Thread: To kill a LED (during shutdown)

During system shutdown, what would be the best was to execute some code after the drives have been unmounted?
The system consists of a x86 system running Debian Linux from a CompactFlash. On the end product there will be no monitor so I need to disable a LED (simple I/O write) to indicate to the user that it is safe to power-down.
My current train of thought is to write a daemon that loads at startup and does the I/O write at exit. But, being a linux noob, I'm not sure how to a) hook the system shutdown to the daemon or b) tie into the exit functionality within the daemon code.
Any suggestions/comments?

Your drives don't all get unmounted. Root gets REMOUNTED as read only. To that end, you'll still have access to everything you'll need. Next, you'll need to look at runlevels 0 and 6 (0 is for HALT and 6 is for reboot). Both of these have an associated /etc/{rc.d,init.d}/ file that executes as the system is going down. You could easily grep inside that directory to find each occurrence of umount or mount -oremount,ro to know where to put your line of bash code that would execute your software.

Code:

THE STUPID CODE TAGS SYSTEM DIDN'T LIKE ME TO USE {} SO I HAD TO PUT THIS IN