A regular blog reader asked me for recommendations on books to learn Unix, and which Unix to learn. I still remember asking my "Unix and Solaris Fundamentals" instructor in 1997 to recommend a book on Unix for me. I thought I would share my response here.
I think, as a beginner, you have to decide what you want to learn. I'll try to keep this description generic yet answer the reader's question. The person who asked the question requested an emphasis on the command line, rather than administration using GUIs.
As you might have guessed, I recommend trying FreeBSD. In fact FreeBSD 7.1 was released today. FreeBSD is a great OS for beginners, especially those who want to rely on the command line.
I am reluctant to suggest trying to learn a new OS without a good reference, but luckily a modern and thorough book arrived a little over a year ago. Michael Lucas' book Absolute BSD, 2nd Ed is probably the best pure introductions to Unix administration available. (I mean that of all the books out there, regardless of OS, Michael's book is the best, especially for beginners.)
Four years ago I posted reasons I like FreeBSD, if you want to see my overall thoughts on the OS.
After reading Michael's book, I suggest deploying services by reading Building a Server with FreeBSD 7
by Bryan J. Hong. Brian wrote a cookbook for building various servers on FreeBSD 7.x.
I don't recommend running FreeBSD on the desktop. I prefer my desktop to "just work," and I work in a GUI environment (although I tend to install software via command line anyway). I used to run FreeBSD on my laptop, but now I use Ubuntu. For me, Ubuntu "just works." I don't worry about anything. That's what I want in a more fluid environment like a desktop. PC-BSD is an option on the desktop, but I don't run it.
If you're more inclined to use Linux everywhere, then I suggest Debian on servers and Ubuntu on your desktop. The nice aspect of pairing these two is that Ubuntu is essentially Debian underneath. Ubuntu (or even Debian) is also more likely to be natively supported for many desktop applications, whereas FreeBSD might be a little less supported.
Richard Bejtlich is teaching new classes in DC and Europe in 2009. Register by 1 Jan and 1 Feb, respectively, for the best rates.