Xubuntu
- /etc/lightdm/lightdm.conf
[SeatDefaults] autologin-user=<USERNAME> autologin-user-timeout=0 user-session=xubuntu greeter-session=lightdm-gtk-greeter
[SeatDefaults] autologin-user=<USERNAME> autologin-user-timeout=0 user-session=xubuntu greeter-session=lightdm-gtk-greeter