[Emacs-diffs] Changes to backups.texi

[Glenn Morris]

CVSROOT:        /sources/emacs
Module name:    emacs
Changes by:     Glenn Morris <gm>       07/09/06 04:09:31

Index: backups.texi
===================================================================
RCS file: backups.texi
diff -N backups.texi
--- backups.texi        7 Apr 2007 02:08:53 -0000       1.40
+++ /dev/null   1 Jan 1970 00:00:00 -0000
@@ -1,756 +0,0 @@
address@hidden -*-texinfo-*-
address@hidden This is part of the GNU Emacs Lisp Reference Manual.
address@hidden Copyright (C) 1990, 1991, 1992, 1993, 1994, 1995, 1999, 2001, 
2002, 2003,
address@hidden   2004, 2005, 2006, 2007  Free Software Foundation, Inc.
address@hidden See the file elisp.texi for copying conditions.
address@hidden ../info/backups
address@hidden Backups and Auto-Saving, Buffers, Files, Top
address@hidden Backups and Auto-Saving
address@hidden backups and auto-saving
-
-  Backup files and auto-save files are two methods by which Emacs tries
-to protect the user from the consequences of crashes or of the user's
-own errors.  Auto-saving preserves the text from earlier in the current
-editing session; backup files preserve file contents prior to the
-current session.
-
address@hidden
-* Backup Files::   How backup files are made; how their names are chosen.
-* Auto-Saving::    How auto-save files are made; how their names are chosen.
-* Reverting::      @code{revert-buffer}, and how to customize what it does.
address@hidden menu
-
address@hidden Backup Files
address@hidden Backup Files
address@hidden backup file
-
-  A @dfn{backup file} is a copy of the old contents of a file you are
-editing.  Emacs makes a backup file the first time you save a buffer
-into its visited file.  Thus, normally, the backup file contains the
-contents of the file as it was before the current editing session.
-The contents of the backup file normally remain unchanged once it
-exists.
-
-  Backups are usually made by renaming the visited file to a new name.
-Optionally, you can specify that backup files should be made by copying
-the visited file.  This choice makes a difference for files with
-multiple names; it also can affect whether the edited file remains owned
-by the original owner or becomes owned by the user editing it.
-
-  By default, Emacs makes a single backup file for each file edited.
-You can alternatively request numbered backups; then each new backup
-file gets a new name.  You can delete old numbered backups when you
-don't want them any more, or Emacs can delete them automatically.
-
address@hidden
-* Making Backups::     How Emacs makes backup files, and when.
-* Rename or Copy::     Two alternatives: renaming the old file or copying it.
-* Numbered Backups::   Keeping multiple backups for each source file.
-* Backup Names::       How backup file names are computed; customization.
address@hidden menu
-
address@hidden Making Backups
address@hidden Making Backup Files
-
address@hidden backup-buffer
-  This function makes a backup of the file visited by the current
-buffer, if appropriate.  It is called by @code{save-buffer} before
-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
address@hidden 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}.
address@hidden defun
-
address@hidden buffer-backed-up
-  This buffer-local variable says whether this buffer's file has
-been backed up on account of this buffer.  If it is address@hidden,
-the backup file has been written.  Otherwise, the file should be backed
-up when it is next saved (if backups are enabled).  This is a
-permanent local; @code{kill-all-local-variables} does not address@hidden
address@hidden defvar
-
address@hidden make-backup-files
-This variable determines whether or not to make backup files.  If it
-is address@hidden, then Emacs creates a backup of each file when it is
-saved for the first time---provided that @code{backup-inhibited}
-is @code{nil} (see below).
-
-The following example shows how to change the @code{make-backup-files}
-variable only in the Rmail buffers and not elsewhere.  Setting it
address@hidden stops Emacs from making backups of these files, which may
-save disk space.  (You would put this code in your init file.)
-
address@hidden
address@hidden
-(add-hook 'rmail-mode-hook
-          (function (lambda ()
-                      (make-local-variable
-                       'make-backup-files)
-                      (setq make-backup-files nil))))
address@hidden group
address@hidden smallexample
address@hidden defopt
-
address@hidden backup-enable-predicate
-This variable's value is a function to be called on certain occasions to
-decide whether a file should have backup files.  The function receives
-one argument, an absolute file name to consider.  If the function returns
address@hidden, backups are disabled for that file.  Otherwise, the other
-variables in this section say whether and how to make backups.
