<?
require 'facebook-php-sdk/src/facebook.php';

$facebook = new Facebook(array(
  'appId'  => '$appId',
  'secret' => '$secret',
));

// Get User ID
$user = $facebook->getUser();

if ($user <> '0' && $user <> '') { /*if valid user id i.e. neither 0 nor blank nor null*/
  try {
  // Proceed knowing you have a logged in user who's authenticated.
    $user_profile = $facebook->api('/me');
  } catch (FacebookApiException $e) { /*sometimes it shows user id even if user in not logged in and it results in Oauth exception. In this case we will set it back to 0.*/
    error_log($e);
    $user = '0';
  }
}
else {/*If user id isn't present just redirect it to login url*/
  header("Location:{$facebook->getLoginUrl(array('req_perms' => 'email,offline_access'))}");
}

$facebook->api('/$group_id/feed/', 'post', array(
    'message' => 'I want to display this message on my wall',
  'link' => 'http://kodilo.ru',
  'picture' => 'http://images.boomsbeat.com/data/images/full/1893/facebook-jpg.jpg',
  'name' => 'The name of the link',
  'caption' => 'Caption of the link',
  'description' => 'Description of the link'
));
?>