for my $x ( reverse 0 .. 2 ) {
    for my $y ( reverse 0 .. 2 ) {
        open my $pipe, '-|', 'prog name', '-f', "file_${x}_$y.ext"
            or die "Cannot open pipe from 'prog name': $!";
        open my $out, '>', "tracker_$x$y.log"
            or die "Cannot open 'tracker_$x$y.log': $!";

        print $out $_ while <$pipe>;

        close $pipe or warn $!
            ? "Error closing 'prog name' pipe: $!"
            : "Exit status $? from 'prog name'";
        }
    }