- BSD redirects here; for other uses see BSD (disambiguation).
Berkeley Software Distribution (BSD) is the name of the UNIX derivative distributed in the 1970s from the University of California, Berkeley. The name is also used collectively for the modern descendants of these distributions.
AT&T Bell Laboratories permitted Berkeley and other universities to use and extend the source code to their UNIX operating system in its infancy. Berkeley used the software as a research base for investigations into operating system design through the 1970s and 1980s.
Eventually, the systems that Berkeley students had developed for their research had replaced almost every component of the AT&T UNIX system, and in the early 1990s the full Berkeley source code was released to the public under the BSD License. This led to a copyright lawsuit between AT&T and Berkeley, USL v. BSDi, which was settled almost entirely in Berkeley's favor, conclusively establishing BSD's free nature.
While the lawsuit was still pending however, it cast a significant doubt over whether the Berkely distribution would remain free. The case lasted nearly two years, and in this time the Linux kernel was released and proliferated. Linus Torvalds, the initial creator of the widely used Linux kernel, has stated that if there had been a free Unix like operating system that could run on 386 architecture (a 386 port of BSD was underway at the time) he likely would not have created Linux. Although it is debatable exactly what effect that would have had on the software landscape since, there is little doubt that it would have been substantial.
Today BSD is developed as a number of descendent free software projects. It is also used in countless proprietary software products, as permitted by the BSD license. For example, Microsoft used BSD-derived code (acquired from a small Scottish company, Spider) in early implementations of TCP/IP for Windows, some of which may still be in use in later versions.
BSD pioneered many of the advances of modern computing. Berkeley's Unix was the first to include library support for the Internet Protocol stacks, Berkeley sockets. By integrating sockets with the UNIX operating system file descriptors, users of their library found it almost as easy to read and write data across the network, as it was to put data on a disk. The AT&T laboratory eventually released their own STREAMS library, which incorporated much of the same functionality in a software stack with better architectural layers, but the already widely-distributed sockets library, together with the unfortunate omission of a function call for polling a set of open sockets (an equivalent of the select call in the Berkeley library), made it difficult to justify porting applications to the new API.
Like AT&T Unix, the BSD kernel is monolithic, meaning that device drivers in the kernel run in ring 0, the core of the operating system. Early versions of BSD were used to form Sun Microsystems' SunOS, founding the first wave of popular Unix workstations.
Current Unix-like operating systems that descend from BSD include:
- FreeBSD.org (http://www.freebsd.org)
- NetBSD.org (http://www.netbsd.org)
- OpenBSD.org (http://www.openbsd.org)
- DragonFlyBSD.org (http://www.dragonflybsd.org/)
- A timeline of BSD and Research UNIX (http://www.freebsd.org/cgi/cvsweb.cgi/~checkout~/src/share/misc/bsd-family-tree?rev=HEAD) (FreeBSD website)
- BSD.org (http://www.bsd.org/)
- Chris Dibona, Mark Stone, Sam Ockman, Open Source (Organization), Brian Behlendorf and J. Scott Bradner. Open Sources: Voices from the Open Source Revolution. O'Reilly & Associates (http://www.oreilly.com/), 1999. Trade paperback, 272 pages. ISBN 156592582. Online at http://www.oreilly.com/catalog/opensources/book/toc.html; Chapter on BSD - "Twenty Years of Berkeley Unix - From AT&T-Owned to Freely Redistributable" (http://www.oreilly.com/catalog/opensources/book/kirkmck.html)