This feels like pretty low quality tech writing compared to the SRE books from Google. Its scope is all over the shop. Topics covered go all the way from "what is Linux" and the most basic introduction to command-line interfaces (echo "Hello World") to scaling a photo sharing service to 100 million users and 50,000 concurrent users. Each chapter barely scratches the surface of what it covers.
I'm a little surprised LinkedIn published this to be honest. I dunno. I've never worked in a big company before so what do I know?