Identify user in a Bash script called by sudo

Question

If I create the script /root/bin/whoami.sh containing:

#!/bin/bash
whoami

and this script is called by a user with a properly

Answer 1

Here is how to get the username of the person who called the script no matter if sudo or not:

if [ $SUDO_USER ]; then user=$SUDO_USER; else user=`whoami`; fi

or a shorter version

[ $SUDO_USER ] && user=$SUDO_USER || user=`whoami`