anche questo l'ho cercato sul manuale ed ho trovato questo

If you get a warning like chmod(): Operation not permitted in /home/folder/public_html/admin/includefiles/fileupload.php on line 24

You can use the ftp_site() function to send a CHMOD command through.

Codice PHP:
<?php

$ftp_details['ftp_user_name'] = $row['username'];
$ftp_details['ftp_user_pass'] = $row['password'];
$ftp_details['ftp_root'] = '/public_html/';
$ftp_details['ftp_server'] = 'ftp'.$_SERVER['HTTP_HOST'];

function chmod_11oo10($path, $mod, $ftp_details)
{
    // extract ftp details (array keys as variable names)
    extract ($ftp_details);
    
    // set up basic connection
    $conn_id = ftp_connect($ftp_server);
    
    // login with username and password
    $login_result = ftp_login($conn_id, $ftp_user_name, $ftp_user_pass);
    
    // try to chmod $path directory
    if (ftp_site($conn_id, 'CHMOD '.$mod.' '.$ftp_root.$path) !== false) {
        $success=TRUE;
    } 
    else {
        $success=FALSE;
    }

    // close the connection
    ftp_close($conn_id);
    return $success;
}
?>