Computers are both my hobby and my profession. I have about 10 of them scattered around my apartment, all running Linux (including my Macs). Since I enjoy upgrading my computers and my computer skills, when I came across Bash it out by Sylvain Leroux, I jumped on the chance to buy it. I use the command line a lot on Debian Linux, and it seemed like a great opportunity to expand my Bash knowledge.
Also:
https://github.com/dylanaraps/pure-sh-bible
https://github.com/dylanaraps/pure-bash-bible