gawk: Regexp Patterns

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1 7.1.1 Regular Expressions as Patterns
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1 Regular expressions are one of the first kinds of patterns presented in
1 this book.  This kind of pattern is simply a regexp constant in the
1 pattern part of a rule.  Its meaning is '$0 ~ /PATTERN/'.  The pattern
1 matches when the input record matches the regexp.  For example:
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1      /foo|bar|baz/  { buzzwords++ }
1      END            { print buzzwords, "buzzwords seen" }
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