So I read through Wiki.
~ ⮀ $ ⮀xbacklight No outputs have backlight property
~ ⮀ $ ⮀ls -a /sys/class/backlight . ..
I'm kinda stuck now. What should I do?
I own Dell Inspiron 15R SE.
Last edited by daGrevis (2013-02-04 11:42:54)
This is normally the case when you are missing graphics drivers. Make sure you have everything you need (maybe re-install the driver for good measure?)
Also, try adding acpi_backlight=vendor or, if that doesn't work, acpi_backlight=legacy as kernel boot parameter and see if it changes anything.
Life's not fair, but the root password helps.
- The BOFH
I added `acpi_osi=Linux acpi_backlight=vendor` to my kernel boot params and woohoo, I have `/sys/class/backlight/dell_backlight/` dir!
There is only one problem. When I try to change the brightness:
~ ⮀ $ ⮀sudo echo 5 > /sys/class/backlight/dell_backlight/brightness
zsh: permission denied: /sys/class/backlight/dell_backlight/brightness
My wild guess is that I'm not in a correct group. Am I right?
Hmm, anyway `echo 5 | sudo tee /sys/class/backlight/dell_backlight/brightness` works w/o being a root.
FYI: echo seems to check for root authority differently then others. Another way to set the brightness to maximum without being root, is to us cp to copy the max_brightness file over the brightness file. This works fine with sudo.
It's not echo, it's because the redirection is not covered by the sudo.
Think of it like (conceptually, if not accurately):
(sudo echo 5) > file
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