DietPi-Software | Desktops: PolicyKit1 error when logging in as non-root

[MichaIng]

Solution

sed -i 's|/usr/sbin/lightdm|systemctl start lightdm|' /DietPi/dietpi/dietpi-login

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Occurs only when logging in as non-root, e.g. "dietpi".

This then prevents shutdown/reboot from menu.

Ref: https://dietpi.com/phpbb/viewtopic.php?f=11&t=5850

[MichaIng]

Hmm with lxdm login manager on LXDE the issue does not appear. No error + shutdown, reboot etc works well. So it's an issue with LightDM or related autostarts or such.

All I find in web is that this error appears when multiple policykit agents are running. But in your case there is definitely only the lxpolkit up, so the issue is from different kind.

LightDM runs as lightdm user, perhaps a permissions issue?

Jep G_CONFIG_INJECT 'greeter-user=' 'greeter-user=root' /etc/lightdm/lightdm.conf solves the issue. So indeed it seems that either the login user or the LightDM user requires permissions for PolicyKit.

[MichaIng]

Found it: It's the way we start it.

LightDM should be started via: systemctl start lightdm

root@VM-Stretch:/var/log/lightdm# systemctl cat lightdm
# /lib/systemd/system/lightdm.service
[Unit]
Description=Light Display Manager
Documentation=man:lightdm(1)
After=systemd-user-sessions.service

[Service]
# temporary safety check until all DMs are converted to correct
# display-manager.service symlink handling
ExecStartPre=/bin/sh -c '[ "$(cat /etc/X11/default-display-manager 2>/dev/null)" = "/usr/sbin/lightdm" ]'
ExecStart=/usr/sbin/lightdm
Restart=always
BusName=org.freedesktop.DisplayManager

• I guess it has something to do with the BusName, required for communication with PolicyKit1 or such. However easy solution.

[MichaIng]

Solved with: #2917