http://qkpm2ov2rjhjkhfsftskqho77uj5rewd5y44unkf6cb7tdhaxwcvh2id.onion/books/apc/APCUPSD%20User%20Manual.html
Note that
Apcupsd is sensitive to the install location of libusb, so beware if you
change it from the default. Apcupsd should be built using gcc, preferably from the XCode
development tools. Currently the maintainer is using gcc-4.0.1 from
XCode 2.4. Other versions of gcc from other sources may also work. Configure and build Apcupsd normally, as described in Building and
Installing Apcupsd .