While the current Smart-UPS (aka SMT) range of UPS from APC has much fewer variables exposed in a way that is useful for fancy apcupsd usage (you’ll find apcupsd in EPEL), they are still amply sufficient for home use. Basically, the UPS gives an estimated time left at current load and the remaining battery level. At home these are anyway the only two readings I want to trigger scripts on.
The must read Secure dynamic DNS howto has all the steps you need to set up DDNS updates with BIND.
What follows are some very terse notes for RHEL5, highlighting steps not directly obvious from that howto.
In the olden days, one would have to manually calculate to get a file system (FS), in a logical volume (LV) that was part of a volume group (VG) living on a software RAID, properly aligned. I would get this calculation wrong in about 10% of the cases.