Re: [BUG] [C-u C-u C-c C-o] open link with external program invalid to open file

[Christopher Miles <numbchild@gmail.com>]

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Maxim, thanks for your detailed explanation.

I confirmed the problem:

#+begin_src emacs-lisp
;;; does not work
(start-process-shell-command "xdg-open" nil "xdg-open /usr/share/icons/gnome/256x256/actions/stock_print.png")

;;; works fine
(start-process-shell-command "feh" nil "feh /usr/share/icons/gnome/256x256/actions/stock_print.png")
#+end_src

For this problem, do you have any workable solution patch?

Here is my =/etc/mailcap=, don't have =~/.mailcap=.

#+begin_src conf
### 
### Begin Red Hat Mailcap
###

audio/*; /usr/bin/xdg-open %s

image/*; /usr/bin/xdg-open %s

application/msword; /usr/bin/xdg-open %s
application/pdf; /usr/bin/xdg-open %s
application/postscript ; /usr/bin/xdg-open %s

text/html; /usr/bin/xdg-open %s ; copiousoutput
#+end_src

Maxim Nikulin <manikulin@gmail.com> writes:

> On 05/09/2020 14:52, Bastien wrote:
>> 
>> stardiviner <numbchild@gmail.com> writes:
>> 
>>> When I press =[C-u C-u C-c C-o]= to open an image file link with system external
>>> program. It can't open the image file.
>> 
>> I cannot reproduce the problem here.
>> 
>> If you still have this issue, can you provide a minimal reproducible
>> example?
>
> Christopher Miles recently posted a link to askubuntu that shed some 
> light on the problem.
>
> I have compared the following commands:
>
> (start-process-shell-command "xdg-open" nil "xdg-open 
> /usr/share/icons/gnome/256x256/actions/stock_print.png")
> (start-process-shell-command "eog" nil "eog 
> /usr/share/icons/gnome/256x256/actions/stock_print.png")
>
> The latter works in my (test) case (Ubuntu-20.04, ubuntu session - 
> gnome), the former does not. If I do not mistake, 
> start-process-shell-command is what org mode uses to open file.
>
> Meaningful lines from strace of the emacs process
>
> 24108 21:39:51 execve("/bin/bash", ["/bin/bash", "-c", "xdg-open 
> /usr/share/icons/gnome/"...], 0x7ffcb1c1fdb0 /* 55 vars */ <unfinished...>
> 24116 21:39:51 execve("/usr/bin/eog", ["eog", 
> "/usr/share/icons/gnome/256x256/a"...], 0x55d009672ec8 /* 57 vars */ 
> <unfinished ...>
> 24108 21:39:51 +++ exited with 0 +++
> 24116 21:39:51 +++ killed by SIGHUP +++
>
> I think, the problem is that start-process-shell-command creates a "pty" 
> process. As soon as main command exits, all children, that belong to the 
> same terminal session created by emacs for the process, got killed.
>
> Calling eog directly works because of it does not attempt to go to 
> background or demonize.
>
> The solution could be (make-process :connection-type 'pipe ...). 
> Personally I would prefer to avoid shell as well when it is not really 
> necessary.
>
> I am surprised that in the discussion of problem related to desktop 
> integration and perhaps even order in which applications able to handle 
> particular file format were installed, nobody mentioned such details, 
> neither for "positive" nor for "negative" results. Probably output of 
> the following commands (for the proper mime type) could be relevant. The 
> complication is that there are several mime handler "databases".
>
> grep image/png /etc/mailcap ~/.mailcap
> xdg-mime query default image/png
>
> (mailcap-parse-mailcaps)
> (mailcap-mime-info "image/png")
>
> For some handlers there might be even a race, sometimes it might work 
> but might fail as well, depending if child could send a message to its 
> server quickly enough. In such case providing of ECM might be a challenge.


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[ stardiviner ]
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