Setting DISPLAY environment variable syntax changes with Gnome

Centos8 Gnome DISPLAY is set like this: export DISPLAY=:0

In other words normally for xWindows you do something like this to set your DISPLAY variable prior to running an xApp like:

export DISPLAY=<machine-name>:0.0

With Gnome the syntax is:

export DISPLAY=:0

All other common version of setting display do not work on Gnome.

One other tip – it appears RHEL 8 no longer allows root account to “xhost +” but other accounts can.

See this for more info:

http://www.teamhealthgroup.net/index.php/2021/09/24/xhost-has-changed-with-rhel-8-xhost-many-times-returns-a-cannot-open-display-try-this-instead/

Another version of xhost that appears to work is (but not from root):

xhost +SI:localuser:oracle

xhost +SI:localuser:oracle
localuser:oracle being added to access control list

[oracle@ol8-19 ~]$ xhost
access control disabled, clients can connect from any host
SI:localuser:oracle