Re: Bug: babel: results switch (output vs. value) has no or wrong effect for sh source block [7.7 (release_7.7.107.g7a82)]

["Sebastien Vauban" <wxhgmqzgwmuf-geNee64TY+gS+FvcfC7Uqw@public.gmane.org>]

Hi András and Eric,

András Major wrote:
>
>> If we did return the value of shell scripts then ":results value" would
>> almost always simply return 0 (or possibly an error message). For this
>> reason shell code blocks do not implement value returns, but rather will
>> always collect results from STDOUT.
>
> I think that this unnecessarily throws away potentially useful
> functionality. Example: I want to fill a table with data such that the value
> of a cell depends on whether a file (whose path is specified by another
> cell, for instance) exists or not. This would be most easily done using an
> sh block which returns a numeric exit code. I don't see a reason for making
> clandestine exceptions to the rules in the manual and strongly suggest that
> the output and value options be honoured for every language.

I must admit that I was not aware of this peculiarity for sh blocks. And I
guess there must be a reason for not honoring value vs output here. If not,
I'd prefer it to exist -- even if Achim showed that both are always possible.

> In order not to break existing Org files, I would suggest that the default
> choice between value and output (when not explicitly specified) depend on
> the language. With this functionality, sh code blocks that don't specify
> ":results output" will still work as they did before.

That possibility already exist. It can be done like this:

#+begin_src emacs-lisp
  (add-to-list 'org-babel-default-header-args:sh '((:results . "value")))
#+end_src

Best regards,
  Seb

-- 
Sebastien Vauban