@c -*-texinfo-*-
@c This is part of the GNU Emacs Lisp Reference Manual.
-@c Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1999, 2001, 2002, 2003,
-@c 2004, 2005, 2006, 2007, 2008 Free Software Foundation, Inc.
+@c Copyright (C) 1990-1995, 1999, 2001-2012 Free Software Foundation, Inc.
@c See the file elisp.texi for copying conditions.
-@setfilename ../../info/backups
-@node Backups and Auto-Saving, Buffers, Files, Top
+@node Backups and Auto-Saving
@chapter Backups and Auto-Saving
@cindex backups and auto-saving
saving the buffer the first time.
If a backup was made by renaming, the return value is a cons cell of
-the form (@var{modes} . @var{backupname}), where @var{modes} are the
-mode bits of the original file, as returned by @code{file-modes}
-(@pxref{File Attributes,, Other Information about Files}), and
-@var{backupname} is the name of the backup. In all other cases, that
-is, if a backup was made by copying or if no backup was made, this
-function returns @code{nil}.
+the form (@var{modes} @var{context} @var{backupname}), where
+@var{modes} are the mode bits of the original file, as returned by
+@code{file-modes} (@pxref{File Attributes,, Other Information about
+Files}), @var{context} is a list describing the original file's
+SELinux context (@pxref{File Attributes}), and @var{backupname} is the
+name of the backup. In all other cases, that is, if a backup was made
+by copying or if no backup was made, this function returns @code{nil}.
@end defun
@defvar buffer-backed-up
@smallexample
@group
(add-hook 'rmail-mode-hook
- (function (lambda ()
- (make-local-variable
- 'make-backup-files)
- (setq make-backup-files nil))))
+ (lambda ()
+ (set (make-local-variable 'make-backup-files) nil)))
@end group
@end smallexample
@end defopt
@code{make-backup-files} instead.
@end defvar
-@defvar backup-directory-alist
+@defopt backup-directory-alist
This variable's value is an alist of filename patterns and backup
directory names. Each element looks like
@smallexample
should contain a single element pairing @samp{"."} with the appropriate
directory name.
-If this variable is @code{nil}, or it fails to match a filename, the
-backup is made in the original file's directory.
+If this variable is @code{nil} (the default), or it fails to match a
+filename, the backup is made in the original file's directory.
On MS-DOS filesystems without long names this variable is always
ignored.
-@end defvar
+@end defopt
-@defvar make-backup-file-name-function
+@defopt make-backup-file-name-function
This variable's value is a function to use for making backups instead
of the default @code{make-backup-file-name}. A value of @code{nil}
gives the default @code{make-backup-file-name} behavior.
This could be buffer-local to do something special for specific
files. If you define it, you may need to change
@code{backup-file-name-p} and @code{file-name-sans-versions} too.
-@end defvar
+@end defopt
@node Rename or Copy
@defopt backup-by-copying
If this variable is non-@code{nil}, Emacs always makes backup files by
-copying.
+copying. The default is @code{nil}.
@end defopt
The following three variables, when non-@code{nil}, cause the second
@defopt backup-by-copying-when-linked
If this variable is non-@code{nil}, Emacs makes backups by copying for
-files with multiple names (hard links).
+files with multiple names (hard links). The default is @code{nil}.
This variable is significant only if @code{backup-by-copying} is
@code{nil}, since copying is always used when that variable is
@end defopt
@defopt backup-by-copying-when-mismatch
-If this variable is non-@code{nil}, Emacs makes backups by copying in cases
-where renaming would change either the owner or the group of the file.
+If this variable is non-@code{nil} (the default), Emacs makes backups
+by copying in cases where renaming would change either the owner or
+the group of the file.
The value has no effect when renaming would not alter the owner or
group of the file; that is, for files which are owned by the user and
@deffn Command auto-save-mode arg
When used interactively without an argument, this command is a toggle
-switch: it turns on auto-saving of the current buffer if it is off, and
-vice versa. With an argument @var{arg}, the command turns auto-saving
-on if the value of @var{arg} is @code{t}, a nonempty list, or a positive
-integer. Otherwise, it turns auto-saving off.
+switch: it turns on auto-saving of the current buffer if it is off,
+and vice versa. When called from Lisp with no argument, it turns
+auto-saving on. With an argument @var{arg}, it turns auto-saving on
+if the value of @var{arg} is @code{t}, a nonempty list, or a positive
+integer; otherwise, it turns auto-saving off.
@end deffn
@defun auto-save-file-name-p filename
the buffer stores a positive value in this variable, thus reenabling
auto-saving. Turning auto-save mode off or on also updates this
variable, so that the substantial decrease in size is forgotten.
+
+If it is @minus{}2, that means this buffer should disregard changes in
+buffer size; in particular, it should not shut off auto-saving
+temporarily due to changes in buffer size.
@end defvar
@defvar auto-save-list-file-name
host name.
@end defvar
-@defvar auto-save-list-file-prefix
+@defopt auto-save-list-file-prefix
After Emacs reads your init file, it initializes
@code{auto-save-list-file-name} (if you have not already set it
non-@code{nil}) based on this prefix, adding the host name and process
ID. If you set this to @code{nil} in your init file, then Emacs does
not initialize @code{auto-save-list-file-name}.
-@end defvar
+@end defopt
@node Reverting
@section Reverting
the buffer. Preserving any additional markers would be problematical.
@end deffn
+@defvar revert-buffer-in-progress-p
+@code{revert-buffer} binds this variable to a non-@code{nil} value
+while it is working.
+@end defvar
+
You can customize how @code{revert-buffer} does its work by setting
the variables described in the rest of this section.
@code{nil}.
@end defvar
-@ignore
- arch-tag: 295a6321-e5ab-46d5-aef5-0bb4f447a67f
-@end ignore
+@c FIXME? Move this section from arevert-xtra to here?
+@defvar buffer-stale-function
+The value of this variable, if non-@code{nil}, specifies a function
+to call to check whether a non-file buffer needs reverting
+@iftex
+(@pxref{Supporting additional buffers,,, emacs-xtra, Specialized Emacs Features}).
+@end iftex
+@ifnottex
+(@pxref{Supporting additional buffers,,, emacs}).
+@end ifnottex
+@end defvar
+