Comment 14 for bug 1670291

In general, scheduling with shutdown command should work. E.g. tested in lxd container that `$ sudo shutdown +4` works correctly.

I wonder if landscape is affected by:
"""
If the time argument is used, 5 minutes before the system goes down the
/run/nologin file is created to ensure that further logins shall not be
allowed.
"""

Also, I see that 'halt' is used, instead of 'poweroff' in landscape, why is that? I would have thought 'poweroff' is more appropriate (shutdown -P +4, or just shutdown +4)