23.3.1 Commands for Saving Files
These are the commands that relate to saving and writing files.
- C-x C-s
- Save the current buffer in its visited file on disk (
- C-x s
- Save any or all buffers in their visited files (
- Forget that the current buffer has been changed (
With prefix argument (C-u), mark the current buffer as changed.
- C-x C-w
- Save the current buffer as a specified file name (
- M-x set-visited-file-name
- Change the file name under which the current buffer will be saved.
When you wish to save the file and make your changes permanent, type
C-x C-s (
save-buffer). After saving is finished, C-x C-s
displays a message like this:
If the selected buffer is not modified (no changes have been made in it
since the buffer was created or last saved), saving is not really done,
because it would have no effect. Instead, C-x C-s displays a message
like this in the echo area:
(No changes need to be saved)
The command C-x s (
save-some-buffers) offers to save any
or all modified buffers. It asks you what to do with each buffer. The
possible responses are analogous to those of
- Save this buffer and ask about the rest of the buffers.
- Don't save this buffer, but ask about the rest of the buffers.
- Save this buffer and all the rest with no more questions.
save-some-buffers without any more saving.
- Save this buffer, then exit
save-some-buffers without even asking
about other buffers.
- View the buffer that you are currently being asked about. When you exit
View mode, you get back to
save-some-buffers, which asks the
- Diff the buffer against its corresponding file, so you can see
what changes you would be saving.
- Display a help message about these options.
C-x C-c, the key sequence to exit Emacs, invokes
save-some-buffers and therefore asks the same questions.
If you have changed a buffer but you do not want to save the changes,
you should take some action to prevent it. Otherwise, each time you use
C-x s or C-x C-c, you are liable to save this buffer by
mistake. One thing you can do is type M-~ (
which clears out the indication that the buffer is modified. If you do
this, none of the save commands will believe that the buffer needs to be
saved. (‘~’ is often used as a mathematical symbol for `not'; thus
M-~ is `not', metafied.) You could also use
set-visited-file-name (see below) to mark the buffer as visiting
a different file name, one which is not in use for anything important.
Alternatively, you can cancel all the changes made since the file was
visited or saved, by reading the text from the file again. This is
called reverting. See Reverting. You could also undo all the
changes by repeating the undo command C-x u until you have undone
all the changes; but reverting is easier.
M-x set-visited-file-name alters the name of the file that the
current buffer is visiting. It reads the new file name using the
minibuffer. Then it marks the buffer as visiting that file name, and
changes the buffer name correspondingly.
does not save the buffer in the newly visited file; it just alters the
records inside Emacs in case you do save later. It also marks the
buffer as “modified” so that C-x C-s in that buffer
If you wish to mark the buffer as visiting a different file and save it
right away, use C-x C-w (
write-file). It is
set-visited-file-name followed by C-x C-s
(except that C-x C-w asks for confirmation if the file exists).
C-x C-s used on a buffer that is not visiting a file has the
same effect as C-x C-w; that is, it reads a file name, marks the
buffer as visiting that file, and saves it there. The default file name in
a buffer that is not visiting a file is made by combining the buffer name
with the buffer's default directory (see File Names).
If the new file name implies a major mode, then C-x C-w switches
to that major mode, in most cases. The command
set-visited-file-name also does this. See Choosing Modes.
If Emacs is about to save a file and sees that the date of the latest
version on disk does not match what Emacs last read or wrote, Emacs
notifies you of this fact, because it probably indicates a problem caused
by simultaneous editing and requires your immediate attention.
See Simultaneous Editing.