OS X is pretty much all BSD userland, because of BSD's more permissive licensing. OS X's bash version is ancient as well; also because of licensing, as far as I

OS X is pretty much all BSD userland, because of BSD's more permissive licensing. OS X's bash version is ancient as well; also because of licensing, as far as I understand. It's not so much that someone would learn exactly the same tools, but that there are more similarities than if they were switching between Windows and Linux.