In this chapter, we'll explain a very practical concept of Bash scripting: functions. We'll show what they are, how we can use them, and why we would want to use them.

After the basics of functions have been introduced, we're taking it a step further and we'll show how functions can have their own input and output.

The concept of a function library will be described and we will start to build our own personal function library that will contain various utility functions.

The following commands will be introduced in this chapter: top, free, declare, case, rev, and return.

The following topics will be covered in this chapter:

• Functions explained
• Augmenting functions with parameters
• Function libraries