It is common to make mistakes in your patterns while you are learning. The best way to learn regular expressions is to give the examples a try yourself, then modify them slightly to test your understanding. If you are interested then I highly recommend going through our regular expression tutorial which goes into more detail. I'll give you an introduction to them here in this section but there is much more they can do. We will be demonstrating them here with grep but many other programs use them (including sed and vi which you learned about in previous sections) and many programming languages make use of them too. we may wish to identify every line which contains an email address or a url in a set of data. Re's are typically used to identify and manipulate specific pieces of data. Regular expressions are similar to the wildcards that we looked at in section 7. Mastering re's just takes practice and time so don't give up. You will be surprised but it will start to make more sense the second time. I find the best approach is to go over the material and experiment on the command line a little, then leave it for a day or 3, then come back and have another go. Re's can be a little hard to get your head around at first so don't worry if this stuff is a little confusing. In this section we will look at another filter which is quite powerful when combined with a concept called regular expressions or re's for short. ![]() In the previous section we looked at a collection of filters that would manipulate data for us. ![]() Discover the power of grep and regular expressions with this easy to follow beginners tutorial with plenty of examples to guide you.
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