Finding the device name of the root partition

I thought this could be useful for someone trying to figure out the device name that a certain directory belongs to. In this example I am using /

ROOT_PART=$(echo /dev/$(lsblk -P | grep -i "mountpoint=\"/\"" | awk '{print $1}' | cut -d "=" -f2 | sed -e 's/^"//' -e 's/"$//'))

If lsblk isn't available for some reason you can also use df and awk:

ROOT_PART=$(df / | awk '/^\/dev/ {print $1}')