linux--Screen Brightness adjustment

After solving the problem of wireless network card, and encountered a new problem, in Ubuntu, can not adjust the screen brightness, using the function keys to see the screen brightness adjustment of the prompt box, but the brightness of the screen has not changed. After a half-day study, there is a way to solve the problem:

1. In fact, under Ubuntu, you can modify the screen brightness by command: "Echo >/sys/class/backlight/acpi_video0/brightness", this command means to set the screen brightness to the maximum value of 10. (The maximum value is saved in the max_brightness file)

2. Unfortunately, the order was executed without any effect. And, in fact, by adjusting the brightness through the shortcut keys, the contents of the file will change as well. That means we've got the wrong device.

3. I found that in the/sys/class/backlight directory, there is another folder, Intel_backlight, using the same command, try to adjust the brightness: "Echo >/sys/class/backlight/ Intel_backlight/brightness ", Effective! (Note that the maximum brightness for this device is 975, so we wrote 500)

4. Test Success! So how can we tell the system that we should use intel_backlight instead of Acpi_video0? Simply, when grub loads the kernel, the e command temporarily modifies the startup script under "Linux/boot/vmlinuz-3.2.0-30-generic root=uuid= 75C414BE-2E17-407A-B699-94F6A398DFF7 ro Acpi_backlight=vendor Quiet Splash "added bold characters.

5. If it goes smoothly, after entering the system, it should be able to adjust the brightness normally, then we can make permanent changes to grub: Edit the file/etc/default/grub, change this line to:

[Plain]View Plaincopyprint?

1. grub_cmdline_linux= "Acpi_backlight=vendor"

Then, update the next grub: "Update-grub" and restart the test.

In the course of the study, reference was made to these two articles:

-Http://www.cnblogs.com/congbo/archive/2012/09/12/2682308.html

-http://blog.csdn.net/linuxzhouying/article/details/7177200: Note that after I joined Nomodeset, Ubuntu will become abnormal, and acpi_ Backlight must be added to the RO, otherwise it is not normal.

Today inadvertently found their ubuntu10.10 system can not adjust the screen brightness, the thing is, I installed the XP and Linux/ubuntu dual system, I use XP system, in order to make the battery longer time, the screen adjust the darker. When I rebooted into the Ubuntu system the screen also became very dark (should be XP on the video card adjustment information in the video card device is saved), but I use Ubuntu brightness adjustment button but found that although the adjustment brightness progress bar is changing, but the screen brightness does not reflect.
My video card is NVs 3100M, in the online toss a bit, found that as long as the/etc/x11/xorg.conf to add a line of configuration information:
Option "Registrydwords" "enablebrightnesscontrol=1"
As follows:


Then log out of the Ubuntu system and log in again.
Note the hardware and system information under Ubuntu:
View motherboard information: LSPCI
View CPU Information: Cat/proc/cpuinfo
View hard Drive Model information: Cat/proc/ide # (IDE hard drive) or CAT/PROC/SCSI # (SCSI HDD)
View memory Information: Cat/proc/meminfo
View video card information: LSPCI | grep VGA
View System version number: Lsb_release-a