NAME

       fdatasync - synchronize the data of a file (REALTIME)

SYNOPSIS

       #include <unistd.h>

       int fdatasync(int fildes);

DESCRIPTION

       The  fdatasync()  function shall force all currently queued I/O operations associated with
       the file indicated by file descriptor fildes to the synchronized I/O completion state.

       The functionality shall be equivalent to fsync() with  the  symbol  _POSIX_SYNCHRONIZED_IO
       defined,  with  the  exception  that  all I/O operations shall be completed as defined for
       synchronized I/O data integrity completion.

RETURN VALUE

       If successful, the fdatasync() function shall return the value 0; otherwise, the  function
       shall return the value -1 and set errno to indicate the error. If the fdatasync() function
       fails, outstanding I/O operations are not guaranteed to have been completed.

ERRORS

       The fdatasync() function shall fail if:

       EBADF  The fildes argument is not a valid file descriptor open for writing.

       EINVAL This implementation does not support synchronized I/O for this file.

       In the event that any of the queued I/O operations  fail,  fdatasync()  shall  return  the
       error conditions defined for read() and write().

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       aio_fsync()  , fcntl() , fsync() , open() , read() , write() , the Base Definitions volume
       of IEEE Std 1003.1-2001, <unistd.h>

COPYRIGHT

       Portions of this text are reprinted and  reproduced  in  electronic  form  from  IEEE  Std
       1003.1,  2003  Edition,  Standard  for Information Technology -- Portable Operating System
       Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003  by
       the  Institute  of  Electrical  and  Electronics Engineers, Inc and The Open Group. In the
       event of any discrepancy between this version and the original IEEE  and  The  Open  Group
       Standard,  the  original  IEEE  and  The  Open Group Standard is the referee document. The
       original Standard can be obtained online at http://www.opengroup.org/unix/online.html .