[NiLuJe]

Again, if you want to keep your device usable, do not touch powerd and/or the framework.

Apart from that, the loop itself looks sane enough. Just kill the process to stop it (if you didn't stop the framework, that is). (You can do it the ugly way, or do it neatly and create/check a pidfile, through whichever means you prefer [doing it manually, or using start-stop-daemon]).

Might I suggest trying your hand at basic shell stuff on a safer playground than a live, in production semi-closed device like the Kindle? (And learning a bit more about your target device/system without blindly trying stuff?).

As for the last question: nope, we're not here to write stuff for you. In fact, we're pretty much completely against it. Helping people figuring out stuff, sure. Making stuff for fun/personal reasons, yup. Pointing people in the right direction, hell yeah. But just straight-up spoon-feeding? MEEP.