Post UNIX Operating System
Plan 9 is a research system developed at Bell Labs born in the late ’80s. There are different forks and versions of Plan 9, but the most documented ones are Plan 9 from Bell Labs, the fourth edition of Plan 9 released by Bell Labs, and 9front, a fork with an ongoing effort to maintain the code and to add features. Most of this document’s content will focus on 9front, not everything will apply to Plan 9 from Bell Labs.
Thanks to Pavina for her take on Glenda.