[babel] using tramp when tangling

[babel] using tramp when tangling

[Maurizio Vitale]

I'd find useful to use tramp syntax in the :tangle specification.
In my case it would be to specify sudo when tangling config files that
are supposed to go to areas not writable by the user running Emacs. 
Something like:

#+begin_src sh :tangle /sudo::/etc/my_config_file
...
#+end_src

other people might be interested in remote access to tangle targets.

Is there a way to achieve the above?

If I try to tangle the above, I get something along the lines that
"tramp cannot append to file". Would it be possible to have org-babel to
(optionally) tangle to a buffer and then save to file in one go?

Thanks a lot for the excellent addition to org-mode.

       Maurizio 

Re: [babel] using tramp when tangling

[Rémi Vanicat]

Maurizio Vitale <mav@cuma.i-did-not-set--mail-host-address--so-tickle-me> writes:

> I'd find useful to use tramp syntax in the :tangle specification.
> In my case it would be to specify sudo when tangling config files that
> are supposed to go to areas not writable by the user running Emacs. 
> Something like:
>
> #+begin_src sh :tangle /sudo::/etc/my_config_file
> ...
> #+end_src
>
> other people might be interested in remote access to tangle targets.
>
> Is there a way to achieve the above?
>
> If I try to tangle the above, I get something along the lines that
> "tramp cannot append to file". Would it be possible to have org-babel to
> (optionally) tangle to a buffer and then save to file in one go?

It's a bug of append-file. We could not use it: (code by Alexey Voinov,
stolen from magit):

--8<---------------cut here---------------start------------->8---
diff --git a/contrib/babel/lisp/org-babel-tangle.el b/contrib/babel/lisp/org-babel-tangle.el
index dd76195..c4ea0d8 100644
--- a/contrib/babel/lisp/org-babel-tangle.el
+++ b/contrib/babel/lisp/org-babel-tangle.el
@@ -127,7 +127,12 @@ exported source code blocks by language."
                         (insert (concat she-bang "\n"))
                         (setq she-banged (cons file-name she-banged)))
                       (org-babel-spec-to-string spec)
-                      (append-to-file nil nil file-name))
+		      (let ((content (buffer-string)))
+			(with-temp-buffer
+			  (insert-file-contents file-name)
+			  (goto-char (point-max))
+			  (insert content)
+			  (write-region nil nil ignore-file))))
                     ;; update counter
                     (setq block-counter (+ 1 block-counter))
                     (add-to-list 'path-collector file-name)))))
--8<---------------cut here---------------end--------------->8---


-- 
Rémi Vanicat

Re: [babel] using tramp when tangling

[Dan Davison]

Maurizio Vitale
<mav@cuma.i-did-not-set--mail-host-address--so-tickle-me> writes:

> I'd find useful to use tramp syntax in the :tangle specification.
> In my case it would be to specify sudo when tangling config files that
> are supposed to go to areas not writable by the user running Emacs. 
> Something like:
>
> #+begin_src sh :tangle /sudo::/etc/my_config_file
> ...
> #+end_src
>
> other people might be interested in remote access to tangle targets.
>
> Is there a way to achieve the above?
>
> If I try to tangle the above, I get something along the lines that
> "tramp cannot append to file". Would it be possible to have org-babel to
> (optionally) tangle to a buffer and then save to file in one go?

I would like this to be possible. As you suggest, the change would
involve not using append-to-file; it shouldn't be that hard. I've added
it to the org-babel TODO list, but if you or anyone else would like to
have a go that would be great.

Dan


>
> Thanks a lot for the excellent addition to org-mode.
>
>        Maurizio 
>
>
>
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> Emacs-orgmode@gnu.org
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Re: Re: [babel] using tramp when tangling

[Dan Davison]

vanicat@debian.org (Rémi Vanicat) writes:

> Maurizio Vitale <mav@cuma.i-did-not-set--mail-host-address--so-tickle-me> writes:
>
>> I'd find useful to use tramp syntax in the :tangle specification.
>> In my case it would be to specify sudo when tangling config files that
>> are supposed to go to areas not writable by the user running Emacs. 
>> Something like:
>>
>> #+begin_src sh :tangle /sudo::/etc/my_config_file
>> ...
>> #+end_src
>>
>> other people might be interested in remote access to tangle targets.
>>
>> Is there a way to achieve the above?
>>
>> If I try to tangle the above, I get something along the lines that
>> "tramp cannot append to file". Would it be possible to have org-babel to
>> (optionally) tangle to a buffer and then save to file in one go?
>
> It's a bug of append-file. We could not use it: (code by Alexey Voinov,
> stolen from magit):

Well that was solved quickly. Thanks Rémi, I've applied that with a
couple of minor changes.

Dan

>
> diff --git a/contrib/babel/lisp/org-babel-tangle.el b/contrib/babel/lisp/org-babel-tangle.el
> index dd76195..c4ea0d8 100644
> --- a/contrib/babel/lisp/org-babel-tangle.el
> +++ b/contrib/babel/lisp/org-babel-tangle.el
> @@ -127,7 +127,12 @@ exported source code blocks by language."
>                          (insert (concat she-bang "\n"))
>                          (setq she-banged (cons file-name she-banged)))
>                        (org-babel-spec-to-string spec)
> -                      (append-to-file nil nil file-name))
> +		      (let ((content (buffer-string)))
> +			(with-temp-buffer
> +			  (insert-file-contents file-name)
> +			  (goto-char (point-max))
> +			  (insert content)
> +			  (write-region nil nil ignore-file))))
>                      ;; update counter
>                      (setq block-counter (+ 1 block-counter))
>                      (add-to-list 'path-collector file-name)))))