@c This file is included either in vc-xtra.texi (when producing the
@c printed version) or in the main Emacs manual (for the on-line version).
-@node Remote Repositories
-@subsection Remote Repositories
-@cindex remote repositories
-
- A common way of using CVS and other more advanced VCSes is to set up
-a central 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 repository server.
-
- One difficulty is that access to a repository server is often slow,
-and that developers might need to work off-line as well. While only
-third-generation decentralized VCses such as GNU Arch or Mercurial
-really solve this problem, VC is designed to reduce the amount of
-network interaction necessary.
-
- If you are using a truly decentralized VCS you can skip the rest of
-this section. It describes backup and local-repository techniques
-that are only useful for Subversion and earlier VCSes.
-
-@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 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
-@iftex
-(@pxref{Backup,,,emacs, the Emacs Manual}).
-@end iftex
-@ifnottex
-(@pxref{Backup}).
-@end ifnottex
-But they follow a similar naming convention.
-
- For a file that comes from a remote 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 ~}
-@iftex
-(@pxref{Old Revisions,,,emacs, the Emacs Manual}),
-@end iftex
-@ifnottex
-(@pxref{Old Revisions}),
-@end ifnottex
-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
-@iftex
-(@pxref{Log Buffer,,,emacs, the Emacs Manual})
-@end iftex
-@ifnottex
-(@pxref{Log Buffer})
-@end ifnottex
-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
-@iftex
-(@pxref{Merging,,,emacs, the Emacs Manual}).
-@end iftex
-@ifnottex
-(@pxref{Merging}).
-@end ifnottex
-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 Revision Tags
-@subsection Revision Tags
-@cindex tags and version control
-
- In a VCS with per-file revision numbers (such as SCCS, RCS, or CVS)
-@dfn{tag} is a named set of file versions (one for each registered
-file) that you can treat as a unit. In a VCS with per-repository
-version numbers (Subversion and most later ones) a tag is simply
-a symbolic name for a revision.
-
- One important kind of tag is a @dfn{release}, a (theoretically)
-stable version of the system that is ready for distribution to users.
-
-@menu
-* Making Revision Tags:: The tag facilities.
-* Revision Tag Caveats:: Things to be careful of when using tags.
-@end menu
-
-@node Making Revision Tags
-@subsubsection Making and Using Revision Tags
-
- There are two basic commands for tags; one makes a
-tag with a given name, the other retrieves a named tag.
-
-@table @code
-@kindex C-x v s
-@findex vc-create-tag
-@item C-x v s @var{name} @key{RET}
-Define the working revision of every registered file in or under the
-current directory as a tag named @var{name}
-(@code{vc-create-tag}).
-
-@kindex C-x v r
-@findex vc-retrieve-tag
-@item C-x v r @var{name} @key{RET}
-For all registered files at or below the current directory level,
-retrieve the tagged revision @var{name}. This command will
-switch to a branch if @var{name} is a branch name and your VCS
-distinguishes branches from tags.
-(@code{vc-retrieve-tag}).
-
-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
-
-Tags are inexpensive, so you need not hesitate to create them whenever
-they are useful. Branches vary in cost depending on your VCS; in
-older ones they may be expensive.
-
- You can give a tag or branch name as an argument to @kbd{C-x v =} or
-@kbd{C-x v ~}
-@iftex
-(@pxref{Old Revisions,,,emacs, the Emacs Manual}).
-@end iftex
-@ifnottex
-(@pxref{Old Revisions}).
-@end ifnottex
-Thus, you can use it to compare a tagged version against the current files,
-or two tagged versions against each other.
-
-@node Revision Tag Caveats
-@subsubsection Revision Tag Caveats
-
- For SCCS, VC implements tags itself; these tags are visible only
-through VC. Most later systems (including CVS, Subversion, bzr, git,
-and hg) have a native tag facility, and VC uses it where
-available; those tags will be visible even when you bypass VC.
-
- There is no support for VC tags using GNU Arch yet.
-
- Under older VCSes (SCCS, RCS, CVS, early versions of Subversion),
-renaming and deletion could create some difficulties with tags. This is
-not a VC-specific problem, but a general design issue in version
-control systems that was not solved effectively until the earliest
-third-generation systems.
-
- In a file-oriented VCS, when you rename a registered file you need
-to rename its master along with it; the command @code{vc-rename-file}
-will do this automatically. If you are using SCCS, you must also
-update the records of the tag, to mention the file by its new name
-(@code{vc-rename-file} does this, too). An old tag 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 tags by hand.
-
- Using @code{vc-rename-file} makes the tag 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 tag, 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
* 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.
+* Revision Tags:: Symbolic names for revisions.
