systemd-machine-id-commit.service - Commit a transient
          machine ID to disk


          systemd-machine-id-commit.service is an early boot service
          responsible for committing transient /etc/machine-id files
          to a writable disk file system. See machine-id(5) for more
          information about machine IDs.

          This service is started after in case
          /etc/machine-id is a mount point of its own (usually from a
          memory file system such as "tmpfs") and /etc is writable.
          The service will invoke systemd-machine-id-setup --commit,
          which writes the current transient machine ID to disk and
          unmount the /etc/machine-id file in a race-free manner to
          ensure that file is always valid and accessible for other
          processes. See systemd-machine-id-setup(1) for details.

          The main use case of this service are systems where
          /etc/machine-id is read-only and initially not initialized.
          In this case, the system manager will generate a transient
          machine ID file on a memory file system, and mount it over
          /etc/machine-id, during the early boot phase. This service
          is then invoked in a later boot phase, as soon as /etc/ has
          been remounted writable and the ID may thus be committed to
          disk to make it permanent.

          systemd(1), systemd-machine-id-setup(1), machine-id(5),

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