Wikipedia (http://en.wikipedia.org/wiki/Plan_9_from_Bell_Labs http://en.wikipedia.org/wiki/Plan_9_from_Bell_Labs) article is a good start. Most notably the /pro

Wikipedia (http://en.wikipedia.org/wiki/Plan_9_from_Bell_Labs http://en.wikipedia.org/wiki/Plan_9_from_Bell_Labs) article is a good start. Most notably the /proc filesystem which represents the state of kernel was lifted straight from Plan 9 into Linux. As for the success of Plan 9, this quote on wikipedia sums it up - Plan 9 failed simply because it fell short of being a compelling enough improvement on Unix to displace its ancestor. Compared to Plan 9, Unix creaks and clanks and has obvious rust spots, but it gets the job done well enough to hold its position. There is a lesson here for ambitious system architects: the most dangerous enemy of a better solution is an existing codebase that is just good enough.