El que te pase... si me funciona. Eso si, lo metí en un zenity para que quedara más interactivo.
Te paso el reporte....
Código BASH:
Ver originallinux-sf0e:/home/sergio/lumimod-master # lumimod
Brillo actual: 51003%
linux-sf0e:/home/sergio/lumimod-master # ls /sys/class/backlight
intel_backlight
linux-sf0e:/home/sergio/lumimod-master # ls /sys/class/backlight/intel_backlight
actual_brightness brightness max_brightness subsystem uevent
bl_power device power type
linux-sf0e:/home/sergio/lumimod-master # cat /sys/class/backlight/intel_backlight/brightness
3984375
linux-sf0e:/home/sergio/lumimod-master # cat /sys/class/backlight/intel_backlight/max_brightness
3984375