The UNIX system: The evolution of the UNIX time-sharing system

This paper presents a brief history of the early development of the UNIX™ operating system. It concentrates on the evolution of the file system, the process-control mechanism, and the idea of pipelined commands. Some attention is paid to social conditions during the development of the system. This paper is reprinted from Lecture Notes on Computer Science, No. 79, Language Design and Programming Methodology, Springer-Verlag, 1980. During the past few years, the UNIX operating system has come into wide use, so wide that its very name has become a trademark of Bell Laboratories. Its important characteristics have become known to many people. It has suffered much rewriting and tinkering since the first publication describing it in 1974,1 but few fundamental changes. However, UNIX was born in 1969 not 1974, and the account of its development makes a little-known and perhaps instructive story. This paper presents a technical and social history of the evolution of the system.