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How to restore backlight brightness automatically?

asked 2017-02-19 05:20:29 -0500

phobos13 gravatar image

updated 2017-02-19 12:28:02 -0500

Hi, I realized that on my laptop the backlight brightness gets properly saved here:

/var/lib/systemd/backlight/pci-0000:00:02.0:backlight:intel_backlight

But it doesn't get restored after reboot. Here's the status of the related service:

$ systemctl status systemd-backlight@backlight:intel_backlight.service
● systemd-backlight@backlight:intel_backlight.service - Load/Save Screen Backlight Brightness of backlight:intel_backlight
   Loaded: loaded (/usr/lib/systemd/system/systemd-backlight@.service; static; vendor preset: disabled)
   Active: active (exited) since So 2017-02-19 11:43:07 CET; 14min ago
     Docs: man:systemd-backlight@.service(8)
  Process: 671 ExecStart=/usr/lib/systemd/systemd-backlight load %i (code=exited, status=0/SUCCESS)
 Main PID: 671 (code=exited, status=0/SUCCESS)

Sure, I could copy the stored brightness to

/sys/class/backlight/intel_backlight/brightness

by myself, but I would like my OS to do this.

Any ideas?

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answered 2017-02-20 14:23:47 -0500

You can do that using rc.local ( https://ask.fedoraproject.org/en/ques... )

sudo touch /etc/rc.d/rc.local
sudo echo '!#/bin/bash' > /etc/rc.d/rc.local
sudo echo 'echo 700 > /sys/class/backlight/intel_backlight/brightness' >> /etc/rc.d/rc.local
sudo echo 'exit 0' >> /etc/rc.d/rc.local
sudo chmod +x /etc/rc.d/rc.local

This changes the brightness to 700 every-time you reboot, you can change the value (here 700) as per your needs!

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Comments

Thanks for your answer but as mentioned above I already know how to do it this way. I'm looking for the reason why systemd fails to do it right. As far as I know the related service is based on a udev rule in /lib/udev/rules.d/99-systemd.rules:

SUBSYSTEM=="backlight", TAG+="systemd", IMPORT{builtin}="path_id", ENV{SYSTEMD_WANTS}+="systemd-backlight@backlight:$name.service"

Maybe this rule is just broken or incomplete?

phobos13 gravatar imagephobos13 ( 2017-02-22 14:06:16 -0500 )edit

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Asked: 2017-02-19 05:20:29 -0500

Seen: 353 times

Last updated: Feb 19 '17