Help with exec.

I need to pipe some data to an external application.

I have this:

while ($row = mysql_fetch_array($theData[0])) {
    $src_ip[] = $row[0];
    $dst_ip[] = $row[1];
    $sig_desc[] = $row[2];

    $rec ++;
    if ( $rec == $recCount ) {
            break;
    }
}

for ($i = 0; $i < sizeof($src_ip); $i++) {
    $tmpResult[] = "$sig_desc[$i],$src_ip[$i],$dst_ip[$i]\n";
}


The external program is called like:

cat results.csv | theprogram outputfilename

Is there a way mimic this w/o outputting $tmpResult to a file first?

Thanks.