This chapter presents the Unix commands of interest to users and programmers. Most of these commands appear in the "Commands" section of the online manual. With rare exception, this book purposely avoids system administration commands, because system administration is beyond its scope. The focus instead is on everyday commands, those used both interactively and for programming.
Summarizing three operating systems that are similar but not identical is a daunting task. In order to make a coherent presentation, the chapter is organized as follows:
This section lists commands that should be available on just about any Unix system. We have included here many commands that are downloadable from the Internet and that are standard with GNU/Linux, such as autoconf or wget, even though they may not come "out of the box" on commercial Unix systems. Wherever possible, we provide a URL from which the source to the command may be downloaded, so that you can build the program yourself if you want it. See the section "Obtaining Compilers" in Chapter 1 for what to do if you don't have a C compiler for your system.
Additionally, we have made an effort to be as concise as possible. For example, GNU-style long options are listed side-by-side with their standard single-letter counterparts. Similarly, several commands have associated with them additional more specialized commands that are needed only rarely. We simply list such commands as "related," ...