What is BSD?

In the middle 1970s, around the time Version 6 was released, AT&T began to license its Unix operating system. At little or no cost, individuals and organizations could obtain the C source code. When the University of California at Berkeley received the source code, Unix co-creator Ken Thompson was there as visiting faculty. With his help, researchers and students, notably Sun co-founder Bill Joy, improved the code and developed the Berkeley Software Distribution (BSD). Funded by a grant from DARPA, the Berkeley Computer Systems Research Group (CSRG) was the most important source of Unix development outside of Bell Labs. Along with AT&T's own System V, BSD became one of the two major Unix flavors.

Compared to System V, BSD was more experimental and innovative. It was favored more by academic and research institutions than commercial enterprises, but strongly influenced the entire Unix world. Unix mainstays such as the C-shell, vi, TCP/IP, and virtual memory all made their first appearances in BSD releases. Sun Microsystem's SunOS was a direct descendant of BSD 4.2, and System V was rewritten in its fourth release to incorporate many BSD features. Many Unix systems are descended from System V release 4 (SVR4), implying a significant, but indirect, BSD influence.

The last version of BSD to come from Berkeley was BSD 4.4, released in 1993. Most BSD systems today are based on BSD 4.4-lite, which is unencumbered by copyright-protected AT&T code. Three of these are freeware operating systems available primarily for IBM-compatible PCs:

• FreeBSD http://www.freebsd.org/
• NetBSD http://www.netbsd.org/
• OpenBSD http://www.openbsd.org/ FreeBSD, NetBSD, and OpenBSD are also available for a number of other non-x86 architectures.

Another prominent BSD-derived operating system is Darwin, which forms the basis of Mac OS X.

For forums about various aspects and implementations of BSD, consult the newsgroups in the comp.unix.bsd.* hierarchy.

At Indiana University, to get support for personal or departmental Linux or Unix systems, see At IU, how do I get support for Linux or Unix?

Also see:

• In Unix, how can I display information about the operating system?
• About Linux
• Where can I learn about the history of Unix?
• What is Unix?
• What are SunOS and Solaris?