`perl -I../lib $switch $tmpfile 2>&1` :
$^O eq 'MacOS' ?
`$^X -I::lib -MMac::err=unix $switch $tmpfile` :
- `./perl $switch $tmpfile 2>&1`;
+ `$^X $switch $tmpfile 2>&1`;
my $status = $?;
$results =~ s/\n+$//;
# allow expected output to be written as if $prog is on STDIN