Another big hole in this book is that we don't cover any of UNIX's communications and networking utilities - things like electronic mail, the World Wide Web, netnews, UUCP, rlogin, rcp, rsh, telnet, ftp, archie, WAIS...and all the wonderful Internet resources that are really the "killer applications" for UNIX.
Why do we leave out this most central of UNIX technologies? There's only one good reason: space. The book was heading up toward 1500 pages, and something had to go. We looked for discrete areas that we could cut. O'Reilly & Associates and other publishers cover networking in depth, so we left that topic to other books.
You'll see other holes as well - the, and utilities for hardcore programmers. We hope you agree, though, that it was better to go for more depth in what we did cover than to try to shoehorn in more superficial material just to say we cover everything.
Article 1.33 has an overview of UNIX networking. And because we didn't want to cut out some good material that fit pretty well with other existing articles, we did leave in a few other networking tips. We just didn't provide as much background or cross-referencing for all of the commands and concepts.