[brudgers]

In the long run, I've learned the most important things from just using Linux, but I used books when starting and occasionally now.

For me, it was Linux in a Nutshell (942 pages in the current edition) because I wanted a reference made of paper instead of pixels.

Later for deep background, Design of the Linux Operating System https://archive.org/details/DesignUNIXOperatingSystem but I picked up an used print copy for <$10.

Those were the best books for me. You are not me. Good luck.