Jan-Piet Mens reminded me of Unix Text Processing, by Dale Dougherty and Tim O’Reilly of wood-cut animal fame. I’ve had the PDF of this book in my home directory for almost as long as I can remember, alongside the Camel Book and many of Michael W Lucas’s Mastery tomes.
I forgot that it’s available under a Creative Commons licence to download! You owe it to yourself to get a copy. The introducion to Unix alone is worth it.