Unix
UNIX System III running on a PDP-11 simulator
DeveloperKen Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna at Bell Labs
Written inC and assembly language
OS familyUnix
Source modelHistorically proprietary software, while some Unix projects (including BSD family and Illumos) are open-source and historical Unix source code is archived.
Initial releaseDevelopment started in 1969
First manual published internally in November 19711
Announced outside Bell Labs in October 19732
Available inEnglish
Kernel typeVaries; monolithic, microkernel, hybrid
Influenced byCTSS,3 Multics
Default
user interface
Command-line interface and Graphical (Wayland and X Window System; Android SurfaceFlinger; macOS Quartz)
LicenseVaries; some versions are proprietary, others are free/libre or open-source software
Official websitewww.opengroup.org/unix-systems

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Footnotes

  1. McIlroy, M. D. (1987). A Research Unix reader: annotated excerpts from the Programmer’s Manual, 1971–1986 (PDF) (Technical report). CSTR. Bell Labs. 139. Archived (PDF) from the original on 11 November 2017.

  2. Ritchie, D. M.; Thompson, K. (1978). “The UNIX Time-Sharing System” (PDF). The Bell System Technical Journal. 57 (6, part 2) (published July–August 1978). doi:10.1145/361011.361061. S2CID 53235982.

  3. Ritchie, Dennis M. (1977). The Unix Time-sharing System: A retrospective (PDF). Tenth Hawaii International Conference on the System Sciences. Retrieved October 23, 2025. a good case can be made that[UNIX] is in essence a modern implementation of MIT’s CTSS system