Changing the timezone in linux is done in a weird method. There is no configuration file where you can edit and change timezone. The method is simple and very easy. You need to link to the timezone you need. Find the timezone file you need in /usr/share/zoneinfo/. Go to correct folder and find the place nearest to you( or with the correct timezone). Now link it to the /etc/localtime with the following command example
ln -sf /usr/share/zoneinfo/Asia/Kolkata /etc/localtime
where Asia/Kolkata stands for the timezone I need.
Edit the file “/etc/sysconfig/clock” and edit the ZONE to ‘Asia/Kolkata’
That’s all !!. Verify the same using the command date