SYNC(8)
NAME
sync − update the super-block
USAGE
/etc/sync
DESCRIPTION
The sync command executes the sync system primitive. You can call sync to ensure that all disk writes have been completed before the processor is halted in a way not suitably done by reboot(8) or halt(8). See sync(2) for details on the system primitive.
The sync operation is not actually necessary on DOMAIN hardware, because the system buffers are automatically written to disk at shutdown. Nevertheless, we provide it in the interest of ensuring compatibility.