Find the exploit
Two of these can permanently drop the UID too 1000. The other two however results in a state where a previous privileged state can be restored. Can you spot which ones are right and which ones not? And most importantly: why?
$< = 1000; $> = 1000; $> = 1000; $< = 1000; $< = $> = 1000 $> = $< = 1000