Sometimes linux feels like a puzzle game.

> Try to start Debian.
> Get a black screen when booting X and no way to switch to a terminal.
> Reboot to single user mode.
> Get a message that sulogin doesn't work because no root password has been set.
> Try to find a live cd.
> Discover that you don't have a live cd handy.
> Boot with init=/bin/sh and rw instead of ro.
> Achieve a root shell.
> Look in Xorg.0.log to find out what you've been expecting all along: nvidia driver broke during package upgrade.
> Create a root password with passwd.
> Reboot to single user mode.
> Log in with new root password.
> Run aptitude to download new packages.
> Get message that hosts can't be resolved.
> Muck about with networking tools until magically the network comes up. (Probably because of a systemd socket trigger.)
> Download updates.
> Reboot.
> Finally be able to log in.