The official answer to that question is simple. UNIX® is any operating system descended from that original Bell Labs software developed by Thompson, Ritchie et al in 1969 and bearing a licence ...

Linux is popular in science due to open-source values, free licenses, and compatibility with custom software. The history of ...

As a reminder that this is a perfectly capable platform for the job, here’s the original UNIX running on a vintage DEC PDP7.