He used troff: "Real Unix books are written using troff and this book follows that time-honored tradition. Camera-ready copy of the book was produced by the au

He used troff: "Real Unix books are written using troff and this book follows that time-honored tradition. Camera-ready copy of the book was produced by the author using the groff package written by James Clark. Many thanks to James Clark for providing this excellent system and for his rapid response to bug fixes. Perhaps someday I will really understand troff footer traps." http://www.troff.org/pubs.html#apue http://www.troff.org/pubs.html#apue