>echo "input" | perl -T -e "use Scalar::Util qw( tainted ); my $var = <STDIN>; print(tainted($var)?1:0, qq{\n})"
1

>set VAR=input & perl -T -e "use Scalar::Util qw( tainted ); my $var = $ENV{VAR}; print(tainted($var)?1:0, qq{\n})"
1