> potentially any interaction with it But that's not what I said. I said programs that do not work without some other program, is, in my opinion, a derivative

> potentially any interaction with it But that's not what I said. I said programs that do not work without some other program, is, in my opinion, a derivative work. I just don't see how the calling mechanism even plays into that judgement. I do agree that there are other licenses such as the AGPL that try to cover these cases. And arguably the online thing is a whole different ball of wax, because you can talk about software using a service, etc. It really is tricky in that case. But I don't see the reason to distinguish between calling a function via the C stdcall mechanism, vs. "popen" and capturing stdout. It's exactly the same, logically, the only difference are details that imho should not matter for the legal case. Right now, if I release a GPL library, what stops someone from coming along and writing a CLI program that just wraps every function with some textual interface, and including that with their closed-source program? The GPL becomes pretty toothless if it's bypassed so easily.