Most of the users have been getting Could not execute auto check for display colors using command /usr/bin/xdpyinfo. Check if the DISPLAY variable is set in Linux environment while checking requirement the oracle installations on Linux 5.2 or later versions. I have tried plenty of options but finally, i have fixed this issue through one Linux commands. The error screenshot desc belows
Steps to resolve this issue:
1) login into root user( su -l root)
2) execute this command : xhost +SI:localuser:oracle
3) login to the oracle user
4) execute ./runInstaller
Now, its working fine.