Beej: thanks a million ! I learnt all about sockets and select() from your guide back at uni over 20 years ago. I was trying to make an autonomous model helicopter for my 3rd year project, fuel oil powered, with a scarily large rotor diameter… so I made this single threaded emergency stop daemon that listened to a few sockets, including the big red button, which would interrupt the test joystick data and write out some engine-off and neutral collective pitch commands instead.

And yes, it worked in a real emergency ! the heli didn’t have any rotors afterwards but we still had our heads.

So I guess you maybe saved my life ?