A great way to learn the basics. It’ll be old, but that’s ok. It’s going to cover all the shell basics and then more. It’s still going to be useful, it’ll cost you pennies, you’ll be able to dip into it when you want, and you’ll be giving to a good cause.
Find an online guide. Print to PDF or save as HTML/ODF/whatever you like. Annotate the document. Now notes and article are searchable. I guess a physical book might have an advantage if the power went out, but at that point you’re going to have other problems implementing the things the book suggests.
Internet service can go out without the power going out, you know. Not everyone has the good fortune to live in a place with quality infrastructure or multiple choices of ISP.