$ mv /etc/localtime /etc/localtime.Old && ln -s /usr/share/zoneinfo/PST8PDT /etc/localtime

Other commands:

Change Time zone to IST:

$ mv /etc/localtime /etc/localtime.Old && ln -s /usr/share/zoneinfo/Asia/Calcutta /etc/localtime

Set the TZ environment variable for quick display time according to preferred Time Zone:

$ export TZ=America/Los_Angeles
$ date

If you have the utility rdate, update the current system time by executing

$ rdate -s pool.ntp.org

You can execute ‘system-config-date’ for setting up date/time and time zone

$ system-config-date

If you’re using Ubuntu, tzconfig is there for you:

$ tzconfig

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