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How do I write a udev rule to persist an attribute on boot?

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Josiah Sprague

I want to persist the value of /sys/devices/platform/lg-laptop/fn_lock to be 1 after a reboot. After doing a lot of research, it seems that the right way to do this is to create a udev rule for it. So I ran udevadm info -a -p /sys/devices/platform/lg-laptop/ which returns this:

looking at device '/devices/platform/lg-laptop':
    KERNEL=="lg-laptop"
    SUBSYSTEM=="platform"
    DRIVER=="lg-laptop"
    ATTR{battery_care_limit}=="0"
    ATTR{driver_override}=="(null)"
    ATTR{fan_mode}=="0"
    ATTR{fn_lock}=="0"

And I made a file /etc/udev/rules.d/99-fnlock.rules with the following content:

ACTION=="change", KERNEL=="lg-laptop", SUBSYSTEM=="platform", ATTRS{fn_lock}="1"

But it doesn't seem to have any effect when I reboot. Is my syntax wrong, or am I misunderstanding how to set attributes with udev?

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th flag
Josiah Sprague

The correct syntax for the rules file was:

SUBSYSTEM=="platform", DRIVER=="lg-laptop", ATTR{fn_lock}="1"

I think my mistake was probably ATTRS{fn_lock} instead of ATTR{fn_lock}, since the matching rules (ones with == operator) seem to be a bit flexible.

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user.dz
It will be easier to find, if set as accepted. Thank you for sharing the solution.
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