Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Multiple Programs in One UNIX Process



Don E. Libes


A small operating system (XINU) was ported to UNIX 4.2BSD. The entire operating system runs as a single UNIX process. The code is approximately 1000 lines of C (including comments) and 6 lines of assembler. All of the code is user-level, and thus presents a system easy to examine, understand, and experiment with further. The code has been used as a base for an application of several cooperating processes communicating through global variables. Alternatively, the system provides semaphores and messages for Interprocess communication.
Proceedings Title
Proceedings of the 1987 Summer USENIX Conference


XINU, UNIX, program, code, system


Libes, D. (1987), Multiple Programs in One UNIX Process, Proceedings of the 1987 Summer USENIX Conference, [online], (Accessed June 16, 2024)


If you have any questions about this publication or are having problems accessing it, please contact

Created September 1, 1987, Updated February 17, 2017