identify user in a bash script called by sudo

Question

Hello,

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

#!/bin/bash
whoami

And this script is called by a user with a properly configured sudo, it will indicate

root

Is there a fast way to obtain the actual user in a script, or will I have to resort to parameters passing along this username?

TIA, Bert

Answer 1

I think $SUDO_USER is valid.

#!/bin/bash
echo $SUDO_USER
whoami

Answer 2

Odd, the system does distinguish between real and effective UIDs, but I can find no program that exports this at shell level.

Answer 3

try:
id -urn