Solve exercises by writing Bash one-liners. The server actually runs your commands and checks whether the output is correct.
If you click on View Solutions, the correct commands other people entered are sorted by character count. So if you want, you can take the optional code golfing challenge.
I gained some knowledge from solving the challenges and looking at the solutions. Mostly you will use
From Wikipedia, the free encyclopedia
Linux is a family of open source Unix-like operating systems based on the Linux kernel, an operating system kernel first released on September 17, 1991 by Linus Torvalds. Linux is typically packaged in a Linux distribution (or distro for short).
Distributions include the Linux kernel and supporting system software and libraries, many of which are provided by the GNU Project. Many Linux distributions use the word “Linux” in their name, but the Free Software Foundation uses the name GNU/Linux to emphasize the importance of GNU software, causing some controversy.