00281nam a2200109 a 450000500170000002000150001708200180003210000210005024500400007126000350011130000250014620251203110625.0  a8120305167  a005.282UbBAC  aBach, Maurice J.  aDesign of the Unix Operating System  aDelhibPearson Educationc1990  axiv,471p.c24 cm. PB