Run the following command as root or using sudo:
# dpkg-reconfigure tzdata
And then select your timezone from the prompts. After that UTC time and local time will be shown as in the following example:
Current default timezone: 'Asia/Singapore' Local time is now: Wed Jun 27 04:55:41 SGT 2012. Universal Time is now: Tue Jun 26 20:55:41 UTC 2012.