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.

nologin - prevent unprivileged users from logging into the system

login(1), shutdown(8) Linux man-pages 6.9.1 2024-05-02 nologin(5)