Some times it happens that when doing system tweaks you accidentally remove the wrong packages which will result in having an unstable and possibly even an unfunctional system. So in order to get through the bad scenario of unusable system it might be in place to create a session entry to your session manager (lightdm, gdm3…) so you can open up a failsafe terminal session if everything else fails on your gui elsewhere.
Here is how you do it. Copy paste the following as a root user or by using sudo
echo ‘[Desktop Entry]
Comment=Terminal client session for emergencies
‘ >> /usr/share/xsessions/terminalsession.desktop
Once you are done a new session entry called terminal session should appear in your session manager. The session entry will only start up terminal client so it will be session independent. Feel free to customize the above example anyway you want since it is only an example showing my preferred choices.