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Showing posts with the label Unix regular expressions

POSIX

This form of regular expression searching is compliant with extended regular expressions (EREs) defined in IEEE POSIX 1003.2. Extended regular expressions are similar in syntax to the traditional Unix regular expressions, with some exceptions. The true power of the ERE's is their ability to be combined together to form searches. The POSIX ERE's are utilized in three methods: Brackets, Quantifiers and Predefined Character Ranges. •  Brackets -                      Brackets ([ ]) provide the capability to find ranges of characters when searching through strings. In non-extended regular expressions, when a search is made against a string for the term "dog", only words that contain the letters d-o-g in sequence are found. With brackets, the search using the [dog] will find any words that contain the letter "d", or the letter "o" or the letter "g". The following are a list of the most commonly used character ranges: 􀂃 [0-9] mat