I can’t seem to find apcupsd (a ups monitor, that shutdowns computers, before you run out of ups power) on Centos 6, surprisingly on Centos 7 this package is available from epel, but not so for Centos 6. Here is a condense howto get the source and compile it. (mainly for my personal use)

wget https://kent.dl.sourceforge.net/project/apcupsd/apcupsd%20-%20Stable/3.14.14/apcupsd-3.14.14.tar.gz
tar xvf apcupsd-3.14.14.tar.gz
cd apcupsd-3.14.14
make install

Then follow settings :

Install APCUPSD on Centos 7