I've set /etc/nologin to contain a custom message, so when users with the /usr/sbin/nologin shell defined in passwd will try to log in, this custom message will appear on their terminal before throwing them out.
Problem is - this error appears for ALL users, even for root (with /bin/bash defined...)
from the nologin man page:
NAME nologin - prevent unprivileged users from logging into the system
DESCRIPTION If the file /etc/nologin exists and is readable, login(1) will allow access only to root. Other users will be shown the contents of this file and their logins will be refused.
Linux mybox02 3.13.0-32-generic #57-Ubuntu SMP Tue Jul 15 03:51:08 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux