Thank you for your reply.
Sorry for the late reply.
I decided to follow the steps from the link mentioned in my opening thread which is https://help.ubuntu.com/community/Po...5110UPSin12.04
1. install nut by "apt-get install nut"
However, I was stuck at the point where I need to edit the following file:
gksudo gedit /etc/udev/rules.d/99_nut-serialups.rules
Well, there is no such file as 99_nut-serialups.rules under /etc/udev/rules.d.
I'm not sure if this procedure is designed for a normal Ubuntu desktop 12.04, not for Server 12.04.
Any help would be greatly appreciated.