ITT: Super Nerd pet peeves:
>thinks the only UNIX systems are Linux and BSD
That's right. Just because it's POSIX compliant doesn't make it unix. The only consumer-grade UNIX OS on the market right now is OSX. BSD is great for hobbyists and servers, but it's far from a consumer-grade OS.
BSD and by extension, OSX, have code herritage, within the kernel leading back to early UNIX. Linux was written from the ground up to be POSIX compliant, which is a fancy way of saying it should be compatible with UNIX stuff, and behaves in a way similar to UNIX, but the code within the Linux kernel (I think no one will argue that's the core of the operating system) has nothing to do with UNIX.
It's more UNIX than Linux is. I didn't say it was a good OS, and I'd never buy an apple product, just that it's UNIX.
I don't see how that's relevent. A shell is just a program running on a computer. FreeBSD and OSX default to tcsh. Linux defaults to bash (usually, depending on the distrobution). It's both possible, and trivial to install either shell on the opposite systems.
A shell is not the operating system.