Having fun with Linux!

I've been struggling with my career! It has recently gotten off the ground and I am really learning a lot of good things. I've been in a Help Desk role for about 2 years now and recently have started feeling as if I have mastered the role, for the most part.
This led me to start researching other things to study. What do I want to do with my career? Do I want to go into Networking? Windows administration? I've been studying up on the CCENT cert and reading a book for it, as well as a book for an MCTS cert. It is all interesting to learn, but nothing has really HOOKED me and made me think "This is definitely where I want to go with my career".
Well, I recently picked up this book: http://www.amazon.com/The-Linux-Command-Line-Introduction/dp/1593273894/ref=sr_1_1?ie=UTF8&qid=1406220334&sr=8-1&keywords=linux+command+line
I don't know what it is, but I am about 6 chapters in and really enjoying it. (I bought the Kindle edition but might actually spring for the physical copy, if anyone has one for sale...)
This is my first experience with Unix/Linux stuff. I am really interested in really digging into this stuff, so now I am coming to you guys. Are there any books you would recommend? Is there an ideal certification track after Linux+? I've already set up my main computer to dual-boot to Ubuntu, that is how bad this is. What about getting into entry level Linux positions? I absolutely never hear about Linux in the Windows environments I have been in, but I see all sorts of job openings.
Thanks for the help!
This led me to start researching other things to study. What do I want to do with my career? Do I want to go into Networking? Windows administration? I've been studying up on the CCENT cert and reading a book for it, as well as a book for an MCTS cert. It is all interesting to learn, but nothing has really HOOKED me and made me think "This is definitely where I want to go with my career".
Well, I recently picked up this book: http://www.amazon.com/The-Linux-Command-Line-Introduction/dp/1593273894/ref=sr_1_1?ie=UTF8&qid=1406220334&sr=8-1&keywords=linux+command+line
I don't know what it is, but I am about 6 chapters in and really enjoying it. (I bought the Kindle edition but might actually spring for the physical copy, if anyone has one for sale...)
This is my first experience with Unix/Linux stuff. I am really interested in really digging into this stuff, so now I am coming to you guys. Are there any books you would recommend? Is there an ideal certification track after Linux+? I've already set up my main computer to dual-boot to Ubuntu, that is how bad this is. What about getting into entry level Linux positions? I absolutely never hear about Linux in the Windows environments I have been in, but I see all sorts of job openings.
Thanks for the help!

Comments
https://help.ubuntu.com/14.04/serverguide/index.html
Most jr level positions should be able to perform many (not all) of those tasks and have at least common knowledge of what each topic is. Ubuntu is definitely very user friendly, but make sure you spend as much time on the command line as possible. Very few services/programs in linux are GUI based like they are in the windows world.
CCENT/CCNA is still good to have in a Linux role because the networking concepts apply the same regardless of OS choice.
As always we are here to help with any specific questions or if you get stuck.
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