^zip Match all strings that start with zip. To specify that a string should strictly start or end with certain character, we can use the hat ( ^) or dollar sign ( $). For example, if you were reading from an ouput, and had to match if it reads "success", you couldn't just write a regex that matches "success", as "not success" and "success did not occur" would also be valid matches. In some cases, you'll need to specify that a string starts and/or ends with certain characters. Use the logical or ( |) between two options. You can use conditionals to specify either-or relations. ? Match the characters a, b or c zero or just once. + Match one or many lowercase alphabet letters. To match an actual question mark, escape it. To match an element zero or just one time, use the question mark ( ?). This is a tighter regulation than the Kleene star, as it ensures there is at least one of the preceding character.
Learn regex plus#
To match a previous element at least once, use the Kleene plus ( +). To match an element zero or many times, use the Kleene star, which is an asterisk ( *) placed after a specific character. If we want to reiterate a single regex expression, we can do so with braces ( Match any digit between 5 and 10 times.Matching zero or many elements Repetitions and Optionals Reiterating a single regex expression
To specify any number of whitespace character use the \s*.Īny non-whitespace character will be \S. The whitespace special character \s will match single type of whitespace - a space, tab, newline or carriage return. Instead of writing we can just write write the range between two letter or numbers, separated by a dash ( -). There is a shortcut to specifying any range of letters or digits. Match any character except for a, b or c. Use the square brackets, just like above, with a hat ( ^) inside of it. Excluding matches to set of specific characters Place each character within square brackets. \b matches the boundary between a word and a non-word character. This is helpful especially for matching punctuations. As you'll learn soon, this is the same as. One alphanumeric characterĪny alphanumeric character including the underscore. To use the actual period scape with a backslash \. This will match any character - a letter, digit or whitespace. To match any non-digit, use the upper-case \D.
If you're looking to learn regular expressions for the shell or the Linux command line, head on over to our Command Line Regular Expressions tutorial page.
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