system/helpers/user_agent_helper.php

<?php  if (!defined('BASEPATH')) exit('No direct script access allowed');
/**
 * Code Igniter
 *
 * An open source application development framework for PHP 4.3.2 or newer
 *
 * @package		CodeIgniter
 * @author		Rick Ellis
 * @copyright	Copyright (c) 2006, pMachine, Inc.
 * @license		http://www.codeignitor.com/user_guide/license.html 
 * @link		http://www.codeigniter.com
 * @since		Version 1.0
 * @filesource
 */
 
// ------------------------------------------------------------------------

/**
 * Code Igniter User Agent Helper
 *
 * @package		CodeIgniter
 * @subpackage	Helpers
 * @category	Helpers
 * @author		Rick Ellis
 * @link		http://www.codeigniter.com/user_guide/helpers/array_helper.html
 */

// ------------------------------------------------------------------------

/**
 * Get the OS of the user currently browsing the site
 *
 * @access	public
 * @return	string
 */	
function get_OS()
{
	if ( ! isset($_SERVER['HTTP_USER_AGENT'])) 
	{
		return 'Unknown OS';
	}
	
	$os = array (
					'windows nt 6.0'	=> 'Windows Longhorn',
					'windows nt 5.2'	=> 'Windows 2003',
					'windows nt 5.0'	=> 'Windows 2000',
					'windows nt 5.1'	=> 'Windows XP',
					'windows nt 4.0'	=> 'Windows NT 4.0',
					'winnt4.0'			=> 'Windows NT 4.0',
					'winnt 4.0'			=> 'Windows NT',
					'winnt'				=> 'Windows NT',
					'windows 98'		=> 'Windows 98',
					'win98'				=> 'Windows 98',
					'windows 95'		=> 'Windows 95',
					'win95'				=> 'Windows 95',
					'windows'			=> 'Unknown Windows OS',
					'mac os x'			=> 'Mac OS X',
					'freebsd'			=> 'FreeBSD',
					'ppc'				=> 'Macintosh',
					'sunos'				=> 'Sun Solaris',
					'linux'				=> 'Linux',
					'debian'			=> 'Debian',
					'beos'				=> 'BeOS',
					'apachebench'		=> 'ApacheBench',
					'aix'				=> 'AIX',
					'irix'				=> 'Irix',
					'osf'				=> 'DEC OSF',
					'hp-ux'				=> 'HP-UX',
					'netbsd'			=> 'NetBSD',
					'bsdi'				=> 'BSDi',
					'openbsd'			=> 'OpenBSD',
					'gnu'				=> 'GNU/Linux',
					'unix'				=> 'Unknown Unix OS'
				);
	
	
	foreach ($os as $key => $val) 
	{
		if (preg_match("|$key|i", $_SERVER['HTTP_USER_AGENT'])) 
		{
			return $val;
		}
	}

	return 'Unknown OS';
}


?>