What you're describing works but probably not for me as you acknowledge. The "PC loses AC while running" part is what I actively try to avoid as part of the greater goal of minimizing risk of damage/data loss. It might be superstitious at this point, modern hardware and filesystems being a bit more resilient, but I feel better not risking it. Since I'm shutting down before the UPS battery dies, and power could restore before it does, there's a real chance power will never be totally lost as far as the motherboard sees it. In that case a boot on AC restoral won't get triggered. Otherwise I agree. It's a lot of work. Or rather a lot of research, RTFM, and understanding before you can even do the a little bit of work to implement it.