[NiLuJe]

KOReader goes with the first approach, which has the advantage of not requiring anything new, because your script is already expecting to resume from an rtc wakeup. It may require some fun (not) roundtrips between UTC and local time, though.

As for the second, you can't even listen to event0 without a patch while Nickel is running, and you'd need to be listening *before* the button press comes in. Without thinking too much about it, this would be messy in shell. And, yes, the evtest shipped by default is broke as hell. I ship the real deal in my stuff, and @frostchutz implemented a minimal solution in C for MiniClock.

Be aware that to properly restart Nickel, you have to match its env & PWD. So you'll also also have to handle the env slurping done by KOReader's startup script *before* killing Nickel.