<?php
function check_back_link($remote_url, $your_link) {
    $match_pattern = preg_quote(rtrim($your_link, "/"), "/");
    $found = false;
    if ($handle = @fopen($remote_url, "r")) {
        while (!feof($handle)) {
            $part = fread($handle, 1024);
            if (preg_match("/<a(.*)href=[\"']".$match_pattern.
"(\/?)[\"'](.*)>(.*)<\/a>/", $part)) {
                $found = true;
                break;
            }
        }
        fclose($handle);
    }
    return $found;
}
// example:
//if (check_back_link("http://www.all4yourwebsite.com", "http://www.finalwebsites.com")) echo "link exists";
?>