FunKey-OS/FunKey/board/funkey/rootfs-overlay/usr/local/sbin/brightness_get_sysfs

#!/bin/sh

SYSTEM_BRIGHTNESS=/sys/class/backlight/backlight/brightness

# Check args
if [ ${#} -ne 0 ]; then
    echo "Usage: $(basename ${0})"
    exit 1
fi

let brightness=$(cat ${SYSTEM_BRIGHTNESS})*10-10
echo ${brightness}
exit 0