FSYNC(2)                             BSD                              FSYNC(2)



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

SYNOPSIS
     fsync(fd)
     int fd;

DESCRIPTION
     fsync causes all modified data and attributes of fd to be moved to a
     permanent storage device.  This normally causes all in-memory modified
     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.

ERRORS
     The fsync fails if any of the following are true:

     [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)

DIAGNOSTICS
     A successful call returns 0.  A failed call returns -1 and sets errno to
     indicate the error.