Plasma Login Manager

From the Plasma Login Manager upstream page:

Plasma Login provides a display manager for KDE Plasma, forked from SDDM and with a new front-end providing a greeter, wallpaper plugin integration and System Settings module (KCM).

Installation

Install the plasma-login-manager package.

Follow Display manager#Loading the display manager to start Plasma Login Manager at boot.

Tip

If migrating from SDDM, remember to disable sddm.service first.

After completing the migration, you can also clean-up and delete the sddm user, which would no longer be used, with the command userdel -r sddm as the root user.

Configuration

After installation, a new section called Login Screen is added to the System Settings app, allowing it to be configured graphically.

To modify it manually, create a configuration file in /etc/plasmalogin.conf. Alternatively, drop configuration files in /etc/plasmalogin.conf.d/.

Custom wallpaper plugins

The KCM (System Settings module) for Plasma Login Manager may fail to list third-party or custom wallpaper plugins, even if they are correctly installed to /usr/share/plasma/wallpapers/.

To use a custom wallpaper plugin in this case: manually specify the plugin ID in the configuration file. Identify the plugin ID (folder name in /usr/share/plasma/wallpapers/ or the Id field in the plugin's metadata.json file). Edit the configuration file as follows:

/etc/plasmalogin.conf

[Greeter]
WallpaperPluginId=your.plugin.id

Save the file and log out or reboot to verify the changes.

Autologin

Plasma Login supports automatic login through its configuration file. For example:

/etc/plasmalogin.conf.d/autologin.conf

[Autologin]
User=john
Session=plasma.desktop

This configuration causes a KDE Plasma session to be started for user john when the system is booted. Available session types can be found in /usr/share/xsessions/ for X and in /usr/share/wayland-sessions/ for Wayland.

To automatically log in to KDE Plasma while simultaneously locking the session (e.g. to allow autostarted apps to warm up), see KDE#Lock screen.

Passwordless login

It is possible to configure Plasma Login to allow logging into some accounts without a password. This differs from automatic login in that the user still has to choose which account to log into, and it differs from simply setting the account password to the empty string in that it only allows interactive users to log in (and not, for example, remote users logged in via SSH).

Plasma Login goes through PAM so you have to create a Plasma Login configuration file /etc/pam.d/plasmalogin for PAM:

/etc/pam.d/plasmalogin

#%PAM-1.0
auth       sufficient   pam_succeed_if.so user ingroup nopasswdlogin
auth       include      system-login
account    include      system-login
session    include      system-login
password   include      system-login

In order to allow unlocking the KDE Plasma lock screen without a password, also create a KDE configuration file /etc/pam.d/kde for PAM:

/etc/pam.d/kde

#%PAM-1.0
auth       sufficient   pam_succeed_if.so user ingroup nopasswdlogin
auth       include      system-login
account    include      system-login
session    include      system-login
password   include      system-login

You must then also be part of the nopasswdlogin user group to be able to login interactively without entering your password.

Unlock KDE Wallet automatically on login

See KDE Wallet#Unlock KDE Wallet automatically on login.