Although Ubuntu is a very easy and intuitive operating system, the truth is that it has as many concepts as the most composed operating system, and that sometimes drives the most novice users crazy.
La Login screen It's one of those concepts that gets people confused even though it's the first we see of Ubuntu. Indeed, the Login Screen is the presentation in which it appears the username that we have created in the installation. Once we insert the password, the Ubuntu GNOME desktop will open with the programs installed by default. This login screen has several options that many are unaware of and that it is good to know.
The first one is that the Ubuntu Login Screen is a program that manages the sessions of the operating system, this program is known as GDM (GNOME Display Manager) and can be changed like almost everything in Ubuntu. There are other session managers such as Lightdm, KDM, XDM or Slim.
If we decide to use GDM, we need to know the parts that make up the Login screen. If you look, after pressing enter, An icon appears at the bottom right. If we press it, all the desktops and graphical environments that we have installed in Ubuntu will appear, of which we can choose one to work during that session or in a predefined way.
GDM is the default session manager or login screen in Ubuntu
If we go to the upper right we will find several icons that will be maintained during the session, one of them is the off button, typical and easy to recognize. There is also the speaker that will allow us to vary the volume of the sound. To the left of these we have the network, either by cable or via WiFi, and right next to it accessibility options. In the center of the upper panel we have the time, calendar and date widget, something that we can simply modify or see.
Unlike in the past in which the Wallpaper or screen background was what we had on our desktop, the latest versions show a solid color, with the logo of the operating system at the bottom. We are talking about Ubuntu, which is a Linux distribution, and all this can be changed. However, it is worth not doing it if we don't want something to stop working, or doing it following a good tutorial and beforehand in a virtual machine, to avoid surprises.
Finally say that the login screen can be avoided by indicating in «System settings» that the session starts directly (something not recommended) but we can never remove the session manager program, that is, we will not be able to uninstall GDM unless we install another session manager, something important to remember.
Possibly now you already know what they are talking about when someone mentions GDM, Lightdm or Xdm, or directly when they say "enter password on login screen«. It is easy and simple.
Hi Joaquin:
I am one of the Ubuntu Spanish translators. I leave you this brief note to inform you that this screen is called in Spanish "access screen" or "login screen". In case you want to avoid unnecessary anglicisms 😉
By the way, the session manager and the screen itself are two different concepts: the manager and the screen complement each other, let me explain: the manager corresponds to the concept of backend ('motor') and the login screen (in English, greeter, with that of frontend ('Interface'). For this reason, the LightDM session manager can have multiple interfaces or greeters installed. Ubuntu's is "Unity Greeter", for example, but elementary OS has a different screen, developed by them, which also uses LightDM as the engine for its operation.
Greetings.
Hi, I have installed Ubuntu Server 20.04 and when I login I cannot access, could you help me, what can I do? Thank you Yun.