I'm posting this here because OS X is my main unix system, though I also use some linux stuff (synology and a ubuntu virtual machine in my mac). I've dabbled with unix off and on for more than 20 ...
The Art of Unix Programming (TAoUP), by Eric S. Raymond, is not a tutorial or how-to book. Instead, it is a book about the history and philosophy of Unix. But no other book has had a greater influence ...