xrandr --output [yourscreendevice] --set Backlight 80 However, in my case (maybe because I have 2 video adapter [cpu/amd] ) the latter xrandr command is equivalent to write in /sys/class/backlight/acpi_video0/brightness which doesn't work.
** Changed in: linux (Ubuntu) Status: Expired => Confirmed -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1225811 Title: 1002:6601 [Dell Inspiron 15R 5521] Can't toggle backlight brightness To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1225811/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs