What is FreeBSD?

This is a question I often hear from people with limited Unix experience.

The short answer: FreeBSD is a member of the Unix family of operating systems, which is completely free, and runs on a variety of different types of computers, but mostly on Intel-based PCs.

This is a fairly big family, and includes systems like IBM's AIX, Apple's A/UX, SGI IRIX, Linux, Apple's OS X, Sun Solaris (a.k.a. Sun OS), and DEC Ultrix just to name a few.

If you're familiar with Linux, you can loosely think of FreeBSD as "Linux on steroids". It's important to note that FreeBSD and Linux are different operating systems, developed independently from each other throughout their long histories. However, to the average end user, FreeBSD and Linux are difficult to tell apart. Although the kernels (the core of the OS, which controls the hardware) are different, FreeBSD and Linux systems run many of the exact same programs such as the KDE and Gnome desktop environments, the gcc and g++ compilers, OpenOffice, and literally thousands of others. The overall capabilities of FreeBSD and Linux are very similar.

The main difference I've noticed, over many years of using both systems, is that FreeBSD is smaller, marginally faster, and more stable. The size factor only comes into play on older hardware. I.e., if you have an old PC you'd like to use to experiment with Unix, donate to a school, or the like, you'll probably have better luck with FreeBSD than with most Linux distributions. I recently installed PC-BSD, a FreeBSD derivative, on a Pentium 233MHz laptop with a 4 gig hard drive, and it's works fairly well. It makes a big difference which Linux distribution you choose. A stock Debian or Gentoo system is about as compact as FreeBSD, while Ubuntu and SUSE are extremely bloated.

On modern hardware, you won't notice much difference between FreeBSD and Linux in size or speed. The difference in stability is only a factor under certain circumstances. Most Linux systems I've managed could run for over a month before requiring a reboot. A few would get flaky sooner than this, and some would last much longer. If you can deal with having to reboot each computer once a month, either system should serve you well. If you have very high stability requirements, I recommend FreeBSD.

In addition to overall system stability, FreeBSD has proven superior in network stability. Over the course of many years, we've run into frequent difficulty sustaining lengthy network connections between Linux and other systems. Note that this would not be an issue for something like a WEB server, which transfers many small files using separate socket connections. In the fMRI research world, however, it's common to transfer many gigabytes of data at a time using http, scp, or NFS. Such transfers have had a high failure rate on our Linux systems. So much so, that I've advised Linux users at MCW to always use rsync for file transfers, since running the same rsync command again will continue from where the last one failed.

Having never heard of FreeBSD, people are often surprised to learn that a significant proportion of the WEB is run on FreeBSD, including well-known WEB servers such as Yahoo!, and many WEB hosting services. Any time you browse the WEB, you're probably using FreeBSD without even knowing it.

For more detailed information, I would suggest starting with the Wikipedia article and possibly Googling "FreeBSD".