There are a number of useful non-printing characters that must be used occasionally. The following table shows the escape sequences used to represent those non-printing characters:

Character | Meaning |
---|---|

\cx |
Matches the control character indicated by x. For example, \cM matches a Control-M or carriage return character. The value of x must be in the range of A-Z or a-z. If not, c is assumed to be a literal 'c' character. |

\f | Matches a form-feed character. Equivalent to \x0c and \cL. |

\n | Matches a newline character. Equivalent to \x0a and \cJ. |

\r | Matches a carriage return character. Equivalent to \x0d and \cM. |

\s | Matches any whitespace character including space, tab, form-feed, etc. Equivalent to [\f\n\r\t\v]. |

\S | Matches any non-whitespace character. Equivalent to [^ \f\n\r\t\v]. |

\t | Matches a tab character. Equivalent to \x09 and \cI. |

\v | Matches a vertical tab character. Equivalent to \x0b and \cK. |