titaniumdecoy

I'm planning to write a PHP script that makes use of various Unix commands such as `rcs`. I know that Windows has DOS built in which can run some commands such as `cd`, `ls`, etc. I was just wondering what commands are supported under Windows and would be compatible with both systems. Is there a list of supported commands under Windows? I know the vast majority of Unix commands are not compatible with Windows, but I just want to check.

Thanks.