* 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
+ If you use RCS or CVS for a program with a @file{ChangeLog} file
@iftex
(@pxref{Change Log,,,emacs, the Emacs Manual}),
@end iftex
@ifnottex
(@pxref{Change Log}),
@end ifnottex
-you can generate change log entries automatically from the version
-control log entries:
+you can generate change log entries from the version control log
+entries of previous commits.
+
+ Note that this only works with RCS or CVS. This procedure would be
+particularly incorrect on a modern changeset-based version control
+system, where changes to the @file{ChangeLog} file would normally be
+committed as part of a changeset. In that case, you should write the
+change log entries first, then pull them into the @samp{*vc-log*}
+buffer when you commit
+@iftex
+(@pxref{Log Buffer,,,emacs, the Emacs Manual}).
+@end iftex
+@ifnottex
+(@pxref{Log Buffer}).
+@end ifnottex
@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.
+Visit the current directory's @file{ChangeLog} file and, for
+registered files in that directory, create new entries for versions
+committed since the most recent change log entry
(@code{vc-update-change-log}).
-This command works with RCS or CVS only, not with any of the 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:
+Bowditch to @file{rcs2log} on 1999-05-22 with log entry @samp{Ignore
+log messages that start with `#'.}. Then @kbd{C-x v a} inserts this
+@file{ChangeLog} entry:
@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:
+If the version control log entry specifies a function name (in
+parenthesis at the beginning of a line), that is reflected in the
+@file{ChangeLog} entry. For example, if a log entry for @file{vc.el}
+is @samp{(vc-do-command): Check call-process status.}, the
+@file{ChangeLog} entry is:
@iftex
@medbreak
@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:
+ 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.
-@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
+@node Renaming and VC
+@subsubsection Renaming VC Work Files and Master Files
+@cindex renaming version-controlled files
-@noindent
-They appear like this in @file{ChangeLog}:
+@table @kbd
+@item M-x vc-rename-file
+Prompt for two file names, @var{VAR} and @var{OLD}, and rename them in
+the version-controlled working tree.
+@end table
-@iftex
-@medbreak
-@end iftex
-@smallexample
-@group
-1999-04-01 Nathaniel Bowditch <nat@@apn.org>
+@findex vc-rename-file
+ If you wish to rename a registered file in a version-controlled
+working tree, use the command @kbd{M-x vc-rename-file}. This prompts
+for two arguments: the file you wish to rename, followed by the new
+name; then it performs the renaming through the version control
+system.
+
+ On modern version control systems that have built-in support for
+renaming, the renaming operation takes effect immediately in the
+working tree, and takes effect in the repository when you commit the
+renamed file. The renamed file retains the full change history of the
+original file.
+
+ On CVS and older version control systems, the @code{vc-rename-file}
+command actually works by creating a copy of the old file under the
+new name, registering it, and deleting the old file. In this case,
+the change history is not preserved.
- * vc.texinfo: Fix expansion typos.
+@node Revision Tags
+@subsubsection Revision Tags
+@cindex revision tag
+@cindex tags for version control
- * vc.el, vc-hooks.el: Don't call expand-file-name.
-@end group
-@end smallexample
-@iftex
-@medbreak
-@end iftex
+ Most version control systems allow you to apply a @dfn{revision tag}
+to a specific version of a version-controlled tree. On modern
+changeset-based version control systems, a revision tag is simply a
+symbolic name for a particular revision. On older file-based systems
+like CVS, each tag is added to the entire set of version-controlled
+files, allowing them to be handled as a unit. Revision tags are
+commonly used to identify releases that are distributed to users.
- 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:
+ There are two basic commands for tags; one makes a tag with a given
+name, the other retrieves a named tag.
-@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
+@table @code
+@kindex C-x v s
+@findex vc-create-tag
+@item C-x v s @var{name} @key{RET}
+Define the working revision of every registered file in or under the
+current directory as a tag named @var{name}
+(@code{vc-create-tag}).
-@noindent
-Then the text in @file{ChangeLog} looks like this:
+@kindex C-x v r
+@findex vc-retrieve-tag
+@item C-x v r @var{name} @key{RET}
+For all registered files at or below the current directory level,
+retrieve the tagged revision @var{name}. This command will switch to a
+branch if @var{name} is a branch name and your VCS distinguishes
+branches from tags. (@code{vc-retrieve-tag}).
-@iftex
-@medbreak
-@end iftex
-@smallexample
-@group
-1999-04-01 Nathaniel Bowditch <nat@@apn.org>
+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
- * vc.texinfo: Fix expansion typos.
- * vc.el, vc-hooks.el: Don't call expand-file-name.
