systemd-user-sessions.service, systemd-user-sessions — Permit user logins after boot, prohibit user logins at shutdown
systemd-user-sessions.service
/usr/lib/systemd/systemd-user-sessions
systemd-user-sessions.service is a
service that controls user logins. After basic system
initialization is complete it removes
/run/nologin, thus permitting logins. Before
system shutdown it creates /run/nologin, thus
prohibiting further logins. At the same time it also kills all
user processes, so that system shutdown may proceed without any
remaining user processes around.