gawk: Regexp Summary
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1 3.9 Summary
1 ===========
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1 * Regular expressions describe sets of strings to be matched. In
1 'awk', regular expression constants are written enclosed between
1 slashes: '/'...'/'.
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1 * Regexp constants may be used standalone in patterns and in
1 conditional expressions, or as part of matching expressions using
1 the '~' and '!~' operators.
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1 * Escape sequences let you represent nonprintable characters and also
1 let you represent regexp metacharacters as literal characters to be
1 matched.
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1 * Regexp operators provide grouping, alternation, and repetition.
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1 * Bracket expressions give you a shorthand for specifying sets of
1 characters that can match at a particular point in a regexp.
1 Within bracket expressions, POSIX character classes let you specify
1 certain groups of characters in a locale-independent fashion.
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1 * Regular expressions match the leftmost longest text in the string
1 being matched. This matters for cases where you need to know the
1 extent of the match, such as for text substitution and when the
1 record separator is a regexp.
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1 * Matching expressions may use dynamic regexps (i.e., string values
1 treated as regular expressions).
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1 * 'gawk''s 'IGNORECASE' variable lets you control the case
1 sensitivity of regexp matching. In other 'awk' versions, use
1 'tolower()' or 'toupper()'.
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