note 36562 added to ref.exec

I am sticking to develope a system management,which management the sysytem through lan and write in php.so we must excute some system command,then i call exec , shell_exec ,or popen to excute "fdisk -l" ,but it not go on. I think i haven't enough privilege to do it,then i try to excute exec("su -l root -c") to let me become root user,but it cann't go on too.what wrong i'am? ---- Manual Page -- http://www.php.net/manual/en/ref.exec.php Edit -- http://master.php.net/manage/user-notes.php?action=edit+36562 Delete -- http://master.php.net/manage/user-notes.php?action=delete+36562&report=yes Reject -- http://master.php.net/manage/user-notes.php?action=reject+36562&report=yes Search -- http://master.php.net/manage/user-notes.php