1,show time and timezone
ubuntu@ip-172-31-18-250:~$ date
Wed Jun 11 00:53:09 UTC 2014

2,set timezone
ubuntu@ip-172-31-18-250:~$ sudo tzconfig
WARNING: the tzconfig command is deprecated, please use:
dpkg-reconfigure tzdata
ubuntu@ip-172-31-18-250:~$ sudo dpkg-reconfigure tzdata

Current default time zone: ‘Asia/Hong_Kong’
Local time is now: Wed Jun 11 14:25:43 HKT 2014.
Universal Time is now: Wed Jun 11 06:25:43 UTC 2014.

ubuntu@ip-172-31-18-250:~$ date
Wed Jun 11 14:25:47 HKT 2014

3，the last , in case of restart, timezone change again
sudo cp /usr/share/zoneinfo/Asia/Hong_Kong /etc/localtime