@c This is part of the Emacs manual.
-@c Copyright (C) 1985,86,87,93,94,95,97,99, 2000, 2001
-@c Free Software Foundation, Inc.
+@c Copyright (C) 1985, 1986, 1987, 1993, 1994, 1995, 1997, 1999, 2000,
+@c 2001, 2002, 2003, 2004, 2005, 2006 Free Software Foundation, Inc.
@c See file emacs.texi for copying conditions.
-@node Files, Buffers, Fixit, Top
+@node Files, Buffers, Keyboard Macros, Top
@chapter File Handling
@cindex files
* Visiting:: Visiting a file prepares Emacs to edit the file.
* Saving:: Saving makes your changes permanent.
* Reverting:: Reverting cancels all the changes not saved.
+@ifnottex
+* Autorevert:: Auto Reverting non-file buffers.
+@end ifnottex
* Auto Save:: Auto Save periodically protects against loss of data.
* File Aliases:: Handling multiple names for one file.
* Version Control:: Version control systems (RCS, CVS and SCCS).
* Directories:: Creating, deleting, and listing file directories.
* Comparing Files:: Finding where two files differ.
+* Diff Mode:: Mode for editing file differences.
* Misc File Ops:: Other things you can do on files.
* Compressed Files:: Accessing compressed files.
* File Archives:: Operating on tar, zip, jar etc. archive files.
* Quoted File Names:: Quoting special characters in file names.
* File Name Cache:: Completion against a list of files you often use.
* File Conveniences:: Convenience Features for Finding Files.
+* Filesets:: Handling sets of files.
@end menu
@node File Names
default directory is kept in the variable @code{default-directory},
which has a separate value in every buffer.
- For example, if the default file name is @file{/u/rms/gnu/gnu.tasks} then
-the default directory is @file{/u/rms/gnu/}. If you type just @samp{foo},
-which does not specify a directory, it is short for @file{/u/rms/gnu/foo}.
-@samp{../.login} would stand for @file{/u/rms/.login}. @samp{new/foo}
-would stand for the file name @file{/u/rms/gnu/new/foo}.
-
@findex cd
@findex pwd
The command @kbd{M-x pwd} displays the current buffer's default
directory, and the command @kbd{M-x cd} sets it (to a value read using
the minibuffer). A buffer's default directory changes only when the
@code{cd} command is used. A file-visiting buffer's default directory
-is initialized to the directory of the file that is visited in that buffer. If
-you create a buffer with @kbd{C-x b}, its default directory is copied
-from that of the buffer that was current at the time.
+is initialized to the directory of the file it visits. If you create
+a buffer with @kbd{C-x b}, its default directory is copied from that
+of the buffer that was current at the time.
+
+ For example, if the default file name is @file{/u/rms/gnu/gnu.tasks}
+then the default directory is normally @file{/u/rms/gnu/}. If you
+type just @samp{foo}, which does not specify a directory, it is short
+for @file{/u/rms/gnu/foo}. @samp{../.login} would stand for
+@file{/u/rms/.login}. @samp{new/foo} would stand for the file name
+@file{/u/rms/gnu/new/foo}.
@vindex insert-default-directory
The default directory actually appears in the minibuffer when the
first slash in the double slash; the result is @samp{/x1/rms/foo}.
@xref{Minibuffer File}.
+@cindex home directory shorthand
+ You can use @file{~/} in a file name to mean your home directory,
+or @file{~@var{user-id}/} to mean the home directory of a user whose
+login name is @code{user-id}@footnote{
+On MS-Windows and MS-DOS systems, where a user doesn't have a home
+directory, Emacs substitutes @file{~/} with the value of the
+environment variable @code{HOME}; see @ref{General Variables}. The
+@file{~@var{user-id}/} construct is supported on those systems only
+for the current user, i.e., only if @var{user-id} is the current
+user's login name.}.
+
@cindex environment variables in file names
@cindex expansion of environment variables
@cindex @code{$} in file names
-@anchor{File Names with $}
- @samp{$} in a file name is used to substitute environment variables.
-For example, if you have used the shell command @command{export
+ @anchor{File Names with $}@samp{$} in a file name is used to
+substitute an environment variable. The environment variable name
+consists of all the alphanumeric characters after the @samp{$};
+alternatively, it can be enclosed in braces after the @samp{$}. For
+example, if you have used the shell command @command{export
FOO=rms/hacks} to set up an environment variable named @env{FOO}, then
you can use @file{/u/$FOO/test.c} or @file{/u/$@{FOO@}/test.c} as an
-abbreviation for @file{/u/rms/hacks/test.c}. The environment variable
-name consists of all the alphanumeric characters after the @samp{$};
-alternatively, it may be enclosed in braces after the @samp{$}. Note
-that shell commands to set environment variables affect Emacs only if
-done before Emacs is started.
+abbreviation for @file{/u/rms/hacks/test.c}. If the environment
+variable is not defined, no substitution occurs: @file{/u/$notdefined}
+stands for itself (assuming the environment variable @env{notdefined}
+is not defined).
-@cindex home directory shorthand
- You can use the @file{~/} in a file name to mean your home directory,
-or @file{~@var{user-id}/} to mean the home directory of a user whose
-login name is @code{user-id}. (On DOS and Windows systems, where a user
-doesn't have a home directory, Emacs substitutes @file{~/} with the
-value of the environment variable @code{HOME}; see @ref{General
-Variables}.)
+ Note that shell commands to set environment variables affect Emacs
+only when done before Emacs is started.
- To access a file with @samp{$} in its name, type @samp{$$}. This pair
-is converted to a single @samp{$} at the same time as variable
-substitution is performed for a single @samp{$}. Alternatively, quote the
-whole file name with @samp{/:} (@pxref{Quoted File Names}). File names
-which begin with a literal @samp{~} should also be quoted with @samp{/:}.
+ To access a file with @samp{$} in its name, if the @samp{$} causes
+expansion, type @samp{$$}. This pair is converted to a single
+@samp{$} at the same time as variable substitution is performed for a
+single @samp{$}. Alternatively, quote the whole file name with
+@samp{/:} (@pxref{Quoted File Names}). File names which begin with a
+literal @samp{~} should also be quoted with @samp{/:}.
@findex substitute-in-file-name
- The Lisp function that performs the substitution is called
+ The Lisp function that performs the @samp{$}-substitution is called
@code{substitute-in-file-name}. The substitution is performed only on
file names read as such using the minibuffer.
- You can include non-ASCII characters in file names if you set the
+ You can include non-@acronym{ASCII} characters in file names if you set the
variable @code{file-name-coding-system} to a non-@code{nil} value.
-@xref{Specify Coding}.
+@xref{File Name Coding}.
@node Visiting
@section Visiting Files
The changes you make with editing commands are made in the Emacs
buffer. They do not take effect in the file that you visited, or any
-place permanent, until you @dfn{save} the buffer. Saving the buffer
+permanent place, until you @dfn{save} the buffer. Saving the buffer
means that Emacs writes the current contents of the buffer into its
visited file. @xref{Saving}.
@kbd{C-g}. File-name completion ignores certain filenames; for more
about this, see @ref{Completion Options}.
-@cindex file selection dialog
- When Emacs is built with a suitable GUI toolkit, it pops up the
-standard File Selection dialog of that toolkit instead of prompting for
-the file name in the minibuffer. On Unix and GNU/Linux platforms, Emacs
-does that when built with LessTif and Motif toolkits; on MS-Windows, the
-GUI version does that by default.
-
- Your confirmation that @kbd{C-x C-f} has completed successfully is the
-appearance of new text on the screen and a new buffer name in the mode
-line. If the specified file does not exist and could not be created, or
-cannot be read, then you get an error, with an error message displayed
-in the echo area.
+ Your confirmation that @kbd{C-x C-f} has completed successfully is
+the appearance of new text on the screen and a new buffer name in the
+mode line. If the specified file does not exist and you could not
+create it, or exists but you can't read it, then you get an error,
+with an error message displayed in the echo area.
If you visit a file that is already in Emacs, @kbd{C-x C-f} does not make
another copy. It selects the existing buffer containing that file.
-However, before doing so, it checks that the file itself has not changed
-since you visited or saved it last. If the file has changed, a warning
-message is shown. @xref{Interlocking,,Simultaneous Editing}.
+However, before doing so, it checks whether the file itself has changed
+since you visited or saved it last. If the file has changed, Emacs offers
+to reread it.
+@vindex large-file-warning-threshold
@cindex maximum buffer size exceeded, error message
- Since Emacs reads the visited file in its entirety, files whose size
-is larger than the maximum Emacs buffer size (@pxref{Buffers}) cannot be
-visited; if you try, Emacs will display an error message saying that the
-maximum buffer size has been exceeded.
+ If you try to visit a file larger than
+@code{large-file-warning-threshold} (the default is 10000000, which is
+about 10 megabytes), Emacs will ask you for confirmation first. You
+can answer @kbd{y} to proceed with visiting the file. Note, however,
+that Emacs cannot visit files that are larger than the maximum Emacs
+buffer size, which is around 256 megabytes on 32-bit machines
+(@pxref{Buffers}). If you try, Emacs will display an error message
+saying that the maximum buffer size has been exceeded.
+
+@cindex file selection dialog
+ On graphical displays there are two additional methods for
+visiting files. Firstly, when Emacs is built with a suitable GUI
+toolkit, commands invoked with the mouse (by clicking on the menu bar
+or tool bar) use the toolkit's standard File Selection dialog instead
+of prompting for the file name in the minibuffer. On Unix and
+GNU/Linux platforms, Emacs does that when built with GTK, LessTif, and
+Motif toolkits; on MS-Windows and Mac, the GUI version does that by default.
+For information on how to customize this, see @ref{Dialog Boxes}.
+
+ Secondly, Emacs supports ``drag and drop''; dropping a file into an
+ordinary Emacs window visits the file using that window. However,
+dropping a file into a window displaying a Dired buffer moves or
+copies the file into the displayed directory. For details, see
+@ref{Drag and Drop}, and @ref{Misc Dired Features}.
@cindex creating files
What if you want to create a new file? Just visit it. Emacs displays
@vindex find-file-run-dired
If the file you specify is actually a directory, @kbd{C-x C-f} invokes
Dired, the Emacs directory browser, so that you can ``edit'' the contents
-of the directory (@pxref{Dired}). Dired is a convenient way to delete,
-look at, or operate on the files in the directory. However, if the
-variable @code{find-file-run-dired} is @code{nil}, then it is an error
-to try to visit a directory.
+of the directory (@pxref{Dired}). Dired is a convenient way to view, delete,
+or operate on the files in the directory. However, if the variable
+@code{find-file-run-dired} is @code{nil}, then it is an error to try
+to visit a directory.
Files which are actually collections of other files, or @dfn{file
archives}, are visited in special modes which invoke a Dired-like
@cindex wildcard characters in file names
@vindex find-file-wildcards
- If the file name you specify contains shell-style wildcard characters,
-Emacs visits all the files that match it. Wildcards include @samp{?},
-@samp{*}, and @samp{[@dots{}]} sequences. @xref{Quoted File Names}, for
-information on how to visit a file whose name actually contains wildcard
-characters. You can disable the wildcard feature by customizing
+ If the file name you specify contains shell-style wildcard
+characters, Emacs visits all the files that match it. Wildcards
+include @samp{?}, @samp{*}, and @samp{[@dots{}]} sequences. To enter
+the wild card @samp{?} in a file name in the minibuffer, you need to
+type @kbd{C-q ?}. @xref{Quoted File Names}, for information on how to
+visit a file whose name actually contains wildcard characters. You
+can disable the wildcard feature by customizing
@code{find-file-wildcards}.
If you visit a file that the operating system won't let you modify,
-Emacs makes the buffer read-only, so that you won't go ahead and make
-changes that you'll have trouble saving afterward. You can make the
-buffer writable with @kbd{C-x C-q} (@code{vc-toggle-read-only}).
-@xref{Misc Buffer}.
+or that is marked read-only, Emacs makes the buffer read-only too, so
+that you won't go ahead and make changes that you'll have trouble
+saving afterward. You can make the buffer writable with @kbd{C-x C-q}
+(@code{toggle-read-only}). @xref{Misc Buffer}.
@kindex C-x C-r
@findex find-file-read-only
- Occasionally you might want to visit a file as read-only in order to
-protect yourself from entering changes accidentally; do so by visiting
-the file with the command @kbd{C-x C-r} (@code{find-file-read-only}).
+ If you want to visit a file as read-only in order to protect
+yourself from entering changes accidentally, visit it with the command
+@kbd{C-x C-r} (@code{find-file-read-only}) instead of @kbd{C-x C-f}.
@kindex C-x C-v
@findex find-alternate-file
default file name in the buffer, with point just after the directory
part; this is convenient if you made a slight error in typing the name.
- If you find a file which exists but cannot be read, @kbd{C-x C-f}
-signals an error.
-
@kindex C-x 4 f
@findex find-file-other-window
@kbd{C-x 4 f} (@code{find-file-other-window}) is like @kbd{C-x C-f}
system. @xref{Frames}.
@findex find-file-literally
- If you wish to edit a file as a sequence of ASCII characters with no special
+ If you wish to edit a file as a sequence of @acronym{ASCII} characters with no special
encoding or conversion, use the @kbd{M-x find-file-literally} command.
It visits a file, like @kbd{C-x C-f}, but does not do format conversion
(@pxref{Formatted Text}), character code conversion (@pxref{Coding
@dfn{Saving} a buffer in Emacs means writing its contents back into the file
that was visited in the buffer.
+@menu
+* Save Commands:: Commands for saving files.
+* Backup:: How Emacs saves the old version of your file.
+* Customize Save:: Customizing the saving of files.
+* Interlocking:: How Emacs protects against simultaneous editing
+ of one file by two users.
+* Shadowing: File Shadowing. Copying files to "shadows" automatically.
+* Time Stamps:: Emacs can update time stamps on saved files.
+@end menu
+
+@node Save Commands
+@subsection Commands for Saving Files
+
+ These are the commands that relate to saving and writing files.
+
@table @kbd
@item C-x C-s
Save the current buffer in its visited file on disk (@code{save-buffer}).
Forget that the current buffer has been changed (@code{not-modified}).
With prefix argument (@kbd{C-u}), mark the current buffer as changed.
@item C-x C-w
-Save the current buffer as a specified file name (@code{write-file}).
+Save the current buffer with a specified file name (@code{write-file}).
@item M-x set-visited-file-name
Change the file name under which the current buffer will be saved.
@end table
View the buffer that you are currently being asked about. When you exit
View mode, you get back to @code{save-some-buffers}, which asks the
question again.
+@item d
+Diff the buffer against its corresponding file, so you can see
+what changes you would be saving.
