Well, this doesn't answer your *specific* question, but I agree with Bitt and his comments about Linux. So, my answer is to not try to start with Linux at all. If you can run a real UNIX machine, you can run a Linux machine (the differences are relatively minor as far as configuration is concerned).

The BSD distros are "real UNIX". I really like OpenBSD, but others really like NetBSD. The cool thing about OpenBSD is their "secure by default" mentality, which is good for beginners IMHO. OpenBSD does not enable very many services by default and you need to manually turn them on if you want to run them. That's good, because you learn how to configure them and you learn how they are started, etc. You will also learn about ssh and some about crytography, since OpenSSH is built in to their system. In today's world, I think that learning about an operating system should *always* include learning about how to secure the operating system.

The obvious advantage of Linux is the tremendous HOWTO resources, which are great and tend to be written for command line & config file editing systems administration.

Keep in mind that you don't *need* to use the widgets with Linux. You can still manually edit all of the files. That's what I do with one of my machines that still runs Linux.

If you've never done anything with Linux/UNIX but you know about computers, the biggest initial learning curve will probably be learning the text editor. Editor of choice is a topic of religious fervor for many, but one thing is certain: vi can be found on *any* UNIX or Linux system. Its actually a powerful editor once you learn it and it has the advantage that you will be able to use it anywhere. Other editors might be great, but what do you do when you're on a system that doesn't have them installed? It sure is a hassle to install an editor just to modify a line or two. Learn vi. There are good online tutorials for it.

FWIW,
Jim