Daemon 'snups.py' monitors three GPIOs. One of them connected to LBO signal and another to on/off button. Transition from HI to LO on any GPIO initiates shutdown. The third GPIO connected to MAINS +5V power (via zener diode in order to limit voltage to safe +3.3V). Transition on the GPIO leads to sending notification by email.

Shutdown script 'sncutpwr.sh' drives button GPIO low. UPS detects the transition and cuts power in 5 seconds (the time determined by RC network). Usually the script should be run by systemd near to actual halt.