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I have a GUI app that I can run from a terminal window on a Raspberry Pi desktop and it displays the GUI output on the screen attached to the HDMI port. In the terminal window I run a command like python myapp.py

If at the same time I am logged in to another computer with an ssh terminal back to the RPi, if I run python myapp.py it fails because it can't connect to the display.

I imagine that it must be possible to do this, and perhaps the python myapp.py needs to be wrapped in a script that supplies appropriate environment variables.

What's the best way to solve this?

  • If your "other computer" runs an X-Windows server (default if using Linux with a GUI) then you can use X-forwarding (-X option in the ssh command). – xenoid Dec 25 '18 at 10:26
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As mentioned in comments, assuming the remote machine is running X Window Server, you can redirect the display to this machine using -X:

From man page:

-X Enables X11 forwarding.

So from remote host:

ssh user@raspberry -X

Then simply run your app:

python myapp.py
  • In response to Kevin... I tried doing 'ssh -X me@RPi as suggested, and then ran the 'python myapp.py' command, but I get an error: pygame.error: Unable to open a console terminal – Padraig H Dec 25 '18 at 17:14
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You need to start an X server on your Raspberry Pi, then just type in DISPLAY=:0 python myapp.py into your SSH session. It should start.

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Success!

Interestingly, it was not necessary to use the -X argument...

From the remote system:

ssh RPi

Then do:

DISPLAY=:0 python myapp.py

Thanks to both responders!

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