This guide assumes that you use Ubuntu or Debian-based GNU/Linux distro. There are two ways to change timezone from bash command line.
sudo dpkg-reconfigure tzdata
or,
sudo ln -sf /usr/share/zoneinfo/Asia/Kuala_Lumpur /etc/localtime
You can also specify other timezone in the second method, for example:
sudo ln -sf /usr/share/zoneinfo/GMT /etc/localtime
or for Eastern Standard Time (US)
sudo ln -sf /usr/share/zoneinfo/EST /etc/localtime
This command is handy when administrating multiple servers across different continents.