Thisbookfollowstheearlierauthoritativeandfull-lengthdescriptionsofthedesignandimplementationofthe4.3BSDand4.4BSDversionsoftheUNIXsystemdevelopedattheUniversityofCaliforniaatBerkeley.SincethefinalBerkeleyreleasein1994,severalgroupshavecontinueddevelopmentof