sync(2)
NAME
sync − update super-block
SYNTAX
sync()
DESCRIPTION
The sync system call causes all information in core memory that should be on disk to be written out. This includes modified super blocks, modified i-nodes, and delayed block I/O.
Programs which examine a file system, for example, fsck or df, use the sync system call. Using sync is mandatory before a boot. The writing, although scheduled, is not necessarily complete upon return from sync.