I came here to post that same book!

When I was a kid I wanted to make an IRC chatbot. I didn't know much, but I read online you could use regular expressions to match text commands. I felt like I needed a book, saved up money, and got my mom to drive me to the next town. Our little library didn't have any computer books. I remember her paging through and asking if I really wanted this "technical manual".

Mastering Regular Expressions was the start to my programming career as well. Having references to a bunch of other languages spurred my curiosity to learn them. I eventually bought some of the O'Reilly Perl books as well.