Ok, so, for what it's worth, the following was successful for me:
sudo systemd-nspawn -bxD/
Practically identical to yours, except I don't give the
machine a name and I get an
-x ephemeral btrfs snapshot of my
/ for the container's root.
That brought up the container's
getty on my terminal's pty and I logged in to
login and all.
I confess I was a bit stumped for a little while, but after a little poking at
systemctl in the container w/
zsh <tab> completion I came up with (run from within the container):
systemctl stop console-getty.service
==== AUTHENTICATING FOR org.freedesktop.systemd1.manage-units ===
Authentication is required to manage system services or other units.
Authenticating as: mikeserv
==== AUTHENTICATION COMPLETE ===
Which got the machine to surrender its terminal control. The only thing is, I started that with
sudo - which also gets its own layer of terminal control to authenticate in the first place. This left me with a blank terminal, and no amount of
kill -CONT "$(pgrep ksh)" was doing me any good. And so I was again stumped for a moment or two, but (in another terminal)...
sudo fuser -v /dev/pts/*
USER PID ACCESS COMMAND
/dev/pts/0: mikeserv 8347 F.... zsh
root 18003 F.... sudo
/dev/pts/13: mikeserv 9553 F.... zsh
mikeserv 16838 F.... ksh
root 17657 F.... sudo
root 17658 F.... systemd-nspawn
/dev/pts/14: root 17675 F.... systemd
Gave me the above list, and so I thought - what the hell?
sudo kill -STOP 17657
And - lo and behold - I had
ksh back in the original terminal. To wrap it up, I needed to verify I could still access the
machine, though, of course, else it would be useless:
MACHINE CLASS SERVICE
localhost-35ceaa76b1306897 container nspawn
sudo machinectl login localhost-35ceaa76b1306897
Connected to machine localhost-35ceaa76b1306897.
Press ^] three times within 1s to exit session.
Arch Linux 4.0.7-2-ARCH (pts/0)
And I got another
getty on another terminal!