Saving the Messages buffer

Saving the Messages buffer

[Sivaram Neelakantan]

Is there an option to simply save the messages buffer after certain
number of lines/chars?  I'm running into some strange issues when ntemacs
kicks off openssl in cygwin and I'd like to save the messages buffer
to debug the issue.

Simply saving the buffer to the same named file with overwrite option?

 sivaram
 -- 

Re: Saving the Messages buffer

[Emanuel Berg]

Sivaram Neelakantan <nsivaram.net@gmail.com> writes:

> Is there an option to simply save the messages buffer
> after certain number of lines/chars?  I'm running
> into some strange issues when ntemacs kicks off
> openssl in cygwin and I'd like to save the messages
> buffer to debug the issue.
>
> Simply saving the buffer to the same named file with
> overwrite option?

One way to do it would be to use the auto-save which
Emacs already uses.

;; These are my values (which are probably default) but
;; even if you already have them, and the mode enabled,
;; it might be interesting to see - use `C-x e' with
;; point to the right of the symbol's names to echo
;; their values. (Otherwise just setup as you please.)

(auto-save-mode)              ; enable auto-save
(setq auto-save-interval 300) ; auto-save every 300 keydowns
(setq auto-save-timeout 30)   ; or after 30 seconds of idle

;; whenever so, save the messages buffer
(add-hook 'auto-save-hook
          (lambda ()
            (with-current-buffer "*Messages*"
              (write-file "~/emacs_messages" nil) ))) ; nil: no confirm

-- 
underground experts united:
http://user.it.uu.se/~embe8573

Re: Saving the Messages buffer

[Emanuel Berg]

Aha, so `auto-save-mode' says that auto-save should
apply to the current buffer. So that doesn't make sense
in my previous post, but the hook should still work, as
long as there are buffers "under the influence" all
round, which is likely.

But, using that to solve the problem of the OP, if the
message buffer could be associated with a file, and
then itself subjected to auto-save-mode, that would be
even better. Try:

(let ((buffer "*Messages*"))
  (with-current-buffer buffer
    (set-visited-file-name buffer t) ; no confirmation
    (auto-save-mode) ))

-- 
underground experts united:
http://user.it.uu.se/~embe8573

Re: Saving the Messages buffer

[Kevin Rodgers]

On 1/21/14 3:58 PM, Emanuel Berg wrote:
> Aha, so `auto-save-mode' says that auto-save should
> apply to the current buffer. So that doesn't make sense
> in my previous post, but the hook should still work, as
> long as there are buffers "under the influence" all
> round, which is likely.
>
> But, using that to solve the problem of the OP, if the
> message buffer could be associated with a file, and
> then itself subjected to auto-save-mode, that would be
> even better. Try:
>
> (let ((buffer "*Messages*"))
>    (with-current-buffer buffer
>      (set-visited-file-name buffer t) ; no confirmation
>      (auto-save-mode) ))

The first arg to set-visited-file-name is FILENAME, not BUFFER.

-- 
Kevin Rodgers
Denver, Colorado, USA

Re: Saving the Messages buffer

[Emanuel Berg]

Kevin Rodgers <kevin.d.rodgers@gmail.com> writes:

>> (let ((buffer "*Messages*")) (with-current-buffer
>> buffer (set-visited-file-name buffer t)
>> (auto-save-mode) ))
>
> The first arg to set-visited-file-name is FILENAME,
> not BUFFER.

Yes, but in that piece of code, "buffer" is not a
buffer, but a *string*, which works both to identify
the buffer (in `with-current-buffer') *and* to specify
a path (in `set-visited-file-name').

If you go to the *Messages* buffer, you will see that
its default-directory is the user home path (if that's
form where Emacs is started), so there is where the
file should go.

The reason the filename is the same as the buffer is
that

> Change name of file visited in current buffer to
> FILENAME.  This also renames the buffer to correspond
> to the new file.

-- 
underground experts united:
http://user.it.uu.se/~embe8573

Re: Saving the Messages buffer

[Emanuel Berg]

Sivaram Neelakantan <nsivaram.net@gmail.com> writes:

> Simply saving the buffer to the same named file with
> overwrite option?

If you don't want to use `auto-save-mode', how about
scheduling the save with the Emacs' "collaborative"
(non-preemptive) idle-timer?

The first argument says how many seconds you should be
idle before Emacs fires off the defun. The `t' says
this shouldn't just happens once, but at every such
instance.

But if you are idle all day, and still get changes to
*Messages*, the function will only be run once, because
(what I can see) it waits for non-idleness before it
resets.

(run-with-idle-timer 10 t
 (lambda ()
   (with-current-buffer "*Messages*"
     (write-file "~/emacs_messages" nil) )))

-- 
underground experts united:
http://user.it.uu.se/~embe8573