-
address@hidden normal-backup-enable-predicate
-The default value is @code{normal-backup-enable-predicate}, which checks
-for files in @code{temporary-file-directory} and
address@hidden
address@hidden defvar
-
address@hidden backup-inhibited
-If this variable is address@hidden, backups are inhibited.  It records
-the result of testing @code{backup-enable-predicate} on the visited file
-name.  It can also coherently be used by other mechanisms that inhibit
-backups based on which file is visited.  For example, VC sets this
-variable address@hidden to prevent making backups for files managed
-with a version control system.
-
-This is a permanent local, so that changing the major mode does not lose
-its value.  Major modes should not set this variable---they should set
address@hidden instead.
address@hidden defvar
-
address@hidden backup-directory-alist
-This variable's value is an alist of filename patterns and backup
-directory names.  Each element looks like
address@hidden
-(@var{regexp} . @var{directory})
address@hidden smallexample
-
address@hidden
-Backups of files with names matching @var{regexp} will be made in
address@hidden  @var{directory} may be relative or absolute.  If it is
-absolute, so that all matching files are backed up into the same
-directory, the file names in this directory will be the full name of the
-file backed up with all directory separators changed to @samp{!} to
-prevent clashes.  This will not work correctly if your filesystem
-truncates the resulting name.
-
-For the common case of all backups going into one directory, the alist
-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.
-
-On MS-DOS filesystems without long names this variable is always
-ignored.
address@hidden defvar
-
address@hidden 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.
address@hidden Names,, Naming Backup Files}.
-
-This could be buffer-local to do something special for specific
-files.  If you define it, you may need to change
address@hidden and @code{file-name-sans-versions} too.
address@hidden defvar
-
-
address@hidden Rename or Copy
address@hidden Backup by Renaming or by Copying?
address@hidden backup files, rename or copy
-
-  There are two ways that Emacs can make a backup file:
-
address@hidden @bullet
address@hidden
-Emacs can rename the original file so that it becomes a backup file, and
-then write the buffer being saved into a new file.  After this
-procedure, any other names (i.e., hard links) of the original file now
-refer to the backup file.  The new file is owned by the user doing the
-editing, and its group is the default for new files written by the user
-in that directory.
-
address@hidden
-Emacs can copy the original file into a backup file, and then overwrite
-the original file with new contents.  After this procedure, any other
-names (i.e., hard links) of the original file continue to refer to the
-current (updated) version of the file.  The file's owner and group will
-be unchanged.
address@hidden itemize
-
-  The first method, renaming, is the default.
-
-  The variable @code{backup-by-copying}, if address@hidden, says to use
-the second method, which is to copy the original file and overwrite it
-with the new buffer contents.  The variable @code{file-precious-flag},
-if address@hidden, also has this effect (as a sideline of its main
-significance).  @xref{Saving Buffers}.
-
address@hidden backup-by-copying
-If this variable is address@hidden, Emacs always makes backup files by
-copying.
address@hidden defopt
-
-  The following three variables, when address@hidden, cause the second
-method to be used in certain special cases.  They have no effect on the
-treatment of files that don't fall into the special cases.
-
address@hidden backup-by-copying-when-linked
-If this variable is address@hidden, Emacs makes backups by copying for
-files with multiple names (hard links).
-
-This variable is significant only if @code{backup-by-copying} is
address@hidden, since copying is always used when that variable is
address@hidden
address@hidden defopt
-
address@hidden backup-by-copying-when-mismatch
-If this variable is address@hidden, 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
-whose group matches the default for a new file created there by the
-user.
-
-This variable is significant only if @code{backup-by-copying} is
address@hidden, since copying is always used when that variable is
address@hidden
address@hidden defopt
-
address@hidden backup-by-copying-when-privileged-mismatch
-This variable, if address@hidden, specifies the same behavior as
address@hidden, but only for certain user-id
-values: namely, those less than or equal to a certain number.  You set
-this variable to that number.
-
-Thus, if you set @code{backup-by-copying-when-privileged-mismatch}
-to 0, backup by copying is done for the superuser only,
-when necessary to prevent a change in the owner of the file.
-
-The default is 200.
address@hidden defopt
-
address@hidden Numbered Backups
address@hidden Making and Deleting Numbered Backup Files
-
-  If a file's name is @file{foo}, the names of its numbered backup
-versions are @address@hidden, for various integers @var{v}, like
-this: @file{foo.~1~}, @file{foo.~2~}, @file{foo.~3~}, @dots{},
address@hidden, and so on.
