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