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Ubuntu调整及保存屏幕亮度失败怎么办?

  在Ubuntu系统中,有时会因为屏幕太亮或太暗需要调节屏幕亮度, 却发现屏幕亮度无法调整,或调整后无法保存,遇到这种问题该如何解决呢?

 Ubuntu调整及保存屏幕亮度失败怎么办?

  测试环境:

  Acer Aspire 5750G

  NVIDIA GeForce GT630M

  Ubuntu 12.04 x86_64

  其他情况解决方法类似。

  调节屏幕亮度

  Fn不能调节屏幕的亮度。因为fn调节的是/sys/class/backlight/acpi_video0/brightness文件,而I卡的文件是/sys/class/backlight/intel_backlight/brightness。

  一、测试代码

  启动系统,出现grub菜单时,按“e”编辑,在有linux内核路径那一行,添加“acpi_backlight=vendor”,如:

  linux /boot/vmlinuz-3.2.0-30-generic root=UUID=75c414be-2e17-407a-b699-94f6a398dff7 ro acpi_backlight=vendor quiet splash

  如果能正常启动,且用fn能调节屏幕亮度,说明成功,接着下一步。

  二、修改grub

  sudo vi /etc/default/grub

  找到:

  GRUB_CMDLINE_LINUX=“”

  改为:

  GRUB_CMDLINE_LINUX=“acpi_backlight=vendor“

  我的grub文件如下:

  # If you change this file, run ‘update-grub’ afterwards to update

  # /boot/grub/grub.cfg.

  # For full documentation of the options in this file, see:

  # info -f grub -n ‘Simple configuration’

  GRUB_DEFAULT=0

  #GRUB_HIDDEN_TIMEOUT=0

  GRUB_HIDDEN_TIMEOUT_QUIET=true

  GRUB_TIMEOUT=3

  GRUB_DISTRIBUTOR=`lsb_release -i -s 2》 /dev/null || echo Debian`

  GRUB_CMDLINE_LINUX_DEFAULT=”quiet splash“

  GRUB_CMDLINE_LINUX=”acpi_backlight=vendor“

  # Uncomment to enable BadRAM filtering, modify to suit your needs

  # This works with Linux (no patch required) and with any kernel that obtains

  # the memory map information from GRUB (GNU Mach, kernel of FreeBSD 。。。)

  #GRUB_BADRAM=”0x01234567,0xfefefefe,0x89abcdef,0xefefefef“

  # Uncomment to disable graphical terminal (grub-pc only)

  #GRUB_TERMINAL=console

  # The resolution used on graphical terminal

  # note that you can use only modes which your graphic card supports via VBE

  # you can see them in real GRUB with the command `vbeinfo‘

  #GRUB_GFXMODE=640×480

  # Uncomment if you don’t want GRUB to pass ”root=UUID=xxx“ parameter to Linux

  #GRUB_DISABLE_LINUX_UUID=true

  # Uncomment to disable generation of recovery mode menu entries

  #GRUB_DISABLE_RECOVERY=”true“

  # Uncomment to get a beep at grub start

  #GRUB_INIT_TUNE=”480 440 1“

  更新grub.cfg

  ➜ ~ sudo update-grub

  查看grub.cfg 发现其中每个启动项都加入了“acpi_backlight=vendor”

  ➜ ~ vi /boot/grub/grub.cfg

  设定屏幕初始亮度

  重启后发现,屏幕亮度又恢复为最大亮度。

  查看影响屏幕亮度的文件

  ➜ ~ vi /sys/class/backlight/intel_backlight/brightness

  调节几次屏幕亮度发现其中数值会改变,我的笔记本数值范围为0~976。

  手动修改该数值,会发现屏幕亮度随之改变(需要root用户执行):

  ➜ ~ su

  Password:

  root@ www.linuxidc.com :/home/congbo# echo 500 》 /sys/class/backlight/intel_backlight/brightness

  因此,将该语句添加到 /etc/rc.local 就能开机自动设定屏幕初始亮度了。

  修改/etc/rc.local如下(需要root用户执行):

  #!/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 500 》 /sys/class/backlight/intel_backlight/brightness

  exit 0

  调节gamma值

  ➜ ~ xgamma -gamma .7

  -》 Red 1.000, Green 1.000, Blue 1.000

  《- Red 0.700, Green 0.700, Blue 0.700

  上面就是Ubuntu调节及保存屏幕亮度失败的解决方法了,出现这种问题的时候,先测试代码,再修改grub即可。

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