Contents are same as US/UK editions. The reasons for the success of the UNIX system are several. It is written in 'C' which is versatile and effective featuring economy of expression, modern control flow and data structures. The system runs on a range of computers from microprocessors to the large main frames, thus having a strong commercial advantage. The source code is available and written in a high level language making the system easier to adapt to different requirements. It is in short a good operating system for programmers.This text will help better understanding to make use of this system both for new and seasoned user. Here the authors have mostly used real examples rather than artificial ones and all examples have been tested directly from the text which is in machine readable form.