00289nam a2200109 a 450000500170000002000150001708200180003210000190005024500350006926000530010430000220015720251203110042.0  a0074630903  a005.432UbDAS  aDas, Sumitabha  aUNIX: concepts and application  aNew DelhibTata McGraw-Hill Publishing Co.c1998  axxv,565p.c23 cm.