SYNC(2) BSD System Calls Manual SYNC(2)NAMEsync — synchronize disk block in-core status with that on disk
The sync() function 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() call is
issued frequently by the user process update(8) (about every 30 seconds).
The function fsync(2) may be used to synchronize individual file descrip‐
SEE ALSOfsync(2), sync(8), update(8)BUGSSync() may return before the buffers are completely flushed.
A sync function call appeared in Version 6 AT&T UNIX.
4th Berkeley Distribution June 4, 1993 4th Berkeley Distribution