The first chapter is kinda dull for me, as an experienced Linux user. But scrolling through, I quickly came upon sed, which I glanced through and taught me some new things. I won't remember it all, but I'll know what I can use sed for. (I usually only used sed for substitution, with `-i`nline or in a pipe.)

I've always meant to learn more about awk, and ctrl+f'ing for that, indeed, chapter 12 is all about awk. I learned how to select rows based on columns, which I've wanted to do multiple times in the past! E.g. `awk '$2 <= 100' testfile` or `awk '$2 ~ /database/' error.log`.

It's practical in the sense that, if you have a topic you want to learn about and need a good tutorial to get started, this seems like a very good place to start.