The
sync ();
system call forces a write of dirty (modified) buffers
in the block buffer cache out
to disk.
The kernel keeps this information in core to reduce
the number of disk I/O transfers required by the system.
As information in the cache is lost after a system crash, a
sync ();
system call is issued
frequently
by the user process
syncer(4)
(about every 30 seconds).
The
fsync(2)
system call
may be used to synchronize individual file descriptor
attributes.
