systemd-time-wait-sync.service (8) - Linux Man Pages
systemd-time-wait-sync.service: Wait Until Kernel Time Synchronized
systemd-time-wait-sync.service, systemd-time-wait-sync - Wait Until Kernel Time Synchronized
systemd-time-wait-sync is a system service that delays the start of units that depend on time-sync.target until the system time has been synchronized with an accurate time source by systemd-timesyncd.service.
systemd-timesyncd.service notifies on successful synchronization. systemd-time-wait-sync also tries to detect when the kernel marks the time as synchronized, but this detection is not reliable and is intended only as a fallback for other services that can be used to synchronize time (e.g., ntpd, chronyd).
- The presence of this file indicates to this service that the system clock has been synchronized.