Explaining BSD

Greg Lehey

Legal Notice

In the open source world, the word “Linux” is almost synonymous with “Operating System”, but it is not the only open source UNIX® operating system. According to the Internet Operating System Counter, as of April 1999 31.3% of the world's network connected machines run Linux. 14.6% run BSD UNIX. Some of the world's largest web operations, such as Yahoo!, run BSD. The world's busiest FTP server of 1999 (now defunct), ftp.cdrom.com, used BSD to transfer 1.4 TB of data a day. Clearly this is not a niche market: BSD is a well-kept secret.

So what is the secret? Why is BSD not better known? This white paper addresses these and other questions.

Throughout this paper, differences between BSD and Linux will be noted like this.


Table of Contents
1 What is BSD?
2 What, a real UNIX®?
3 Why is BSD not better known?
4 Comparing BSD and Linux

1 What is BSD?

BSD stands for “Berkeley Software Distribution”. It is the name of distributions of source code from the University of California, Berkeley, which were originally extensions to AT&T's Research UNIX operating system. Several open source operating system projects are based on a release of this source code known as 4.4BSD-Lite. In addition, they comprise a number of packages from other Open Source projects, including notably the GNU project. The overall operating system comprises:

This, and other documents, can be downloaded from ftp://ftp.FreeBSD.org/pub/FreeBSD/doc/.

For questions about FreeBSD, read the documentation before contacting <questions@FreeBSD.org>.
For questions about this documentation, e-mail <doc@FreeBSD.org>.