λ /var/log$ sudo tail lightdm/lightdm.log
[+0.19s] DEBUG: Creating shared data directory /var/lib/lightdm-data/lightdm
[+0.19s] DEBUG: Session pid=6582: Logging to /var/log/lightdm/x-0-greeter.log
[+0.24s] DEBUG: Activating VT 7
[+0.24s] DEBUG: Activating login1 session c3
[+0.39s] DEBUG: Session pid=6582: Greeter connected version=1.10.5
[+0.47s] DEBUG: Session pid=6582: Exited with return value 0
[+0.47s] DEBUG: Seat: Session stopped
[+0.47s] DEBUG: Seat: Stopping; failed to start a greeter
[+0.47s] DEBUG: Seat: Stopping
[+0.47s] DEBUG: Seat: Stopping display server
[+0.47s] DEBUG: Sending signal 15 to process 6567
[+0.62s] DEBUG: Process 6567 exited with return value 0
[+0.62s] DEBUG: DisplayServer x-0: X server stopped
[+0.62s] DEBUG: Releasing VT 7
[+0.62s] DEBUG: DisplayServer x-0: Removing X server authority /var/run/lightdm/root/:0
[+0.62s] DEBUG: Seat: Display server stopped
[+0.62s] DEBUG: Seat: Stopped
[+0.62s] DEBUG: Required seat has stopped
[+0.62s] DEBUG: Stopping display manager
[+0.62s] DEBUG: Display manager stopped
[+0.62s] DEBUG: Stopping daemon
[+0.63s] DEBUG: Exiting with return value 1