It is what it is, trying to define it makes for a good bonfire story but that's about it. Today there are only "Unix-like" and UNIX certified systems left. And

It is what it is, trying to define it makes for a good bonfire story but that's about it. Today there are only "Unix-like" and UNIX certified systems left. And I bet it wouldn't be too hard to certify MS Windows with SFU installed, as a UNIX.