Brightness is reset to maximum on every restart

Solution 1:

You could try adding a line to /etc/rc.local that will set the desired brightness level. To edit the file, run

sudo -H gedit /etc/rc.local

and add the following

echo X > /sys/class/backlight/intel_backlight/brightness

so that the end result looks like this

#!/bin/sh -e
#
# rc.local
#
# This script is executed at the end of each multiuser runlevel.
# Make sure that the script will "exit 0" on success or any other
# value on error.
#
# In order to enable or disable this script just change the execution
# bits.
#
# By default this script does nothing.

echo X > /sys/class/backlight/intel_backlight/brightness

exit 0

Substitute X by the desired brightness level.

In case /etc/rc.local doesn't exist, as is the case with new Ubuntu releases, you'll need to create it, and make eecutable with the following commands:

printf '%s\n' '#!/bin/bash' 'exit 0' | sudo tee -a /etc/rc.local
sudo chmod +x /etc/rc.local

PS: Alternatively, there may be /sys/class/backlight/acpi_video0/brightness instead of the above. Brightness levels vary wildly, and may range from 0 to 10 or to 1000. To find the maximum value, try

cat /sys/class/backlight/acpi_video0/max_brightness
or
cat /sys/class/backlight/intel_backlight/max_brightness

Solution 2:

I converted my small script for saving and restoring backlight (brightness) level to Ubuntu package. It is located in my PPA and named sysvinit-backlight.
It contains sysvinit init-script, placed in /etc/init.d/sysvinit-backlight.
It is compatible with Ubuntu 12.04 LTS and 14.04 LTS.

For newer versions of Ubuntu my PPA is not needed as they use builtin systemd-backlight service.

You can install my script with the following commands:

sudo add-apt-repository ppa:nrbrtx/sysvinit-backlight
sudo apt-get update
sudo apt-get install sysvinit-backlight

You can remove it by

sudo apt-get purge sysvinit-backlight

Please note: if you have installed the previous version of my script, please remove it by

sudo rm /etc/rc?.d/?25backlight /etc/init.d/brightness /etc/rc?.d/?25brightness

The script functionality is:

• save backlight (brightness) levels of all video adapters and keyboard on reboot and shutdown (runlevel 0 and 6)
• load backlight (brightness) levels for all video adapters and keyboard on boot (runlevels S, 1, 2, 3, 4 and 5)

The script options are:

• sudo service sysvinit-backlight status (show current brightness levels and saved in files values)
• sudo service sysvinit-backlight start (set saved levels from files)
• sudo service sysvinit-backlight stop (save current levels to files)

You can contact me here or on launchpad.

Solution 3:

Easiest way:

1. Open a terminal window.

2. Type in the following command then hit Enter after it.

   sudo apt-get install xbacklight
   

3. Open the Startup Applications Preferences menu.

4. Click the Add button and add the following information:

   • Name: Brightness
   • Command: xbacklight -set 60

5. Replace 60 with whatever brightness level you prefer.

Source: Set Startup Display Brightness

Solution 4:

Before try workarounds in rc.local, it is worth to try the following:

• adding simple: quiet splash acpi_backlight=vendor to grub looks to be enough on my configuration.

  1. sudo gedit /etc/default/grub

  2. replace
     GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
     with
     GRUB_CMDLINE_LINUX_DEFAULT="quiet splash nomodeset acpi_backlight=vendor"

  3. sudo update-grub and reboot.

worked on:

• Ubuntu 12.04 LTS (Asus U31SD-XH51 )
• Ubuntu 14.04 LTS (Dell 14z)
• Ubuntu 14.04 LTS (Lenovo g500, remove nomodeset and it will work fine)