Recently, I tried to open a QGIS project on Ubuntu, but I can only use Ubuntu's terminal for that which gives me the following error:
QGIS starting in non-interactive mode not supported. You are seeing this message most likely because you have no DISPLAY environment variable set.
So I understand QGIS can't be used without a graphic device.
Is there any (Open Source) GIS software that allows you to work only through Ubuntu's terminal or at least one that lets you open projects only using Ubuntu's terminal (where the project could have been made through a graphic device)?