in reply to pass ARGV to STDIN

Maybe I'm misunderstanding what you want to do, but the situation is that the child will already have a copy of @ARGV (as it was at the time of the fork), so there's not really a need to pass it... This is a one-time thing, though. In case you'd need to pass further info after the fork, you'd have to use regular IPC mechanisms, as the child is a separate process then.