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SXEmacs periodically saves all files that you are visiting; this is called 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. See Auto-Saving: Protection Against Disasters in The SXEmacs User’s Manual, for information on auto-save for users. Here we describe the functions used to implement auto-saving and the variables that control them.
This buffer-local variable is the name of the file used for
auto-saving the current buffer. It is nil
if the buffer
should not be auto-saved.
buffer-auto-save-file-name => "/xcssun/users/rms/lewis/#files.texi#"
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 arg, the command turns auto-saving
on if the value of arg is t
, a nonempty list, or a positive
integer. Otherwise, it turns auto-saving off.
This function returns a non-nil
value if filename is a
string that could be the name of an auto-save file. It works based on
knowledge of the naming convention for auto-save files: a name that
begins and ends with hash marks (‘#’) is a possible auto-save file
name. The argument filename should not contain a directory part.
(make-auto-save-file-name) ⇒ "/xcssun/users/rms/lewis/#files.texi#"
(auto-save-file-name-p "#files.texi#") ⇒ 0
(auto-save-file-name-p "files.texi") ⇒ nil
The standard definition of this function is as follows:
(defun auto-save-file-name-p (filename) "Return non-nil if FILENAME can be yielded by..." (string-match "^#.*#$" filename))
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 make-auto-save-file-name
correspondingly.
This function returns the file name to use for auto-saving the current
buffer. This is just the file name with hash marks (‘#’) appended
and prepended to it. This function does not look at the variable
auto-save-visited-file-name
(described below); you should check
that before calling this function.
(make-auto-save-file-name) ⇒ "/xcssun/users/rms/lewis/#backup.texi#"
The standard definition of this function is as follows:
(defun make-auto-save-file-name () "Return file name to use for auto-saves \ of current buffer. …" (if buffer-file-name
(concat (file-name-directory buffer-file-name) "#" (file-name-nondirectory buffer-file-name) "#") (expand-file-name (concat "#%" (buffer-name) "#"))))
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 auto-save-file-name-p
in a corresponding way.
If this variable is non-nil
, SXEmacs 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 nil
, so
auto-save files have distinct names that are created by
make-auto-save-file-name
.
When you change the value of this variable, the value does not take
effect until the next time auto-save mode is reenabled in any given
buffer. If auto-save mode is already enabled, auto-saves continue to go
in the same file name until auto-save-mode
is called again.
This function returns t
if the current buffer has been
auto-saved since the last time it was read in or 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 nil
.
The value of this variable is the number of characters that SXEmacs reads from the keyboard between auto-saves. Each time this many more characters are read, auto-saving is done for all buffers in which it is enabled.
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, SXEmacs auto-saves any buffers that need it.
Note: Actually, the specified timeout is multiplied by a factor depending on the size of the current buffer.
This normal hook is run whenever an auto-save is about to happen.
If this variable is non-nil
, buffers that are visiting files
have auto-saving enabled by default. Otherwise, they do not.
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.
Normally, if any buffers are auto-saved, a message that says
‘Auto-saving...’ is displayed in the echo area while auto-saving is
going on. However, if no-message is non-nil
, the message
is inhibited.
If current-only is non-nil
, only the current buffer
is auto-saved.
This function deletes the current buffer’s auto-save file if
delete-auto-save-files
is non-nil
. It is called every
time a buffer is saved.
This variable is used by the function
delete-auto-save-file-if-necessary
. If it is non-nil
,
Emacs deletes auto-save files when a true save is done (in the visited
file). This saves disk space and unclutters your directory.
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 the visited file name has not changed, this function does nothing.
The value of this buffer-local variable is the length of the current buffer as of the last time it was 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 -1, that means auto-saving is temporarily shut off in this buffer due to a substantial deletion. Explicitly saving the buffer stores a positive value in this variable, thus reenabling auto-saving. Turning auto-save mode off or on also alters this variable.
This variable (if non-nil
) specifies a file for recording the
names of all the auto-save files. Each time SXEmacs 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.
If SXEmacs exits normally, it deletes this file. If SXEmacs crashes, you
can look in the file to find all the auto-save files that might contain
work that was otherwise lost. The recover-session
command uses
these files.
The default name for this file is in your home directory and starts with ‘.saves-’. It also contains the SXEmacs process ID and the host name.
Next: Reverting, Previous: Backup Files, Up: Backups and Auto-Saving [Contents][Index]