Amazing that UNIX and now Linux has stood the test of time for so long. The Creation of the Unix* Operating System:
After three decades of use, the UNIX* computer operating system from Bell Labs is still regarded as one of the most powerful, versatile, and flexible operating systems (OS) in the computer world. Its popularity is due to many factors, including its ability to run a wide variety of machines, from micros to supercomputers, and its portability -- all of which led to its adoption by many manufacturers.
The system also fostered a distinctive approach to software design -- solving a problem by interconnecting simpler tools, rather than creating large monolithic application programs.
Its development and evolution led to a new philosophy of computing, and it has been a never-ending source of both challenges and joy to programmers around the world.