I disabled a backlight ... .service under two different names over the past few months. But then I would see a problem in journalctl -b -1 or notice a hanging process in the shutdown. The following command did not work.
sudo sytemctl disable systemd-backlight@backlight:acpi_video1.service
however the following worked.
sudo systemctl mask systemd-backlight@backlight:acpi_video1.service
As in man systemctl "This is a stronger version of disable, since it prohibits all kinds of activation of the unit, including enablement and manual activation. Use this option with care." Sounds kind of like kill -9
If anyone has any softer gentler ways to disable backlights - I would appreciate. "mask" is working quite well however. TIA
Edit later via #debian-systemd
<damjan> those backlight services are probably triggered by udev so disabling them didn't mean anything
<damjan> you can still start a disabled service, and that's what udev does (more or less)
man systemd-backlight@.service talks about changing one line
systemd.restore_state=
Takes a boolean argument. Defaults to "1". If "0", does not restore
the backlight settings on boot. However, settings will still be
stored on shutdown.
but that line is not present in my /lib/systemd/system/systemd-backlight@.service file. And it might not work anyway.
I will investigate more via search engines about udev's input into backlighting. From what I read mask is basically ln -s foo.service to /dev/null and that does seem rather kill -9 level.
