$ perl -Twle 'eval {open my $fh, "+>$0"}; print $@ =~ /Insecure/ ? "Taint mode on" : "Taint mode off"'
Taint mode on
$ perl  -wle 'eval {open my $fh, "+>$0"}; print $@ =~ /Insecure/ ? "Taint mode on" : "Taint mode off"'
Taint mode off
$