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linux mint 13 lightdm login screen

A few days ago, we've posted an article on how to install MDM (Mint Display Manager) in Ubuntu, and according to the comments, some Linux Mint users don't like MDM and further more, there's a bug and MDM crashes for some users, so here's the reverse too: how to use LightDM instead of MDM in Linux Mint.

Replace Mint Display Manager (MDM) with LightDM in Linux Mint

The instructions below work under both Linux Mint Cinnamon edition and MATE edition.

1. Install LightDM.

To install LightDM and the required packages to use it in Linux Mint Cinnamon / MATE, use the following command:
sudo apt-get install lightdm gnome-settings-daemon indicator-session unity-greeter ubuntu-mono light-themes
During the installation, you'll be asked if you want to use MDM or LightDM as the default display manager - here, select LightDM:

lightdm mdm

In my test, "unity-greeter" was set as default (as it should be) for Linux Mint 13 Cinnamon edition, but not for the MATE edition, which causes LightDM not to start. So let's check to see if "unity-greeter" is used at the default greeter by opening the "/etc/lightdm/lightdm.conf":
gksu gedit /etc/lightdm/lightdm.conf

This is how the file should look like:

(the last line should say "mate" if you're using MATE edition or "cinnamon" if you're using the Cinnamon edition). If the "greeter-session" is not set to "unity-greeter" like above, modify the file and save it.

2. Optional: remove the Ubuntu logo.

The Ubuntu logo is displayed by default in the LightDM login screen, and since you're using Linux Mint, you may not want this. To remove it (we won't remove it from the filesystem, just rename it), use the command below:
sudo mv /usr/share/unity-greeter/logo.png /usr/share/unity-greeter/logo.png.old
Update: or you can use a Linux Mint logo instead - see THIS Linux Mint forums post (thanks to bimsebasse!).

3. Optional: remove the "Guest Session" entry.

If you want to remove the "Guest Session" entry from the LightDM login screen, you can edit the /etc/lightdm/lightdm.conf file and add "allow-guest=false" (without the quotes) at the bottom of t he file. To do this, open /etc/lightdm/lightdm.conf with a text editor:
gksu gedit /etc/lightdm/lightdm.conf
and add "allow-guest=false" at the bottom of the file. Here's how the file should look after editing it:
When you're done, save the file.

4. Restart your computer and LightDM should be used by default instead of Mint Display Manager (MDM).

Switching back to MDM from LightDM

If you don't want to use LightDM anymore and want to go back to using Mint Display Manager, all you have to do is run:
sudo dpkg-reconfigure mdm
and then select MDM.

More info about this, here: How To Switch Between GDM, LightDM Or KDM In Ubuntu.

Thanks to Burjans for the tip; via com-sl.org