When two users edit the same file at the same time, they are likely
to interfere with each other. Emacs tries to prevent this situation
from arising by recording a @dfn{file lock} when a file is being
-modified. (File locks are not implemented on Microsoft systems.)
+modified.
Emacs can then detect the first attempt to modify a buffer visiting a
file that is locked by another Emacs job, and ask the user what to do.
The file lock is really a file, a symbolic link with a special name,
-stored in the same directory as the file you are editing.
+stored in the same directory as the file you are editing. (On file
+systems that do not support symbolic links, a regular file is used.)
When you access files using NFS, there may be a small probability that
you and another user will both lock the same file ``simultaneously''.
system does not support locking.
@end defun
- File locking is not supported on some systems. On systems that do not
-support it, the functions @code{lock-buffer}, @code{unlock-buffer} and
-@code{file-locked-p} do nothing and return @code{nil}. It is also
-possible to disable locking, by setting the variable @code{create-lockfiles}.
-
@defopt create-lockfiles
If this variable is @code{nil}, Emacs does not lock files.
@end defopt
@end itemize
If you wish, you can replace the @code{ask-user-about-lock} function
-with your own version that makes the decision in another way. The code
-for its usual definition is in @file{userlock.el}.
+with your own version that makes the decision in another way.
@end defun
@node Information about Files