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o5gmmob8
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Joined: 17 Oct 2003
Posts: 539
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 Posted: Tue Feb 11, 2025 1:01 pm Post subject: [SOLVED] chgrp / chmod brightness so xbacklight works |
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I installed acpilight and changed the permissions on the file:
/sys/devices/pci0000:00/0000:00:02.0/drm/card0/card0-eDP-1/intel_backlight/brightness
to be :video
664
That seems a bit hackish, is there a better way to do it?
Last edited by o5gmmob8 on Wed Feb 12, 2025 4:47 pm; edited 1 time in total |
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Ralphred
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Joined: 31 Dec 2013
Posts: 725
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| Posted: Tue Feb 11, 2025 5:03 pm Post subject: |
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| Quote: | | That seems a bit hackish, is there a better way to do it? |
Adding a udev rule to set the mode and group owner on "add" would be using udev "as intended", but for something that only gets added once local.d is much less work... |
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o5gmmob8
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Joined: 17 Oct 2003
Posts: 539
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| Posted: Tue Feb 11, 2025 5:08 pm Post subject: |
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Fair point.
That device is 'added' every time the system boots, though, right? Is that what you're proposing then, or were you completely advocating for hard-coding the path?
| Code: | | find /sys/devices/ -type f -path '*/*_backlight/brightness' -exec chmod 664 {} + |
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Ralphred
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Joined: 31 Dec 2013
Posts: 725
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| Posted: Wed Feb 12, 2025 12:34 pm Post subject: |
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| o5gmmob8 wrote: | | That device is 'added' every time the system boots, though, right? |
Yep | Quote: | | Is that what you're proposing then? |
Yeah, my udev-foo is weak, it takes me forever to make them work, but by combining two rules I have that do work with the info you've provided | /etc/udev/rules.d/XY-backlight-permissions.rules: | | DEVPATH=="/devices/pci0000:00/0000:00:02.0/drm/card0/card0-eDP-1/intel_backlight/brightness", ACTION=="add", MODE="0664", GROUP="video" |
should* work. If the path is wont to change then you can glob parts of it so "/devices/pci*intel_backlight/brightness" should also match.
*I've only ever used DEVPATH== to run scripts on certain devices being added, but MODE and GROUP directives should work as far as I know. |
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o5gmmob8
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Joined: 17 Oct 2003
Posts: 539
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| Posted: Wed Feb 12, 2025 4:45 pm Post subject: |
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I agree with you, there isn't a singular way to do this and for me, udev rules are much less understood by me than cron or local.d. So, I will heed your advice and put this in /etc/local.d. I believe for some reason I historically put startup scripts in crontab for some reason and that requires slightly more complexity because you must specify @reboot. Then, if cron isn't running, it becomes a bit more involved to troubleshoot.
It'd just be easier to drop it in /etc/local.d and be done with it. |
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