Set default screen brightness on Lenovo X220

Okay. Which of the following commands affect brightness?

Code:

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echo 15 | sudo tee /sys/class/backlight/acpi_video0/brightness

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Code:

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echo 6 | sudo tee /sys/class/backlight/acpi_video0/brightness

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Code:

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echo 2324 | sudo tee /sys/class/backlight/intel_backlight/brightness

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Code:

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echo 4648 | sudo tee /sys/class/backlight/intel_backlight/brightness

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The following commands affected me this way...

Maximized brightness.

Code:

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echo 15 | sudo tee /sys/class/backlight/acpi_video0/brightness

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O.O - Set to current brightness

Code:

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echo 6 | sudo tee /sys/class/backlight/acpi_video0/brightness

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I guess the best I can do is have the computer start at optimal brightness, not where I left off.

Quote:

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Originally Posted by epikvision

I guess the best I can do is have the computer start at optimal brightness, not where I left off.

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To do so, edit /etc/rc.local and above the exit 0 command, add the line:

Code:

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echo 6 > /sys/class/backlight/acpi_video0/brightness

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Quote:

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Originally Posted by Toz

To do so, edit /etc/rc.local and above the exit 0 command, add the line:

Code:

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echo 6 > /sys/class/backlight/acpi_video0/brightness

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I did that, but it didn't work. This is what I got from running the script.

Code:

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john@kotux:/etc$ sudo ./rc.local
./rc.local: 14: ./rc.local: cannot create /sys/class/backlight/acpi_vide0/brightness: Directory nonexistent

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try installing xbacklight and use lightdm to set it
xbacklight -set 50
the 50 is a percentage

Code:

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~$ cat /etc/lightdm/lightdm.conf
[SeatDefaults]
greeter-session=lightdm-gtk-greeter
user-session=xubuntu
greeter-setup-script = sh -c 'xbacklight -set 50'

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Quote:

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Originally Posted by epikvision

I did that, but it didn't work. This is what I got from running the script.

Code:

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john@kotux:/etc$ sudo ./rc.local
./rc.local: 14: ./rc.local: cannot create /sys/class/backlight/acpi_vide0/brightness: Directory nonexistent

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You misspelled acpi_video0. The command should be:

Code:

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echo 6 > /sys/class/backlight/acpi_video0/brightness

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Quote:

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Originally Posted by Toz

You misspelled acpi_video0. The command should be:

Code:

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echo 6 > /sys/class/backlight/acpi_video0/brightness

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Wow, all it took was a typo... Anyway, now it's all good. I'll consider the lightdm solution too for another machine, but finally, this issue has been conquered.

Before I mark the thread as 'solved,' I would like to know if there is any development happening to allow screen brightness to match that of the current session by startup.

Quote:

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Originally Posted by epikvision

Before I mark the thread as 'solved,' I would like to know if there is any development happening to allow screen brightness to match that of the current session by startup.

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I was hoping to solve this particular issue by using a kernel parameter. However, none seemed to work for your system. Hence the workaround. You may want to create a bug report if you want to follow up with a proper solution.