php_uname Returns information about the operating system PHP is running on stringphp_uname stringmode php_uname returns a description of the operating system PHP is running on. For the name of just the operating system, consider using the PHP_OS constant, but be reminded this constant will contain the operating system PHP was built on. On Unix, the output reverts to displaying the operating system information PHP was built on if it cannot determine the currently running OS. mode defines what information is returned: 'a': This is the default. Contains all modes in the sequence "s n r v m". 's': Operating system name. eg. FreeBSD. 'n': Host name. eg. localhost.example.com. 'r': Release name. eg. 5.1.2-RELEASE. 'v': Version information. Varies a lot between operating systems. 'm': Machine type. eg. i386. ]]> There are also some related Predefined PHP constants that may come in handy, for example: ]]> See also phpversion, php_sapi_name, and phpinfo.