:Devil Book: n. "The Design and Implementation of the 4.3BSD
UNIX Operating System", by Samuel J. Leffler, Marshall Kirk
McKusick, Michael J. Karels, and John S. Quarterman (Addison-Wesley
Publishers, 1989, ISBN 0-201-06196-1) --- the standard reference
book on the internals of {BSD} UNIX. So called because the
cover has a picture depicting a little devil (a visual play on
{daemon}) in sneakers, holding a pitchfork (referring to one of
the characteristic features of UNIX, the `fork(2)' system
call).
-- The AI Hackers Dictionary