@item C-h
Display a help message about these options.
@end table
a different file name, one which is not in use for anything important.
Alternatively, you can cancel all the changes made since the file was
visited or saved, by reading the text from the file again. This is
-called @dfn{reverting}. @xref{Reverting}. You could also undo all the
+called @dfn{reverting}. @xref{Reverting}. (You could also undo all the
changes by repeating the undo command @kbd{C-x u} until you have undone
-all the changes; but reverting is easier.
+all the changes; but reverting is easier.) You can also kill the buffer.
@findex set-visited-file-name
@kbd{M-x set-visited-file-name} alters the name of the file that the
@kindex C-x C-w
@findex write-file
If you wish to mark the buffer as visiting a different file and save it
-right away, use @kbd{C-x C-w} (@code{write-file}). It is precisely
-equivalent to @code{set-visited-file-name} followed by @kbd{C-x C-s}.
+right away, use @kbd{C-x C-w} (@code{write-file}). It is
+equivalent to @code{set-visited-file-name} followed by @kbd{C-x C-s}
+(except that @kbd{C-x C-w} asks for confirmation if the file exists).
@kbd{C-x C-s} used on a buffer that is not visiting a file has the
same effect as @kbd{C-x C-w}; that is, it reads a file name, marks the
buffer as visiting that file, and saves it there. The default file name in
by simultaneous editing and requires your immediate attention.
@xref{Interlocking,, Simultaneous Editing}.
-@vindex require-final-newline
- If the value of the variable @code{require-final-newline} is @code{t},
-Emacs silently puts a newline at the end of any file that doesn't
-already end in one, every time a file is saved or written. If the value
-is @code{nil}, Emacs leaves the end of the file unchanged; if it's
-neither @code{nil} nor @code{t}, Emacs asks you whether to add a
-newline. The default is @code{nil}.
-
-@menu
-* Backup:: How Emacs saves the old version of your file.
-* Interlocking:: How Emacs protects against simultaneous editing
- of one file by two users.
-* Shadowing: File Shadowing.
- Copying files to "shadows" automatically.
-* Time Stamps:: Emacs can update time stamps on saved files.
-@end menu
-
@node Backup
@subsection Backup Files
@cindex backup file
Control}), the variable @code{vc-make-backup-files} determines whether
to make backup files. By default it is @code{nil}, since backup files
are redundant when you store all the previous versions in a version
-control system. @xref{General VC Options}.
+control system.
+@iftex
+@xref{General VC Options,,,emacs-xtra, Specialized Emacs Features}.
+@end iftex
+@ifnottex
+@xref{General VC Options}.
+@end ifnottex
+
+
+ At your option, Emacs can keep either a single backup for each file,
+or make a series of numbered backup files for each file that you edit.
@vindex backup-enable-predicate
@vindex temporary-file-directory
for temporary files, specified by @code{temporary-file-directory} or
@code{small-temporary-file-directory}.
- At your option, Emacs can keep either a single backup file or a series of
-numbered backup files for each file that you edit.
-
Emacs makes a backup for a file only the first time the file is saved
from one buffer. No matter how many times you save a file, its backup file
continues to contain the contents from before the file was visited.
newly saved contents if you save again.
@menu
-* Names: Backup Names. How backup files are named;
- choosing single or numbered backup files.
+* One or Many: Numbered Backups. Whether to make one backup file or many.
+* Names: Backup Names. How backup files are named.
* Deletion: Backup Deletion. Emacs deletes excess numbered backups.
* Copying: Backup Copying. Backups can be made by copying or renaming.
@end menu
+@node Numbered Backups
+@subsubsection Numbered Backups
+
+@vindex version-control
+ The choice of single backup file or multiple numbered backup files
+is controlled by the variable @code{version-control}. Its possible
+values are:
+
+@table @code
+@item t
+Make numbered backups.
+@item nil
+Make numbered backups for files that have numbered backups already.
+Otherwise, make single backups.
+@item never
+Never make numbered backups; always make single backups.
+@end table
+
+@noindent
+The usual way to set this variable is globally, through your
+@file{.emacs} file or the customization buffer. However, you can set
+@code{version-control} locally in an individual buffer to control the
+making of backups for that buffer's file. For example, Rmail mode
+locally sets @code{version-control} to @code{never} to make sure that
+there is only one backup for an Rmail file. @xref{Locals}.
+
+@cindex @env{VERSION_CONTROL} environment variable
+ If you set the environment variable @env{VERSION_CONTROL}, to tell
+various GNU utilities what to do with backup files, Emacs also obeys the
+environment variable by setting the Lisp variable @code{version-control}
+accordingly at startup. If the environment variable's value is @samp{t}
+or @samp{numbered}, then @code{version-control} becomes @code{t}; if the
+value is @samp{nil} or @samp{existing}, then @code{version-control}
+becomes @code{nil}; if it is @samp{never} or @samp{simple}, then
+@code{version-control} becomes @code{never}.
+
@node Backup Names
@subsubsection Single or Numbered Backups
- If you choose to have a single backup file (this is the default),
-the backup file's name is normally constructed by appending @samp{~} to the
-file name being edited; thus, the backup file for @file{eval.c} would
-be @file{eval.c~}.
+ When Emacs makes a single backup file, its name is normally
+constructed by appending @samp{~} to the file name being edited; thus,
+the backup file for @file{eval.c} would be @file{eval.c~}.
@vindex make-backup-file-name-function
@vindex backup-directory-alist
@code{backup-directory-alist} applies to numbered backups just as
usual.
-@vindex version-control
- The choice of single backup or numbered backups is controlled by the
-variable @code{version-control}. Its possible values are
-
-@table @code
-@item t
-Make numbered backups.
-@item nil
-Make numbered backups for files that have numbered backups already.
-Otherwise, make single backups.
-@item never
-Never make numbered backups; always make single backups.
-@end table
-
-@noindent
-You can set @code{version-control} locally in an individual buffer to
-control the making of backups for that buffer's file. For example,
-Rmail mode locally sets @code{version-control} to @code{never} to make sure
-that there is only one backup for an Rmail file. @xref{Locals}.
-
-@cindex @env{VERSION_CONTROL} environment variable
- If you set the environment variable @env{VERSION_CONTROL}, to tell
-various GNU utilities what to do with backup files, Emacs also obeys the
-environment variable by setting the Lisp variable @code{version-control}
-accordingly at startup. If the environment variable's value is @samp{t}
-or @samp{numbered}, then @code{version-control} becomes @code{t}; if the
-value is @samp{nil} or @samp{existing}, then @code{version-control}
-becomes @code{nil}; if it is @samp{never} or @samp{simple}, then
-@code{version-control} becomes @code{never}.
-
@node Backup Deletion
@subsubsection Automatic Deletion of Backups
default, both variables are 2.
@vindex delete-old-versions
- If @code{delete-old-versions} is non-@code{nil}, Emacs deletes the
-excess backup files silently. If it is @code{nil}, the default, Emacs
-asks you whether it should delete the excess backup versions.
+ If @code{delete-old-versions} is @code{t}, Emacs deletes the excess
+backup files silently. If it is @code{nil}, the default, Emacs asks
+you whether it should delete the excess backup versions. If it has
+any other value, then Emacs never automatically deletes backups.
Dired's @kbd{.} (Period) command can also be used to delete old versions.
@xref{Dired Deletion}.
any alternate names for the same file. This has nothing to do with
Emacs---the version control system does it.
+@node Customize Save
+@subsection Customizing Saving of Files
+
+@vindex require-final-newline
+ If the value of the variable @code{require-final-newline} is
+@code{t}, saving or writing a file silently puts a newline at the end
+if there isn't already one there. If the value is @code{visit}, Emacs
+adds a newline at the end of any file that doesn't have one, just
+after it visits the file. (This marks the buffer as modified, and you
+can undo it.) If the value is @code{visit-save}, that means to add
+newlines both on visiting and on saving. If the value is @code{nil},
+Emacs leaves the end of the file unchanged; if it's neither @code{nil}
+nor @code{t}, Emacs asks you whether to add a newline. The default is
+@code{nil}.
+
+@vindex mode-require-final-newline
+ Many major modes are designed for specific kinds of files that are
+always supposed to end in newlines. These major modes set the
+variable @code{require-final-newline} according to
+@code{mode-require-final-newline}. By setting the latter variable,
+you can control how these modes handle final newlines.
+
+@vindex write-region-inhibit-fsync
+ When Emacs saves a file, it invokes the @code{fsync} system call to
+force the data immediately out to disk. This is important for safety
+if the system crashes or in case of power outage. However, it can be
+disruptive on laptops using power saving, because it requires the disk
+to spin up each time you save a file. Setting
+@code{write-region-inhibit-fsync} to a non-@code{nil} value disables
+this synchronization. Be careful---this means increased risk of data
+loss.
+
@node Interlocking
@subsection Protection against Simultaneous Editing
@subsection Shadowing Files
@cindex shadow files
@cindex file shadows
+@findex shadow-initialize
@table @kbd
@item M-x shadow-initialize
@node Time Stamps
@subsection Updating Time Stamps Automatically
-@findex time-stamp
@cindex time stamps
@cindex modification dates
@cindex locale, date format
or like this:
@example
-Time-stamp: ""
+Time-stamp: " "
@end example
+@findex time-stamp
Then add the hook function @code{time-stamp} to the hook
-@code{write-file-functions}; that hook function will automatically update
+@code{before-save-hook}; that hook function will automatically update
the time stamp, inserting the current date and time when you save the
file. You can also use the command @kbd{M-x time-stamp} to update the
time stamp manually. For other customizations, see the Custom group
the current buffer. Since reverting a buffer unintentionally could lose
a lot of work, you must confirm this command with @kbd{yes}.
- @code{revert-buffer} keeps point at the same distance (measured in
-characters) from the beginning of the file. If the file was edited only
-slightly, you will be at approximately the same piece of text after
-reverting as before. If you have made drastic changes, the same value of
-point in the old file may address a totally different piece of text.
+ @code{revert-buffer} tries to position point in such a way that, if
+the file was edited only slightly, you will be at approximately the
+same piece of text after reverting as before. However, if you have made
+drastic changes, point may wind up in a totally different piece of text.
Reverting marks the buffer as ``not modified'' until another change is
made.
@cindex mode, Auto-Revert
@findex global-auto-revert-mode
@findex auto-revert-mode
+@findex auto-revert-tail-mode
+
+ You may find it useful to have Emacs revert files automatically when
+they change. Three minor modes are available to do this.
+
+ @kbd{M-x global-auto-revert-mode} enables Global Auto-Revert mode,
+which periodically checks all file buffers and reverts when the
+corresponding file has changed. @kbd{M-x auto-revert-mode} enables a
+local version, Auto-Revert mode, which applies only to the current
+buffer.
+
+ You can use Auto-Revert mode to ``tail'' a file such as a system
+log, so that changes made to that file by other programs are
+continuously displayed. To do this, just move the point to the end of
+the buffer, and it will stay there as the file contents change.
+However, if you are sure that the file will only change by growing at
+the end, use Auto-Revert Tail mode instead
+(@code{auto-revert-tail-mode}). It is more efficient for this.
+
@vindex auto-revert-interval
-You may find it useful to have Emacs revert files automatically when
-they change. Two minor modes are available to do this. In Global
-Auto-Revert mode, Emacs periodically checks all file buffers and
-reverts any when the corresponding file has changed. The local
-variant, Auto-Revert mode, applies only to buffers in which it was
-activated. Checking the files is done at intervals determined by the
-variable @code{auto-revert-interval}.
+ The variable @code{auto-revert-interval} controls how often to check
+for a changed file. Since checking a remote file is too slow, these
+modes do not check or revert remote files.
+
+ @xref{VC Mode Line}, for Auto Revert peculiarities in buffers that
+visit files under version control.
+
+@ifnottex
+@include arevert-xtra.texi
+@end ifnottex
@node Auto Save
@section Auto-Saving: Protection Against Disasters
It prevents you from losing more than a limited amount of work if the
system crashes.
- When Emacs determines that it is time for auto-saving, each buffer is
-considered, and is auto-saved if auto-saving is turned on for it and it
-has been changed since the last time it was auto-saved. The message
-@samp{Auto-saving...} is displayed in the echo area during auto-saving,
-if any files are actually auto-saved. Errors occurring during
-auto-saving are caught so that they do not interfere with the execution
-of commands you have been typing.
+ When Emacs determines that it is time for auto-saving, it considers
+each buffer, and each is auto-saved if auto-saving is enabled for it
+and it has been changed since the last time it was auto-saved. The
+message @samp{Auto-saving...} is displayed in the echo area during
+auto-saving, if any files are actually auto-saved. Errors occurring
+during auto-saving are caught so that they do not interfere with the
+execution of commands you have been typing.
@menu
* Files: Auto Save Files. The file where auto-saved changes are
@samp{#} to the front and rear of buffer name, then
adding digits and letters at the end for uniqueness. For
example, the @samp{*mail*} buffer in which you compose messages to be
-sent might auto-saved in a file named @file{#*mail*#704juu}. Auto-save file
+sent might be auto-saved in a file named @file{#*mail*#704juu}. Auto-save file
names are made this way unless you reprogram parts of Emacs to do
something different (the functions @code{make-auto-save-file-name} and
@code{auto-save-file-name-p}). The file name to be used for auto-saving
@cindex auto-save for remote files
@vindex auto-save-file-name-transforms
-The variable @code{auto-save-file-name-transforms} allows a
-degree of control over the auto-save file name. The default value is
-set up to put the auto-save files for remote files
-(@pxref{Remote Files}) into the temporary file directory on the local
-machine.
+ The variable @code{auto-save-file-name-transforms} allows a degree
+of control over the auto-save file name. It lets you specify a series
+of regular expressions and replacements to transform the auto save
+file name. The default value puts the auto-save files for remote
+files (@pxref{Remote Files}) into the temporary file directory on the
+local machine.
When you delete a substantial part of the text in a large buffer, auto
save turns off temporarily in that buffer. This is because if you
deleted the text unintentionally, you might find the auto-save file more
useful if it contains the deleted text. To reenable auto-saving after
this happens, save the buffer with @kbd{C-x C-s}, or use @kbd{C-u 1 M-x
-auto-save}.
+auto-save-mode}.
@vindex auto-save-visited-file-name
If you want auto-saving to be done in the visited file rather than
@vindex delete-auto-save-files
A buffer's auto-save file is deleted when you save the buffer in its
-visited file. To inhibit this, set the variable @code{delete-auto-save-files}
-to @code{nil}. Changing the visited file name with @kbd{C-x C-w} or
-@code{set-visited-file-name} renames any auto-save file to go with
-the new visited name.
