Replace current buffer text with the text of the visited file on disk.
This undoes all changes since the file was visited or saved.
With a prefix argument, offer to revert from latest auto-save file, if
that is more recent than the visited file.
This command also implements an interface for special buffers
that contain text which doesn't come from a file, but reflects
some other data instead (e.g. Dired buffers, `buffer-list'
buffers). This is done via the variable `revert-buffer-function'.
In these cases, it should reconstruct the buffer contents from the
When called from Lisp, the first argument is IGNORE-AUTO; only offer
to revert from the auto-save file when this is nil. Note that the
sense of this argument is the reverse of the prefix argument, for the
sake of backward compatibility. IGNORE-AUTO is optional, defaulting
Optional second argument NOCONFIRM means don't ask for confirmation
at all. (The variable `revert-without-query' offers another way to
revert buffers without querying for confirmation.)
Optional third argument PRESERVE-MODES non-nil means don't alter
the files modes. Normally we reinitialize them using `normal-mode'.
This function binds `revert-buffer-in-progress-p' non-nil while it operates.
If the value of `revert-buffer-function' is non-nil, it is called to
do all the work for this command. Otherwise, the hooks
`before-revert-hook' and `after-revert-hook' are run at the beginning
and the end, and if `revert-buffer-insert-file-contents-function' is non-nil, it is called instead of rereading visited file contents.