$repl = '\";`hacked`;\"';

##</code><code>##

sub munge_string {
    my ( $str, $pat, $repl ) = @_;
    # make $repl safe to eval
    $repl =~ tr/\0//d;
    $repl =~ s/([^A-Za-z0-9\$])/\\$1/g;
    $repl = '"' . $repl . '"';
    $str =~ s/$pat/$repl/eeg;
  return $str;
}