The effective uid of this process. For example:
$< = $>; # set real to effective uid
($<,$>) = ($>,$<); # swap real and effective uids
You can change both the effective uid and the real uid at the same time by using POSIX::setuid()
. Changes to $>
require a check to $!
to detect any possible errors after an attempted change.
$<
and $>
can be swapped only on machines supporting setreuid()
.
Mnemonic: it's the uid you went to, if you're running setuid.