Can’t Start GUI Programs via Command Line – Wrong DISPLAY Variable

command linedisplay-managerxorg

I am using Ubuntu 18.10 and I cannot launch GUI programs via the command line. This applies to subl (for Sublime Text) and Firefox. When trying to start Firefox via CLI; it prints: Invalid MIT-MAGIC-COOKIE-1 key.

My environment shows:

➜ echo $DISPLAY
:0.0

And I do have a file with that cookie:

➜ echo $XAUTHORITY 
/run/user/1000/gdm/Xauthority
➜ cat /run/user/1000/gdm/Xauthority
voltaireMIT-MAGIC-COOKIE-1OZ��8�ص������v�voltaireMIT-MAGIC-COOKIE-1OZ��8�ص������v%

Also:

➜ xauth list
voltaire/unix:  MIT-MAGIC-COOKIE-1  4f5abfd438eb88d8b586f0fbad8aee76
#ffff#766f6c7461697265#:  MIT-MAGIC-COOKIE-1  4f5abfd438eb88d8b586f0fbad8aee76

It seems that two Xorg processes are running:

➜ ps aux | grep xorg
root      1400  0.0  0.1 213748 48068 tty1     Sl+  09:29   0:00 /usr/lib/xorg/Xorg vt1 -displayfd 3 -auth /run/user/121/gdm/Xauthority -background none -noreset -keeptty -verbose 7 -core
root      4701  1.9  0.5 658612 195732 tty2    Sl+  09:30   1:50 /usr/lib/xorg/Xorg vt2 -displayfd 3 -auth /run/user/1000/gdm/Xauthority -background none -noreset -keeptty -verbose 7 -core

I previously had lightdm installed to fix a login issue, and I have the current NVIDIA graphics drivers installed on my system. I guess this is very much related?

When I run:

DISPLAY=:1 subl

it works!

What could I do to fix this?

Update

I deleted ~/.Xauthority and rebooted, but the problem still remains.

Best Answer

The issue was that DISPLAY was incorrectly set to :0.0 by a shell configuration file. Once I removed that, launching programs from the shell was possible again.

You can use this command to search through all the default shell configuration files:

grep "DISPLAY" ~/.bashrc ~/.profile ~/.bash_profile ~/bash.login \
               ~/.bash_aliases /etc/bash.bashrc /etc/profile \
               /etc/profile.d/* /etc/environment 2> /dev/null

There are indeed two Xorg processes, which is expected behavior, so this should not be an issue in itself.

Also, the .Xauthority file does not seem to be necessary.

Related Question