+visited file. (You can inhibit this by setting the variable
+@code{delete-auto-save-files} to @code{nil}.) Changing the visited
+file name with @kbd{C-x C-w} or @code{set-visited-file-name} renames
+any auto-save file to go with the new visited name.
@node Auto Save Control
@subsection Controlling Auto-Saving
@node File Aliases
@section File Name Aliases
+@cindex symbolic links (visiting)
+@cindex hard links (visiting)
Symbolic links and hard links both make it possible for several file
names to refer to the same file. Hard links are alternate names that
@file{foo} is just an alias. More complex cases occur when symbolic
links point to directories.
- If you visit two names for the same file, normally Emacs makes
-two different buffers, but it warns you about the situation.
-
-@vindex find-file-existing-other-name
+@vindex find-file-existing-other-name
@vindex find-file-suppress-same-file-warnings
+
Normally, if you visit a file which Emacs is already visiting under
a different name, Emacs displays a message in the echo area and uses
the existing buffer visiting that file. This can happen on systems
-that support symbolic links, or if you use a long file name on a
-system that truncates long file names. You can suppress the message by
-setting the variable @code{find-file-suppress-same-file-warnings} to a
-non-@code{nil} value. You can disable this feature entirely by setting
-the variable @code{find-file-existing-other-name} to @code{nil}: then
-if you visit the same file under two different names, you get a separate
-buffer for each file name.
+that support hard or symbolic links, or if you use a long file name on
+a system that truncates long file names, or on a case-insensitive file
+system. You can suppress the message by setting the variable
+@code{find-file-suppress-same-file-warnings} to a non-@code{nil}
+value. You can disable this feature entirely by setting the variable
+@code{find-file-existing-other-name} to @code{nil}: then if you visit
+the same file under two different names, you get a separate buffer for
+each file name.
@vindex find-file-visit-truename
@cindex truenames of files
@dfn{Version control systems} are packages that can record multiple
versions of a source file, usually storing the unchanged parts of the
file just once. Version control systems also record history information
-such as the creation time of each version, who created it, and a
+such as the creation time of each version, who created it, and a
description of what was changed in that version.
The Emacs version control interface is called VC. Its commands work
-with three version control systems---RCS, CVS, and SCCS. The GNU
-project recommends RCS and CVS, which are free software and available
-from the Free Software Foundation. We also have free software to
-replace SCCS, known as CSSC; if you are using SCCS and don't want to
-make the incompatible change to RCS or CVS, you can switch to CSSC.
+with different version control systems---currently, it supports CVS,
+GNU Arch, RCS, Meta-CVS, Subversion, and SCCS. Of these, the GNU
+project distributes CVS, GNU Arch, and RCS; we recommend that you use
+either CVS or GNU Arch for your projects, and RCS for individual
+files. We also have free software to replace SCCS, known as CSSC; if
+you are using SCCS and don't want to make the incompatible change to
+RCS or CVS, you can switch to CSSC.
+
+ VC is enabled by default in Emacs. To disable it, set the
+customizable variable @code{vc-handled-backends} to @code{nil}
+@iftex
+(@pxref{Customizing VC,,,emacs-xtra, Specialized Emacs Features}).
+@end iftex
+@ifnottex
+(@pxref{Customizing VC}).
+@end ifnottex
+
@menu
* Introduction to VC:: How version control works in general.
* Old Versions:: Examining and comparing old versions.
* Secondary VC Commands:: The commands used a little less frequently.
* Branches:: Multiple lines of development.
+@ifnottex
* Remote Repositories:: Efficient access to remote CVS servers.
* Snapshots:: Sets of file versions treated as a unit.
* Miscellaneous VC:: Various other commands and features of VC.
* Customizing VC:: Variables that change VC's behavior.
+@end ifnottex
@end menu
@node Introduction to VC
@node Version Systems
@subsubsection Supported Version Control Systems
-@cindex RCS
@cindex back end (version control)
- VC currently works with three different version control systems or
-``back ends'': RCS, CVS, and SCCS.
-
- RCS is a free version control system that is available from the Free
-Software Foundation. It is perhaps the most mature of the supported
-back ends, and the VC commands are conceptually closest to RCS. Almost
-everything you can do with RCS can be done through VC.
+ VC currently works with six different version control systems or
+``back ends'': CVS, GNU Arch, RCS, Meta-CVS, Subversion, and SCCS.
@cindex CVS
- CVS is built on top of RCS, and extends the features of RCS, allowing
-for more sophisticated release management, and concurrent multi-user
-development. VC supports basic editing operations under CVS, but for
-some less common tasks you still need to call CVS from the command line.
-Note also that before using CVS you must set up a repository, which is a
-subject too complex to treat here.
+ CVS is a free version control system that is used for the majority
+of free software projects today. It allows concurrent multi-user
+development either locally or over the network. Some of its
+shortcomings, corrected by newer systems such as GNU Arch, are that it
+lacks atomic commits or support for renaming files. VC supports all
+basic editing operations under CVS, but for some less common tasks you
+still need to call CVS from the command line. Note also that before
+using CVS you must set up a repository, which is a subject too complex
+to treat here.
+
+@cindex GNU Arch
+@cindex Arch
+ GNU Arch is a new version control system that is designed for
+distributed work. It differs in many ways from old well-known
+systems, such as CVS and RCS. It supports different transports for
+interoperating between users, offline operations, and it has good
+branching and merging features. It also supports atomic commits, and
+history of file renaming and moving. VC does not support all
+operations provided by GNU Arch, so you must sometimes invoke it from
+the command line, or use a specialized module.
+
+@cindex RCS
+ RCS is the free version control system around which VC was initially
+built. The VC commands are therefore conceptually closest to RCS.
+Almost everything you can do with RCS can be done through VC. You
+cannot use RCS over the network though, and it only works at the level
+of individual files, rather than projects. You should use it if you
+want a simple, yet reliable tool for handling individual files.
+
+@cindex SVN
+@cindex Subversion
+ Subversion is a free version control system designed to be similar
+to CVS but without CVS's problems. Subversion supports atomic commits,
+and versions directories, symbolic links, meta-data, renames, copies,
+and deletes. It can be used via http or via its own protocol.
+
+@cindex MCVS
+@cindex Meta-CVS
+ Meta-CVS is another attempt to solve problems arising in CVS. It
+supports directory structure versioning, improved branching and
+merging, and use of symbolic links and meta-data in repositories.
@cindex SCCS
SCCS is a proprietary but widely used version control system. In
-terms of capabilities, it is the weakest of the three that VC
-supports. VC compensates for certain features missing in SCCS
-(snapshots, for example) by implementing them itself, but some other VC
-features, such as multiple branches, are not available with SCCS. You
-should use SCCS only if for some reason you cannot use RCS.
+terms of capabilities, it is the weakest of the six that VC supports.
+VC compensates for certain features missing in SCCS (snapshots, for
+example) by implementing them itself, but some other VC features, such
+as multiple branches, are not available with SCCS. Since SCCS is
+non-free, not respecting its users freedom, you should not use it;
+use its free replacement CSSC instead. But you should use CSSC only
+if for some reason you cannot use RCS, or one of the higher-level
+systems such as CVS or GNU Arch.
+
+In the following, we discuss mainly RCS, SCCS and CVS. Nearly
+everything said about CVS applies to GNU Arch, Subversion and Meta-CVS
+as well.
@node VC Concepts
@subsubsection Concepts of Version Control
CVS normally allows each user to modify his own copy of the work file
at any time, but requires merging with changes from other users at
check-in time. However, CVS can also be set up to require locking.
+@iftex
+(@pxref{CVS Options,,,emacs-xtra, Specialized Emacs Features}).
+@end iftex
+@ifnottex
(@pxref{CVS Options}).
+@end ifnottex
+
@node Types of Log File
@subsubsection Types of Log File
@cindex types of log file
-@cindex log File, types of
+@cindex log File, types of
@cindex version control log
-GNU projects under a revision control system generally possess
-@emph{two} types of log for changes. One is the per-file log
-maintained by the revision control system: each time you check in a
-change, you must fill out a @dfn{log entry} for the change (@pxref{Log
-Buffer}). This kind of log is called the @dfn{version control log},
-also the @dfn{revision control log}, @dfn{RCS log}, or @dfn{CVS log}.
-
-The other kind of log is the change log file, typically a file called
-@file{ChangeLog}. It provides a chronological record of all changes
-to a large portion of a program---one directory and its
-subdirectories. A small program would use one @file{ChangeLog} file;
-a large program may well merit a @file{ChangeLog} file in each major
-directory. @xref{Change Log}.
-
-When you use version control, you can use just the per-file log if you
-wish, or you can use both kinds of logs. When you use both, you
-typically want to write just one entry for each change. You can write
+ Projects that use a revision control system can have @emph{two}
+types of log for changes. One is the per-file log maintained by the
+revision control system: each time you check in a change, you must
+fill out a @dfn{log entry} for the change (@pxref{Log Buffer}). This
+kind of log is called the @dfn{version control log}, also the
+@dfn{revision control log}, @dfn{RCS log}, or @dfn{CVS log}.
+
+ The other kind of log is the file @file{ChangeLog} (@pxref{Change
+Log}). It provides a chronological record of all changes to a large
+portion of a program---typically one directory and its subdirectories.
+A small program would use one @file{ChangeLog} file; a large program
+may well merit a @file{ChangeLog} file in each major directory.
+@xref{Change Log}.
+
+ A project maintained with version control can use just the per-file
+log, or it can use both kinds of logs. It can handle some files one
+way and some files the other way. Each project has its policy, which
+you should follow.
+
+ When the policy is to use both, you typically want to write an entry
+for each change just once, then put it into both logs. You can write
the entry in @file{ChangeLog}, then copy it to the log buffer when you
check in the change. Or you can write the entry in the log buffer
while checking in the change, and later use the @kbd{C-x v a} command
-to copy it to @file{ChangeLog} (@pxref{Change Logs and VC}).
+to copy it to @file{ChangeLog}
+@iftex
+(@pxref{Change Logs and VC,,,emacs-xtra, Specialized Emacs Features}).
+@end iftex
+@ifnottex
+(@pxref{Change Logs and VC}).
+@end ifnottex
+
@node VC Mode Line
@subsection Version Control and the Mode Line
that it is modified. If the file is locked by some other user (for
instance, @samp{jim}), that is displayed as @samp{RCS:jim:1.3}.
+@vindex auto-revert-check-vc-info
+ When Auto Revert mode (@pxref{Reverting}) reverts a buffer that is
+under version control, it updates the version control information in
+the mode line. However, Auto Revert mode may not properly update this
+information if the version control status changes without changes to
+the work file, from outside the current Emacs session. If you set
+@code{auto-revert-check-vc-info} to @code{t}, Auto Revert mode updates
+the version control status information every
+@code{auto-revert-interval} seconds, even if the work file itself is
+unchanged. The resulting CPU usage depends on the version control
+system, but is usually not excessive.
+
@node Basic VC Editing
@subsection Basic Editing under Version Control
either locking or check-in, depending on the situation.
@table @kbd
-@item C-x C-q
@itemx C-x v v
Perform the next logical version control operation on this file.
@end table
@findex vc-next-action
-@findex vc-toggle-read-only
@kindex C-x v v
-@kindex C-x C-q @r{(Version Control)}
- Strictly speaking, the command for this job is @code{vc-next-action},
-bound to @kbd{C-x v v}. However, the normal meaning of @kbd{C-x C-q} is
-to make a read-only buffer writable, or vice versa; we have extended it
-to do the same job properly for files managed by version control, by
-performing the appropriate version control operations. When you type
-@kbd{C-x C-q} on a registered file, it acts like @kbd{C-x v v}.
-
The precise action of this command depends on the state of the file,
and whether the version control system uses locking or not. SCCS and
RCS normally use locking; CVS normally does not use locking.
+@findex vc-toggle-read-only
+@kindex C-x C-q @r{(Version Control)}
+ As a special convenience that is particularly useful for files with
+locking, you can let Emacs check a file in or out whenever you change
+its read-only flag. This means, for example, that you cannot
+accidentally edit a file without properly checking it out first. To
+achieve this, bind the key @kbd{C-x C-q} to @kbd{vc-toggle-read-only}
+in your @file{~/.emacs} file. (@xref{Init Rebinding}.)
+
@menu
* VC with Locking:: RCS in its default mode, SCCS, and optionally CVS.
* Without Locking:: Without locking: default mode for CVS.
-* Advanced C-x C-q:: Advanced features available with a prefix argument.
+* Advanced C-x v v:: Advanced features available with a prefix argument.
* Log Buffer:: Features available in log entry buffers.
@end menu
-
-@node VC with Locking
+
+@node VC with Locking
@subsubsection Basic Version Control with Locking
If locking is used for the file (as with SCCS, and RCS in its default
-mode), @kbd{C-x C-q} can either lock a file or check it in:
+mode), @kbd{C-x v v} can either lock a file or check it in:
@itemize @bullet
@item
-If the file is not locked, @kbd{C-x C-q} locks it, and
+If the file is not locked, @kbd{C-x v v} locks it, and
makes it writable so that you can change it.
@item
-If the file is locked by you, and contains changes, @kbd{C-x C-q} checks
+If the file is locked by you, and contains changes, @kbd{C-x v v} checks
in the changes. In order to do this, it first reads the log entry
for the new version. @xref{Log Buffer}.
@item
If the file is locked by you, but you have not changed it since you
-locked it, @kbd{C-x C-q} releases the lock and makes the file read-only
+locked it, @kbd{C-x v v} releases the lock and makes the file read-only
again.
@item
-If the file is locked by some other user, @kbd{C-x C-q} asks you whether
+If the file is locked by some other user, @kbd{C-x v v} asks you whether
you want to ``steal the lock'' from that user. If you say yes, the file
becomes locked by you, but a message is sent to the person who had
formerly locked the file, to inform him of what has happened.
unmodified; it flips to @samp{:} as soon as you save any changes in the
work file.
- Here is what @kbd{C-x C-q} does when using CVS:
+ Here is what @kbd{C-x v v} does when using CVS:
@itemize @bullet
@item
@item
If there are no new changes in the master file, but you have made
-modifications in your work file, @kbd{C-x C-q} checks in your changes.
+modifications in your work file, @kbd{C-x v v} checks in your changes.
In order to do this, it first reads the log entry for the new version.
@xref{Log Buffer}.
@item
-If the file is not modified, the @kbd{C-x C-q} does nothing.
+If the file is not modified, the @kbd{C-x v v} does nothing.
@end itemize
These rules also apply when you use RCS in the mode that does not
since you began editing it, and when this happens, his changes will be
effectively removed when you check in your version (though they will
remain in the master file, so they will not be entirely lost). You must
-therefore verify the current version is unchanged, before you check in your
-changes. We hope to eliminate this risk and provide automatic merging
-with RCS in a future Emacs version.
