Busybox grep regular expressions code#
Once mastered, regular expressions provide developers with the ability to locate patterns of text in source code and documentation at design time. In this series, you'll learn more about how the syntax for this and other regular expressions work.Īs just demonstrated, a regex can be a powerful tool for finding text according to a particular pattern in a variety of situations. This example is but one of many uses for regular expressions. *, which matches any block of code text bracketed by tags, to the HTTP request body as part of your search for script injection code. Malicious code can appear in any number of ways, but you know that injected script code will always appear between HTML tags. For example, imagine you need to write code verifying that all content in the body of an HTTP POST request is free of script injection attacks. Use of regular expressions in the real world can get much more complex-and powerful-than that. 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.
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.
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