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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 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.

SEE ALSO

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

HISTORY

     The sync() function appeared in Version 6 AT&T UNIX.

BUGS

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