v h} command (@code{vc-insert-headers}) to | |
| 1406 insert a suitable header string. | |
| 1407 | |
| 1408 @table @kbd | |
| 1409 @item C-x v h | |
| 1410 Insert headers in a file for use with your version-control system. | |
| 1411 @end table | |
| 1412 | |
| 1413 @vindex vc-header-alist | |
| 1414 The default header string is @samp{\$Id\$} for RCS and @samp{\%W\%} | |
| 1415 for SCCS. (The actual strings inserted do not have the backslashes | |
| 1416 in them. They were placed in the Info source file so that the | |
| 1417 strings don't get interpreted as version-control headers when the | |
| 1418 Info source files are maintained under version control.) You can | |
| 1419 specify other headers to insert by setting the variable | |
| 1420 @code{vc-header-alist}. Its value is a list of elements of the form | |
| 1421 @code{(@var{program} . @var{string})} where @var{program} is @code{RCS} | |
| 1422 or @code{SCCS} and @var{string} is the string to use. | |
| 1423 | |
| 1424 Instead of a single string, you can specify a list of strings; then | |
| 1425 each string in the list is inserted as a separate header on a line of | |
| 1426 its own. | |
| 1427 | |
| 1428 It is often necessary to use ``superfluous'' backslashes when writing | |
| 1429 the strings that you put in this variable. This is to prevent the | |
| 1430 string in the constant from being interpreted as a header itself if the | |
| 1431 Emacs Lisp file containing it is maintained with version control. | |
| 1432 | |
| 1433 @vindex vc-comment-alist | |
| 1434 Each header is inserted surrounded by tabs, inside comment delimiters, | |
| 1435 on a new line at the start of the buffer. Normally the ordinary comment | |
| 1436 start and comment end strings of the current mode are used, but for | |
| 1437 certain modes, there are special comment delimiters for this purpose; | |
| 1438 the variable @code{vc-comment-alist} specifies them. Each element of | |
| 1439 this list has the form @code{(@var{mode} @var{starter} @var{ender})}. | |
| 1440 | |
| 1441 @vindex vc-static-header-alist | |
| 1442 The variable @code{vc-static-header-alist} specifies further strings | |
| 1443 to add based on the name of the buffer. Its value should be a list of | |
| 1444 elements of the form @code{(@var{regexp} . @var{format})}. Whenever | |
| 1445 @var{regexp} matches the buffer name, @var{format} is inserted as part | |
| 1446 of the header. A header line is inserted for each element that matches | |
| 1447 the buffer name, and for each string specified by | |
| 1448 @code{vc-header-alist}. The header line is made by processing the | |
| 1449 string from @code{vc-header-alist} with the format taken from the | |
| 1450 element. The default value for @code{vc-static-header-alist} is: | |
| 1451 | |
| 1452 @example | |
| 1453 @group | |
| 1454 (("\\.c$" . | |
| 1455 "\n#ifndef lint\nstatic char vcid[] = \"\%s\";\n\ | |
| 1456 #endif /* lint */\n")) | |
| 1457 @end group | |
| 1458 @end example | |
| 1459 | |
| 1460 @noindent | |
| 1461 which specifies insertion of a string of this form: | |
| 1462 | |
| 1463 @example | |
| 1464 @group | |
| 1465 | |
| 1466 #ifndef lint | |
| 1467 static char vcid[] = "@var{string}"; | |
| 1468 #endif /* lint */ | |
| 1469 @end group | |
| 1470 @end example | |
| 1471 | |
| 1472 @node ListDir, Comparing Files, Version Control, Files | |
| 1473 @section Listing a File Directory | |
| 1474 | |
| 1475 @cindex file directory | |
| 1476 @cindex directory listing | |
| 1477 Files are organized by Unix into @dfn{directories}. A @dfn{directory | |
| 1478 listing} is a list of all the files in a directory. Emacs provides | |
| 1479 directory listings in brief format (file names only) and verbose format | |
| 1480 (sizes, dates, and authors included). | |
| 1481 | |
| 1482 @table @kbd | |
| 1483 @item C-x C-d @var{dir-or-pattern} | |
| 1484 Print a brief directory listing (@code{list-directory}). | |
| 1485 @item C-u C-x C-d @var{dir-or-pattern} | |
| 1486 Print a verbose directory listing. | |
| 1487 @end table | |
| 1488 | |
| 1489 @findex list-directory | |
| 1490 @kindex C-x C-d | |
| 1491 To print a directory listing, use @kbd{C-x C-d} | |
| 1492 (@code{list-directory}). This command prompts in the minibuffer for a | |
| 1493 file name which is either a directory to be listed or pattern | |
