The shell provides many mechanisms to customize your work environment. As we've mentioned before, the shell is more than a command interpreter---it is also a powerful programming language. While writing shell scripts is an extensive subject, we'd like to introduce you to some of the ways that you can simplify your work on a UNIX system by using these advanced features of the shell.
As we have mentioned before, different shells use different syntaxes when executing shell scripts. For example, Tcsh uses a C-like syntax, while Bourne shells use another type of syntax. In this section, we won't be running into many of the differences between the two, but we will assume that shell scripts are executed using the Bourne shell syntax.