The path of a PHP script that is silly and unclear

Gossip will not say, or directly put forward today's question, to be exact, a number of similar to the current script information about the global variable constants of the distinction.

First put the code:

 
 "Echo __file__;echo"
 
 "Echo $_server[' Script_filename '];echo"
 
 "Echo $_server[' remote_addr '];echo"
 
 "Echo $_server[' query_string '];echo"
 
 ";

The address in the browser is the root directory of http://localhost/test/test4.php?a=3 localhost.

Now a look, the original carefully read really a bit confused.

Post the results, do not explain more, I believe many people are also at a glance.

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