http://www.thaiabc.com/fb/th_comment/short.php
<?php
session_start();
require_once '../lib/src/facebook.php';
$facebook = new Facebook(array( 'appId' => 'xxx', 'secret' => 'xxx', 'cookie' => true, ));
$user = $facebook->getUser();
if ($user) {
try { $user_profile = $facebook->api('/me?fields=id,name,link,email'); } 
catch (FacebookApiException $e) { error_log($e); $user = null; }
}
if ($user) { 
$logoutUrl = $facebook->getLogoutUrl(); 
} else { 
$loginUrl = $facebook->getLoginUrl(array('scope' => 'user_photos,user_photo_video_tags')); 
}
?>
<?php if (!$user): ?> 
ยังไม่ Log In <br><a href="<?php echo $loginUrl; ?>" target='_top'>ลงชื่อเข้าระบบ</a>
<?php endif ?>
<?php if ($user): ?>
ยินดีต้อนรับ <?=$user_profile["name"];?> 
<br/><a href="<?php echo $logoutUrl; ?>">ลงชื่อออกจากระบบ</a>
<?php endif ?>