systemd-update-utmp.service (8) - Linux Man Pages
systemd-update-utmp.service: Write audit and utmp updates at bootup, runlevel changes and shutdown
systemd-update-utmp.service, systemd-update-utmp-runlevel.service, systemd-update-utmp - Write audit and utmp updates at bootup, runlevel changes and shutdown
systemd-update-utmp-runlevel.service is a service that writes SysV runlevel changes to utmp and wtmp, as well as the audit logs, as they occur. systemd-update-utmp.service does the same for system reboots and shutdown requests.