Is this a hacker’s tool?

Over the last few days, I have had lots of site hits looking for rather strange URLs on this blog such as:

I took a look at the file the url refers to. Here it is:

/\/\/\ Response CMD /\/\/\

Changing this CMD will result in corrupt scanning !

Can someone who understands PHP tell me what this is trying to do? It is clearly a scanning/hacking tool designed to retrieve data - I guess to help with further exploits. But I can't quite work it out, especially the
if((@eregi("uid",ex("id"))) || (@eregi("Windows",ex("net start")))){
echo("Safe Mode of this Server is : ");

It's a php script so why should it care if the site is on Windows or Linux? Any takers...