APC UPS Battery-Backed Power Supply Monitor for CentOS
The APC Smart-UPS battery-backup devices in the lab support using a daemon, apcupsd, running on CentosOS, which monitors the power-state of the UPS over a USB cable, and if there is a power failure, and the battery is getting close to empty, it will initiate an automatic shutdown. This shutdown won't of course 'save' any open docs you might have, but it will 'cleanly' shutdown the computer, which can prevent the corruption of the hard disk if power to the computer were to otherwise just turn off when the battery drains.
The APC Smart-UPS should be connected to your computer by a USB cable for this functionality to work. Do not use the strange serial port ethernet look-alike cable (toss it in the trash, it's useless).
To install 'apcupsd', sudo access, or the help of nmrhelp, is needed. These are the steps:
BUILD SOURCE
goto: http://www.apcupsd.org/
get source code and build, note that --enable-usb must be included, but that --enable-nis and --enable-gapcmon are optional:
./configure --enable-usb --enable-nis --enable-gapcmon make make install
EDIT CONFIG
edit /etc/apcupsd/apcupsd.conf and set the following fields:
UPSCABLE usb UPSTYPE usb DEVICE
note that 'DEVICE' is empty. you could also optionally set:
UPSNAME TERRIER-APC-UPS
FIRST-TIME START AND CHECK
sudo /etc/rc.d/init.d/apcupsd start /sbin/apcaccess
in the output of apcaccess, make sure 'STATUS' is ONLINE, confirming USB connection.
the start command is only necessary after first-time install. or you can just reboot the system, and just run /sbin/apcaccess to confirm that apcupsd is actually running.
TEST
Open a terminal, then unplug the power cord from the UPS to simulate a power failure. You should see this message on the terminal:
Broadcast message from root@terrier (Thu Apr 16 17:25:25 2015): Power failure on UPS TERRIER-APC-UPS. Running on batteries.
IF YOU SEE THIS MESSAGE, YOU SHOULD IMMEDIATELY SAVE YOUR OPEN DOCS AND SHUTDOWN THE COMPUTER 
The battery will only last a couple minutes and the daemon will shutdown the computer without any warning, so it is important to save stuff right away.
If you plug-in the power cord to the UPS, simulating power restoration, you should see:
Broadcast message from root@terrier (Thu Apr 16 17:24:36 2015): Power has returned on UPS TERRIER-APC-UPS...
GAPCMON
If built with --enable-nis --enable-gapcmon, then 'gapcmon' is a gui application (see http://gapcmon.sourceforge.net/) to get status. Note that you must click 'add' for it to find your UPS to add to the display screen. This same feature could be used to connect to every apcupsd in the lab, if monitoring everyone's power supply was desired.
BIOS
Independent from this UPS thing, you should also configure the BIOS (press F2 on power-up) to set the Power Options to turn on after a power failure. Otherwise, when power is restored, you'd have to manually press the power-on button on your computer.