In this chapter, we will talk about the most mysterious part of using stream editor (sed) and AWK. They are regular expressions, or regexes for short. In the previous chapters, we discussed some regular expressions shyly and that's because we don't need to dig into them without a good understanding.
If you understand how regular expressions are written, you will save a lot of time and effort. With regular expressions, you will unleash the real power behind sed and AWK and will use them professionally.
This chapter will cover the following aspects:
- Regular expression engines
- Defining BRE patterns
- Defining ERE patterns
- Using grep