+therefore verify that the current version is unchanged, before you
+check in your changes. We hope to eliminate this risk and provide
+automatic merging with RCS in a future Emacs version.
In addition, locking is possible with RCS even in this mode, although
-it is not required; @kbd{C-x C-q} with an unmodified file locks the
+it is not required; @kbd{C-x v v} with an unmodified file locks the
file, just as it does with RCS in its normal (locking) mode.
-@node Advanced C-x C-q
-@subsubsection Advanced Control in @kbd{C-x C-q}
+@node Advanced C-x v v
+@subsubsection Advanced Control in @kbd{C-x v v}
@cindex version number to check in/out
When you give a prefix argument to @code{vc-next-action} (@kbd{C-u
-C-x C-q}), it still performs the next logical version control
+C-x v v}), it still performs the next logical version control
operation, but accepts additional arguments to specify precisely how
to do the operation.
version to select; this lets you start working from an older version,
or on another branch. If you do not enter any version, that takes you
to the highest version on the current branch; therefore @kbd{C-u C-x
-C-q @key{RET}} is a convenient way to get the latest version of a file from
+v v @key{RET}} is a convenient way to get the latest version of a file from
the repository.
@item
@cindex specific version control system
Instead of the version number, you can also specify the name of a
version control system. This is useful when one file is being managed
-with two version control systems at the same time (@pxref{Local
-Version Control}).
+with two version control systems at the same time
+@iftex
+(@pxref{Local Version Control,,,emacs-xtra, Specialized Emacs
+Features}).
+@end iftex
+@ifnottex
+(@pxref{Local Version Control}).
+@end ifnottex
+
@end itemize
@node Log Buffer
@subsubsection Features of the Log Entry Buffer
- When you check in changes, @kbd{C-x C-q} first reads a log entry. It
+ When you check in changes, @kbd{C-x v v} first reads a log entry. It
pops up a buffer called @samp{*VC-Log*} for you to enter the log entry.
-When you are finished, type @kbd{C-c C-c} in the @samp{*VC-Log*} buffer.
-That is when check-in really happens.
+
+ Sometimes the @samp{*VC-Log*} buffer contains default text when you enter it,
+typically the last log message entered. If it does, mark and point
+are set around the entire contents of the buffer so that it is easy to
+kill the contents of the buffer with @kbd{C-w}.
+
+@findex log-edit-insert-changelog
+ If you work by writing entries in the @file{ChangeLog}
+(@pxref{Change Log}) and then commit the change under revision
+control, you can generate the Log Edit text from the ChangeLog using
+@kbd{C-c C-a} (@kbd{log-edit-insert-changelog}). This looks for
+entries for the file(s) concerned in the top entry in the ChangeLog
+and uses those paragraphs as the log text. This text is only inserted
+if the top entry was made under your user name on the current date.
+@iftex
+@xref{Change Logs and VC,,,emacs-xtra, Specialized Emacs Features},
+@end iftex
+@ifnottex
+@xref{Change Logs and VC},
+@end ifnottex
+for the opposite way of working---generating ChangeLog entries from
+the revision control log.
+
+ In the @samp{*VC-Log*} buffer, @kbd{C-c C-f} (@kbd{M-x
+log-edit-show-files}) shows the list of files to be committed in case
+you need to check that. (This can be a list of more than one file if
+you use VC Dired mode or PCL-CVS.
+@iftex
+@xref{VC Dired Mode,,,emacs-xtra, Specialized Emacs Features},
+@end iftex
+@ifnottex
+@xref{VC Dired Mode},
+@end ifnottex
+and @ref{Top, , About PCL-CVS, pcl-cvs, PCL-CVS --- The Emacs
+Front-End to CVS}.)
+
+ When you have finished editing the log message, type @kbd{C-c C-c} to
+exit the buffer and commit the change.
To abort check-in, just @strong{don't} type @kbd{C-c C-c} in that
buffer. You can switch buffers and do other editing. As long as you
own.
@item C-x v =
-Compare the current buffer contents with the latest checked-in version
-of the file.
+Compare the current buffer contents with the master version from which
+you started editing.
@item C-u C-x v = @var{file} @key{RET} @var{oldvers} @key{RET} @var{newvers} @key{RET}
Compare the specified two versions of @var{file}.
@item C-x v g
-Display the result of the CVS annotate command using colors.
+Display the file with per-line version information and using colors.
@end table
@findex vc-version-other-window
It is usually more convenient to compare two versions of the file,
with the command @kbd{C-x v =} (@code{vc-diff}). Plain @kbd{C-x v =}
compares the current buffer contents (saving them in the file if
-necessary) with the last checked-in version of the file. @kbd{C-u C-x
-v =}, with a numeric argument, reads a file name and two version
-numbers, then compares those versions of the specified file. Both
-forms display the output in a special buffer in another window.
+necessary) with the master version from which you started editing the
+file (this is not necessarily the latest version of the file).
+@kbd{C-u C-x v =}, with a numeric argument, reads a file name and two
+version numbers, then compares those versions of the specified file.
+Both forms display the output in a special buffer in another window.
You can specify a checked-in version by its number; an empty input
specifies the current contents of the work file (which may be different
from all the checked-in versions). You can also specify a snapshot name
-(@pxref{Snapshots}) instead of one or both version numbers.
+@iftex
+(@pxref{Snapshots,,,emacs-xtra, Specialized Emacs Features})
+@end iftex
+@ifnottex
+(@pxref{Snapshots})
+@end ifnottex
+instead of one or both version numbers.
If you supply a directory name instead of the name of a registered
file, this command compares the two specified versions of all registered
the options in @code{vc-rcs-diff-switches}. The
@samp{vc@dots{}diff-switches} variables are @code{nil} by default.
- Unlike the @kbd{M-x diff} command, @kbd{C-x v =} does not try to
-locate the changes in the old and new versions. This is because
-normally one or both versions do not exist as files when you compare
-them; they exist only in the records of the master file.
-@xref{Comparing Files}, for more information about @kbd{M-x diff}.
+ The buffer produced by @kbd{C-x v =} supports the commands of
+Compilation mode (@pxref{Compilation Mode}), such as @kbd{C-x `} and
+@kbd{C-c C-c}, in both the ``old'' and ``new'' text, and they always
+find the corresponding locations in the current work file. (Older
+versions are not, in general, present as files on your disk.)
@findex vc-annotate
@kindex C-x v g
- For CVS-controlled files, you can display the result of the CVS
-annotate command, using colors to enhance the visual appearance. Use
-the command @kbd{M-x vc-annotate} to do this. It creates a new buffer
-to display file's text, colored to show how old each part is. Text
-colored red is new, blue means old, and intermediate colors indicate
-intermediate ages. By default, the time scale is 360 days, so that
-everything more than one year old is shown in blue.
+ For some back ends, you can display the file @dfn{annotated} with
+per-line version information and using colors to enhance the visual
+appearance, with the command @kbd{M-x vc-annotate}. It creates a new
+buffer (the ``annotate buffer'') displaying the file's text, with each
+part colored to show how old it is. Text colored red is new, blue means
+old, and intermediate colors indicate intermediate ages. By default,
+the color is scaled over the full range of ages, such that the oldest
+changes are blue, and the newest changes are red.
When you give a prefix argument to this command, it uses the
minibuffer to read two arguments: which version number to display and
-annotate (instead of the current file contents), and a stretch factor
-for the time scale. A stretch factor of 0.1 means that the color
-range from red to blue spans the past 36 days instead of 360 days. A
-stretch factor greater than 1 means the color range spans more than a
-year.
+annotate (instead of the current file contents), and the time span in
+days the color range should cover.
+
+ From the annotate buffer, these and other color scaling options are
+available from the @samp{VC-Annotate} menu. In this buffer, you can
+also use the following keys to browse the annotations of past revisions,
+view diffs, or view log entries:
+
+@table @kbd
+@item P
+Annotate the previous revision, that is to say, the revision before
+the one currently annotated. A numeric prefix argument is a repeat
+count, so @kbd{C-u 10 P} would take you back 10 revisions.
+
+@item N
+Annotate the next revision---the one after the revision currently
+annotated. A numeric prefix argument is a repeat count.
+
+@item J
+Annotate the revision indicated by the current line.
+
+@item A
+Annotate the revision before the one indicated by the current line.
+This is useful to see the state the file was in before the change on
+the current line was made.
+
+@item D
+Display the diff between the current line's revision and the previous
+revision. This is useful to see what the current line's revision
+actually changed in the file.
+
+@item L
+Show the log of the current line's revision. This is useful to see
+the author's description of the changes in the revision on the current
+line.
+
+@item W
+Annotate the workfile version--the one you are editing. If you used
+@kbd{P} and @kbd{N} to browse to other revisions, use this key to
+return to your current version.
+@end table
@node Secondary VC Commands
@subsection The Secondary Commands of VC
@menu
* Registering:: Putting a file under version control.
* VC Status:: Viewing the VC status of files.
-* VC Undo:: Cancelling changes before or after check-in.
-* VC Dired Mode:: Listing files managed by version control.
+* VC Undo:: Canceling changes before or after check-in.
+@ifnottex
+* VC Dired Mode:: Listing files managed by version control.
* VC Dired Commands:: Commands to use in a VC Dired buffer.
+@end ifnottex
@end menu
@node Registering
To register the file, Emacs must choose which version control system
to use for it. If the file's directory already contains files
registered in a version control system, Emacs uses that system. If
-there is more than one system in use for a directory, Emacs uses the one
-that appears first in @code{vc-handled-backends} (@pxref{Customizing VC}).
-On the other hand, if there are no files already registered,
-Emacs uses the first system from @code{vc-handled-backends} that could
-register the file---for example, you cannot register a file under CVS if
-its directory is not already part of a CVS tree.
-
- With the default value of @code{vc-handled-backends}, this means
-that Emacs uses RCS if there are any files under RCS control, CVS if
-there are any files under CVS, SCCS if any files are under SCCS, or
-RCS as the ultimate default.
+there is more than one system in use for a directory, Emacs uses the
+one that appears first in @code{vc-handled-backends}
+@iftex
+(@pxref{Customizing VC,,,emacs-xtra, Specialized Emacs Features}).
+@end iftex
+@ifnottex
+(@pxref{Customizing VC}).
+@end ifnottex
+On the other hand, if there are no files already registered, Emacs uses
+the first system from @code{vc-handled-backends} that could register
+the file (for example, you cannot register a file under CVS if its
+directory is not already part of a CVS tree); with the default value
+of @code{vc-handled-backends}, this means that Emacs uses RCS in this
+situation.
If locking is in use, @kbd{C-x v i} leaves the file unlocked and
-read-only. Type @kbd{C-x C-q} if you wish to start editing it. After
+read-only. Type @kbd{C-x v v} if you wish to start editing it. After
registering a file with CVS, you must subsequently commit the initial
-version by typing @kbd{C-x C-q}.
+version by typing @kbd{C-x v v}. Until you do that, the version
+appears as @samp{@@@@} in the mode line.
@vindex vc-default-init-version
@cindex initial version number to register
To view the detailed version control status and history of a file,
type @kbd{C-x v l} (@code{vc-print-log}). It displays the history of
changes to the current file, including the text of the log entries. The
-output appears in a separate window.
+output appears in a separate window. The point is centered at the
+revision of the file that is currently being visited.
+
+ In the change log buffer, you can use the following keys to move
+between the logs of revisions and of files, to view past revisions, and
+to view diffs:
+
+@table @kbd
+@item p
+Move to the previous revision-item in the buffer. (Revision entries in the log
+buffer are usually in reverse-chronological order, so the previous
+revision-item usually corresponds to a newer revision.) A numeric
+prefix argument is a repeat count.
+
+@item n
+Move to the next revision-item (which most often corresponds to the
+previous revision of the file). A numeric prefix argument is a repeat
+count.
+
+@item P
+Move to the log of the previous file, when the logs of multiple files
+are in the log buffer
+@iftex
+(@pxref{VC Dired Mode,,,emacs-xtra, Specialized Emacs Features}).
+@end iftex
+@ifnottex
+(@pxref{VC Dired Mode}).
+@end ifnottex
+Otherwise, just move to the beginning of the log. A numeric prefix
+argument is a repeat count, so @kbd{C-u 10 P} would move backward 10
+files.
+
+@item N
+Move to the log of the next file, when the logs of multiple files are
+in the log buffer
+@iftex
+(@pxref{VC Dired Mode,,,emacs-xtra, Specialized Emacs Features}).
+@end iftex
+@ifnottex
+(@pxref{VC Dired Mode}).
+@end ifnottex
+It also takes a numeric prefix argument as a repeat count.
+
+@item f
+Visit the revision indicated at the current line, like typing @kbd{C-x
+v ~} and specifying this revision's number (@pxref{Old Versions}).
+
+@item d
+Display the diff (@pxref{Comparing Files}) between the revision
+indicated at the current line and the next earlier revision. This is
+useful to see what actually changed when the revision indicated on the
+current line was committed.
+@end table
@node VC Undo
@subsubsection Undoing Version Control Actions
@table @kbd
@item C-x v u
-Revert the buffer and the file to the last checked-in version.
+Revert the buffer and the file to the version from which you started
+editing the file.
@item C-x v c
Remove the last-entered change from the master for the visited file.
@kindex C-x v u
@findex vc-revert-buffer
If you want to discard your current set of changes and revert to the
-last version checked in, use @kbd{C-x v u} (@code{vc-revert-buffer}).
-This leaves the file unlocked; if locking is in use, you must first lock
-the file again before you change it again. @kbd{C-x v u} requires
-confirmation, unless it sees that you haven't made any changes since the
-last checked-in version.
+version from which you started editing the file, use @kbd{C-x v u}
+(@code{vc-revert-buffer}). This leaves the file unlocked; if locking
+is in use, you must first lock the file again before you change it
+again. @kbd{C-x v u} requires confirmation, unless it sees that you
+haven't made any changes with respect to the master version.
@kbd{C-x v u} is also the command to unlock a file if you lock it and
then decide not to change it.
@findex vc-cancel-version
To cancel a change that you already checked in, use @kbd{C-x v c}
(@code{vc-cancel-version}). This command discards all record of the
-most recent checked-in version. @kbd{C-x v c} also offers to revert
-your work file and buffer to the previous version (the one that precedes
-the version that is deleted).
+most recent checked-in version, but only if your work file corresponds
+to that version---you cannot use @kbd{C-x v c} to cancel a version
+that is not the latest on its branch. @kbd{C-x v c} also offers to
+revert your work file and buffer to the previous version (the one that
+precedes the version that is deleted).
If you answer @kbd{no}, VC keeps your changes in the buffer, and locks
the file. The no-revert option is useful when you have checked in a
erroneous check-in, fix the error, and check the file in again.