-@end group
-@end smallexample
+ You can give a tag or branch name as an argument to @kbd{C-x v =} or
+@kbd{C-x v ~}
@iftex
-@medbreak
+(@pxref{Old Revisions,,,emacs, the Emacs Manual}).
@end iftex
+@ifnottex
+(@pxref{Old Revisions}).
+@end ifnottex
+Thus, you can use it to compare a tagged version against the current files,
+or two tagged versions against each other.
- 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 tags (@pxref{Revision Tags}) that
-mention the file, so that they use the new name; despite this, the
-tag thus modified may not completely work (@pxref{Revision Tag Caveats}).
-
- Some back ends 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.
+ On SCCS, VC implements tags itself; these tags are visible only
+through VC. Most later systems (including CVS, Subversion, bzr, git,
+and hg) have a native tag facility, and VC uses it where available;
+those tags will be visible even when you bypass VC.
- You cannot use @code{vc-rename-file} on a file that is locked by
-someone else.
+ In a file-oriented VCS, when you rename a registered file you need
+to rename its master along with it; the command @code{vc-rename-file}
+will do this automatically. If you are using SCCS, you must also
+update the records of the tag, to mention the file by its new name
+(@code{vc-rename-file} does this, too). An old tag 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 tags by hand. Using @code{vc-rename-file} makes the tag 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 tag, 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 Version Headers
@subsubsection Inserting Version Control Headers
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, see
+registered in more than one system, 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, see
@iftex
@ref{Registering,,,emacs, the Emacs Manual},
@end iftex
@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-global-switches
+ You can specify additional command line options to pass to all CVS
+operations in the variable @code{vc-cvs-global-switches}. These
+switches are inserted immediately after the @code{cvs} command, before
+the name of the operation to invoke.
@vindex vc-stay-local
@vindex vc-cvs-stay-local
@cindex remote repositories (CVS)
- When a file's repository is on a remote machine, VC tries to keep
+ When using a CVS repository on a remote machine, VC can try keeping
network interactions to a minimum. This is controlled by the variable
@code{vc-cvs-stay-local}. There is another variable,
@code{vc-stay-local}, which enables the feature also for other back
only about @code{vc-cvs-stay-local}, but everything applies to
@code{vc-stay-local} as well.
-If @code{vc-cvs-stay-local} 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}},
+ If @code{vc-cvs-stay-local} is @code{t} (the default), VC determines
+the version control status of each file using only the entry in the
+local CVS subdirectory and the information returned by previous CVS
+commands. As a consequence, if you have modified a file and somebody
+else has checked in other changes, you will not be notified of the
+conflict until you try to commit.
+
+ If you change @code{vc-cvs-stay-local} to @code{nil}, 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.
+
+ 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.
+
+@cindex automatic version backups
+ When using a remote repository, Emacs normally makes @dfn{automatic
+version backups} of the original versions of each edited file. These
+local backups are made whenever you save the first changes to a file,
+and they are removed after you commit your changes to the repository.
+(Note that these are not the same as ordinary Emacs backup files;
@iftex
-@pxref{Merging,,,emacs, the Emacs Manual}).
+@pxref{Backup,,,emacs, the Emacs Manual}.)
@end iftex
@ifnottex
-@pxref{Merging}).
+@pxref{Backup}.)
@end ifnottex
+Commands like @kbd{C-x v =} and @kbd{C-x v u} make use of automatic
+version backups, if possible, to avoid having to access the network.
- 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}).
+ Setting @code{vc-cvs-stay-local} to @code{nil} disables the making
+of automatic 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.
+@cindex manual version backups
+ Automatic version backups have names of the form
+@w{@code{@var{file}.~@var{version}.~}}. This is similar to the name
+that @kbd{C-x v ~} saves old versions to
+@iftex
+(@pxref{Old Revisions,,,emacs, the Emacs Manual}),
+@end iftex
+@ifnottex
+(@pxref{Old Revisions}),
+@end ifnottex
+except for the additional dot (@samp{.}) after the version. The
+relevant VC commands can use both kinds of version backups. The main
+difference is that the ``manual'' version backups made by @kbd{C-x v
+~} are not deleted automatically when you commit.
-@vindex vc-cvs-global-switches
- You can specify additional command line options to pass to all CVS
-operations in the variable @code{vc-cvs-global-switches}. These
-switches are inserted immediately after the @code{cvs} command, before
-the name of the operation to invoke.
+@cindex locking (CVS)
+ CVS does not use locking by default, but there are ways to enable
+locking-like behavior using its @env{CVSREAD} or @dfn{watch} feature;
+see the CVS documentation for details. If that case, you can use
+@kbd{C-x v v} in Emacs to toggle locking, as you would for a
+locking-based version control system (@pxref{VC With A Locking VCS}).
projects / emacs.git / commitdiff