An OS from the folks that gave us UNIX, Plan 9 is a distributed operating system in which everything is a file, unlike UNIX, where most things are files. Based on the RISC approach to operating systems, Plan 9 doesn't have much in the way of features, but the programmer can always create features. It didn't catch on, and the developers went on to work on Inferno.
The excellent Wily editor in UNIX is a clone of Plan 9's Acme editor.

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

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