Preface This book follows the earlier authoritative and full-length descriptions of the design and implementation of the 4.3BSD and 4.4BSD versions of the UNIX system developed at the University of California at Berkeley. Since the final Berkeley release in 1994, several groups have continued development of BSD. This book details FreeBSD, the system with the largest set of developers and the most widely distributed releases. Although the FreeBSD distribution includes nearly 1000 utility programs in its base system and nearly 10,000 optional utilities in its ports collection, this book concentrates almost exclusively on the kernel.