I install the backbox linux in my HP Satellite L55 and confuse with the display brightness setting. It goes too bright for my eyes. And can’t find the setting to lower it down.

I install xbacklight and try to set it. But it was not work.

The setting that I need to add is in the grub boot loader menu.

The source is here.

acpi_backlight=vendor

Write the line in /etc/default/grub at line which contain :

GRUB_CMDLINE_LINUX_DEFAULT=”splash acpi_backlight=vendor”

then update the grub and reboot

sudo update-grub