How can I find changes before saving a file?

How can I find changes before saving a file?

[PL]

If I have edited a file and want to see what changes I have made, how
can I do that? I can of course use "Ctrl-x u" to undo the changes
one-by-one, but that's not really what I want to do. Then I would have
to re-do the un-doings to get the file back...

Another way is to copy the file on disk, save the file, and compare
with the copy. But that means I have to save the file. I want to be
able to find the edits *before* I save.

Any ideas, anyone?

Rgds
Peter

Re: How can I find changes before saving a file?

[Unknown]

PL wrote:

> If I have edited a file and want to see what changes I have made, how
> can I do that? I can of course use "Ctrl-x u" to undo the changes
> one-by-one, but that's not really what I want to do. Then I would have
> to re-do the un-doings to get the file back...
> 
> Another way is to copy the file on disk, save the file, and compare
> with the copy. But that means I have to save the file. I want to be
> able to find the edits *before* I save.
> 
> Any ideas, anyone?

Look into highlight-changes-mode.  I don't see a reason why this can't be done 
using the undo information, though.  That sounds smarter and more efficient 
to me.

--
Le

Re: How can I find changes before saving a file?

[Kai Großjohann]

deleteallspam@yahoo.com (PL) writes:

> If I have edited a file and want to see what changes I have made, how
> can I do that?

You could compare the file with its backup.  But that only works
after saving, of course.  (Why do you want to do it before saving?)

-- 
A turnip curses Elvis

Re: How can I find changes before saving a file?

[Roland Winkler]

kai.grossjohann@uni-duisburg.de (Kai Großjohann) writes:

> > If I have edited a file and want to see what changes I have made, how
> > can I do that?
> 
> You could compare the file with its backup.  But that only works
> after saving, of course.

You could temporarily rename the modified buffer, load the file once
more into emacs and start an ediff session.

Re: How can I find changes before saving a file?

[Ehud Karni]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On 12 Feb 2003 15:14:12 +0100, Roland Winkler <Roland.Winkler@physik.uni-erlangen.de> wrote:
>
> kai.grossjohann@uni-duisburg.de (Kai Großjohann) writes:
>
> > > If I have edited a file and want to see what changes I have made, how
> > > can I do that?
> >
> > You could compare the file with its backup.  But that only works
> > after saving, of course.
>
> You could temporarily rename the modified buffer, load the file once
> more into emacs and start an ediff session.

I think renaming the buffer wouldn't do, Emacs still remembers the DISK
file name (even after renaming), visiting the file again will go back
to the same buffer.

You could do M-x shell-command cat <file-name> and compare the
current buffer with "*Shell Command Output*".

Ehud.


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Re: How can I find changes before saving a file?

[John Paul Wallington]

Ehud Karni wrote:

> > > > If I have edited a file and want to see what changes I have
> > > > made, how can I do that?
> > > 
> > > You could compare the file with its backup.  But that only works
> > > after saving, of course.
> > 
> > You could temporarily rename the modified buffer, load the file
> > once more into emacs and start an ediff session.
[...]  
>  You could do M-x shell-command cat <file-name> and compare the
>  current buffer with "*Shell Command Output*".

You could use the command `diff-buffer-with-file' from Emacs CVS HEAD.
There is `ibuffer-diff-with-file' in the Ibuffer package too.

Re: How can I find changes before saving a file?

[PL]

Thanks, that's pretty much what I was looking for! 

I seem to have too old emacs version (20.4.*) so M-x compare-windows
does not work (at least it doesn't for me). One should have 20.6 and
later according to other postings.

But "Tools->Compare->Two Buffers" does the job just fine!

Rgds
Peter

"Ehud Karni" <ehud@unix.mvs.co.il> wrote in message news:<mailman.1868.1045061850.21513.help-gnu-emacs@gnu.org>...
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
> 
> I think renaming the buffer wouldn't do, Emacs still remembers the DISK
> file name (even after renaming), visiting the file again will go back
> to the same buffer.
> 
> You could do M-x shell-command cat <file-name> and compare the
> current buffer with "*Shell Command Output*".
> 
> Ehud.
>