function getServerSoftware($key = 'SERVER_SOFTWARE')
{
	$regex = "/(?<software>\w+)\/(?<version>[0-9.a-z]*)/";
		
	if(isset($_SERVER[$key]) && preg_match_all($regex, $_SERVER[$key], $arr))
		return array_combine($arr['software'], $arr['version']);
	else
		return array();
}

//USAGE EXAMPLE

//get array
$serverInfo = getServerInfo();

//print apache version
echo $serverInfo['Apache'];

//print all information
foreach($serverInfo as $software=>$version) echo "{$software}: {$version}<br>\n";

function getServerSoftware($key = 'SERVER_SOFTWARE')
	{
		$regex = "/(?<software>\w+)\/(?<version>[0-9.a-z]*)/";
		
		if(isset($_SERVER[$key]) && preg_match_all($regex, $_SERVER[$key], $arr))
			return array_combine($arr['software'], $arr['version']);
		else
			return array();
	}

this function return associative array from SERVER_SOFTWARE

Get Apache Version and other installed software versions as associative array

regex, php, apache

PHP