gawk: Regexp

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1 3 Regular Expressions
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1 A "regular expression", or "regexp", is a way of describing a set of
1 strings.  Because regular expressions are such a fundamental part of
1 'awk' programming, their format and use deserve a separate major node.
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1    A regular expression enclosed in slashes ('/') is an 'awk' pattern
1 that matches every input record whose text belongs to that set.  The
1 simplest regular expression is a sequence of letters, numbers, or both.
1 Such a regexp matches any string that contains that sequence.  Thus, the
1 regexp 'foo' matches any string containing 'foo'.  Thus, the pattern
1 '/foo/' matches any input record containing the three adjacent
1 characters 'foo' _anywhere_ in the record.  Other kinds of regexps let
1 you specify more complicated classes of strings.
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Menu

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· Regexp Usage                How to Use Regular Expressions.
· Escape Sequences            How to write nonprinting characters.
· Regexp Operators            Regular Expression Operators.
· Bracket Expressions         What can go between '[...]'.
· Leftmost Longest            How much text matches.
· Computed Regexps            Using Dynamic Regexps.
· GNU Regexp Operators        Operators specific to GNU software.
· Case-sensitivity            How to do case-insensitive matching.
· Regexp Summary              Regular expressions summary.
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