Hello:
I would be happy to learn about a safe way to boot amd64 debian8 (gnome3) and debian9 (xfce) to terminal, followed by startx and either gnome-session or what is correct for xfce. My older method of killing gdm does no more work well. Booting into gui is often giving problems in scientific use of linux. My interest is in:
-- Examining all that is loaded during boot
-- Working from the terminal without gnome/xfce when running number-crunching codes.