use warnings;
use strict;
use IPC::Open3;
use feature qw(say);

my ( $wtr, $rdr, $err );
my $pid = open3( $wtr, $rdr, $err, 'perl', 'dummy.pl' );

while (<$rdr>) {

    print $_;

}

while (<$err>) {

    print $_;

}

close($err);
close($rdr);
close($wtr);

waitpid( $pid, 0 );