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 revert-buffer
command. See section `Reverting a Buffer' in The GNU Emacs Manual.
If the argument check-auto-save is non-nil
, and the
latest auto-save file is more recent than the visited file,
revert-buffer
asks the user whether to use that instead.
Otherwise, it always uses the text of the visited file itself.
Interactively, check-auto-save is set if there is a numeric prefix
argument.
Normally, revert-buffer
asks for confirmation before it changes
the buffer; but if the argument noconfirm is non-nil
,
revert-buffer
does not ask for confirmation.
Reverting tries to preserve marker positions in the buffer by using the
replacement feature of 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; then 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.
You can customize how revert-buffer
does its work by setting
these variables--typically, as buffer-local variables.
nil
, it is called as a function with no arguments to do
the work of reverting. If the value is 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, give this variable a buffer-local value that is a function to regenerate the contents.
nil
, is 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, t
if
the user has asked to read the auto-save file.
revert-buffer
before actually
inserting the modified contents--but only if
revert-buffer-function
is nil
.
Font Lock mode uses this hook to record that the buffer contents are no longer fontified.
revert-buffer
after actually inserting
the modified contents--but only if revert-buffer-function
is
nil
.
Font Lock mode uses this hook to recompute the fonts for the updated buffer contents.
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