When @kbd{C-x v c} does not revert the buffer, it unexpands all
-version control headers in the buffer instead (@pxref{Version Headers}).
+version control headers in the buffer instead
+@iftex
+(@pxref{Version Headers,,,emacs-xtra, Specialized Emacs Features}).
+@end iftex
+@ifnottex
+(@pxref{Version Headers}).
+@end ifnottex
This is because the buffer no longer corresponds to any existing
-version. If you check it in again, the check-in process will expand the
-headers properly for the new version number.
+version. If you check it in again, the check-in process will expand
+the headers properly for the new version number.
However, it is impossible to unexpand the RCS @samp{@w{$}Log$} header
automatically. If you use that header feature, you have to unexpand it
under CVS, because canceling versions is very dangerous and discouraged
with CVS.
-@node VC Dired Mode
-@subsubsection Dired under VC
-
-@cindex PCL-CVS
-@pindex cvs
-@cindex CVS Dired Mode
- The VC Dired Mode described here works with all the version control
-systems that VC supports. Another more powerful facility, designed
-specifically for CVS, is called PCL-CVS. @xref{Top, , About PCL-CVS,
-pcl-cvs, PCL-CVS --- The Emacs Front-End to CVS}.
-
-@kindex C-x v d
-@findex vc-directory
- When you are working on a large program, it is often useful to find
-out which files have changed within an entire directory tree, or to view
-the status of all files under version control at once, and to perform
-version control operations on collections of files. You can use the
-command @kbd{C-x v d} (@code{vc-directory}) to make a directory listing
-that includes only files relevant for version control.
-
-@vindex vc-dired-terse-display
- @kbd{C-x v d} creates a buffer which uses VC Dired Mode. This looks
-much like an ordinary Dired buffer (@pxref{Dired}); however, normally it
-shows only the noteworthy files (those locked or not up-to-date). This
-is called @dfn{terse display}. If you set the variable
-@code{vc-dired-terse-display} to @code{nil}, then VC Dired shows all
-relevant files---those managed under version control, plus all
-subdirectories (@dfn{full display}). The command @kbd{v t} in a VC
-Dired buffer toggles between terse display and full display (@pxref{VC
-Dired Commands}).
-
-@vindex vc-dired-recurse
- By default, VC Dired produces a recursive listing of noteworthy or
-relevant files at or below the given directory. You can change this by
-setting the variable @code{vc-dired-recurse} to @code{nil}; then VC
-Dired shows only the files in the given directory.
-
- The line for an individual file shows the version control state in the
-place of the hard link count, owner, group, and size of the file. If
-the file is unmodified, in sync with the master file, the version
-control state shown is blank. Otherwise it consists of text in
-parentheses. Under RCS and SCCS, the name of the user locking the file
-is shown; under CVS, an abbreviated version of the @samp{cvs status}
-output is used. Here is an example using RCS:
-
-@smallexample
-@group
- /home/jim/project:
-
- -rw-r--r-- (jim) Apr 2 23:39 file1
- -r--r--r-- Apr 5 20:21 file2
-@end group
-@end smallexample
-
-@noindent
-The files @samp{file1} and @samp{file2} are under version control,
-@samp{file1} is locked by user jim, and @samp{file2} is unlocked.
-
- Here is an example using CVS:
-
-@smallexample
-@group
- /home/joe/develop:
-
- -rw-r--r-- (modified) Aug 2 1997 file1.c
- -rw-r--r-- Apr 4 20:09 file2.c
- -rw-r--r-- (merge) Sep 13 1996 file3.c
-@end group
-@end smallexample
-
- Here @samp{file1.c} is modified with respect to the repository, and
-@samp{file2.c} is not. @samp{file3.c} is modified, but other changes
-have also been checked in to the repository---you need to merge them
-with the work file before you can check it in.
-
-@vindex vc-directory-exclusion-list
- When VC Dired displays subdirectories (in the ``full'' display mode),
-it omits some that should never contain any files under version control.
-By default, this includes Version Control subdirectories such as
-@samp{RCS} and @samp{CVS}; you can customize this by setting the
-variable @code{vc-directory-exclusion-list}.
-
- You can fine-tune VC Dired's format by typing @kbd{C-u C-x v d}---as in
-ordinary Dired, that allows you to specify additional switches for the
-@samp{ls} command.
-
-@node VC Dired Commands
-@subsubsection VC Dired Commands
-
- All the usual Dired commands work normally in VC Dired mode, except
-for @kbd{v}, which is redefined as the version control prefix. You can
-invoke VC commands such as @code{vc-diff} and @code{vc-print-log} by
-typing @kbd{v =}, or @kbd{v l}, and so on. Most of these commands apply
-to the file name on the current line.
-
- The command @kbd{v v} (@code{vc-next-action}) operates on all the
-marked files, so that you can lock or check in several files at once.
-If it operates on more than one file, it handles each file according to
-its current state; thus, it might lock one file, but check in another
-file. This could be confusing; it is up to you to avoid confusing
-behavior by marking a set of files that are in a similar state.
-
- If any files call for check-in, @kbd{v v} reads a single log entry,
-then uses it for all the files being checked in. This is convenient for
-registering or checking in several files at once, as part of the same
-change.
-
-@findex vc-dired-toggle-terse-mode
-@findex vc-dired-mark-locked
- You can toggle between terse display (only locked files, or files not
-up-to-date) and full display at any time by typing @kbd{v t}
-(@code{vc-dired-toggle-terse-mode}). There is also a special command
-@kbd{* l} (@code{vc-dired-mark-locked}), which marks all files currently
-locked (or, with CVS, all files not up-to-date). Thus, typing @kbd{* l
-t k} is another way to delete from the buffer all files except those
-currently locked.
+@ifnottex
+@c vc1-xtra.texi needs extra level of lowering.
+@lowersections
+@include vc1-xtra.texi
+@raisesections
+@end ifnottex
@node Branches
@subsection Multiple Branches of a File
features. Each such independent line of development is called a
@dfn{branch}. VC allows you to create branches, switch between
different branches, and merge changes from one branch to another.
-Please note, however, that branches are only supported for RCS at the
-moment.
+Please note, however, that branches are not supported for SCCS.
A file's main line of development is usually called the @dfn{trunk}.
The versions on the trunk are normally numbered 1.1, 1.2, 1.3, etc. At
* Switching Branches:: How to get to another existing branch.
* Creating Branches:: How to start a new branch.
* Merging:: Transferring changes between branches.
-* Multi-User Branching:: Multiple users working at multiple branches
+* Multi-User Branching:: Multiple users working at multiple branches
in parallel.
@end menu
@node Switching Branches
@subsubsection Switching between Branches
- To switch between branches, type @kbd{C-u C-x C-q} and specify the
+ To switch between branches, type @kbd{C-u C-x v v} and specify the
version number you want to select. This version is then visited
@emph{unlocked} (write-protected), so you can examine it before locking
it. Switching branches in this way is allowed only when the file is not
To create a new branch from a head version (one that is the latest in
the branch that contains it), first select that version if necessary,
-lock it with @kbd{C-x C-q}, and make whatever changes you want. Then,
-when you check in the changes, use @kbd{C-u C-x C-q}. This lets you
+lock it with @kbd{C-x v v}, and make whatever changes you want. Then,
+when you check in the changes, use @kbd{C-u C-x v v}. This lets you
specify the version number for the new version. You should specify a
suitable branch number for a branch starting at the current version.
For example, if the current version is 2.5, the branch number should be
To create a new branch at an older version (one that is no longer the
head of a branch), first select that version (@pxref{Switching
-Branches}), then lock it with @kbd{C-x C-q}. You'll be asked to
+Branches}), then lock it with @kbd{C-x v v}. You'll be asked to
confirm, when you lock the old version, that you really mean to create a
new branch---if you say no, you'll be offered a chance to lock the
latest version instead.
- Then make your changes and type @kbd{C-x C-q} again to check in a new
+ Then make your changes and type @kbd{C-x v v} again to check in a new
version. This automatically creates a new branch starting from the
selected version. You need not specially request a new branch, because
that's the only way to add a new version at a point that is not the head
After the branch is created, you ``stay'' on it. That means that
subsequent check-ins create new versions on that branch. To leave the
branch, you must explicitly select a different version with @kbd{C-u C-x
-C-q}. To transfer changes from one branch to another, use the merge
+v v}. To transfer changes from one branch to another, use the merge
command, described in the next section.
@node Merging
As an example, suppose that you have finished a certain feature on
branch 1.3.1. In the meantime, development on the trunk has proceeded
to version 1.5. To merge the changes from the branch to the trunk,
-first go to the head version of the trunk, by typing @kbd{C-u C-x C-q
+first go to the head version of the trunk, by typing @kbd{C-u C-x v v
@key{RET}}. Version 1.5 is now current. If locking is used for the file,
-type @kbd{C-x C-q} to lock version 1.5 so that you can change it. Next,
+type @kbd{C-x v v} to lock version 1.5 so that you can change it. Next,
type @kbd{C-x v m 1.3.1 @key{RET}}. This takes the entire set of changes on
branch 1.3.1 (relative to version 1.3, where the branch started, up to
the last version on the branch) and merges it into the current version
records.
This technique works reliably and automatically, provided that the
-source files contain RCS version headers (@pxref{Version Headers}). The
-headers enable Emacs to be sure, at all times, which version number is
-present in the work file.
+source files contain RCS version headers
+@iftex
+(@pxref{Version Headers,,,emacs-xtra, Specialized Emacs Features}).
+@end iftex
+@ifnottex
+(@pxref{Version Headers}).
+@end ifnottex
+The headers enable Emacs to be sure, at all times, which version
+number is present in the work file.
If the files do not have version headers, you must instead tell Emacs
explicitly in each session which branch you are working on. To do this,
-first find the file, then type @kbd{C-u C-x C-q} and specify the correct
+first find the file, then type @kbd{C-u C-x v v} and specify the correct
branch number. This ensures that Emacs knows which branch it is using
during this particular editing session.
-@node Remote Repositories
-@subsection Remote Repositories
-@cindex remote repositories (CVS)
-
- A common way of using CVS is to set up a central CVS repository on
-some Internet host, then have each developer check out a personal
-working copy of the files on his local machine. Committing changes to
-the repository, and picking up changes from other users into one's own
-working area, then works by direct interactions with the CVS server.
-
- One difficulty is that access to the CVS server is often slow, and
-that developers might need to work off-line as well. VC is designed
-to reduce the amount of network interaction necessary.
-
-@menu
-* Version Backups:: Keeping local copies of repository versions.
-* Local Version Control:: Using another version system for local editing.
-@end menu
-
-@node Version Backups
-@subsubsection Version Backups
-@cindex version backups
-
-@cindex automatic version backups
- When VC sees that the CVS repository for a file is on a remote
-machine, it automatically makes local backups of unmodified versions
-of the file---@dfn{automatic version backups}. This means that you
-can compare the file to the repository version (@kbd{C-x v =}), or
-revert to that version (@kbd{C-x v u}), without any network
-interactions.
-
- The local copy of the unmodified file is called a @dfn{version
-backup} to indicate that it corresponds exactly to a version that is
-stored in the repository. Note that version backups are not the same
-as ordinary Emacs backup files (@pxref{Backup}). But they follow a
-similar naming convention.
-
- For a file that comes from a remote CVS repository, VC makes a
-version backup whenever you save the first changes to the file, and
-removes it after you have committed your modified version to the
-repository. You can disable the making of automatic version backups by
-setting @code{vc-cvs-stay-local} to @code{nil} (@pxref{CVS Options}).
-
-@cindex manual version backups
- The name of the automatic version backup for version @var{version}
-of file @var{file} is @code{@var{file}.~@var{version}.~}. This is
-almost the same as the name used by @kbd{C-x v ~} (@pxref{Old
-Versions}), the only difference being the additional dot (@samp{.})
-after the version number. This similarity is intentional, because
-both kinds of files store the same kind of information. The file made
-by @kbd{C-x v ~} acts as a @dfn{manual version backup}.
-
- All the VC commands that operate on old versions of a file can use
-both kinds of version backups. For instance, @kbd{C-x v ~} uses
-either an automatic or a manual version backup, if possible, to get
-the contents of the version you request. Likewise, @kbd{C-x v =} and
-@kbd{C-x v u} use either an automatic or a manual version backup, if
-one of them exists, to get the contents of a version to compare or
-revert to. If you changed a file outside of Emacs, so that no
-automatic version backup was created for the previous text, you can
-create a manual backup of that version using @kbd{C-x v ~}, and thus
-obtain the benefit of the local copy for Emacs commands.
-
- The only difference in Emacs's handling of manual and automatic
-version backups, once they exist, is that Emacs deletes automatic
-version backups when you commit to the repository. By contrast,
-manual version backups remain until you delete them.
-
-@node Local Version Control
-@subsubsection Local Version Control
-@cindex local version control
-@cindex local back end (version control)
-
-When you make many changes to a file that comes from a remote
-repository, it can be convenient to have version control on your local
-machine as well. You can then record intermediate versions, revert to
-a previous state, etc., before you actually commit your changes to the
-remote server.
-
-VC lets you do this by putting a file under a second, local version
-control system, so that the file is effectively registered in two
-systems at the same time. For the description here, we will assume
-that the remote system is CVS, and you use RCS locally, although the
-mechanism works with any combination of version control systems
-(@dfn{back ends}).
-
-To make it work with other back ends, you must make sure that the
-``more local'' back end comes before the ``more remote'' back end in
-the setting of @code{vc-handled-backends} (@pxref{Customizing VC}). By
-default, this variable is set up so that you can use remote CVS and
-local RCS as described here.
-
-To start using local RCS for a file that comes from a remote CVS
-server, you must @emph{register the file in RCS}, by typing @kbd{C-u
-C-x v v rcs @key{RET}}. (In other words, use @code{vc-next-action} with a
-prefix argument, and specify RCS as the back end.)
-
-You can do this at any time; it does not matter whether you have
-already modified the file with respect to the version in the CVS
-repository. If possible, VC tries to make the RCS master start with
-the unmodified repository version, then checks in any local changes
-as a new version. This works if you have not made any changes yet, or
-if the unmodified repository version exists locally as a version
-backup (@pxref{Version Backups}). If the unmodified version is not
-available locally, the RCS master starts with the modified version;
-the only drawback to this is that you cannot compare your changes
-locally to what is stored in the repository.
-
-The version number of the RCS master is derived from the current CVS
-version, starting a branch from it. For example, if the current CVS
-version is 1.23, the local RCS branch will be 1.23.1. Version 1.23 in
-the RCS master will be identical to version 1.23 under CVS; your first
-changes are checked in as 1.23.1.1. (If the unmodified file is not
-available locally, VC will check in the modified file twice, both as
-1.23 and 1.23.1.1, to make the revision numbers consistent.)
