Is it possible to get the real username inside of a script that was called using sudo?

Question

I have a script that I call with sudo -- sudo script, and I want to be able to see the username of the user running the script (not root).

Sticking whoami or id -un inside the script just gives me root.

Answer 1

sudo creates an environment variable called SUDO_USER. You can use it in your script like so:

echo $SUDO_USER

Answer 2

You can look at the SUDO_USER, SUDO_UID or SUDO_GID environmental variables to find this information.