Chapter 5. Working on a Unix System
Unix has a wealth of functions, and you'll want to be aware of a particular subset of them before you start running programs and collecting data. In Chapter 4, we talked about how to organize and manage your files in Unix, as well as how to move around the filesystem. In this chapter we take you on a whirlwind tour through the common Unix commands you'll need to know to work efficiently. We discuss the Unix shell itself, issuing commands in Unix, viewing, editing, and extracting information from your files, shell scripts, and working in a multiuser environment.
Once you've learned to use some of these Unix commands, you'll find that they are astonishingly powerful and flexible, allowing you to modify files in ways that are impossible, or at least not easy, with a conventional word-processing program. For example, with a single command you can find all the instances of a pattern in every file under your home directory. A few simple tricks can create a script that will process every file in your source data directory identically. Another simple script can update a customized local copy of a database every night while you're sleeping.
The Unix Shell
When you log into a Unix system or open a new window in your system's window manager interface, the system automatically starts a program called a shell for you. The shell program interprets the commands you enter and provides you with a working environment and an interface to the operating system. It's ...