Because patterns are processed as double quoted strings, the following
    also work:

        \t          tab                   (HT, TAB)
        \n          newline               (LF, NL)
        \r          return                (CR)
        \f          form feed             (FF)
        \a          alarm (bell)          (BEL)
        \e          escape (think troff)  (ESC)
        \033        octal char (think of a PDP-11)
        \x1B        hex char
        \x{263a}    wide hex char         (Unicode SMILEY)
        \c[         control char
        \N{name}    named char
        \l          lowercase next char (think vi)
        \u          uppercase next char (think vi)
        \L          lowercase till \E (think vi)
        \U          uppercase till \E (think vi)
        \E          end case modification (think vi)
        \Q          quote (disable) pattern metacharacters till \E