How to Change System time and timezone in linux ( IST )

1. check current time .
2.change the date and time using below date command.

[root@pgham postgresql-9.3beta2]# date -s "5 Jul 2013 18:18:14"

Fri Jul  5 18:18:14 PDT 2013

3.change the time zone of the computer.

[root@pgham postgresql-9.3beta2]# cd /etc/

[root@pgham etc]# ln -sf /usr/share/zoneinfo/Asia/Calcutta localtime

4. verify date changed or not.

[root@pgham etc]# date

Fri Jul  5 18:22:29 IST 2013

[root@pgham etc]#