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Egrep Patterns

The escape character is a backslash (\). You can use it to escape meta characters to use them in their plain character form.

In the following examples literal 'E' and 'F' denote any expression, whether a pattern or a character.

  • (

    Start a capturing subexpression.

  • )

    End a capturing subexpression.

  • E|F

    Disjunction, match either E or F (inclusive). E is preferred if both match.

  • E*

    Act as Kleene star, match E zero or more times.

  • E+

    Closure, match E one or more times.

  • E?

    Option, match E optionally once.

  • .

    Match any character except for newline characters (\n, \f, \r) and the NULL byte.

  • E{n}

    Match E exactly n times.

  • E{n,} or E{n,0}

    Match E n or more times.

  • E{,n} or E{0,n}

    Match E at most n times.

  • E{n,m}

    Match E no less than n times and no more than m times.

  • [

    Start a character set, see Section Character Sets For Egrep.

  • $$

    Match the empty string at the end of the input or at the end of a line.

  • ^

    Match the empty string at the start of the input or at the beginning of a line.

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