A beginner’s guide to regular expressions with grep

A regular expression (also called a regex or regexp) is a rule that a computer can use to match characters or groups of characters within a larger body of text. For instance, using regular expressions, you could find all the instances of the word cat in a document, or all instances of a word that begins with c and ends with t. Use of regular expressions in the real world can get much more complex—and powerful—than that. For example, imagine you need to write code verifying that all content in th...

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