The shell is the ultimate UNIX power tool.

It is the design of the shell-including basic features like pipes, filters, and redirection, and the idea of an environment where small programs can do big things by working together-that makes all the rest possible.

Some new UNIX users program only in Perl. Perl does do many things that are otherwise difficult or impossible, and Perl scripts can be run on other operating systems. But we believe there's plenty of room for the original UNIX "small is beautiful" philosophy.

Whether you program the shell or not, the next four chapters will help you use it interactively.