调节亮度
sudo vim /etc/X11/xorg.conf
加一句：Option "RegistryDwords" "EnableBrightnessControl=1"
保存亮度
1、解决reboot后无法保存屏幕亮度：
sudo gedit /etc/rc.local
插入这句话到代码中：
echo 0 > /sys/class/backlight/acpi_video0/brightness
如下：
#!/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 0 > /sys/class/backlight/acpi_video0/brightness
exit 0
其中echo 后面的值为0-10，对应为0到100%,如echo 5表示一半亮度
保存后退出，重启就可以了。
注意：大多数人都是acpi_video0，根据自己/sys/class/backlight/下面文件决定
2、亮度调节
亮度调节依赖与你的bios和内核版本，你可以尝试以下代码：
kernel boot选项：
当你启动系统时，出现在grup的屏幕时，按e键进行编辑，在kernel这一行添加：
nomodeset acpi_backlight=vendor
Intel - nomodeset acpi_backlight=intel Acer - acpi_backlight=acer_acpi or even acpi_osi=Linux acpi_backlight=legacy.
quiet splash nomodeset acpi_backlight=vendor
# command line
sudo -e /etc/default/grub
# graphical
gksu gedit /etc/default/grub
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash nomodeset acpi_backlight=vendor"
