How do you find the original user through multiple

Question

When running a script via sudo or su I want to get the original user. This should happen regardless of multiple sudo or su runs inside of each other and specifically sudo su -.

Answer 1

user1683793's findUser() function ported to bash and extended so it returns usernames stored in NSS libraries as well.

#!/bin/bash

function findUser() {
    thisPID=$$
    origUser=$(whoami)
    thisUser=$origUser

    while [ "$thisUser" = "$origUser" ]
    do
        ARR=($(ps h -p$thisPID -ouser,ppid;))
        thisUser="${ARR[0]}"
        myPPid="${ARR[1]}"
        thisPID=$myPPid
    done

    getent passwd "$thisUser" | cut -d: -f1
}

user=$(findUser)
echo "logged in: $user"

Answer 2

THIS_USER=`pstree -lu -s $$ | grep --max-count=1 -o '([^)]*)' | head -n 1 | sed 's/[()]//g'`

That's the only thing that worked for me.