This script will copy brightness settings from source device to destination device.
Copy process is required for me because I have two graphic cards. One is integrated intel and second is amd radeon. When xfce power manager decides on what device brightness should be set it uses first available (I think). For me it decides to use intel card which is not used for display.
I haven't found any working solution which will allow to select on destination device in xfce power manager. To make this work I decided to write simple bash script which will monitor for changes in intel_backlight (acpi_video1) and copy current brightness level to destination decided. So it will copy brightness level from intel card to amd card.
ionotify binary must be installed:
sudo apt-get install
copy backlight-copy to /usr/local/sbin copy backlight-copy.init.d to /etc/init.d directory and configure this script to be executed on boot.
sudo cp backlight-copy /usr/local/sbin
sudo cp backlight-copy.init.d /etc/init.d/backlight-copy
sudo update-rc.d backlight-copy defaultsand that's all now when you change brightness level using fn keys intel brightness settings will be copied to radeon card.