-
-If you do not use locking under CVS (the default), locking is also
-disabled for RCS, so that editing under RCS works exactly as under
-CVS.
-
-When you are done with local editing, you can commit the final version
-back to the CVS repository by typing @kbd{C-u C-x v v cvs @key{RET}}.
-This initializes the log entry buffer (@pxref{Log Buffer}) to contain
-all the log entries you have recorded in the RCS master; you can edit
-them as you wish, and then commit in CVS by typing @kbd{C-c C-c}. If
-the commit is successful, VC removes the RCS master, so that the file
-is once again registered under CVS only. (The RCS master is not
-actually deleted, just renamed by appending @samp{~} to the name, so
-that you can refer to it later if you wish.)
-
-While using local RCS, you can pick up recent changes from the CVS
-repository into your local file, or commit some of your changes back
-to CVS, without terminating local RCS version control. To do this,
-switch to the CVS back end temporarily, with the @kbd{C-x v b} command:
-
-@table @kbd
-@item C-x v b
-Switch to another back end that the current file is registered
-under (@code{vc-switch-backend}).
-
-@item C-u C-x v b @var{backend} @key{RET}
-Switch to @var{backend} for the current file.
-@end table
-
-@kindex C-x v b
-@findex vc-switch-backend
-@kbd{C-x v b} does not change the buffer contents, or any files; it
-only changes VC's perspective on how to handle the file. Any
-subsequent VC commands for that file will operate on the back end that
-is currently selected.
-
-If the current file is registered in more than one back end, typing
-@kbd{C-x v b} ``cycles'' through all of these back ends. With a
-prefix argument, it asks for the back end to use in the minibuffer.
-
-Thus, if you are using local RCS, and you want to pick up some recent
-changes in the file from remote CVS, first visit the file, then type
-@kbd{C-x v b} to switch to CVS, and finally use @kbd{C-x v m
-@key{RET}} to merge the news (@pxref{Merging}). You can then switch
-back to RCS by typing @kbd{C-x v b} again, and continue to edit
-locally.
-
-But if you do this, the revision numbers in the RCS master no longer
-correspond to those of CVS. Technically, this is not a problem, but
-it can become difficult to keep track of what is in the CVS repository
-and what is not. So we suggest that you return from time to time to
-CVS-only operation, using @kbd{C-u C-x v v cvs @key{RET}}.
-
-@node Snapshots
-@subsection Snapshots
-@cindex snapshots and version control
-
- A @dfn{snapshot} is a named set of file versions (one for each
-registered file) that you can treat as a unit. One important kind of
-snapshot is a @dfn{release}, a (theoretically) stable version of the
-system that is ready for distribution to users.
-
-@menu
-* Making Snapshots:: The snapshot facilities.
-* Snapshot Caveats:: Things to be careful of when using snapshots.
-@end menu
-
-@node Making Snapshots
-@subsubsection Making and Using Snapshots
-
- There are two basic commands for snapshots; one makes a
-snapshot with a given name, the other retrieves a named snapshot.
-
-@table @code
-@kindex C-x v s
-@findex vc-create-snapshot
-@item C-x v s @var{name} @key{RET}
-Define the last saved versions of every registered file in or under the
-current directory as a snapshot named @var{name}
-(@code{vc-create-snapshot}).
-
-@kindex C-x v r
-@findex vc-retrieve-snapshot
-@item C-x v r @var{name} @key{RET}
-For all registered files at or below the current directory level, select
-whatever versions correspond to the snapshot @var{name}
-(@code{vc-retrieve-snapshot}).
-
-This command reports an error if any files are locked at or below the
-current directory, without changing anything; this is to avoid
-overwriting work in progress.
-@end table
-
- A snapshot uses a very small amount of resources---just enough to record
-the list of file names and which version belongs to the snapshot. Thus,
-you need not hesitate to create snapshots whenever they are useful.
-
- You can give a snapshot name as an argument to @kbd{C-x v =} or
-@kbd{C-x v ~} (@pxref{Old Versions}). Thus, you can use it to compare a
-snapshot against the current files, or two snapshots against each other,
-or a snapshot against a named version.
-
-@node Snapshot Caveats
-@subsubsection Snapshot Caveats
-
-@cindex named configurations (RCS)
- VC's snapshot facilities are modeled on RCS's named-configuration
-support. They use RCS's native facilities for this, so under VC
-snapshots made using RCS are visible even when you bypass VC.
-
-@c worded verbosely to avoid overfull hbox.
- For SCCS, VC implements snapshots itself. The files it uses contain
-name/file/version-number triples. These snapshots are visible only
-through VC.
-
- A snapshot is a set of checked-in versions. So make sure that all the
-files are checked in and not locked when you make a snapshot.
-
- File renaming and deletion can create some difficulties with snapshots.
-This is not a VC-specific problem, but a general design issue in version
-control systems that no one has solved very well yet.
-
- If you rename a registered file, you need to rename its master along
-with it (the command @code{vc-rename-file} does this automatically). If
-you are using SCCS, you must also update the records of the snapshot, to
-mention the file by its new name (@code{vc-rename-file} does this,
-too). An old snapshot that refers to a master file that no longer
-exists under the recorded name is invalid; VC can no longer retrieve
-it. It would be beyond the scope of this manual to explain enough about
-RCS and SCCS to explain how to update the snapshots by hand.
-
- Using @code{vc-rename-file} makes the snapshot remain valid for
-retrieval, but it does not solve all problems. For example, some of the
-files in your program probably refer to others by name. At the very
-least, the makefile probably mentions the file that you renamed. If you
-retrieve an old snapshot, the renamed file is retrieved under its new
-name, which is not the name that the makefile expects. So the program
-won't really work as retrieved.
-
-@node Miscellaneous VC
-@subsection Miscellaneous Commands and Features of VC
-
- This section explains the less-frequently-used features of VC.
-
-@menu
-* Change Logs and VC:: Generating a change log file from log entries.
-* Renaming and VC:: A command to rename both the source and master
- file correctly.
-* Version Headers:: Inserting version control headers into working files.
-@end menu
-
-@node Change Logs and VC
-@subsubsection Change Logs and VC
-
- If you use RCS or CVS for a program and also maintain a change log
-file for it (@pxref{Change Log}), you can generate change log entries
-automatically from the version control log entries:
-
-@table @kbd
-@item C-x v a
-@kindex C-x v a
-@findex vc-update-change-log
-Visit the current directory's change log file and, for registered files
-in that directory, create new entries for versions checked in since the
-most recent entry in the change log file.
-(@code{vc-update-change-log}).
-
-This command works with RCS or CVS only, not with SCCS.
-
-@item C-u C-x v a
-As above, but only find entries for the current buffer's file.
-
-@item M-1 C-x v a
-As above, but find entries for all the currently visited files that are
-maintained with version control. This works only with RCS, and it puts
-all entries in the log for the default directory, which may not be
-appropriate.
-@end table
-
- For example, suppose the first line of @file{ChangeLog} is dated
-1999-04-10, and that the only check-in since then was by Nathaniel
-Bowditch to @file{rcs2log} on 1999-05-22 with log text @samp{Ignore log
-messages that start with `#'.}. Then @kbd{C-x v a} visits
-@file{ChangeLog} and inserts text like this:
-
-@iftex
-@medbreak
-@end iftex
-@smallexample
-@group
-1999-05-22 Nathaniel Bowditch <nat@@apn.org>
-
- * rcs2log: Ignore log messages that start with `#'.
-@end group
-@end smallexample
-@iftex
-@medbreak
-@end iftex
-
-@noindent
-You can then edit the new change log entry further as you wish.
-
- Some of the new change log entries may duplicate what's already in
-ChangeLog. You will have to remove these duplicates by hand.
-
- Normally, the log entry for file @file{foo} is displayed as @samp{*
-foo: @var{text of log entry}}. The @samp{:} after @file{foo} is omitted
-if the text of the log entry starts with @w{@samp{(@var{functionname}):
-}}. For example, if the log entry for @file{vc.el} is
-@samp{(vc-do-command): Check call-process status.}, then the text in
-@file{ChangeLog} looks like this:
-
-@iftex
-@medbreak
-@end iftex
-@smallexample
-@group
-1999-05-06 Nathaniel Bowditch <nat@@apn.org>
-
- * vc.el (vc-do-command): Check call-process status.
-@end group
-@end smallexample
-@iftex
-@medbreak
-@end iftex
-
- When @kbd{C-x v a} adds several change log entries at once, it groups
-related log entries together if they all are checked in by the same
-author at nearly the same time. If the log entries for several such
-files all have the same text, it coalesces them into a single entry.
-For example, suppose the most recent check-ins have the following log
-entries:
-
-@flushleft
-@bullet{} For @file{vc.texinfo}: @samp{Fix expansion typos.}
-@bullet{} For @file{vc.el}: @samp{Don't call expand-file-name.}
-@bullet{} For @file{vc-hooks.el}: @samp{Don't call expand-file-name.}
-@end flushleft
-
-@noindent
-They appear like this in @file{ChangeLog}:
-
-@iftex
-@medbreak
-@end iftex
-@smallexample
-@group
-1999-04-01 Nathaniel Bowditch <nat@@apn.org>
-
- * vc.texinfo: Fix expansion typos.
-
- * vc.el, vc-hooks.el: Don't call expand-file-name.
-@end group
-@end smallexample
-@iftex
-@medbreak
-@end iftex
-
- Normally, @kbd{C-x v a} separates log entries by a blank line, but you
-can mark several related log entries to be clumped together (without an
-intervening blank line) by starting the text of each related log entry
-with a label of the form @w{@samp{@{@var{clumpname}@} }}. The label
-itself is not copied to @file{ChangeLog}. For example, suppose the log
-entries are:
-
-@flushleft
-@bullet{} For @file{vc.texinfo}: @samp{@{expand@} Fix expansion typos.}
-@bullet{} For @file{vc.el}: @samp{@{expand@} Don't call expand-file-name.}
-@bullet{} For @file{vc-hooks.el}: @samp{@{expand@} Don't call expand-file-name.}
-@end flushleft
-
-@noindent
-Then the text in @file{ChangeLog} looks like this:
-
-@iftex
-@medbreak
-@end iftex
-@smallexample
-@group
-1999-04-01 Nathaniel Bowditch <nat@@apn.org>
-
- * vc.texinfo: Fix expansion typos.
- * vc.el, vc-hooks.el: Don't call expand-file-name.
-@end group
-@end smallexample
-@iftex
-@medbreak
-@end iftex
-
- A log entry whose text begins with @samp{#} is not copied to
-@file{ChangeLog}. For example, if you merely fix some misspellings in
-comments, you can log the change with an entry beginning with @samp{#}
-to avoid putting such trivia into @file{ChangeLog}.
-
-@node Renaming and VC
-@subsubsection Renaming VC Work Files and Master Files
-
-@findex vc-rename-file
- When you rename a registered file, you must also rename its master
-file correspondingly to get proper results. Use @code{vc-rename-file}
-to rename the source file as you specify, and rename its master file
-accordingly. It also updates any snapshots (@pxref{Snapshots}) that
-mention the file, so that they use the new name; despite this, the
-snapshot thus modified may not completely work (@pxref{Snapshot
-Caveats}).
-
- You cannot use @code{vc-rename-file} on a file that is locked by
-someone else.
-
-@node Version Headers
-@subsubsection Inserting Version Control Headers
-
- Sometimes it is convenient to put version identification strings
-directly into working files. Certain special strings called
-@dfn{version headers} are replaced in each successive version by the
-number of that version.
-
- If you are using RCS, and version headers are present in your working
-files, Emacs can use them to determine the current version and the
-locking state of the files. This is more reliable than referring to the
-master files, which is done when there are no version headers. Note
-that in a multi-branch environment, version headers are necessary to
-make VC behave correctly (@pxref{Multi-User Branching}).
-
- Searching for version headers is controlled by the variable
-@code{vc-consult-headers}. If it is non-@code{nil} (the default),
-Emacs searches for headers to determine the version number you are
-editing. Setting it to @code{nil} disables this feature.
-
-@kindex C-x v h
-@findex vc-insert-headers
- You can use the @kbd{C-x v h} command (@code{vc-insert-headers}) to
-insert a suitable header string.
-
-@table @kbd
-@item C-x v h
-Insert headers in a file for use with your version-control system.
-@end table
-
-@vindex vc-header-alist
- The default header string is @samp{@w{$}Id$} for RCS and
-@samp{@w{%}W%} for SCCS. You can specify other headers to insert by
-setting the variable @code{vc-header-alist}. Its value is a list of
-elements of the form @code{(@var{program} . @var{string})} where
-@var{program} is @code{RCS} or @code{SCCS} and @var{string} is the
-string to use.
-
- Instead of a single string, you can specify a list of strings; then
-each string in the list is inserted as a separate header on a line of
-its own.
-
- It is often necessary to use ``superfluous'' backslashes when
-writing the strings that you put in this variable. For instance, you
-might write @code{"$Id\$"} rather than @code{"$Id@w{$}"}. The extra
-backslash prevents the string constant from being interpreted as a
-header, if the Emacs Lisp file containing it is maintained with
-version control.
-
-@vindex vc-comment-alist
- Each header is inserted surrounded by tabs, inside comment delimiters,
-on a new line at point. Normally the ordinary comment
-start and comment end strings of the current mode are used, but for
-certain modes, there are special comment delimiters for this purpose;
-the variable @code{vc-comment-alist} specifies them. Each element of
-this list has the form @code{(@var{mode} @var{starter} @var{ender})}.
-
-@vindex vc-static-header-alist
- The variable @code{vc-static-header-alist} specifies further strings
-to add based on the name of the buffer. Its value should be a list of
-elements of the form @code{(@var{regexp} . @var{format})}. Whenever
-@var{regexp} matches the buffer name, @var{format} is inserted as part
-of the header. A header line is inserted for each element that matches
-the buffer name, and for each string specified by
-@code{vc-header-alist}. The header line is made by processing the
-string from @code{vc-header-alist} with the format taken from the
-element. The default value for @code{vc-static-header-alist} is as follows:
-
-@example
-@group
-(("\\.c$" .
- "\n#ifndef lint\nstatic char vcid[] = \"\%s\";\n\
-#endif /* lint */\n"))
-@end group
-@end example
-
-@noindent
-It specifies insertion of text of this form:
-
-@example
-@group
-
-#ifndef lint
-static char vcid[] = "@var{string}";
-#endif /* lint */
-@end group
-@end example
-
-@noindent
-Note that the text above starts with a blank line.
-
- If you use more than one version header in a file, put them close
-together in the file. The mechanism in @code{revert-buffer} that
-preserves markers may not handle markers positioned between two version
-headers.
