-s   enables rudimentary switch parsing for switches on the command line
         after the program name but before any filename arguments (or before
         an argument of --). This means you can have switches with two
         leading dashes (--help). Any switch found there is removed from
         @ARGV and sets the corresponding variable in the Perl program. The
         following program prints "1" if the program is invoked with a -xyz
         switch, and "abc" if it is invoked with -xyz=abc.

             #!/usr/bin/perl -s
             if ($xyz) { print "$xyz\n" }

         Do note that --help creates the variable ${-help}, which is not
         compliant with "strict refs".