usr/lib/systemd/system/firstboot.service

   1 [Unit]
   2 Description=firstboot configuration service
   3 After=udev.service
   4 ConditionPathExists=!/opt/etc/.firstboot
   5
   6 [Service]
   7 Type=oneshot
   8 ExecStart=/etc/rc.d/rc.firstboot
   9
  10 [Install]
  11 WantedBy=sysinit.target