用root 用户可以正常xhost + ,xclock 显示图形化界面，
而oracle 用户图形化提示 no protocol specified
办法是：直接用oracle 用户xshell登录，不要root 切换过去。
Connecting to 192.168.56.131:22...
Connection established.
To escape to local shell,press ‘Ctrl+Alt+]‘.
Connection established.
To escape to local shell,press ‘Ctrl+Alt+]‘.
/usr/bin/xauth: creating new authority file /home/oracle/.Xauthority
[ [email protected] ~]$ xhost +
access control disabled,clients can connect from any host
[ [email protected] ~]$ cd /opt/database/
[ [email protected] database]$ ls
install response rpm runInstaller sshsetup stage welcome.html
[ [email protected] database]$ env|grep DISPLAY
DISPLAY=localhost:10.0
[ [email protected] database]$ xhost + access control disabled,clients can connect from any host
[ [email protected] ~]$ xhost +
access control disabled,clients can connect from any host
[ [email protected] ~]$ cd /opt/database/
[ [email protected] database]$ ls
install response rpm runInstaller sshsetup stage welcome.html
[ [email protected] database]$ env|grep DISPLAY
DISPLAY=localhost:10.0
[ [email protected] database]$ xhost + access control disabled,clients can connect from any host
