I want to be able to run (just) a program/few programs under a test user named "test" and at the same time benefit of the GUI of the program. I need this because I want to be able to save test settings without conflicting with my own settings. What I found so far is that I can either:

  • use su test to switch to the user, but then I can not run programs with GUI... they complain about not having a display:

    No protocol specified

    ** (gedit:17086): WARNING **: Could not open X display No protocol specified

    (gedit:17086): Gtk-WARNING **: cannot open display: :0

  • use the dm-tool switch-to-user test to actually switch over to that user

Any Idea how I can run programs as another user without having to change users and desktops each time?

  • 1
    Google and read about X authorization (xauth, .Xauthority). IIRC Gnome or rather gdm botched this at some stage by hardlinking the MIT "cookies", but I don't remember details. So you may have to look closely.
    – dirkt
    Commented Nov 3, 2016 at 16:43
  • Please write up your solution and answer your own question, so others with the same problem can profit from your work.
    – dirkt
    Commented Nov 4, 2016 at 11:46

2 Answers 2


I finally found a solution as provided in this answer

All I had to do was run the following command as root:

xhost si:localuser:test

Apparently this command allows the user to use the display server.

Please edit this answer if you know more about this issue.

xhost +localhost

then su test ..

  • I tried it.. it does not work... I get the same error when running gedit
    – dasj19
    Commented Nov 3, 2016 at 14:08

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