PHP Manual: php

Description

string php_uname ( [string mode] )

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 is a single character that 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.

Example 1. Some php_uname() examples

<?php
echo php_uname();
echo PHP_OS;

/* Some possible outputs:
Linux localhost 2.4.21-0.13mdk #1 Fri Mar 14 15:08:06 EST 2003 i686
Linux

FreeBSD localhost 3.2-RELEASE #15: Mon Dec 17 08:46:02 GMT 2001
FreeBSD

Windows NT XN1 5.1 build 2600
WINNT
*/

if (strtoupper(substr(PHP_OS, 0, 3)) === 'WIN') {
    echo 'This is a server using Windows!';
} else {
    echo 'This is a server not using Windows!';
}

?>

There are also some related Predefined PHP constants that may come in handy, for example:

Example 2. A few OS related constant examples

<?php
// *nix
echo DIRECTORY_SEPARATOR; // /
echo PHP_SHLIB_SUFFIX;    // so
echo PATH_SEPARATOR;      // :

// Win*
echo DIRECTORY_SEPARATOR; // \
echo PHP_SHLIB_SUFFIX;    // dll
echo PATH_SEPARATOR;      // ;
?>