本文保留屏幕亮度方法适合使用笔记本的朋友，大家都知道，过亮的屏幕不但刺眼而且缩短LCD屏幕寿命，不幸的是，Ubuntu默认关机后并不保存当前屏幕亮度配置数据，每次开机都要重新设置亮度，很不方便。本文介绍的方法可以彻底解决这个问题！
1.修改/etc/default/acpi-support
ENABLE_LAPTOP_MODE=true
2.修改 /etc/laptop-mode/laptop-mode.conf
交流电模式下使用 laptop mode
#
# Enable laptop mode when on AC power.
#
ENABLE_LAPTOP_MODE_ON_AC=1
＃电池那也可设为1
使用 laptop mode 进行LCD亮度控制
#
# Should laptop mode tools control LCD brightness?
#
CONTROL_BRIGHTNESS=1
#
# Commands to execute to set the brightness on your LCD
#
BATT_BRIGHTNESS_COMMAND=”echo 0″
LM_AC_BRIGHTNESS_COMMAND=”echo 9″
NOLM_AC_BRIGHTNESS_COMMAND=”echo 9″
BRIGHTNESS_OUTPUT=”/sys/class/backlight/acpi_video1/brightness”
如果你不明白上面的设置的意思，可以参考下面的说明：
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# * If your system has the file “/proc/acpi/video/VID/LCD/brightness” (VID may
# be VID1 or similar), use this file as BRIGHTNESS_OUTPUT, and use
# the command “echo “. The possible values can be listed using the
# command:
#
# cat /proc/acpi/video/VID/LCD/brightness
# * If you have a file /sys/class/backlight/…/brightness, then you can use
# that file as BRIGHTNESS_OUTPUT, and the command “echo “.
#
# As far as I understand it the values are between 0 and
# the value contained in the file /sys/class/backlight/…/max_brightness.
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