ftp_chmod

<?php
$file = 'public_html/index.php';

// 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 $file to 644
if (ftp_chmod($conn_id, 0644, $file) !== false) {
 echo "$file chmoded successfully to 644\n";
} else {
 echo "could not chmod $file\n";
}

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