DISPLAY variable is set Failed

While executing runInstaller.sh, we may encounter with the issue like below

 [oracle@localhost database]$ ./runInstaller 
Starting Oracle Universal Installer...

Checking Temp space: must be greater than 120 MB.   Actual 60785 MB    Passed
Checking swap space: must be greater than 150 MB.   Actual 6111 MB    Passed
Checking monitor: must be configured to display at least 256 colors
    >>> Could not execute auto check for display colors using command /usr/bin/xdpyinfo. Check if the DISPLAY variable is set.    Failed <<<<

Some requirement checks failed. You must fulfill these requirements before

continuing with the installation,

Continue? (y/n) [n] 


Action Plan:
============

[oracle@localhost ~]$ hostname 
localhost.localdomain
[oracle@localhost ~]$ echo $DISPALY

[oracle@localhost ~]$ export DISPALY=localhost.localdomain:0.0

[oracle@localhost ~]$ exit

=> Close the current terminal and open new terminal and give a try.

If you still face this issue.
===================

connect/switch to server as "oracle" user like below and try again