Re: Is `make-process' doing this?

[Eli Zaretskii]

> From: Joost Kremers <address@hidden>
> Date: Sun, 16 Oct 2016 21:02:55 +0200
> 
> Run `emacs -Q', start IELM (for convenience) and type:
> 
> IELM> (start-process "some-process" nil "evince" 
> "~/path/to/some.pdf")
> 
> (Assuming that ~/path/to/some.pdf is an existing pdf file, of 
> course). This brings up an evince window with the error message:
> 
> Unable to open document "file:///home/joost/~/path/to/some.pdf".
> 
> The point is that if I do this from a shell (either some terminal 
> emulator, or even eshell or M-x shell in Emacs), it works fine. 
> So:
> 
> ~ $ evince ~/path/to/some.pdf
> 
> starts evince and opens the file without issue. 

Because the shell expands the tilde.  See the hint from Andreas.

> So I was wondering if it is `make-process' that adds the 
> "file:///home/joost/" part, or if it is evince, and if the latter, 
> if there is something about `make-process' that keeps evince from 
> recognising the argument as an absolute path inspite of the fact 
> that it starts with a tilde.

Neither 'start-process' nor 'make-process' can expand arguments via
'expand-file-name', because they simply don't know which arguments are
file names and which aren't, with the single exception: the program's
executable file name.  So it's up to your code to do that for any
other arguments that you know are file names.