php_uname
    (PHP 4 >= 4.0.2)
php_uname -- 
     Returns information about the operating system PHP was built on
    
Description
string 
php_uname ( void )
     php_uname() returns a string with a
     description of the operating system PHP is built on.  If you're just
     wanting the name of the operating system, consider using the
     PHP_OS constant.
    
     
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
// Win*
echo DIRECTORY_SEPARATOR; // ;
echo PHP_SHLIB_SUFFIX;    // dll
?>  |  
  | 
    
     See also phpversion(), 
     php_sapi_name(), and 
     phpinfo().