RHEL7 默认是最小化安装（Minimal Install），没有图形界面，
我们应该选择Server with GUI。若已错过此步骤，我们采用以下方式补充安装GUI界面。
# yum group list
Available Environment Groups:
Minimal Install
Compute Node
Infrastructure Server
File and Print Server
Basic Web Server
Virtualization Host
Server with GUI
GNOME Desktop
KDE Plasma Workspaces
Development and Creative Workstation
Available Groups:
Compatibility Libraries
Console Internet Tools
Development Tools
Graphical Administration Tools
Legacy UNIX Compatibility
Scientific Support
Security Tools
Smart Card Support
System Administration Tools
System Management
# yum -y groupinstall "Server with GUI"
原文：http://www.cnblogs.com/edward2013/p/5082653.html