| 1494 containing wildcards for the files to be listed. For example, | |
| 1495 | |
| 1496 @example | |
| 1497 C-x C-d /u2/emacs/etc @key{RET} | |
| 1498 @end example | |
| 1499 | |
| 1500 @noindent | |
| 1501 lists all the files in directory @file{/u2/emacs/etc}. An example of | |
| 1502 specifying a file name pattern is: | |
| 1503 | |
| 1504 @example | |
| 1505 C-x C-d /u2/emacs/src/*.c @key{RET} | |
| 1506 @end example | |
| 1507 | |
| 1508 Normally, @kbd{C-x C-d} prints a brief directory listing containing just | |
| 1509 file names. A numeric argument (regardless of value) tells it to print a | |
| 1510 verbose listing (like @code{ls -l}). | |
| 1511 | |
| 1512 @vindex list-directory-brief-switches | |
| 1513 @vindex list-directory-verbose-switches | |
| 1514 Emacs obtains the text of a directory listing by running @code{ls} in | |
| 1515 an inferior process. Two Emacs variables control the switches passed to | |
| 1516 @code{ls}: @code{list-directory-brief-switches} is a string giving the | |
| 1517 switches to use in brief listings (@code{"-CF"} by default). | |
| 1518 @code{list-directory-verbose-switches} is a string giving the switches | |
| 1519 to use in a verbose listing (@code{"-l"} by default). | |
| 1520 | |
| 1521 The variable @code{directory-abbrev-alist} is an alist of abbreviations | |
| 1522 for file directories. The list consists of elements of the form | |
| 1523 @code{(FROM . TO)}, each meaning to replace @code{FROM} with @code{TO} | |
| 1524 when it appears in a directory name. This replacement is done when | |
| 1525 setting up the default directory of a newly visited file. Every @code{FROM} | |
| 1526 string should start with `@samp{^}'. | |
| 1527 | |
| 1528 Use this feature when you have directories which you normally refer to | |
| 1529 via absolute symbolic links. Make @code{TO} the name of the link, and | |
| 1530 @code{FROM} the name it is linked to. | |
| 1531 | |
| 1532 @node Comparing Files, Dired, ListDir, Files | |
| 1533 @section Comparing Files | |
| 1534 @cindex comparing files | |
| 1535 | |
| 1536 @findex diff | |
| 1537 @vindex diff-switches | |
| 1538 The command @kbd{M-x diff} compares two files, displaying the | |
| 1539 differences in an Emacs buffer named @samp{*Diff*}. It works by running | |
| 1540 the @code{diff} program, using options taken from the variable | |
| 1541 @code{diff-switches}, whose value should be a string. | |
| 1542 | |
| 1543 The buffer @samp{*Diff*} has Compilation mode as its major mode, so | |
| 1544 you can use @kbd{C-x `} to visit successive changed locations in the two | |
| 1545 source files. You can also move to a particular hunk of changes and | |
| 1546 type @kbd{C-c C-c} to find the corresponding source location. You can | |
| 1547 also use the other special commands of Compilation mode: @key{SPC} and | |
| 1548 @key{DEL} for scrolling, and @kbd{M-p} and @kbd{M-n} for cursor motion. | |
| 1549 @xref{Compilation}. | |
| 1550 | |
| 1551 @findex diff-backup | |
| 1552 The command @kbd{M-x diff-backup} compares a specified file with its most | |
| 1553 recent backup. If you specify the name of a backup file, | |
| 1554 @code{diff-backup} compares it with the source file that it is a backup | |
| 1555 of. | |
| 1556 | |
| 1557 @findex compare-windows | |
| 1558 @cindex comparing files | |
| 1559 The command @kbd{M-x compare-windows} compares the text in the current | |
| 1560 window with that in the next window. Comparison starts at point in each | |
| 1561 window. Point moves forward in each window, a character at a time in each | |
| 1562 window, until the next characters in the two windows are different. Then | |
| 1563 the command is finished. For more information about windows in Emacs, | |
| 1564 @ref{Windows}. | |
| 1565 | |
| 1566 @vindex compare-ignore-case | |
| 1567 With a numeric argument, @code{compare-windows} ignores changes in | |
| 1568 whitespace. If the variable @code{compare-ignore-case} is | |
| 1569 non-@code{nil}, it ignores differences in case as well. | |
| 1570 | |
| 1571 @node Dired, Misc File Ops, Comparing Files, Files | |
| 1572 @section Dired, the Directory Editor | |
| 1573 @cindex Dired | |
| 1574 @cindex deletion (of files) | |
| 1575 | |
