Enable/disable gnome session (GDM)
To set your system to always boot to a console rather than GDM:
systemctl set-default multi-user.target
To revert the previous command and have your system always boot straight into GDM:
systemctl set-default graphical.target
To check the current boot target:
systemctl get-default
To temporarily stop GDM:
systemctl stop gdm
To see the status of GDM:
systemctl status gdm
To start GDM manually:
systemctl start gdm