I have a rather simplistic understanding of file permissions on *nix systems. I understand that there is a file owner and file group, but is there a hard and fast rule on whether the said file owner must belong to the file group also? Or put another way, can a file belong to a group that the owner is not a part of?
If so (or if not), why? I'd like to increase my understanding... I can't seem to find anything that specifically talks about this out on the interwebs... I'm also open to some good reading material on the subject.