how to make nginx not cache php file

[perlish]

Hi all:
  When I use nginx-0.7.59 as a revers proxy and cache server,it also cache the php file,how to make it not cache php file ?
I thought the php file is not need to be cached.

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,2437,2437#msg-2437