| 1576 Dired makes it easy to delete or visit many of the files in a single | |
| 1577 directory at once. It creates an Emacs buffer containing a listing of the | |
| 1578 directory. You can use the normal Emacs commands to move around in this | |
| 1579 buffer and special Dired commands to operate on the files. | |
| 1580 | |
| 1581 @menu | |
| 1582 * Enter: Dired Enter. How to invoke Dired. | |
| 1583 * Edit: Dired Edit. Editing the Dired buffer. | |
| 1584 * Deletion: Dired Deletion. Deleting files with Dired. | |
| 1585 * Immed: Dired Immed. Other file operations through Dired. | |
| 1586 @end menu | |
| 1587 | |
| 1588 @node Dired Enter, Dired Edit, Dired, Dired | |
| 1589 @subsection Entering Dired | |
| 1590 | |
| 1591 @findex dired | |
| 1592 @kindex C-x d | |
| 1593 @vindex dired-listing-switches | |
| 1594 To invoke dired, type @kbd{C-x d} or @kbd{M-x dired}. The command reads a | |
| 1595 directory name or wildcard file name pattern as a minibuffer argument just | |
| 1596 like the @code{list-directory} command, @kbd{C-x C-d}. Where @code{dired} | |
| 1597 differs from @code{list-directory} is in naming the buffer after the | |
| 1598 directory name or the wildcard pattern used for the listing, and putting | |
| 1599 the buffer into Dired mode so that the special commands of Dired are | |
| 1600 available in it. The variable @code{dired-listing-switches} is a string | |
| 1601 used as an argument to @code{ls} in making the directory; this string | |
| 1602 @i{must} contain @samp{-l}. | |
| 1603 | |
| 1604 @findex dired-other-window | |
| 1605 @kindex C-x 4 d | |
| 1606 To display the Dired buffer in another window rather than in the selected | |
| 1607 window, use @kbd{C-x 4 d} (@code{dired-other-window)} instead of @kbd{C-x d}. | |
| 1608 | |
| 1609 @node Dired Edit, Dired Deletion, Dired Enter, Dired | |
| 1610 @subsection Editing in Dired | |
| 1611 | |
| 1612 Once the Dired buffer exists, you can switch freely between it and other | |
| 1613 Emacs buffers. Whenever the Dired buffer is selected, certain special | |
| 1614 commands are provided that operate on files that are listed. The Dired | |
| 1615 buffer is ``read-only'', and inserting text in it is not useful, so | |
| 1616 ordinary printing characters such as @kbd{d} and @kbd{x} are used for Dired | |
| 1617 commands. Most Dired commands operate on the file described by the line | |
| 1618 that point is on. Some commands perform operations immediately; others | |
| 1619 ``flag'' a file to be operated on later. | |
| 1620 | |
| 1621 Most Dired commands that operate on the current line's file also treat a | |
| 1622 numeric argument as a repeat count, meaning to act on the files of the | |
| 1623 next few lines. A negative argument means to operate on the files of the | |
| 1624 preceding lines, and leave point on the first of those lines. | |
| 1625 | |
| 1626 All the usual Emacs cursor motion commands are available in Dired | |
| 1627 buffers. Some special purpose commands are also provided. The keys | |
| 1628 @kbd{C-n} and @kbd{C-p} are redefined so that they try to position | |
| 1629 the cursor at the beginning of the filename on the line, rather than | |
| 1630 at the beginning of the line. | |
| 1631 | |
| 1632 For extra convenience, @key{SPC} and @kbd{n} in Dired are equivalent to | |
| 1633 @kbd{C-n}. @kbd{p} is equivalent to @kbd{C-p}. Moving by lines is done so | |
| 1634 often in Dired that it deserves to be easy to type. @key{DEL} (move up and | |
| 1635 unflag) is often useful simply for moving up.@refill | |
| 1636 | |
| 1637 The @kbd{g} command in Dired runs @code{revert-buffer} to reinitialize | |
| 1638 the buffer from the actual disk directory and show any changes made in the | |
| 1639 directory by programs other than Dired. All deletion flags in the Dired | |
| 1640 buffer are lost when this is done. | |
| 1641 | |
| 1642 @node Dired Deletion, Dired Immed, Dired Edit, Dired | |
| 1643 @subsection Deleting Files With Dired | |
| 1644 | |
| 1645 The primary use of Dired is to flag files for deletion and then delete | |
| 1646 them. | |
| 1647 | |
| 1648 @table @kbd | |
| 1649 @item d | |
| 1650 Flag this file for deletion. | |
| 1651 @item u | |
| 1652 Remove deletion-flag on this line. | |
| 1653 @item @key{DEL} | |
| 1654 Remove deletion-flag on previous line, moving point to that line. | |