-
address@hidden version-control
-This variable controls whether to make a single non-numbered backup
-file or multiple numbered backups.
-
address@hidden @asis
address@hidden @code{nil}
-Make numbered backups if the visited file already has numbered backups;
-otherwise, do not.  This is the default.
-
address@hidden @code{never}
-Do not make numbered backups.
-
address@hidden @var{anything else}
-Make numbered backups.
address@hidden table
address@hidden defopt
-
-  The use of numbered backups ultimately leads to a large number of
-backup versions, which must then be deleted.  Emacs can do this
-automatically or it can ask the user whether to delete them.
-
address@hidden kept-new-versions
-The value of this variable is the number of newest versions to keep
-when a new numbered backup is made.  The newly made backup is included
-in the count.  The default value address@hidden
address@hidden defopt
-
address@hidden kept-old-versions
-The value of this variable is the number of oldest versions to keep
-when a new numbered backup is made.  The default value address@hidden
address@hidden defopt
-
-  If there are backups numbered 1, 2, 3, 5, and 7, and both of these
-variables have the value 2, then the backups numbered 1 and 2 are kept
-as old versions and those numbered 5 and 7 are kept as new versions;
-backup version 3 is excess.  The function @code{find-backup-file-name}
-(@pxref{Backup Names}) is responsible for determining which backup
-versions to delete, but does not delete them itself.
-
address@hidden delete-old-versions
-If this variable is @code{t}, then saving a file deletes excess
-backup versions silently.  If it is @code{nil}, that means
-to ask for confirmation before deleting excess backups.
-Otherwise, they are not deleted at all.
address@hidden defopt
-
address@hidden dired-kept-versions
-This variable specifies how many of the newest backup versions to keep
-in the Dired command @kbd{.} (@code{dired-clean-directory}).  That's the
-same thing @code{kept-new-versions} specifies when you make a new backup
-file.  The default address@hidden
address@hidden defopt
-
address@hidden Backup Names
address@hidden Naming Backup Files
-
-  The functions in this section are documented mainly because you can
-customize the naming conventions for backup files by redefining them.
-If you change one, you probably need to change the rest.
-
address@hidden backup-file-name-p filename
-This function returns a address@hidden value if @var{filename} is a
-possible name for a backup file.  It just checks the name, not whether
-a file with the name @var{filename} exists.
-
address@hidden
address@hidden
-(backup-file-name-p "foo")
-     @result{} nil
address@hidden group
address@hidden
-(backup-file-name-p "foo~")
-     @result{} 3
address@hidden group
address@hidden smallexample
-
-The standard definition of this function is as follows:
-
address@hidden
address@hidden
-(defun backup-file-name-p (file)
-  "Return non-nil if FILE is a backup file \
-name (numeric or not)..."
-  (string-match "~\\'" file))
address@hidden group
address@hidden smallexample
-
address@hidden
-Thus, the function returns a address@hidden value if the file name ends
-with a @samp{~}.  (We use a backslash to split the documentation
-string's first line into two lines in the text, but produce just one
-line in the string itself.)
-
-This simple expression is placed in a separate function to make it easy
-to redefine for customization.
address@hidden defun
-
address@hidden make-backup-file-name filename
-This function returns a string that is the name to use for a
-non-numbered backup file for file @var{filename}.  On Unix, this is just
address@hidden with a tilde appended.
-
-The standard definition of this function, on most operating systems, is
-as follows:
-
address@hidden
address@hidden
-(defun make-backup-file-name (file)
-  "Create the non-numeric backup file name for FILE..."
-  (concat file "~"))
address@hidden group
address@hidden smallexample
-
-You can change the backup-file naming convention by redefining this
-function.  The following example redefines @code{make-backup-file-name}
-to prepend a @samp{.} in addition to appending a tilde:
-
address@hidden
address@hidden
-(defun make-backup-file-name (filename)
-  (expand-file-name
-    (concat "." (file-name-nondirectory filename) "~")
-    (file-name-directory filename)))
address@hidden group
-
address@hidden
-(make-backup-file-name "backups.texi")
-     @result{} ".backups.texi~"
address@hidden group
address@hidden smallexample
-
-Some parts of Emacs, including some Dired commands, assume that backup
-file names end with @samp{~}.  If you do not follow that convention, it
-will not cause serious problems, but these commands may give
-less-than-desirable results.
address@hidden defun
-
address@hidden find-backup-file-name filename
-This function computes the file name for a new backup file for
address@hidden  It may also propose certain existing backup files for
-deletion.  @code{find-backup-file-name} returns a list whose @sc{car} is
-the name for the new backup file and whose @sc{cdr} is a list of backup
-files whose deletion is proposed.  The value can also be @code{nil},
-which means not to make a backup.
