Having said this, we must acknowledge that this book is strongly oriented towards Unix (including Linux), with Windows NT as a major secondary theme. There are several reasons for this orientation. First, these operating systems are the dominant operating systems in the Internet world. Unix is still the predominant operating system for Internet servers, although Windows NT is a strong presence. Another reason is, of course, that our own experience is primarily in the Unix world; we have entered the world of Windows NT only recently, as it started to intersect with the world of the Internet. Although we do speak Windows NT, we do so with a strong Unix accent.

Linux, while it is not strictly speaking Unix, is a close relative of the Unix we have spent our careers working with. In many cases, it is truer to the Unix tradition than commercial operating systems entitled to use the Unix trademark. While we do mention Linux by name in some places, you should bear in mind that all of our statements about Unix are meant to include Linux except when we explicitly state otherwise.