[redeeman]

assign yourself permission to the device(may or may not happen by default depending on your distribution), and you can actuate it in /sys/class/leds/inputXX::scrolllock/brightness.

probably also exists other tools to do it. this is then generic linux LED framework

[foresto]

I am aware of sysfs LED controls. They don't solve this problem, because access to them requires privileges (or permissions assigned by someone with privileges). It's not reasonable to expect that, just as it's not reasonable to expect a sysadmin to grant users permission to the keyboard device node before they can type anything.

Moreover, granting permissions on the sysfs nodes won't distinguish between a user who is logged in to the current virtual console and one who is not. Wayland correctly delegates keyboard ownership to compositors, but they have no way to expose the keyboard's outputs (the LEDs) because Wayland hasn't yet defined a protocol for doing so.

X11 has a protocol for this, and X servers handle it just fine. They account for different users and LED states on each virtual console, and do not require clients to have any special permissions. It's an area where Wayland fails to be a suitable replacement.