A little script to utilize the http://useragentstring.com API

uastring.php

<?php
// Test script for detecting the OS by user agent string
// uses the API from http://www.useragentstring.com
// Do not forget to add caching! Continuously hitting the
// API is bad for performance of both the API and your
// application.

$apiParams = array(
    'uas' => $_SERVER['HTTP_USER_AGENT'],
    'getJSON' => 'os_name'
);


$apiLocation = "http://www.useragentstring.com/";
$queryString = http_build_query($apiParams);

$requestUrl = $apiLocation . '?' . $queryString;

$jsonResponse = file_get_contents($requestUrl);
$responseData = json_decode($jsonResponse);


echo "<pre>";
echo "Requested api at: " . $requestUrl;

echo "\nYour os is: " .  $responseData->$apiParams['getJSON'];
echo "</pre>";