Developed by the people who devised UNIX i.e. Bell Labs it takes OS development back into the realm of research. While UNIX can be said to be a research tool the OS principles remain largely the same throughout all developments. Plan 9 ( taken from the title of the Worst Film Ever Made, Ed Wood's Plan 9 From Outer Space ) is an attempt to work on the concept of operating system from the ground up, reworking the whole idea using modern concepts and technology.

While Inferno has become the commerical up-shot of Plan 9, the operating system has not become defunct but is instead the Open Source development project that drives Inferno, similar to the relationship between MacOS X and Darwin.

Key features that distinguish Plan 9 from other Unix-like systems include;

  • Rio: Rio is the window system and the first thing you will see when you boot your system.
  • Acme: Acme is an extended UI that is a hybrid of window system, editor and shell, achieving much of the functionality of Emacs and its clones.
  • Plumber: Plumber is the behind-the-scenes combinatorial engine of Plan9. It offers such UNIX functionality as piping and other program flow controls.
  • PQ: A query application for the native "implicit rational database".
  • Troff: A version of the UNIX original, updated for Unicode.
  • Total File Representation: Everything in Plan 9 is represented as a file, unlike UNIX which only partially implements this feature.

Plan 9 can be obtained at