| 1655 @item x | |
| 1656 Delete the files that are flagged for deletion. | |
| 1657 @item # | |
| 1658 Flag all auto-save files (files whose names start and end with @samp{#}) | |
| 1659 for deletion (@pxref{Auto Save}). | |
| 1660 @item ~ | |
| 1661 Flag all backup files (files whose names end with @samp{~}) for deletion | |
| 1662 (@pxref{Backup}). | |
| 1663 @item .@: @r{(Period)} | |
| 1664 Flag excess numeric backup files for deletion. The oldest and newest | |
| 1665 few backup files of any one file are exempt; the middle ones are flagged. | |
| 1666 @end table | |
| 1667 | |
| 1668 You can flag a file for deletion by moving to the line describing the | |
| 1669 file and typing @kbd{d} or @kbd{C-d}. The deletion flag is visible as a | |
| 1670 @samp{D} at the beginning of the line. Point is moved to the beginning of | |
| 1671 the next line, so that repeated @kbd{d} commands flag successive files. | |
| 1672 | |
| 1673 The files are flagged for deletion rather than deleted immediately to | |
| 1674 avoid the danger of deleting a file accidentally. Until you direct Dired | |
| 1675 to delete the flagged files, you can remove deletion flags using the | |
| 1676 commands @kbd{u} and @key{DEL}. @kbd{u} works just like @kbd{d}, but | |
| 1677 removes flags rather than making flags. @key{DEL} moves upward, removing | |
| 1678 flags; it is like @kbd{u} with numeric argument automatically negated. | |
| 1679 | |
| 1680 To delete the flagged files, type @kbd{x}. This command first displays a | |
| 1681 list of all the file names flagged for deletion, and requests confirmation | |
| 1682 with @kbd{yes}. Once you confirm, all the flagged files are deleted, and their | |
| 1683 lines are deleted from the text of the Dired buffer. The shortened Dired | |
| 1684 buffer remains selected. If you answer @kbd{no} or quit with @kbd{C-g}, you | |
| 1685 return immediately to Dired, with the deletion flags still present and no | |
| 1686 files actually deleted. | |
| 1687 | |
| 1688 The @kbd{#}, @kbd{~}, and @kbd{.} commands flag many files for | |
| 1689 deletion, based on their names. These commands are useful precisely | |
| 1690 because they do not actually delete any files; you can remove the | |
| 1691 deletion flags from any flagged files that you really wish to keep.@refill | |
| 1692 | |
| 1693 @kbd{#} flags for deletion all files that appear to have been made by | |
| 1694 auto-saving (that is, files whose names begin and end with @samp{#}). | |
| 1695 @kbd{~} flags for deletion all files that appear to have been made as | |
| 1696 backups for files that were edited (that is, files whose names end with | |
| 1697 @samp{~}). | |
| 1698 | |
| 1699 @vindex dired-kept-versions | |
| 1700 @kbd{.} (Period) flags just some of the backup files for deletion: only | |
| 1701 numeric backups that are not among the oldest few nor the newest few | |
| 1702 backups of any one file. Normally @code{dired-kept-versions} (not | |
| 1703 @code{kept-new-versions}; that applies only when saving) specifies the | |
| 1704 number of newest versions of each file to keep, and | |
| 1705 @code{kept-old-versions} specifies the number of oldest versions to keep. | |
| 1706 Period with a positive numeric argument, as in @kbd{C-u 3 .}, specifies the | |
| 1707 number of newest versions to keep, overriding @code{dired-kept-versions}. | |
| 1708 A negative numeric argument overrides @code{kept-old-versions}, using minus | |
| 1709 the value of the argument to specify the number of oldest versions of each | |
| 1710 file to keep.@refill | |
| 1711 | |
| 1712 @node Dired Immed, , Dired Deletion, Dired | |
| 1713 @subsection Immediate File Operations in Dired | |
| 1714 | |
| 1715 Some file operations in Dired take place immediately when they are | |
| 1716 requested. | |
| 1717 | |
| 1718 @table @kbd | |
| 1719 @item C | |
| 1720 Copies the file described on the current line. You must supply a file name | |
| 1721 to copy to, using the minibuffer. | |
| 1722 @item f | |
| 1723 Visits the file described on the current line. It is just like typing | |
| 1724 @kbd{C-x C-f} and supplying that file name. If the file on this line is a | |
| 1725 subdirectory, @kbd{f} actually causes Dired to be invoked on that | |
| 1726 subdirectory. @xref{Visiting}. | |
