<?php

// android store
if (preg_match('#android#i', $_SERVER ['HTTP_USER_AGENT'])) {
    header('Location: market://details?id=com.google.android.apps.maps');
    exit;
}

// ios
if (preg_match('#(iPad|iPhone|iPod)#i', $_SERVER ['HTTP_USER_AGENT'])) {
    header('Location: itms://itunes.apple.com/us/app/');
    exit;
}

// for another os
echo $_SERVER ['HTTP_USER_AGENT'];