Using Gnome gsettings on GDM user

Written on April 10, 2018

Arch GDM wiki suggests that if you need to change some config for gdm, that must be done on gdm user. As a first option, it’s suggested that you run the command below to get shell access to gdm:

# machinectl shell gdm@

That’s unfortunally is not working:

Connected to the local host. Press ^] three times within 1s to exit session.
/sbin/nologin: invalid option -- 'l'
Try 'nologin --help' for more information.
Connection to the local host terminated.terminated

A bug has been filed on upstream already, so that should be a matter of time to get it fixed on next systemd release.

An alternative for that is running su enforcing a different shell:

# su gdm -s /bin/sh -c 'gsettings set org.gnome.desktop.interface scaling-factor 2' 

However, it fails me:

(process:10904): dconf-WARNING **: 04:08:52.321: failed to commit changes to dconf: Cannot autolaunch D-Bus without X11 $DISPLAY

After some googling, I found a fix to that issue. We basically need to ensure that dbus is running by prepending the command with dbus-launch.

su gdm -s /bin/sh -c 'dbus-launch gsettings set org.gnome.desktop.interface scaling-factor 2'

This should do the trick.