Looks like the author is just using some apps that happen to run on Unix. I write all my books using vi (not vim!), troff and friends, make, and ghostview (gv)

Looks like the author is just using some apps that happen to run on Unix. I write all my books using vi (not vim!), troff and friends, make, and ghostview (gv) for the layout. Plus a couple of shell/awk/sed scripts for making the TOC, index, etc. I cannot imagine any better tools for the job. I tried LateX, which only got me into trouble, and Lout, which was fun, but too complex in the end. After 20-something books, above turns out to be the sweet spot.