This chapter introduces regular expressions, and the main commands that we can use to leverage their power. We'll first look at the theory behind regular expressions, before moving deeper into practical examples of using regular expressions with grep and sed.

We will also explain globbing, and how it is used on the command line.

The following commands will be introduced in this chapter: grep, set, egrep, and sed.

The following topics will be covered in this chapter:

• What are regular expressions?
• Globbing
• Using regular expressions with egrep and sed