How to set up automatic login in Linux with SDDM

SDDM is an X11 and Wayland display manager based on QML.

In my Linux installations, the SDDM display manager performed better than GDM, LightDM. So if you're having trouble with other display managers, try SDDM.

Make sure that the OS uses SDDM:

systemctl status display-manager

The line

sddm.service - Simple Desktop Display Manager

confirms that SDDM is used as the display manager on this Linux.

SDDM supports automatic login using the configuration file of this display manager.

For the configuration file, you need to know the values of two variables:

• Linux username to be automatically logged in
• session name (which desktop environment to run)

To find out the name of the current user in the OS, run the following command:

echo $USER

In my example username:

mial

To find out the session names for X, run the command:

ls -l /usr/share/xsessions/

To find out session names for Wayland, run the command:

ls -l /usr/share/wayland-sessions/

I want to use X session, available on my system are:

• cinnamon2d
• cinnamon
• gnome-xorg

From this list, I choose cinnamon.

Now we need to edit the /etc/sddm.conf.d/autologin.conf file. If this file does not exist, then create it. The /etc/sddm.conf.d/ directory may also not be present on your system. If so, then first create it:

sudo mkdir /etc/sddm.conf.d/

Now open the file for editing or create it:

sudo gedit /etc/sddm.conf.d/autologin.conf

Add the following lines to this file:

[Autologin]
User=USER
Session=SESSION

Where:

• USER is the username
• SESSION is the X or Wayland session

In my case it turned out like this:

[Autologin]
User=mial
Session=cinnamon

Save and close the file.

Restart your computer to verify that automatic login is now working: