Magento - set/get Session Variable

magento-get-set-session-variable.php

<?php
  /* 
  * create new session variable foo_data 
  * You have two options, for the session name, "frontend" for frontend session or "adminhtml" for admin session
  */
  Mage::getSingleton("core/session", array("name" => "frontend"));

  // This will get the session of the current logged in user.
  $session = Mage::getSingleton('customer/session');

  $session->setFooData($login['passcode']); //$login['passcode'] is example

  $session = Mage::getSingleton('customer/session');
  if($session) {
     $myData = $session->getFooData();
  }

  //And this will login to Magento from outside:
  $session = Mage::getSingleton('customer/session', array('name' => 'frontend'));
  $session->login($row['mail'], $row['field_magentopass_value']);
  $session->setCustomerAsLoggedIn($session->getCustomer());
  //$row['mail'] is the email with user is registered $row['field_magentopass_value'] is the password
?>