From the preface: "My work has depended on the generosity of free software authors. I wrote the book in LATEX 2ε. Three cheers for Donald Knuth and Leslie Lamp

From the preface: "My work has depended on the generosity of free software authors. I wrote the book in LATEX 2ε. Three cheers for Donald Knuth and Leslie Lamport! Our computers run the GNU/Linux operating system. I use emacs, perl, and gnuplot every day. Thank you Richard Stallman, thank you Linus Torvalds, thank you everyone"