In doing RAC Workshop, we use VMware to create a server named “rac1″ and then copy all the files as to another server “rac2″. The two servers are the same just after the copy process, including all the IP setting and hostname. We need to change the 2nd server with different hostname.

Change the hostname on a running machine:

$hostname NEW_NAME

This is active right away and will remain like that until the system will be rebooted. You will most probably need to exit the current shell in order to see the change in your shell prompt.

Change the hostname permanently on Redhat based systems:

$vi /etc/sysconfig/network

edit the new Hostname in this file

Reference:

1. http://www.ducea.com/2006/08/07/how-to-change-the-hostname-of-a-linux-system/

$su – oracle
$env | grep DISPLAY
DISPLAY=:0.0
$xclock
Xlib: connection to “:0.0″ refused by server
Xlib: No protocol specified

Error: Can’t open display: :0.0

The problem is that the local users were not authorized to access control on xhost. To solve this problem, you need to make the authorization using “root”.

[root@localhost]# xhost
access control enabled, only authorized clients can connect
[root@localhost]# xhost +oracle
xhost:   bad hostname “oracle”
[root@localhost]# xhost +local:oracle
non-network local connections being added to access control list
[root@localhost]# su – oracle
[oracle@localhost] $ xclock

xclock successfully started.

Sometimes, there is communication problem between guest Linux server and Windows XP host server. Applications or tools like OEM or DBCA might have problems or appear freezed. Using xhost to show the GUI on Linux server would be much more stable.