while ( <$client> ) {
   next unless /\S/;       # blank line

   chomp;

   my %commands = (
     'quit'  => sub { $exit = 1; last; },
     'title' => \&title,
     'next'  => \&next_title,
     'prev'  => \&prev_title,
   );

   if ( defined( $commands{$_} ) ) {
     $commands{$_}->();
   } else {
     print $client "Commands: quit title prev next", $CRLF;
   }
}