|NOLOGIN(5)||Linux Programmer's Manual||NOLOGIN(5)|
nologin - prevent unprivileged users from logging into the system
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. This provides a simple way of temporarily disabling all unprivileged logins.
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