Ubuntu 19.10 change desktop environment

I've installed another desktop environment which I would like to try. I am not sure how to switch to it.

Is there still a button on the log in screen that will switch desktop environments? This same question for previous versions of ubuntu yields screenshots of this button. But I cannot find any button on the log in screen that does this.

So, in ubuntu 19.10, does there exist a button to switch desktop environments? If so, where is it? If not, what is an alternative method to switch desktop environments after I've already installed one?

██████@████-linux:~$ ls /usr/share/xsessions
gnome-flashback-compiz.desktop ubuntu.desktop
gnome-flashback-metacity.desktop

The gear icon does not show up for me, as the answers indicate it should.

Solved. I was not logged out properly. I locked the screen thinking that was logging out. Logging out properly fixed the issue.

2 Answers

Ubuntu 19.10 uses GDM3 as login manager. Also this login manager allows you to login to a different session ("desktop environment") during login.

• Make sure you selected your user on the login screen such that your password is displayed.
• Before entering the password, click the "cog" icon to select a session.

(Screen for Ubuntu 18.04 but similar in 19.10) The session you selected will stay in effect during subsequent logins until you choose another session.

For your particular case: your screenshot shows you are currently logged in. What you are showing is a lock screen. Your session is still active, but the lock screen protects your account so other people could not get access while you are away from the computer without having logged out. By default, it will kick in when the screen is blanked after a certain time of inactivity (configurable on Settings - Power). In Ubuntu, you can also lock the computer yourself with the hotkey Super+l). Thus

• Enter your password to return to your current session
• In the top right corner on the top bar, click the status menu button
• In the menu, click the entry showing your name. Then click "log out".

Now, you will have effectively logged out of your session. You will now have a cog to select another session for logging in.

You have to logout from your current session or reboot and then:

• if you are using GDM3 - select your login name and then click on gear button and select needed session:

• if you are using LighDM - click on circle button and select needed session:

Notes:

1. GNOME FlashBack is usually installed by sudo apt-get install gnome-session-flashback
2. One can switch between GDM3 and LightDM using sudo dpkg-reconfigure gdm3 or sudo dpkg-reconfigure lightdm (install it first with sudo apt-get install lightdm if not installed)