opendarwin man page for fsync

FSYNC(2)						      BSD System Calls Manual							  FSYNC(2)

NAME
     fsync -- synchronize a file's in-core state with that on disk

SYNOPSIS
     #include <unistd.h>

     int
     fsync(int fd);

DESCRIPTION
     Fsync() causes all modified data and attributes of fd to be moved to a permanent storage device.  This normally results in all in-core modi-
     fied copies of buffers for the associated file to be written to a disk.

     Fsync() should be used by programs that require a file to be in a known state, for example, in building a simple transaction facility.

RETURN VALUES
     A 0 value is returned on success.	A -1 value indicates an error.

ERRORS
     The fsync() fails if:

     [EBADF]		fd is not a valid descriptor.

     [EINVAL]		fd refers to a socket, not to a file.

     [EIO]		An I/O error occurred while reading from or writing to the file system.

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

HISTORY
     The fsync() function call appeared in 4.2BSD.

4.2 Berkeley Distribution					   June 4, 1993 					 4.2 Berkeley Distribution