if ($caseno == 5) {
    my $null;
    my $dev;
    open($null, ">", $dev="/dev/null") or
      open($null, ">", $dev="NUL:") or 
      die "Cannot open /dev/null nor NUL:";
    close ($null);
    my $resp = get_case($matchp->[0],"2>$dev");
    $resp =~ m{$weak_match_expr};
    ($rcase,$name, $rstr) = ($1,$2,$3);
    $resp = get_case($matchp->[0],"2>&1 >$dev");
    $resp =~ m{$weak_match_expr};
    $rstr = $2;
  }
  ....
  ok($rcase && $caseno == $rcase, "received testcase $caseno");
  if (length($re)) {ok($rstr =~ m{$re}, $name)}
}