Re: $< and setuid: quite different animals?

[almut]

in reply to $< and setuid: quite different animals?

Try it the other way round (first effective, then real):

$> = $uid;
$< = $uid;
...

$ sudo strace ./switchback.pl 2>&1 | grep '^setr'
setresuid(-1, 65534, -1)                = 0
setreuid(65534, 4294967295)             = 0
setresuid(-1, 0, -1)                    = -1 EPERM (Operation not perm
+itted)
setreuid(0, 4294967295)                 = -1 EPERM (Operation not perm
+itted)