-
-Two variables, @code{kept-old-versions} and @code{kept-new-versions},
-determine which backup versions should be kept.  This function keeps
-those versions by excluding them from the @sc{cdr} of the value.
address@hidden Backups}.
-
-In this example, the value says that @file{~rms/foo.~5~} is the name
-to use for the new backup file, and @file{~rms/foo.~3~} is an ``excess''
-version that the caller should consider deleting now.
-
address@hidden
address@hidden
-(find-backup-file-name "~rms/foo")
-     @result{} ("~rms/foo.~5~" "~rms/foo.~3~")
address@hidden group
address@hidden smallexample
address@hidden defun
-
address@hidden Emacs 19 feature
address@hidden file-newest-backup filename
-This function returns the name of the most recent backup file for
address@hidden, or @code{nil} if that file has no backup files.
-
-Some file comparison commands use this function so that they can
-automatically compare a file with its most recent backup.
address@hidden defun
-
address@hidden Auto-Saving
address@hidden Auto-Saving
address@hidden @cindex auto-saving   Lots of symbols starting with auto-save 
here.
-
-  Emacs periodically saves all files that you are visiting; this is
-called @dfn{auto-saving}.  Auto-saving prevents you from losing more
-than a limited amount of work if the system crashes.  By default,
-auto-saves happen every 300 keystrokes, or after around 30 seconds of
-idle time.  @xref{Auto Save, Auto Save, Auto-Saving: Protection Against
-Disasters, emacs, The GNU Emacs Manual}, for information on auto-save
-for users.  Here we describe the functions used to implement auto-saving
-and the variables that control them.
-
address@hidden buffer-auto-save-file-name
-This buffer-local variable is the name of the file used for
-auto-saving the current buffer.  It is @code{nil} if the buffer
-should not be auto-saved.
-
address@hidden
address@hidden
-buffer-auto-save-file-name
-     @result{} "/xcssun/users/rms/lewis/#backups.texi#"
address@hidden group
address@hidden example
address@hidden defvar
-
address@hidden 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.
address@hidden deffn
-
address@hidden auto-save-file-name-p filename
-This function returns a address@hidden value if @var{filename} is a
-string that could be the name of an auto-save file.  It assumes
-the usual naming convention for auto-save files: a name that
-begins and ends with hash marks (@samp{#}) is a possible auto-save file
-name.  The argument @var{filename} should not contain a directory part.
-
address@hidden
address@hidden
-(make-auto-save-file-name)
-     @result{} "/xcssun/users/rms/lewis/#backups.texi#"
address@hidden group
address@hidden
-(auto-save-file-name-p "#backups.texi#")
-     @result{} 0
address@hidden group
address@hidden
-(auto-save-file-name-p "backups.texi")
-     @result{} nil
address@hidden group
address@hidden example
-
-The standard definition of this function is as follows:
-
address@hidden
address@hidden
-(defun auto-save-file-name-p (filename)
-  "Return non-nil if FILENAME can be yielded by..."
-  (string-match "^#.*#$" filename))
address@hidden group
address@hidden example
-
-This function exists so that you can customize it if you wish to
-change the naming convention for auto-save files.  If you redefine it,
-be sure to redefine the function @code{make-auto-save-file-name}
-correspondingly.
address@hidden defun
-
address@hidden make-auto-save-file-name
-This function returns the file name to use for auto-saving the current
-buffer.  This is just the file name with hash marks (@samp{#}) prepended
-and appended to it.  This function does not look at the variable
address@hidden (described below); callers of this
-function should check that variable first.
-
address@hidden
address@hidden
-(make-auto-save-file-name)
-     @result{} "/xcssun/users/rms/lewis/#backups.texi#"
address@hidden group
address@hidden example
-
-Here is a simplified version of the standard definition of this
-function:
-
address@hidden
address@hidden
-(defun make-auto-save-file-name ()
-  "Return file name to use for auto-saves \
-of current buffer.."
