* 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.
@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}. (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}.)
+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
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, the GUI version does that by default.
+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 the ``drag and drop'' protocol on the X
-window system. 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}, @ref{Misc Dired
-Features}.
+ 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
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.
@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
@cindex Auto Save mode
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
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,d, you should not use it;
+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.
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
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
@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
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.
-@xref{Change Logs and VC}, 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. @xref{VC Dired Mode}, and @ref{Top, , About PCL-CVS,
-pcl-cvs, PCL-CVS --- The Emacs Front-End to CVS}.)
+@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.
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}.
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 some backends, you can display the file @dfn{annotated} with
+ 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 time scale is 360 days, so that
-everything more than one year old is shown in blue.
+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, you can use the following keys to browse the
-annotations of past revisions, view diffs, or view log entries:
+ 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
@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 the latest version.
+return to your current version.
@end table
@node Secondary VC Commands
* Registering:: Putting a file under version control.
* VC Status:: Viewing the VC status of files.
* 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 in
-this situation.
+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 v v} if you wish to start editing it. After
@item P
Move to the log of the previous file, when the logs of multiple files
-are in the log buffer (@pxref{VC Dired Mode}). 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.
+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 (@pxref{VC Dired Mode}). It also takes a numeric
-prefix argument as a repeat count.
+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
@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 no
-files are marked, @kbd{v v} operates on the file in the current line.
-
- 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
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,
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, by committing your local changes back to the
-repository 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
-snapshots made using RCS through VC 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.
-
-@c ??? What about CVS?
-
- 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.
-
-@c ??? What about other back ends?
-
-@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}).
-
- Some backends do not provide an explicit rename operation to their
-repositories. After issuing @code{vc-rename-file}, use @kbd{C-x v v}
-on the original and renamed buffers and provide the necessary edit
-log.
-
- 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.
-
-@c ??? How does this relate to CVS?
-
- 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-@var{backend}-header
- 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 variables @code{vc-@var{backend}-header} where
-@var{backend} is @code{rcs} or @code{sccs}.
-
- 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 may be necessary to use apparently-superfluous backslashes when
-writing the strings that you put in this variable. For instance, you
-might write @code{"$Id\$"} rather than @code{"$Id@w{$}"}. The extra
-backslash prevents the string constant from being interpreted as a
-header, if the Emacs Lisp file containing it is maintained with
-version control.
-
-@vindex vc-comment-alist
- Each header is inserted surrounded by tabs, inside comment delimiters,
-on a new line at point. Normally the ordinary comment
-start and comment end strings of the current mode are used, but for
-certain modes, there are special comment delimiters for this purpose;
-the variable @code{vc-comment-alist} specifies them. Each element of
-this list has the form @code{(@var{mode} @var{starter} @var{ender})}.
-
-@vindex vc-static-header-alist
- The variable @code{vc-static-header-alist} specifies further strings
-to add based on the name of the buffer. Its value should be a list of
-elements of the form @code{(@var{regexp} . @var{format})}. Whenever
-@var{regexp} matches the buffer name, @var{format} is inserted as part
-of the header. A header line is inserted for each element that matches
-the buffer name, and for each string specified by
-@code{vc-@var{backend}-header}. The header line is made by processing the
-string from @code{vc-@var{backend}-header} with the format taken from the
-element. The default value for @code{vc-static-header-alist} is as follows:
-
-@example
-@group
-(("\\.c$" .
- "\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
-SVN SCCS Arch MCVS)}, so it contains all six version systems that are
-currently supported. If you want VC to ignore one or more of these
-systems, exclude its name from the list. To disable VC entirely, set
-this variable to @code{nil}.
-
-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 v v} 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 v v}
-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 v v} 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 v v} 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}).
-
-@vindex vc-cvs-global-switches
- The variable @code{vc-cvs-global-switches}, if non-@code{nil},
-should be a string specifying switches to pass to CVS for all CVS
-operations.
-
- 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
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.
+@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
@code{diff-backup} compares it with the source file that it is a backup
of.
-@findex diff-goto-source
-@findex diff-mode
-@cindex Diff mode
- The @samp{*diff*} buffer uses Diff mode, which enables you to use
-@kbd{C-x `} to visit successive changed locations in the two source
-files, as in Compilation mode (@pxref{Compilation Mode}.) You can
-also move to a particular hunk of changes and type @kbd{C-c C-c}
-(@code{diff-goto-source}) to visit the corresponding source location.
-
-@cindex patches
- Differences between versions of files are often distributed as
-patches, which are the output from the @command{diff} program. You
-can use Diff mode to operate on a patch by typing @kbd{M-x diff-mode}.
-
@findex compare-windows
The command @kbd{M-x compare-windows} compares the text in the
current window with that in the next window. (For more information
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
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