note 49901 added to ref.exec

I'm newbie PHP i want ask about this exec(); How i can execute linux command as root like : >> change ifconfig >> change iptable/ipchain >> or command for change configuration of my linux server that must have root access ok... please help me thanks.... ---- Manual Page -- http://www.php.net/manual/en/ref.exec.php Edit -- http://master.php.net/manage/user-notes.php?action=edit+49901 Delete: added to the manual -- http://master.php.net/manage/user-notes.php?action=delete+49901&report=yes&reason=added+to+the+manual Delete: bad code -- http://master.php.net/manage/user-notes.php?action=delete+49901&report=yes&reason=bad+code Delete: spam -- http://master.php.net/manage/user-notes.php?action=delete+49901&report=yes&reason=spam Delete: useless -- http://master.php.net/manage/user-notes.php?action=delete+49901&report=yes&reason=useless Delete: other reasons -- http://master.php.net/manage/user-notes.php?action=delete+49901&report=yes Reject -- http://master.php.net/manage/user-notes.php?action=reject+49901&report=yes Search -- http://master.php.net/manage/user-notes.php