-  (if buffer-file-name
address@hidden group
address@hidden
-      (concat
-       (file-name-directory buffer-file-name)
-       "#"
-       (file-name-nondirectory buffer-file-name)
-       "#")
-    (expand-file-name
-     (concat "#%" (buffer-name) "#"))))
address@hidden group
address@hidden example
-
-This exists as a separate function so that you can redefine it to
-customize the naming convention for auto-save files.  Be sure to
-change @code{auto-save-file-name-p} in a corresponding way.
address@hidden defun
-
address@hidden auto-save-visited-file-name
-If this variable is address@hidden, Emacs auto-saves buffers in
-the files they are visiting.  That is, the auto-save is done in the same
-file that you are editing.  Normally, this variable is @code{nil}, so
-auto-save files have distinct names that are created by
address@hidden
-
-When you change the value of this variable, the new value does not take
-effect in an existing buffer until the next time auto-save mode is
-reenabled in it.  If auto-save mode is already enabled, auto-saves
-continue to go in the same file name until @code{auto-save-mode} is
-called again.
address@hidden defopt
-
address@hidden recent-auto-save-p
-This function returns @code{t} if the current buffer has been
-auto-saved since the last time it was read in or saved.
address@hidden defun
-
address@hidden set-buffer-auto-saved
-This function marks the current buffer as auto-saved.  The buffer will
-not be auto-saved again until the buffer text is changed again.  The
-function returns @code{nil}.
address@hidden defun
-
address@hidden auto-save-interval
-The value of this variable specifies how often to do auto-saving, in
-terms of number of input events.  Each time this many additional input
-events are read, Emacs does auto-saving for all buffers in which that is
-enabled.  Setting this to zero disables autosaving based on the
-number of characters typed.
address@hidden defopt
-
address@hidden auto-save-timeout
-The value of this variable is the number of seconds of idle time that
-should cause auto-saving.  Each time the user pauses for this long,
-Emacs does auto-saving for all buffers in which that is enabled.  (If
-the current buffer is large, the specified timeout is multiplied by a
-factor that increases as the size increases; for a million-byte
-buffer, the factor is almost 4.)
-
-If the value is zero or @code{nil}, then auto-saving is not done as a
-result of idleness, only after a certain number of input events as
-specified by @code{auto-save-interval}.
address@hidden defopt
-
address@hidden auto-save-hook
-This normal hook is run whenever an auto-save is about to happen.
address@hidden defvar
-
address@hidden auto-save-default
-If this variable is address@hidden, buffers that are visiting files
-have auto-saving enabled by default.  Otherwise, they do not.
address@hidden defopt
-
address@hidden Command do-auto-save &optional no-message current-only
-This function auto-saves all buffers that need to be auto-saved.  It
-saves all buffers for which auto-saving is enabled and that have been
-changed since the previous auto-save.
-
-If any buffers are auto-saved, @code{do-auto-save} normally displays a
-message saying @samp{Auto-saving...} in the echo area while
-auto-saving is going on.  However, if @var{no-message} is
address@hidden, the message is inhibited.
-
-If @var{current-only} is address@hidden, only the current buffer
-is auto-saved.
address@hidden deffn
-
address@hidden delete-auto-save-file-if-necessary &optional force
-This function deletes the current buffer's auto-save file if
address@hidden is address@hidden  It is called every
-time a buffer is saved.
-
-Unless @var{force} is address@hidden, this function only deletes the
-file if it was written by the current Emacs session since the last
-true save.
address@hidden defun
-
address@hidden delete-auto-save-files
-This variable is used by the function
address@hidden  If it is address@hidden,
-Emacs deletes auto-save files when a true save is done (in the visited
-file).  This saves disk space and unclutters your directory.
address@hidden defopt
-
address@hidden rename-auto-save-file
-This function adjusts the current buffer's auto-save file name if the
-visited file name has changed.  It also renames an existing auto-save
-file, if it was made in the current Emacs session.  If the visited
-file name has not changed, this function does nothing.
address@hidden defun
-
address@hidden buffer-saved-size
-The value of this buffer-local variable is the length of the current
-buffer, when it was last read in, saved, or auto-saved.  This is
-used to detect a substantial decrease in size, and turn off auto-saving
-in response.
-
-If it is @minus{}1, that means auto-saving is temporarily shut off in
-this buffer due to a substantial decrease in size.  Explicitly saving
-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.
address@hidden defvar
-
address@hidden auto-save-list-file-name
-This variable (if address@hidden) specifies a file for recording the
-names of all the auto-save files.  Each time Emacs does auto-saving, it
-writes two lines into this file for each buffer that has auto-saving
-enabled.  The first line gives the name of the visited file (it's empty
-if the buffer has none), and the second gives the name of the auto-save
-file.
