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(emacs)CVS Options

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Options specific for CVS
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   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.

   For one thing, you can set the `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
`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 `CVSREAD' for the first time, make sure to
check out all your modules anew, so that the file protections are set
correctly.

   Another way to achieve something similar to locking is to use the
"watch" feature of CVS.  If a file is being watched, CVS makes it
read-only by default, and you must also use `C-x C-q' in Emacs to make
it writable.  VC calls `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.

   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
`vc-cvs-stay-local'.  If it is `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 `C-x v m
<RET>', Note: Merging).

   When `vc-cvs-stay-local' is `t', VC also makes local version
backups, so that simple diff and revert operations are completely local
(Note: Version Backups).

   On the other hand, if you set `vc-cvs-stay-local' to `nil', then VC
queries the remote repository _before_ it decides what to do in
`vc-next-action' (`C-x v v'), just as it does for local repositories.
It also does not make any version backups.

   You can also set `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.