http://qkpm2ov2rjhjkhfsftskqho77uj5rewd5y44unkf6cb7tdhaxwcvh2id.onion/books/apc/APCUPSD%20User%20Manual.html
This manual is divided into parts which increase in technical depth
as they go. If you have just bought a state-of-the-art smart UPS
with a USB or Ethernet interface, and you are running a current
version of Red Hat or SUSE Linux, then apcupsd is
very nearly plug-and-play and you will have to read only the Basic
User's Guide .