-
-When Emacs exits normally, it deletes this file; if Emacs crashes, you
-can look in the file to find all the auto-save files that might contain
-work that was otherwise lost.  The @code{recover-session} command uses
-this file to find them.
-
-The default name for this file specifies your home directory and starts
-with @samp{.saves-}.  It also contains the Emacs process @acronym{ID} and the
-host name.
address@hidden defvar
-
address@hidden auto-save-list-file-prefix
-After Emacs reads your init file, it initializes
address@hidden (if you have not already set it
address@hidden) 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}.
address@hidden defvar
-
address@hidden Reverting
address@hidden Reverting
-
-  If you have made extensive changes to a file and then change your mind
-about them, you can get rid of them by reading in the previous version
-of the file with the @code{revert-buffer} command.  @xref{Reverting, ,
-Reverting a Buffer, emacs, The GNU Emacs Manual}.
-
address@hidden Command revert-buffer &optional ignore-auto noconfirm 
preserve-modes
-This command replaces the buffer text with the text of the visited
-file on disk.  This action undoes all changes since the file was visited
-or saved.
-
-By default, if the latest auto-save file is more recent than the visited
-file, and the argument @var{ignore-auto} is @code{nil},
address@hidden asks the user whether to use that auto-save
-instead.  When you invoke this command interactively, @var{ignore-auto}
-is @code{t} if there is no numeric prefix argument; thus, the
-interactive default is not to check the auto-save file.
-
-Normally, @code{revert-buffer} asks for confirmation before it changes
-the buffer; but if the argument @var{noconfirm} is address@hidden,
address@hidden does not ask for confirmation.
-
-Normally, this command reinitializes the buffer's major and minor modes
-using @code{normal-mode}.  But if @var{preserve-modes} is
address@hidden, the modes remain unchanged.
-
-Reverting tries to preserve marker positions in the buffer by using the
-replacement feature of @code{insert-file-contents}.  If the buffer
-contents and the file contents are identical before the revert
-operation, reverting preserves all the markers.  If they are not
-identical, reverting does change the buffer; in that case, it preserves
-the markers in the unchanged text (if any) at the beginning and end of
-the buffer.  Preserving any additional markers would be problematical.
address@hidden deffn
-
-You can customize how @code{revert-buffer} does its work by setting
-the variables described in the rest of this section.
-
address@hidden revert-without-query
-This variable holds a list of files that should be reverted without
-query.  The value is a list of regular expressions.  If the visited file
-name matches one of these regular expressions, and the file has changed
-on disk but the buffer is not modified, then @code{revert-buffer}
-reverts the file without asking the user for confirmation.
address@hidden defopt
-
-  Some major modes customize @code{revert-buffer} by making
-buffer-local bindings for these variables:
-
address@hidden revert-buffer-function
address@hidden of revert-buffer-function}
-The value of this variable is the function to use to revert this
-buffer.  If address@hidden, it should be a function with two optional
-arguments to do the work of reverting.  The two optional arguments,
address@hidden and @var{noconfirm}, are the arguments that
address@hidden received.  If the value is @code{nil}, reverting
-works the usual way.
-
-Modes such as Dired mode, in which the text being edited does not
-consist of a file's contents but can be regenerated in some other
-fashion, can give this variable a buffer-local value that is a function to
-regenerate the contents.
address@hidden defvar
-
address@hidden revert-buffer-insert-file-contents-function
-The value of this variable, if address@hidden, specifies the function to use to
-insert the updated contents when reverting this buffer.  The function
-receives two arguments: first the file name to use; second, @code{t} if
-the user has asked to read the auto-save file.
-
-The reason for a mode to set this variable instead of
address@hidden is to avoid duplicating or replacing the
-rest of what @code{revert-buffer} does: asking for confirmation,
-clearing the undo list, deciding the proper major mode, and running the
-hooks listed below.
address@hidden defvar
-
address@hidden before-revert-hook
-This normal hook is run by @code{revert-buffer} before
-inserting the modified contents---but only if
address@hidden is @code{nil}.
address@hidden defvar
-
address@hidden after-revert-hook
-This normal hook is run by @code{revert-buffer} after inserting
-the modified contents---but only if @code{revert-buffer-function} is
address@hidden
address@hidden defvar
-
address@hidden
-   arch-tag: 295a6321-e5ab-46d5-aef5-0bb4f447a67f
address@hidden ignore