In this Chapter, you discovered a little bit about how to use the Mac OS X Unix underpinnings, known as Darwin, as well as a little history about Unix in general. You saw how to use the Terminal application, modify your Unix shell environment, enter commands in the shell, switch from one shell to another, and write shell scripts. You also saw that we barely touch the surface of this complex subject, and we’ve given you some pointers to learn more if you’re interested.