Start RHEL 7/ OL 7 in Graphical mode (GUI)

[root@odi12c ~]# yum groupinstall "Server with GUI"

[root@odi12c ~]# systemctl get-default

multi-user.target

[root@odi12c ~]# systemctl set-default graphical.target

Removed symlink /etc/systemd/system/default.target.

Created symlink from /etc/systemd/system/default.target to /usr/lib/systemd/system/graphical.target.

[root@odi12c ~]# systemctl get-default

graphical.target

[root@odi12c ~]# reboot