Having worked in the Microsoft/C#/.NET space for almost ten years prior to my current job, I didn’t work with Linux and Bash all that much. I worked with Linux primarily as a hobby back in college. Of course, when you work in this industry, many skills can transfer over to different tech stacks. However, since my current position is primarily all about working with CentOS Linux and open-source software, I had to take a refresher before doing my interviews and supporting the platforms I’m working with.
For those who want to get their hands dirty a bit with Linux and Bash, I recommend Linux Journey. I had much prior knowledge working with Linux, so this site was more for “fine-tuning” my knowledge a bit, but if you want to gain a useful skill, this is the site to use – and it’s free! Don’t expect to be an expert overnight, but rather think of it as laying the foundation as well as gauging your interest in working with the most popular open-source platform on the planet (remember that Android is built off the Linux kernel).
It’s worth a try and it might be valuable career knowledge later on.