Note: this version of nut has been patched. The original version I used when I first configured NUT waited until the UPS signaled a low battery before shutting down the system. By the time the UPS sent this signal, there was not enough battery left to shut down the system safely. I found a patch on the internet that allows the UPS to fake a low battery signal after running on battery power for X number of seconds.

Note: the version I am running is 44.1, and it works well, and I dont have time to try to upgrade and possibly have to patch the new version. I just use the saved 44.1 source I have in my archives.

unzip the tgz, and change into the source directory

./configure

make

make install

Note: the startup script /etc/rc runs when the system boots. The start of this file is early enough to place a 'running on line power' only check. If the system is running on battery, it can safely signal the UPS to cut power. (nothing has been mounted other than read-only early in this file)

Install a battery check into /etc/rc:

in the file /etc/rc, just above stty status '^T' place the following code:

# =============================================================
# BEFORE DOING ANYTHING, MAKE SURE THE SYSTEM ISN'T BOOTING OFF
# OF UPS BATTERY POWER!
echo "Preventing boot-up from battery power..."
/sbin/mount -a -r -t nonfs
echo "$(/usr/local/ups/bin/genericups -t 2 -b /dev/cuaa1)"
sleep 2
# =============================================================

Restore NUT configuration:

backup and restore /usr/local/ups/etc

chown uucp /var/state/ups