Comment 3 for bug 860003

The greeters were moved to /usr/sbin but the PATH only contains /usr/lib/lightdm/lightdm:/usr/local/bin:/usr/bin:/bin. They used to be in libexecdir which is manually added to the path in session.c:session_start.

The greeter log at ~/.cache/lightdm/log/:1-greeter.log contains:

exec: 33: lightdm-gtk-greeter: not found

which is from /usr/lib/lightdm/lightdm-greeter-session. As a workaround until this is fixed, adding /usr/sbin to PATH before the exec on line 33 in that file will allow the greeter to start.

This isn't an issue when lightdm runs normally because /usr/sbin is part of the environment received from pam, but some of the setup is skipped in the --test-mode session, and in the log above the pam environment is empty.