PHP缓存而不会弄乱文件权限（另外，如何在PHP中模拟ASP应用程序变量）

I'm trying to implement some kind of caching in a PHP script that will go out to many different clients/sites, which will be deployed by fairly non-technical users, using a variety of web hosts. Due to the non-technical nature of the users, I'd like to avoid asking them to tweak file permissions. The caching needs to be across sessions, so using session variables is out. If I was coding this in ASP I'd use application variables, but they don't exist in PHP (to my knowledge)I'm trying to implement some kind of caching in