.Dd January 30, 2015 .Dt SYNC 1 .Os .Sh NAME .Nm sync .Nd flush disk cache .Sh SYNOPSIS .Nm .Sh DESCRIPTION .Nm invokes .Xr sync 2 to flush all unwritten changes to the disk. This is usually done before shutting down, rebooting or halting. .Sh SEE ALSO .Xr fsync 2 , .Xr sync 2