Problem on installing Oracle product in Linux through GUI

When installing Oracle Database/JDE/Server Manager in Linux GUI mode using Oracle account, the following error occur.

To rectify the issue:

1. login to the Linux console with root account
2. type in DISPLAY=:0.0
3. type in export DISPLAY
4. type in xhost +
5. login to oracle account su - oracle
6. type in DISPLAY=:0.0
7. type in export DISPLAY
8. type xclock and see if the previous said error still appears or not. 
9. if a clock appears that means configuration is done. 
10. You may proceed to install using oracle account in Linux. 

Install GUI in Oracle JD Edwards 9.1.4.4 VM Templates Servers

1.   Issue following command to install the GNOME and X system.

      [root@E1SVR ~]# yum -y groupinstall "X Window System"
      [root@E1SVR ~]# yum -y groupinstall "GONE Desktop Environment"

2.   Reboot server.

3.   Start GUI with the following command

      [root@E1SVR ~]# init 5