Every time I reboot my laptop the brightness goes back to 100% in Gnome. I wish it would keep the last one setting. Here is a quick workaround for that:-) edit the /etc/rc.local file by typing: vim /etc/rc.local and add the following line:
echo 5 > /sys/class/backlight/acpi_video0/brightness
It looks like this:
root@ProBook:~# cat /sys/class/backlight/acpi_video0/brightness
20
root@ProBook:~# echo 5 > /sys/class/backlight/acpi_video0/brightness
root@ProBook:~# vim /etc/rc.local
root@ProBook:~# cat /etc/rc.local
#!/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 12 > /sys/class/backlight/acpi_video0/brightness
exit 0
root@ProBook:~#
After the reboot the Gnome keeps our settings 🙂