Text Processing with Ruby

Appendix 1A Shell Primer

It’s common, even among programmers with some significant experience, to have used the command line only in the most basic way: to type commands one at a time and observe their output. But the Unix shell is a powerful programming environment in its own right.

In case you’re not familiar with using the shell in this way, here is a basic primer. The examples in it will work whether you use bash or zsh, the two most common shells, and the principles hold for any Unix shell—so if your computer is running Linux, BSD, or Mac OS X, all of the examples will work without any additional effort from you. Windows users who install Cygwin^[16] can use all of this functionality, too.