Nexus7 Ubuntu 13.04 backlight brightness control
[System Settings] -> [Brightness & Lock] is not possible to adjust the brightness on.
Enter the terminal
sudo tee /sys/class/backlight/pwm-backlight/brightness
echo 200 | sudo tee /sys/class/backlight/pwm-backlight/brightness
sudo /usr/lib/gnome-settings-daemon/gsd-backlight-helper --set-brightness 200
If you enter 0 to 255 brightness changes.
(Max brightness can be seen with the command.
sudo /usr/lib/gnome-settings-daemon/gsd-backlight-helper --get-max-brightness)
After the [System Settings] -> [Brightness & Lock] in the brightness can be adjusted.
However, after a reboot of 40 brightness changes....-_-;;;;