wget检查远程文件是否存在的方法

HTTP/1.1 200 OK
  Date: Thu, 15 Nov 2012 03:16:27 GMT
  Server: BWS/1.0
  Content-Length: 9803
  Content-Type: text/html;charset=gbk
  Cache-Control: private
  Expires: Thu, 15 Nov 2012 03:16:27 GMT
  Set-Cookie: BAIDUID=D9437ABF9E8126F93E0DD75AB654B85B:FG=1; expires=Thu, 15-Nov
-42 03:16:27 GMT; path=/; domain=.baidu.com
  P3P: CP=" OTI DSP COR IVA OUR IND COM "
  Connection: Close