My take is that plan 9 is basically a "pure" rewrite of a unix/posix OS, that takes many underlying principles of unix to their logical conclusions, without the taint of the incremental evolution of the existing systems, yet nevertheless informed by the lessons learned operating real OS systems. The incompatibility is why it hasn't moved forward, though many of the good ideas that are compatible with systems like bsd/linux have since been ported over.
It is really useful exercise to consider, in hindsight, how could we have built a better unix? And a bunch of really smart people participated and came up with some great ideas.
My take is that plan 9 is basically a "pure" rewrite of a unix/posix OS, that takes many underlying principles of unix to their logical conclusions, without the taint of the incremental evolution of the existing systems, yet nevertheless informed by the lessons learned operating real OS systems. The incompatibility is why it hasn't moved forward, though many of the good ideas that are compatible with systems like bsd/linux have since been ported over.
It is really useful exercise to consider, in hindsight, how could we have built a better unix? And a bunch of really smart people participated and came up with some great ideas.