php获取linux命令结果的实例

public function get_server_ip() { 	if (PHP_SAPI === 'cli'){	 	$buffer = "";		 $handle = popen("ifconfig eth0|grep 'inet addr'|awk -F'[ :]' '{print $13}'", 'r');			while(!feof($handle)) {			 $buffer.=fgets($handle);			}			pclose($handle);		 $server_ip = rtrim($buffer); 	}else{	 	if (isset($_SERVER)) { 		  if($_SERVER['SERVER_ADDR']) {		   $server_ip = $_SERVER['SERVER_ADDR']; 		  } else { 		   $server_ip = $_SERVER['LOCAL_ADDR']; 		  } 		 } else { 		  $server_ip = getenv('SERVER_ADDR');		 } 	}	 return $server_ip; 	}