1.6.3. Which Unix?

The choice is commonly between some sort of Linux and FreeBSD. Both are technically acceptable. If you already know someone who has one of these OSs and is willing to help you get used to yours, then it would make sense to follow them. If you are an Apple user, OS X has a Unix core and includes Apache.

Failing that, the difference between the two paths is mainly a legal one, turning on their different interperations of open source licensing.

Linux lives at http://www.linux.org, and there are more than 160 different distributions from which Linux can be obtained free or in prepackaged pay-for formats. It is rather ominously described as a "Unix-type" operating system, which sometimes means that long-established Unix standards have been "improved", not always in an upwards direction.

Linux supports Apache, and most of the standard distributions include it. However, the default position of the Config files may vary from platform to platform, though usually on Linux they are to be found in /etc. Under Red Hat Linux they will be in/etc/httpd/conf by default.

FreeBSD ("BSD" means "Berkeley Software Distribution" — as in the University of California, Berkeley, where the version of Unix FreeBSD is derived from) lives at http://www.freebsd.org. We have been using FreeBSD for a long time and think it is the best environment.

If you look at http://www.netcraft.com and go to What's that site running?, you can examine any web site you like. If you choose, let's say, http://www.microsoft.com, you will discover that the site's uptime (length of time between rebooting the server) is about 12 days, on average. One assumes that Microsoft's servers are running under their own operating systems. The page Longest uptimes, also at Netcraft, shows that many Apache servers running Unix have uptimes of more than 1380 days (which is probably as long as Netcraft had been running the survey when we looked at it). One of the authors (BL) has a server running FreeBSD that has been rebooted once in 15 years, and that was when he moved house.

The whole of FreeBSD is freely available from http://www.freebsd.org/. But we would suggest that it's well worth spending a few dollars to get the software on CD-ROM or DVD plus a manual that takes you though the installation process.

If you plan to run Apache 2.0 on FreeBSD, you need to install FreeBSD 4.x to take advantage of Apache's support for threads: earlier versions of FreeBSD do not support them, at least not well enough to run Apache.

If you use FreeBSD, you will find (we hope) that it installs from the CD-ROM easily enough, but that it initially lacks several things you will need later. Among these are Perl, Emacs, and some better shell than sh (we like bash and ksh), so it might be sensible to install them straightaway from their lurking places on the CD-ROM.