Plan 9 from Bell Labs

rio, default user interface of Plan 9 from Bell Labs
rio, default user interface of Plan 9 from Bell Labs
Screenshot of Plan 9 installation
Listing processes with list contents of directory (ls, lc) command in /proc
Plan 9 running acme and rc
The wmii X window manager was inspired by acme, a text editor from the Plan 9 project.

Distributed operating system, originating in the Computing Science Research Center at Bell Labs in the mid-1980s, and building on UNIX concepts first developed there in the late 1960s.

- Plan 9 from Bell Labs

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Ken Thompson

American pioneer of computer science.

Thompson (left) with Dennis Ritchie
DEC PDP-7, as used for initial work on Unix
Thompson (sitting) and Ritchie working together at a PDP-11
Version 6 Unix running on the SIMH PDP-11 simulator, with "/usr/ken" still present
Plan 9 from Bell Labs, running the acme text editor, and the rc shell

He also invented the B programming language, the direct predecessor to the C programming language, and was one of the creators and early developers of the Plan 9 operating system.


American multinational telecommunications equipment company headquartered in Murray Hill, New Jersey.

Lucent advert for Inferno in IEEE Internet Computing, Volume 1, Number 2, March–April 1997
Lucent Headquarters

Shortly after the Lucent renaming in 1996, Lucent's Plan 9 project released a development of their work as the Inferno OS in 1997.

Dennis Ritchie

American computer scientist.

Dennis Ritchie at the Japan Prize Foundation in May 2011
Ken Thompson (left) and Dennis Ritchie (right)
Version 7 Unix for the PDP-11, including Dennis Ritchie's home directory:
Dennis Ritchie with Doug McIlroy (left) in May 2011
Ritchie engaged in conversation in a chalet in the mountains surrounding Salt Lake City at the 1984 Usenix conference.
At the same Usenix 1984 conference, Dennis Ritchie is visible in the middle, wearing a striped sweater, behind Steven Bellovin wearing a baseball cap.

Ritchie was also involved with the development of the Plan 9 and Inferno operating systems, and the programming language Limbo.

Rob Pike

Canadian programmer and author.

Rob Pike at OSCON 2010

He is best known for his work on the Go programming language and at Bell Labs, where he was a member of the Unix team and was involved in the creation of the Plan 9 from Bell Labs and Inferno operating systems, as well as the Limbo programming language.

Windowing system

Software that manages separately different parts of display screens.

Typical elements of a window. The window decoration is either drawn by the window manager or by the client. The drawing of the content is the task of the client.
The basic components of a GUI: The display server implements the windowing system. A simple window manager merely draws the window decorations, but compositing window managers do more.
The X.Org Server communicates with its clients, e.g. Amarok, over the X11 protocol
X Window System logo
The Wayland display server protocol
Wayland logo

8½ and rio for Plan 9

Inferno (operating system)

Distributed operating system started at Bell Labs and now developed and maintained by Vita Nuova Holdings as free software under the MIT License.

Inferno 4th Edition
Lucent advertisement for Inferno in IEEE Internet Computing, Volume 1, Number 2, March–April 1997

Inferno was based on the experience gained with Plan 9 from Bell Labs, and the further research of Bell Labs into operating systems, languages, on-the-fly compilers, graphics, security, networking and portability.

Universal Coded Character Set

Standard set of characters defined by the international standard ISO/IEC 10646, Information technology — Universal Coded Character Set (UCS) (plus amendments to that standard), which is the basis of many character encodings, improving as characters from previously unrepresented typing systems are added.

A human computer, with microscope and calculator, 1952

Rob Pike and Ken Thompson, the designers of the Plan 9 operating system, devised a new, fast and well-designed mixed-width encoding, which came to be called UTF-8,


Family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, and others.

Unix System III running on a PDP-11 simulator
Unix System III running on a PDP-11 simulator
Version 7 Unix, the Research Unix ancestor of all modern Unix systems
Ken Thompson (sitting) and Dennis Ritchie working together at a PDP-11
The Common Desktop Environment (CDE), part of the COSE initiative
Ken Thompson and Dennis Ritchie, principal developers of Research Unix
Photo from USENIX 1984, including Dennis Ritchie (center)
Plan 9 from Bell Labs extends Unix design principles and was developed as a successor to Unix.
Promotional license plate by Digital Equipment Corporation
HP9000 workstation running HP-UX, a certified Unix operating system

The Plan 9 operating system pushed this model even further and eliminated the need for additional mechanisms.

Concurrent computing

Form of computing in which several computations are executed concurrently—during overlapping time periods—instead of sequentially—with one completing before the next starts.

Computer simulation, one of the main cross-computing methodologies.

Alef—concurrent, with threads and message passing, for system programming in early versions of Plan 9 from Bell Labs


An rc session

rc (for "run commands") is the command line interpreter for Version 10 Unix and Plan 9 from Bell Labs operating systems.