| 1727 @item o | |
| 1728 Like @kbd{f}, but uses another window to display the file's buffer. The | |
| 1729 Dired buffer remains visible in the first window. This is like using | |
| 1730 @kbd{C-x 4 C-f} to visit the file. @xref{Windows}. | |
| 1731 @item R | |
| 1732 Renames the file described on the current line. You must supply a file | |
| 1733 name to rename to, using the minibuffer. | |
| 1734 @item v | |
| 1735 Views the file described on this line using @kbd{M-x view-file}. Viewing a | |
| 1736 file is like visiting it, but is slanted toward moving around in the file | |
| 1737 conveniently and does not allow changing the file. @xref{Misc File | |
| 1738 Ops,View File}. Viewing a file that is a directory runs Dired on that | |
| 1739 directory.@refill | |
| 1740 @end table | |
| 1741 | |
| 1742 @node Misc File Ops, , Dired, Files | |
| 1743 @section Miscellaneous File Operations | |
| 1744 | |
| 1745 Emacs has commands for performing many other operations on files. | |
| 1746 All operate on one file; they do not accept wildcard file names. | |
| 1747 | |
| 1748 @findex add-name-to-file | |
| 1749 You can use the command @kbd{M-x add-name-to-file} to add a name to an | |
| 1750 existing file without removing the old name. The new name must belong | |
| 1751 on the file system that the file is on. | |
| 1752 | |
| 1753 @findex append-to-file | |
| 1754 @kbd{M-x append-to-file} adds the text of the region to the end of the | |
| 1755 specified file. | |
| 1756 | |
| 1757 @findex copy-file | |
| 1758 @cindex copying files | |
| 1759 @kbd{M-x copy-file} reads the file @var{old} and writes a new file | |
| 1760 named @var{new} with the same contents. Confirmation is required if a | |
| 1761 file named @var{new} already exists, because copying overwrites the old | |
| 1762 contents of the file @var{new}. | |
| 1763 | |
| 1764 @findex delete-file | |
| 1765 @cindex deletion (of files) | |
| 1766 @kbd{M-x delete-file} deletes a specified file, like the @code{rm} | |
| 1767 command in the shell. If you are deleting many files in one directory, it | |
| 1768 may be more convenient to use Dired (@pxref{Dired}). | |
| 1769 | |
| 1770 @findex insert-file | |
| 1771 @kbd{M-x insert-file} inserts a copy of the contents of a specified | |
| 1772 file into the current buffer at point, leaving point unchanged before the | |
| 1773 contents and the mark after them. @xref{Mark}. | |
| 1774 | |
| 1775 @findex make-symbolic-link | |
| 1776 @kbd{M-x make-symbolic-link} reads two file names @var{old} and | |
| 1777 @var{linkname}, and then creates a symbolic link named @var{linkname} | |
| 1778 and pointing at @var{old}. Future attempts to open file | |
| 1779 @var{linkname} will then refer to the file named @var{old} at the time | |
| 1780 the opening is done, or will result in an error if the name @var{old} is | |
| 1781 not in use at that time. Confirmation is required if you create the | |
| 1782 link while @var{linkname} is in use. Note that not all systems support | |
| 1783 symbolic links. | |
| 1784 | |
| 1785 @findex rename-file | |
| 1786 @kbd{M-x rename-file} reads two file names @var{old} and @var{new} using | |
| 1787 the minibuffer, then renames file @var{old} as @var{new}. If a file named | |
| 1788 @var{new} already exists, you must confirm with @kbd{yes} or renaming is not | |
| 1789 done; this is because renaming causes the previous meaning of the | |
| 1790 name @var{new} to be lost. If @var{old} and @var{new} are on different | |
| 1791 file systems, the file @var{old} is copied and deleted. | |
| 1792 | |
| 1793 @findex view-file | |
| 1794 @cindex viewing | |
| 1795 @kbd{M-x view-file} allows you to scan or read a file by sequential | |
| 1796 screenfuls. It reads a file name argument using the minibuffer. After | |
| 1797 reading the file into an Emacs buffer, @code{view-file} reads and displays | |
| 1798 one windowful. You can then type @key{SPC} to scroll forward one window, | |
| 1799 or @key{DEL} to scroll backward. Various other commands are provided for | |
| 1800 moving around in the file, but none for changing it; type @kbd{C-h} while | |
| 1801 viewing a file for a list of them. Most commands are the default Emacs | |
| 1802 cursor motion commands. To exit from viewing, type @kbd{C-c}. |