First we have to login in to server as root user and check which timezone currently running on server. Run date command on shell.

roo@host[~]date
Sun Aug 8 06:55:36 GMT 2010

The above result shows that we are currently using GMT time zone. For example we want to change time zone from GMT to BST. Refer following steps to change the timezone.

roo@host[~]ln -sf /usr/share/zoneinfo/BST /etc/localtime
Now run date command again to check the current timezone set for your server.

root@host[#]# date
Sun Aug 8 07:57:29 BST 2010
Note : All timezone files are present in /usr/share/zoneinfo directory, we can use any timezone file as per requirement.