Trigger on file change

[Guy Van Sanden]

I need to have a script run everytime a file changes.
The file only changes once every month (tops), but the script needs to
be run rather fast after the change (5-10 minutes)

I thought of leaving the script looping, making a checksum / date check
every time and sleeping the rest, but it seems like a lot of overhead
(disk access).

Does anyone know of a utility that can do this, possibly one that can
monitor filehandlers in the kernel?

Thanks

Guy