* 3 * * * /path_to_script/cronjob.php?username=test&password=test&code=1234

* 3 * * * /path_to_script/cronjob.php username=test password=test code=1234

<?php

var_dump($argv);

/*
array(4) {
  [0]=>
  string(27) "/path_to_script/cronjob.php"
  [1]=>
  string(13) "username=test"
  [2]=>
  string(13) "password=test"
  [3]=>
  string(9) "code=1234"
}
*/

parse_str($argv[3], $params);

echo $params['code']; // 1234

session_start();

if (isset($_SESSION['user']))
{
  include '/path/to/script/outside/of/web-root';
}
else
{
  die('No access.');
}

* 3 * * * /path_to_script/cronjob.php?username=test&password=test&code=1234

* 3 * * * /path_to_script/cronjob.php username=test password=test code=1234

$str = "first=value&arr[]=foo+bar&arr[]=baz";
parse_str($str);
echo $first;  // value
echo $arr[0]; // foo bar
echo $arr[1]; // baz

* 3 * * * /path_to_script/cronjob.php username=test password=test code=1234