opendarwin man page for sync

SYNC(2) 						      BSD System Calls Manual							   SYNC(2)

NAME
     sync -- synchronize disk block in-core status with that on disk

SYNOPSIS
     #include <unistd.h>

     void
     sync(void);

DESCRIPTION
     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 descriptor attributes.

SEE ALSO
     fsync(2), sync(8), update(8)

BUGS
     Sync() may return before the buffers are completely flushed.

HISTORY
     A sync() function call appeared in Version 6 AT&T UNIX.

4th Berkeley Distribution					   June 4, 1993 					 4th Berkeley Distribution