Samsung ATIV Book 9 keyboard backlight toggle

backlight.sh

#!/usr/bin/env bash

# Path can depend on laptop model
FILE=/sys/firmware/efi/efivars/KBDBacklitLvl-8be4df61-93ca-11d2-aa0d-00e098032b8c
NOW=$(xxd -p ${FILE})

if [ "0700000000" == "${NOW}" ]; then
  echo 0700000005 | xxd -p -r > ${FILE}
  echo "Backlight enabled"
else
  echo 0700000000 | xxd -p -r > ${FILE}
  echo "Backlight disabled"
fi

echo "Reboot required!"

Please try this https://github.com/k2qwerty2k/samsung-ativbook-kb-led with some changes (need change DMI check for you note).