[arch-general] Systemd screen brightness

[Norbert Zeh]

Aurko Roy [2012.08.15 2040 +0530]:
> On Wed, Aug 15, 2012 at 4:45 PM, Norbert Zeh <nzeh at cs.dal.ca> wrote:
> 
> >
> > You can achieve the same by adding the instructions to write to
> > /sys/class/backlight/acpi_video0/brightness to an appropriate file in
> > tmpfiles.d.
> > Read the section on temporary files in the systemd page on the archwiki.
> >
> > Cheers,
> > Norbert
> >
> >
> Thanks for the reference. So something like
> 
> 'w /sys/class/backlight/acpi_video0/brightness - - - - 0'
> 
> should do the job, except that /sys/class/backlight/acpi_video0 does not
> exist since acpi does not seem to be running (I recall reading somewhere
> that systemd handles most acpi functionality, is that correct?).

My apologies.  I wasn't aware that the particular file you're trying to write to
exists only if acpid is running.  I personally went back to running acpid
because systemd's handling of ACPI events is too rudimentary for my needs.  As
far as I understand from the manpage, you can only set under which conditions it
should handle Lid/Sleep/Power button events.  If these conditions are met,
systemd handles these events the way systemd thinks they should be handled, and
there seems to be no room to customize it.  Since I never ever shut down my
laptop except using "halt" or now "systemctl poweroff", I found it convenient to
set the action for power button events to be to put the machine to sleep, as
this avoids the finger gymnastics required to activate the sleep button.  This
type of customization is possible using acpid but doesn't seem to be possible
using systemd alone.

Cheers,
Norbert