Well suited to medium-scale general purpose computing, the Unix time- sharing operating system is deservedly popular with academic institutions, research laboratories, and commercial establishments alike. Its user com- munity, which until recently was made up mostly of experienced computer professionals, is now attracting many people concerned with computer applications rather than systems. Such people are mainly interested in putting Unix software to work effectively, hence need a good knowledge of its external characteristics but not of its internal structure. The present book is intended for this new audience, people who have never encountered the Unix system before but who do have some acquaintance with computing. While helping the beginning user get started is a primary aim of this book, it is also intended to serve as a handy reference subsequently. However, it is not intended to replace the definitive Unix system documen- tation. The Unix operating system as it now exists at most installations (popularly, though somewhat inaccurately, called Version 7 Unix) is sub- stantially as described by the Seventh Edition of the system manuals. This book emphasizes Version 7 and systems closely related to it, but it does also describe some other facilities in wide use. Many people have been instrumental in shaping this book and the author wishes to express his gratitude to them all. Particular thanks are due to David Lowther, for our many helpful discussions; and to the many students whose suggestions enlivened the task.
