For a period of about a year, I used Linux as my primary desktop operating system. Today, I spend much of my time on Mac OSX, which has a very similar underlying structure (both are Unix-based). In addition, I also administrate my own web server, which runs CentOS with cPanel/WHM.
In 2013, I took a course in Unix Programming at the University of Alabama in Huntsville. Throughout the semester, I was introduced to many advanced command line techniques such, including awk, sed, grep, processes, and unix-specific concepts in C++ programming.
In 2015 and 2016, I enrolled in several other relevent courses, including Cloud Computing (which covered OpenStack in detail), Client/Server Architectures, and Network Security.