bug#57854: 29.0.50; Different exit code in Emacs and terminal for identical process

[Eli Zaretskii]

> From: dalanicolai <dalanicolai@gmail.com>
> Date: Sat, 17 Sep 2022 15:37:08 +0200
> Cc: 57854@debbugs.gnu.org
> 
> Indeed, when invoking the command from the shell prompt using /dev/null as 
> input
>  (pdftocio ... < /dev/null), then the command does not return an error (i.e. 
> exit code is 0).
> 
> So, indeed there is a difference between invoking it from Emacs and invoking 
> it from the
> shell prompt (without the /dev/null input). This might not be considered a 
> bug, but it is not
> trivial to me, that using call-process implies sending the null-device as 
> input.
> 
> Is there a way to call a process from elisp, without sending the input?

You could use start-process instead, and then wait for the process to
finish.  It would complicate the Lisp program, though.

> Otherwise, I would
> probably change this into a 'documentation bug' report, in the sense that it 
> would be nice
> if this detail was mentioned in the docs (I think it is not currently).

The doc string of call-process already says that:

 The program’s input comes from file INFILE (nil means ‘null-device’).