Live Signal to Running Linux App?

Is there a way to communicate with a running Linux binary from the system - i.e. send a live signal to its process ID with "kill", and have something in the code like "OnReceivedSignal(int signal)" to wake up when it receives it?

Currently the only way I've thought of for another Linux process to communicate something to the app is to have Unity check for a file every second or so that the other process has to create. A bit clunky.

Thanks.