In any Red Hat based (RHEL/CentOS/Fedora) Server, exchange time zone to PST/PDT quickly:

# mv /etc/localtime /etc/localtime.ancient && ln -s /usr/share/zoneinfo/PST8PDT /etc/localtime

or set zone to IST:

# mv /etc/localtime /etc/localtime.ancient && ln -s /usr/share/zoneinfo/Calcutta /etc/localtime

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

# export TZ=America/Los_Angeles

and then view the productivity of date command.

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

# rdate -s pool.ntp.org

or You can do ’system-config-date’ for setting up date/time and time zone:

# system-config-date

or better install ntp to sync date/time involuntarily from time server:

# yum install ntp

# chkconfig ntpd on

# ntpdate pool.ntp.org

# /etc/init.d/ntpd start

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

# tzconfig

REFERENCES

http://linuxadminzone.com/exchange-timezone-in-your-linux-server-quickly/