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SYNC(2) 		       System Calls Manual			 SYNC(2)

NAME
     sync -- schedule file system updates

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <unistd.h>

     void
     sync(void);

DESCRIPTION
     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 in-
     formation in the cache is lost after a system crash, a sync()  system  call
     is  issued  frequently by the kernel process syncer(4) (about every 30 sec-
     onds).

     The fsync(2) system call may be used to  synchronize  individual  file  de-
     scriptor attributes.

SEE ALSO
     fsync(2), syncer(4), sync(8)

HISTORY
     The sync() function appeared in Version 3 AT&T UNIX.

BUGS
     The  sync()  system  call	may  return  before  the  buffers are completely
     flushed.

FreeBSD ports 15.quarterly	December 1, 2017			 SYNC(2)

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