How can I learn more about OS X under the hood?

Episode 1321 (1:21:17)

Brian from Fairview, CA
Apple iPad Pro

Brian has the iPad Pro. He is now all Apple and his boss has made him the expert for all things Mac. Leo says that Apple has quite a bit of information online. iTunesU is a great place to start and it's free. He should also look at MacPorts or HomeBrew. Since Brian is a Linux guy, and under the hood OS X is essentially BSD, he'll be right at home.