Per process network usage ?

Hi reddit,

I'm looking for a way to get the amount of data transferred by a specific process. The only thing I've found that comes close to this is nethogs, but it doesn't seem to be very accurate, and it's "top-like" (which is not very usable in scripts).

Ideally, I'd like something like

~# magictool -p PID RX bytes: xxxx TX bytes: yyyy 

Does that exists ? Or how would one write such a tool ?

Thanks for any input.