How do you tell if a user is logged in as root on Mac OS X?

Question

If I sudo /bin/bash, the who and w command does not show a root login on Mac OS X. How do you enable this?

Answer 1

There is a log in the /var/log directory called auth.log where you can see if somebody su or sudo to root.

Dec 23 00:32:43 hostname su: user to root on /dev/pts/3