SDDM vs. LightDM – Which is Best?

The DM in SDDM and LightDM stands for display manager. A display manager manages user logins and graphic display servers, and it is used to begin a session on an X server, using the same or a different computer. The user is presented with a login screen in a DM, and the session can start when the user enters valid credentials, i.e. their password and username.

There are many different display managers and it is sometimes difficult to choose the right one, but the most prominent ones are SDDM and LightDM. Keep reading to find out what each of them brings to the table, and you will also learn how to change between them.

SDDM: The Basics

Simple Desktop Display Manager is the default graphical login program for KDE desktop, also called Plasma. It operates on Wayland windowing systems and X11 systems. It is quick, easy to use, beautifully designed. It also offers customization, with a wide range of themes.

Its base is Qt and the QML language. SDDM is the default DM not just for KDE, but LXQt as well, which are both based on Qt environments for desktop. It was written from the ground up in C++11.

If you want to install SDDM, you can login as root or you can use the following command to install it:

sudo apt-get install sddm

You’ll be prompted to enter your password and confirm the installation, just type ‘y‘ and press Enter.

Once the installation is complete, a new window should appear asking you to set your default display manager. Select sddm and then Ok.

You can also change any Ubuntu or Debian Linux distribution default display manager. There is a tool for reconfiguration if you already installed a package and want to switch to it. Use the following command to switch the default display manager to SDDM:

sudo dpkg-reconfigure sddm

The same window as above will appear, prompting you to select your default display manager.

LightDM: The Basics

LightDM is another cross-desktop DM. It is a GDM alternative developed by Canonical. Unsurprisingly, the main feature of this display manager is that it’s light-weight, which means it offers great performance while using little memory. Additionally, it is very customizable, much like SSDM.

It has Qt and Gtk support. Besides various desktop technologies, it also supports various display technology, such as Wayland, Mir, and X windowing systems. The complexity of code in this display manager is not that high.

Other features which are supported include remote login, as well as sessions from guest users. Themes are rendered using a web kit. Finally, it is completely independent of Gnome.

Here is how you can install LightDM, you can login as root or you can use the following command to install it:

sudo apt-get install lightdm

Again, enter your password when prompted and then ‘y‘ to confirm the installation. The same display manager window will appear after installation and prompt you to select your choice.

As with SDDM, you can make LightDM your default display manager. Use this command:

sudo dpkg-reconfigure lightdm

The same display manager window as shown above will appear.

Novice users of LightDM would be advised to have a backup display manager such as slim or GDM.

SDDM vs. LightDM: Pros and Cons

One of LightDM’s upsides are the gorgeous greeters, such as Unity Greeter. Greeters are important for LightDM because its lightness depends on the greeter. Some users say that these greeters need more dependencies compared to other greeters which are also lightweight.

SDDM wins in terms of theme variation, which can be animated in the form of gifs and video. Eye candy is a thing here because you can also add music or sounds, as well as different QML animation combos.

While QML experts will enjoy it, others might find it difficult to use the SDDM customization perks. Some even say this DM is bloated due to its Qt dependency.

LightDM’s flaws include the lack of Wayland compatibility and lackluster documentation options.

Overall, LightDM sits in the second place among Linux display managers, while SDDM is at the third place. It is a close battle, and it comes down to personal preference.

Simple vs. Light

Ultimately, it is hard to say which of these is the “right” display manager. Both the Simple and Light display managers fulfill their purpose, both are simple enough to set up and use, although customization can be a bit of a handful. Some Linux users will tell you one is better, while others will swear by the other. The best way to decide is to test each of them yourself and figure out what suits you best.

Which of these display managers do you prefer? Cast your vote in the comments below.