$post_data = array("fax_file"=>'@'.$r_file, "aa"=>'bb'); //文件绝对路径，前面要加@，表明是文件上传.

function uploadByCURL($post_data,$post_url){
    $curl = curl_init();
    curl_setopt($curl, CURLOPT_URL, $post_url);
    curl_setopt($curl, CURLOPT_POST, 1);
    curl_setopt($curl, CURLOPT_POSTFIELDS, $post_data);
    curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($curl, CURLOPT_HEADER, 0);
    $result = curl_exec($curl);
    curl_close($curl);
    return $result;
}