Plan 9 was developed by Bell Labs as a successor to Unix. Although for various reasons it never quite materialized as such, a fair amount of development still went into Plan 9. My question is, what - if anything - from Plan 9 has made its way into modern Unix?
What aspects of Plan 9 have made their way into Unix?
unix;history;plan9
The clone(2) system call in linux is said to have been modeled after Plan 9's rfork(). (I personally don't see how the timing works out.) This paper claims that Plan 9 inspired the mount/filesystem namespace.The /proc filesystem appears to have come to Plan 9 from 8th Edition Unix, rather than the other way around.