-
-@node Customizing VC
-@subsection Customizing VC
-
-@vindex vc-handled-backends
-The variable @code{vc-handled-backends} determines which version
-control systems VC should handle. The default value is @code{(RCS CVS
-SCCS)}, so it contains all three version systems that are currently
-supported. If you want VC to ignore one or more of these systems,
-exclude its name from the list.
-
-The order of systems in the list is significant: when you visit a file
-registered in more than one system (@pxref{Local Version Control}),
-VC uses the system that comes first in @code{vc-handled-backends} by
-default. The order is also significant when you register a file for
-the first time, @pxref{Registering} for details.
-
-@menu
-* General VC Options:: Options that apply to multiple back ends.
-* RCS and SCCS:: Options for RCS and SCCS.
-* CVS Options:: Options for CVS.
-@end menu
-
-@node General VC Options
-@subsubsection General Options
-
-@vindex vc-make-backup-files
- Emacs normally does not save backup files for source files that are
-maintained with version control. If you want to make backup files even
-for files that use version control, set the variable
-@code{vc-make-backup-files} to a non-@code{nil} value.
-
-@vindex vc-keep-workfiles
- Normally the work file exists all the time, whether it is locked or
-not. If you set @code{vc-keep-workfiles} to @code{nil}, then checking
-in a new version with @kbd{C-x C-q} deletes the work file; but any
-attempt to visit the file with Emacs creates it again. (With CVS, work
-files are always kept.)
-
-@vindex vc-follow-symlinks
- Editing a version-controlled file through a symbolic link can be
-dangerous. It bypasses the version control system---you can edit the
-file without locking it, and fail to check your changes in. Also,
-your changes might overwrite those of another user. To protect against
-this, VC checks each symbolic link that you visit, to see if it points
-to a file under version control.
-
- The variable @code{vc-follow-symlinks} controls what to do when a
-symbolic link points to a version-controlled file. If it is @code{nil},
-VC only displays a warning message. If it is @code{t}, VC automatically
-follows the link, and visits the real file instead, telling you about
-this in the echo area. If the value is @code{ask} (the default), VC
-asks you each time whether to follow the link.
-
-@vindex vc-suppress-confirm
- If @code{vc-suppress-confirm} is non-@code{nil}, then @kbd{C-x C-q}
-and @kbd{C-x v i} can save the current buffer without asking, and
-@kbd{C-x v u} also operates without asking for confirmation. (This
-variable does not affect @kbd{C-x v c}; that operation is so drastic
-that it should always ask for confirmation.)
-
-@vindex vc-command-messages
- VC mode does much of its work by running the shell commands for RCS,
-CVS and SCCS. If @code{vc-command-messages} is non-@code{nil}, VC
-displays messages to indicate which shell commands it runs, and
-additional messages when the commands finish.
-
-@vindex vc-path
- You can specify additional directories to search for version control
-programs by setting the variable @code{vc-path}. These directories
-are searched before the usual search path. It is rarely necessary to
-set this variable, because VC normally finds the proper files
-automatically.
-
-@node RCS and SCCS
-@subsubsection Options for RCS and SCCS
-
-@cindex non-strict locking (RCS)
-@cindex locking, non-strict (RCS)
- By default, RCS uses locking to coordinate the activities of several
-users, but there is a mode called @dfn{non-strict locking} in which
-you can check-in changes without locking the file first. Use
-@samp{rcs -U} to switch to non-strict locking for a particular file,
-see the @code{rcs} manual page for details.
-
- When deducing the version control state of an RCS file, VC first
-looks for an RCS version header string in the file (@pxref{Version
-Headers}). If there is no header string, VC normally looks at the
-file permissions of the work file; this is fast. But there might be
-situations when the file permissions cannot be trusted. In this case
-the master file has to be consulted, which is rather expensive. Also
-the master file can only tell you @emph{if} there's any lock on the
-file, but not whether your work file really contains that locked
-version.
-
-@vindex vc-consult-headers
- You can tell VC not to use version headers to determine the file
-status by setting @code{vc-consult-headers} to @code{nil}. VC then
-always uses the file permissions (if it is supposed to trust them), or
-else checks the master file.
-
-@vindex vc-mistrust-permissions
- You can specify the criterion for whether to trust the file
-permissions by setting the variable @code{vc-mistrust-permissions}.
-Its value can be @code{t} (always mistrust the file permissions and
-check the master file), @code{nil} (always trust the file
-permissions), or a function of one argument which makes the decision.
-The argument is the directory name of the @file{RCS} subdirectory. A
-non-@code{nil} value from the function says to mistrust the file
-permissions. If you find that the file permissions of work files are
-changed erroneously, set @code{vc-mistrust-permissions} to @code{t}.
-Then VC always checks the master file to determine the file's status.
-
- VC determines the version control state of files under SCCS much as
-with RCS. It does not consider SCCS version headers, though. Thus,
-the variable @code{vc-mistrust-permissions} affects SCCS use, but
-@code{vc-consult-headers} does not.
-
-@node CVS Options
-@subsubsection Options specific for CVS
-
-@cindex locking (CVS)
- By default, CVS does not use locking to coordinate the activities of
-several users; anyone can change a work file at any time. However,
-there are ways to restrict this, resulting in behavior that resembles
-locking.
-
-@cindex CVSREAD environment variable (CVS)
- For one thing, you can set the @env{CVSREAD} environment variable
-(the value you use makes no difference). If this variable is defined,
-CVS makes your work files read-only by default. In Emacs, you must
-type @kbd{C-x C-q} to make the file writable, so that editing works
-in fact similar as if locking was used. Note however, that no actual
-locking is performed, so several users can make their files writable
-at the same time. When setting @env{CVSREAD} for the first time, make
-sure to check out all your modules anew, so that the file protections
-are set correctly.
-
-@cindex cvs watch feature
-@cindex watching files (CVS)
- Another way to achieve something similar to locking is to use the
-@dfn{watch} feature of CVS. If a file is being watched, CVS makes it
-read-only by default, and you must also use @kbd{C-x C-q} in Emacs to
-make it writable. VC calls @code{cvs edit} to make the file writable,
-and CVS takes care to notify other developers of the fact that you
-intend to change the file. See the CVS documentation for details on
-using the watch feature.
-
-@vindex vc-cvs-stay-local
-@cindex remote repositories (CVS)
- When a file's repository is on a remote machine, VC tries to keep
-network interactions to a minimum. This is controlled by the variable
-@code{vc-cvs-stay-local}. If it is @code{t} (the default), then VC uses
-only the entry in the local CVS subdirectory to determine the file's
-state (and possibly information returned by previous CVS commands). One
-consequence of this is that when you have modified a file, and somebody
-else has already checked in other changes to the file, you are not
-notified of it until you actually try to commit. (But you can try to
-pick up any recent changes from the repository first, using @kbd{C-x v m
-@key{RET}}, @pxref{Merging}).
-
- When @code{vc-cvs-stay-local} is @code{t}, VC also makes local
-version backups, so that simple diff and revert operations are
-completely local (@pxref{Version Backups}).
-
- On the other hand, if you set @code{vc-cvs-stay-local} to @code{nil},
-then VC queries the remote repository @emph{before} it decides what to
-do in @code{vc-next-action} (@kbd{C-x v v}), just as it does for local
-repositories. It also does not make any version backups.
-
- You can also set @code{vc-cvs-stay-local} to a regular expression
-that is matched against the repository host name; VC then stays local
-only for repositories from hosts that match the pattern.
+@ifnottex
+@include vc2-xtra.texi
+@end ifnottex
@node Directories
@section File Directories
listing} is a list of all the files in a directory. Emacs provides
commands to create and delete directories, and to make directory
listings in brief format (file names only) and verbose format (sizes,
-dates, and authors included). There is also a directory browser called
-Dired; see @ref{Dired}.
+dates, and authors included). Emacs also includes a directory browser
+feature called Dired; see @ref{Dired}.
@table @kbd
@item C-x C-d @var{dir-or-pattern} @key{RET}
@vindex list-directory-brief-switches
@vindex list-directory-verbose-switches
- The text of a directory listing is obtained by running @code{ls} in an
-inferior process. Two Emacs variables control the switches passed to
-@code{ls}: @code{list-directory-brief-switches} is a string giving the
-switches to use in brief listings (@code{"-CF"} by default), and
-@code{list-directory-verbose-switches} is a string giving the switches to
-use in a verbose listing (@code{"-l"} by default).
+ The text of a directory listing is mostly obtained by running
+@code{ls} in an inferior process. Two Emacs variables control the
+switches passed to @code{ls}: @code{list-directory-brief-switches} is
+a string giving the switches to use in brief listings (@code{"-CF"} by
+default), and @code{list-directory-verbose-switches} is a string
+giving the switches to use in a verbose listing (@code{"-l"} by
+default).
+
+@vindex directory-free-space-program
+@vindex directory-free-space-args
+ In verbose directory listings, Emacs adds information about the
+amount of free space on the disk that contains the directory. To do
+this, it runs the program specified by
+@code{directory-free-space-program} with arguments
+@code{directory-free-space-args}.
@node Comparing Files
@section Comparing Files
running the @code{diff} program, using options taken from the variable
@code{diff-switches}. The value of @code{diff-switches} should be a
string; the default is @code{"-c"} to specify a context diff.
-
- The buffer @samp{*diff*} has Compilation mode as its major mode, so
-you can use @kbd{C-x `} to visit successive changed locations in the two
-source files. You can also move to a particular hunk of changes and
-type @key{RET} or @kbd{C-c C-c}, or click @kbd{Mouse-2} on it, to move
-to the corresponding source location. You can also use the other
-special commands of Compilation mode: @key{SPC} and @key{DEL} for
-scrolling, and @kbd{M-p} and @kbd{M-n} for cursor motion.
-@xref{Compilation}.
+@xref{Top,, Diff, diff, Comparing and Merging Files}, for more
+information about @command{diff} output formats.
@findex diff-backup
The command @kbd{M-x diff-backup} compares a specified file with its most
of.
@findex compare-windows
- The command @kbd{M-x compare-windows} compares the text in the current
-window with that in the next window. Comparison starts at point in each
-window, and each starting position is pushed on the mark ring in its
-respective buffer. Then point moves forward in each window, a character
-at a time, until a mismatch between the two windows is reached. Then
-the command is finished. For more information about windows in Emacs,
-@ref{Windows}.
+ The command @kbd{M-x compare-windows} compares the text in the
+current window with that in the next window. (For more information
+about windows in Emacs, @ref{Windows}.) Comparison starts at point in
+each window, after pushing each initial point value on the mark ring
+in its respective buffer. Then it moves point forward in each window,
+one character at a time, until it reaches characters that don't match.
+Then the command exits.
+
+ If point in the two windows is followed by non-matching text when
+the command starts, @kbd{M-x compare-windows} tries heuristically to
+advance up to matching text in the two windows, and then exits. So if
+you use @kbd{M-x compare-windows} repeatedly, each time it either
+skips one matching range or finds the start of another.
@vindex compare-ignore-case
+@vindex compare-ignore-whitespace
With a numeric argument, @code{compare-windows} ignores changes in
whitespace. If the variable @code{compare-ignore-case} is
-non-@code{nil}, it ignores differences in case as well.
-
-@findex diff-mode
-@cindex diffs
-@cindex patches
-@cindex Diff mode
- Differences between versions of files are often distributed as
-@dfn{patches}, which are the output from @command{diff} or a version
-control system that uses @command{diff}. @kbd{M-x diff-mode} turns on
-Diff mode, a major mode for viewing and editing patches, either as
-``unified diffs'' or ``context diffs.''
+non-@code{nil}, the comparison ignores differences in case as well.
+If the variable @code{compare-ignore-whitespace} is non-@code{nil},
+@code{compare-windows} normally ignores changes in whitespace, and a
+prefix argument turns that off.
@cindex Smerge mode
@findex smerge-mode
mode provides commands to resolve conflicts by selecting specific
changes.
- See also @ref{Emerge}, and @ref{Top,,, ediff, The Ediff Manual}, for
-convenient facilities for merging two similar files.
+@iftex
+@xref{Emerge,,, emacs-xtra, Specialized Emacs Features},
+@end iftex
+@ifnottex
+@xref{Emerge},
+@end ifnottex
+for the Emerge facility, which provides a powerful interface for
+merging files.
+
+@node Diff Mode
+@section Diff Mode
+@cindex Diff mode
+@findex diff-mode
+@cindex patches, editing
+
+ Diff mode is used for the output of @kbd{M-x diff}; it is also
+useful for editing patches and comparisons produced by the
+@command{diff} program. To select Diff mode manually, type @kbd{M-x
+diff-mode}.
+
+ One general feature of Diff mode is that manual edits to the patch
+automatically correct line numbers, including those in the hunk
+header, so that you can actually apply the edited patch. Diff mode
+also provides the following commands to navigate, manipulate and apply
+parts of patches:
+
+@table @kbd
+@item M-n
+Move to the next hunk-start (@code{diff-hunk-next}).
+
+@item M-p
+Move to the previous hunk-start (@code{diff-hunk-prev}).
+
+@item M-@}
+Move to the next file-start, in a multi-file patch
+(@code{diff-file-next}).
+
+@item M-@{
+Move to the previous file-start, in a multi-file patch
+(@code{diff-file-prev}).
+
+@item M-k
+Kill the hunk at point (@code{diff-hunk-kill}).
+
+@item M-K
+In a multi-file patch, kill the current file part.
+(@code{diff-file-kill}).
+
+@item C-c C-a
+Apply this hunk to its target file (@code{diff-apply-hunk}). With a
+prefix argument of @kbd{C-u}, revert this hunk.
+
+@item C-c C-c
+Go to the source corresponding to this hunk (@code{diff-goto-source}).
+
+@item C-c C-e
+Start an Ediff session with the patch (@code{diff-ediff-patch}).
+@xref{Top, Ediff, Ediff, ediff, The Ediff Manual}.
+
+@item C-c C-n
+Restrict the view to the current hunk (@code{diff-restrict-view}).
+@xref{Narrowing}. With a prefix argument of @kbd{C-u}, restrict the
+view to the current patch of a multiple file patch. To widen again,
+use @kbd{C-x n w}.
+
+@item C-c C-r
+Reverse the direction of comparison for the entire buffer
+(@code{diff-reverse-direction}).
+
+@item C-c C-s
+Split the hunk at point (@code{diff-split-hunk}). This is for
+manually editing patches, and only works with the unified diff format.
+
+@item C-c C-u
+Convert the entire buffer to unified format
+(@code{diff-context->unified}). With a prefix argument, convert
+unified format to context format. In Transient Mark mode, when the
+mark is active, this command operates only on the region.
