In the second part of this book, we will not try to cover all the Unix shells, as we did in Part 1. Instead, we will look at two powerful shells,
zsh, in a bit more detail. They are both freely available on all the most common operating systems. We will show you how to configure both shells and make them do more for you, expanding on many of the points in Part 1 as well as introducing some new ways of controlling the shell from the command line. Later, in Part 3, we will start to string things together to make programs (which in shell language are called scripts and functions). For now, most of what we tell you will be in short chunks, making it easy for you to try things out.