To design with portability in mind, you may want to first test for the platform on which the script is running. PHP defines the constant PHP_OS, which contains the name of the operating system on which the PHP parser is executing. Possible values for the PHP_OS constant include “HP-UX”, “Darwin” (Mac OS), “Linux”, “SunOS”, “WIN32”, and “WINNT”. You may also want to consider the php_uname() built-in function; it returns even more operating system information
The following code shows how to test for a Windows platform:
<?php
if (PHP_OS == 'WIN32' || PHP_OS == 'WINNT') {
echo "You are on a Windows System";
}
else {
// some other platform
echo "You are NOT on a Windows System";
}
?>