+
+@item C-c C-w
+Refine the current hunk so that it disregards changes in whitespace
+(@code{diff-refine-hunk}).
+@end table
+
+ @kbd{C-x 4 a} in Diff mode operates on behalf of the target file,
+but gets the function name from the patch itself. @xref{Change Log}.
+This is useful for making log entries for functions that are deleted
+by the patch.
@node Misc File Ops
@section Miscellaneous File Operations
for moving around in the file, but none for changing it; type @kbd{?}
while viewing for a list of them. They are mostly the same as normal
Emacs cursor motion commands. To exit from viewing, type @kbd{q}.
-The commands for viewing are defined by a special major mode called View
+The commands for viewing are defined by a special minor mode called View
mode.
A related command, @kbd{M-x view-buffer}, views a buffer already present
@findex write-region
@kbd{M-x write-region} is the inverse of @kbd{M-x insert-file}; it
copies the contents of the region into the specified file. @kbd{M-x
-append-to-file} adds the text of the region to the end of the specified
-file. @xref{Accumulating Text}.
+append-to-file} adds the text of the region to the end of the
+specified file. @xref{Accumulating Text}. The variable
+@code{write-region-inhibit-fsync} applies to these commands, as well
+as saving files; see @ref{Customize Save}.
@findex delete-file
@cindex deletion (of files)
to be lost. If @var{old} and @var{new} are on different file systems, the
file @var{old} is copied and deleted.
+ If the argument @var{new} is just a directory name, the real new
+name is in that directory, with the same non-directory component as
+@var{old}. For example, @kbd{M-x rename-file RET ~/foo RET /tmp RET}
+renames @file{~/foo} to @file{/tmp/foo}. The same rule applies to all
+the remaining commands in this section. All of them ask for
+confirmation when the new file name already exists, too.
+
@findex add-name-to-file
@cindex hard links (creation)
The similar command @kbd{M-x add-name-to-file} is used to add an
additional name to an existing file without removing its old name.
The new name is created as a ``hard link'' to the existing file.
The new name must belong on the same file system that the file is on.
-On Windows, this command works only if the file resides in an NTFS
+On MS-Windows, this command works only if the file resides in an NTFS
file system. On MS-DOS, it works by copying the file.
@findex copy-file
@cindex copying files
- @kbd{M-x copy-file} reads the file @var{old} and writes a new file named
-@var{new} with the same contents. Confirmation is required if a file named
-@var{new} already exists, because copying has the consequence of overwriting
-the old contents of the file @var{new}.
+ @kbd{M-x copy-file} reads the file @var{old} and writes a new file
+named @var{new} with the same contents.
@findex make-symbolic-link
+@cindex symbolic links (creation)
@kbd{M-x make-symbolic-link} reads two file names @var{target} and
-@var{linkname}, then creates a symbolic link named @var{linkname}, which
-points at @var{target}. The effect is that future attempts to open file
-@var{linkname} will refer to whatever file is named @var{target} at the
-time the opening is done, or will get an error if the name @var{target} is
-not in use at that time. This command does not expand the argument
-@var{target}, so that it allows you to specify a relative name
-as the target of the link.
-
- Confirmation is required when creating the link if @var{linkname} is
-in use. Note that not all systems support symbolic links; on systems
-that don't support them, this command is not defined.
+@var{linkname}, then creates a symbolic link named @var{linkname},
+which points at @var{target}. The effect is that future attempts to
+open file @var{linkname} will refer to whatever file is named
+@var{target} at the time the opening is done, or will get an error if
+the name @var{target} is nonexistent at that time. This command does
+not expand the argument @var{target}, so that it allows you to specify
+a relative name as the target of the link.
+
+ Not all systems support symbolic links; on systems that don't
+support them, this command is not defined.
@node Compressed Files
@section Accessing Compressed Files
@cindex mode, Auto Compression
@pindex gzip
-@findex auto-compression-mode
-@vindex auto-compression-mode
- Emacs comes with a library that can automatically uncompress
-compressed files when you visit them, and automatically recompress them
-if you alter them and save them. To enable this feature, type the
-command @kbd{M-x auto-compression-mode}. You can enable it permanently
-by customizing the option @code{auto-compression-mode}.
-
- When automatic compression (which implies automatic uncompression as
-well) is enabled, Emacs recognizes compressed files by their file names.
-File names ending in @samp{.gz} indicate a file compressed with
+ Emacs automatically uncompresses compressed files when you visit
+them, and automatically recompresses them if you alter them and save
+them. Emacs recognizes compressed files by their file names. File
+names ending in @samp{.gz} indicate a file compressed with
@code{gzip}. Other endings indicate other compression programs.
Automatic uncompression and compression apply to all the operations in
saving it, inserting its contents into a buffer, loading it, and byte
compiling it.
+@findex auto-compression-mode
+@vindex auto-compression-mode
+ To disable this feature, type the command @kbd{M-x
+auto-compression-mode}. You can disenable it permanently by
+customizing the variable @code{auto-compression-mode}.
+
@node File Archives
@section File Archives
@cindex mode, tar
would in Dired, and visit the subfiles contained in the archive.
However, not all Dired commands are available in Tar mode.
- If you enable Auto Compression mode (@pxref{Compressed Files}), then
+ If Auto Compression mode is enabled (@pxref{Compressed Files}), then
Tar mode is used also for compressed archives---files with extensions
@samp{.tgz}, @code{.tar.Z} and @code{.tar.gz}.
The keys @kbd{e}, @kbd{f} and @key{RET} all extract a component file
-into its own buffer. You can edit it there and when you save the buffer
-the edited version will replace the version in the Tar buffer. @kbd{v}
-extracts a file into a buffer in View mode. @kbd{o} extracts the file
-and displays it in another window, so you could edit the file and
-operate on the archive simultaneously. @kbd{d} marks a file for
+into its own buffer. You can edit it there, and if you save the
+buffer, the edited version will replace the version in the Tar buffer.
+@kbd{v} extracts a file into a buffer in View mode. @kbd{o} extracts
+the file and displays it in another window, so you could edit the file
+and operate on the archive simultaneously. @kbd{d} marks a file for
deletion when you later use @kbd{x}, and @kbd{u} unmarks a file, as in
Dired. @kbd{C} copies a file from the archive to disk and @kbd{R}
-renames a file. @kbd{g} reverts the buffer from the archive on disk.
+renames a file within the archive. @kbd{g} reverts the buffer from
+the archive on disk.
The keys @kbd{M}, @kbd{G}, and @kbd{O} change the file's permission
bits, group, and owner, respectively.
@section Remote Files
@cindex Tramp
- In the following, file access via FTP will be discussed. In
-addition to that facility, it is also possible to access remote files
-through a shell connection. @xref{Top, The Tramp Manual,, tramp, The
-Tramp Manual}.
-
@cindex FTP
@cindex remote file access
- You can refer to files on other machines using a special file name syntax:
+ You can refer to files on other machines using a special file name
+syntax:
@example
@group
/@var{host}:@var{filename}
/@var{user}@@@var{host}:@var{filename}
/@var{user}@@@var{host}#@var{port}:@var{filename}
+/@var{method}:@var{user}@@@var{host}:@var{filename}
+/@var{method}:@var{user}@@@var{host}#@var{port}:@var{filename}
@end group
@end example
@noindent
-When you do this, Emacs uses the FTP program to read and write files on
-the specified host. It logs in through FTP using your user name or the
-name @var{user}. It may ask you for a password from time to time; this
-is used for logging in on @var{host}. The form using @var{port} allows
-you to access servers running on a non-default TCP port.
-
-For using Tramp, the file name syntax looks like this:
-
-@example
-@group
-/[@var{host}]@var{filename}
-/[@var{user}@@@var{host}]@var{filename}
-/[@var{method}/@var{user}@@@var{host}]@var{filename}
-@end group
-@end example
+To carry out this request, Emacs uses either the FTP program or a
+remote-login program such as @command{ssh}, @command{rlogin}, or
+@command{telnet}. You can always specify in the file name which
+method to use---for example,
+@file{/ftp:@var{user}@@@var{host}:@var{filename}} uses FTP, whereas
+@file{/ssh:@var{user}@@@var{host}:@var{filename}} uses @command{ssh}.
+When you don't specify a method in the file name, Emacs chooses
+the method as follows:
+
+@enumerate
+@item
+If the host name starts with @samp{ftp.} (with dot), then Emacs uses
+FTP.
+@item
+If the user name is @samp{ftp} or @samp{anonymous}, then Emacs uses
+FTP.
+@item
+Otherwise, Emacs uses @command{ssh}.
+@end enumerate
@noindent
-Note that the square brackets are part of the file names.
+Remote file access through FTP is handled by the Ange-FTP package, which
+is documented in the following. Remote file access through the other
+methods is handled by the Tramp package, which has its own manual.
+@xref{Top, The Tramp Manual,, tramp, The Tramp Manual}.
+
+When the Ange-FTP package is used, Emacs logs in through FTP using your
+user name or the name @var{user}. It may ask you for a password from
+time to time; this is used for logging in on @var{host}. The form using
+@var{port} allows you to access servers running on a non-default TCP
+port.
@cindex backups for remote files
@vindex ange-ftp-make-backup-files
Normally, if you do not specify a user name in a remote file name,
that means to use your own user name. But if you set the variable
@code{ange-ftp-default-user} to a string, that string is used instead.
-(The Emacs package that implements FTP file access is called
-@code{ange-ftp}.)
@cindex anonymous FTP
@vindex ange-ftp-generate-anonymous-password
@code{ange-ftp-generate-anonymous-password} controls what happens: if
the value of this variable is a string, then that string is used as
the password; if non-@code{nil} (the default), then the value of
-@code{user-mail-address} is used; if @code{nil}, the user is prompted
-for a password as normal.
+@code{user-mail-address} is used; if @code{nil}, then Emacs prompts
+you for a password as usual.
@cindex firewall, and accessing remote files
@cindex gateway, and remote file access with @code{ange-ftp}
@section Quoted File Names
@cindex quoting file names
+@cindex file names, quote special characters
You can @dfn{quote} an absolute file name to prevent special
characters and syntax in it from having their special effects.
The way to do this is to add @samp{/:} at the beginning.
When typing a file name in the minibuffer, @kbd{C-@key{tab}}
(@code{file-cache-minibuffer-complete}) completes it using the file
name cache. If you repeat @kbd{C-@key{tab}}, that cycles through the
-possible completions of what you had originally typed. Note that the
-@kbd{C-@key{tab}} character cannot be typed on most text-only
-terminals.
+possible completions of what you had originally typed. (However, note
+that the @kbd{C-@key{tab}} character cannot be typed on most text-only
+terminals.)
The file name cache does not fill up automatically. Instead, you
load file names into the cache using these commands:
Clear the cache; that is, remove all file names from it.
@end table
+ The file name cache is not persistent: it is kept and maintained
+only for the duration of the Emacs session. You can view the contents
+of the cache with the @code{file-cache-display} command.
+
@node File Conveniences
@section Convenience Features for Finding Files
+ In this section, we introduce some convenient facilities for finding
+recently-opened files, reading file names from a buffer, and viewing
+image files.
+
@findex recentf-mode
@vindex recentf-mode
@findex recentf-save-list
@code{recent-file-list} to a file, and @kbd{M-x recentf-edit-list}
edits it.
-@findex auto-image-file-mode
-@findex mode, auto-image-file
-@cindex images, visiting
-@cindex visiting image files
-@vindex image-file-name-regexps
-@vindex image-file-name-extensions
- When Auto-image-file minor mode is enabled, visiting an image file
-displays it as an image, not as text. Likewise, inserting an image
-file into a buffer inserts it as an image. This works only when Emacs
-can display the relevant image type. The variables
-@code{image-file-name-extensions} or @code{image-file-name-regexps}
-control which file names are recognized as containing images.
-
The @kbd{M-x ffap} command generalizes @code{find-file} with more
powerful heuristic defaults (@pxref{FFAP}), often based on the text at
point. Partial Completion mode offers other features extending
@code{find-file}, which can be used with @code{ffap}.
@xref{Completion Options}.
+
+@findex image-mode
+@findex image-toggle-display
+@cindex images, viewing
+ Visiting image files automatically selects Image mode. This major
+mode allows you to toggle between displaying the file as an image in
+the Emacs buffer, and displaying its underlying text representation,
+using the command @kbd{C-c C-c} (@code{image-toggle-display}). This
+works only when Emacs can display the specific image type.
+
+@findex thumbs-mode
+@findex mode, thumbs
+ Thumbs mode is a major mode for viewing directories containing many
+image files. To use it, type @kbd{M-x thumbs} and specify the
+directory to view. The images in that directory will be displayed in
+a @samp{Thumbs} buffer as @dfn{thumbnails}; type @kbd{RET} on a
+thumbnail to view the full-size image. Thumbs mode requires the
+@file{convert} program, which is part of the ImageMagick software
+package.
+
+@node Filesets
+@section Filesets
+@cindex filesets
+
+@findex filesets-init
+ If you regularly edit a certain group of files, you can define them
+as a @dfn{fileset}. This lets you perform certain operations, such as
+visiting, @code{query-replace}, and shell commands on all the files
+at once. To make use of filesets, you must first add the expression
+@code{(filesets-init)} to your @file{.emacs} file (@pxref{Init File}).
+This adds a @samp{Filesets} menu to the menu bar.
+
+@findex filesets-add-buffer
+@findex filesets-remove-buffer
+ The simplest way to define a fileset is by adding files to it one
+at a time. To add a file to fileset @var{name}, visit the file and
+type @kbd{M-x filesets-add-buffer @kbd{RET} @var{name} @kbd{RET}}. If
+there is no fileset @var{name}, this creates a new one, which
+initially creates only the current file. The command @kbd{M-x
+filesets-remove-buffer} removes the current file from a fileset.
+
+ You can also edit the list of filesets directly, with @kbd{M-x
+filesets-edit} (or by choosing @samp{Edit Filesets} from the
+@samp{Filesets} menu). The editing is performed in a Customize buffer
+(@pxref{Easy Customization}). Filesets need not be a simple list of
+files---you can also define filesets using regular expression matching
+file names. Some examples of these more complicated filesets are
+shown in the Customize buffer. Remember to select @samp{Save for
+future sessions} if you want to use the same filesets in future Emacs
+sessions.
+
+ You can use the command @kbd{M-x filesets-open} to visit all the
+files in a fileset, and @kbd{M-x filesets-close} to close them. Use
+@kbd{M-x filesets-run-cmd} to run a shell command on all the files in
+a fileset. These commands are also available from the @samp{Filesets}
+menu, where each existing fileset is represented by a submenu.
+
+@ignore
+ arch-tag: 768d32cb-e15a-4cc1-b7bf-62c00ee12250
+@end ignore