LightDM

Default display manager for Ubuntu.

Sources

Desktop chosen on last login:

echo $GDMSESSION

Configuration file:

less /etc/lightdm/lightdm.conf

Don't edit the configuration file directly, use this instead:

sudo /usr/lib/lightdm/lightdm-set-defaults --hide-users true

Options:

allow-guest
--autologin-user <username>: auto-login the given user at startup without asking for password.
```
sudo /usr/lib/lightdm/lightdm-set-defaults --autologin "$USER"
```
--session <session>: which session to log into. Examples: Ubuntu, LXDE, etc.

The possibilities can be found at:
```
ls /usr/share/xsessions
```
display-setup-script=[script|command]
--hide-users <true-false>: if false, don't show user list to select from.

This prevent users from discovering the names of all users on the system.

Restart LightDM:

sudo restart lightdm

Also restarts X. Closes all your programs that have windows.

Only do this on a tty, not on an xterminal probably because your terminal is going to die in the middle of the operation

log files

When things go wrong... First go to a TTY with Ctrl + Alt + F2, then check:

And also check /var/log/Xorg.X.log, as X problems can cause login to fail.