FDATASYNC(3)               POSIX Programmer's Manual              FDATASYNC(3)



PROLOG
       This manual page is part of the POSIX Programmer's Manual.  The OS
       implementation of this interface may differ (consult the corresponding
       OS manual page for details of OS behavior), or the interface may not be
       implemented on OS.

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.

       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
       Note that even if the file descriptor is not open for writing, if there
       are any pending write requests on the underlying file, then that I/O
       will be completed prior to the return of fdatasync().

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       aio__fsync(), fcntl(), fsync(), open(), read(), write()

       The Base Definitions volume of POSIX.1-2017, <unistd.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1-2017, Standard for Information Technology --
       Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 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 .

       Any typographical or formatting errors that appear in this page are
       most likely to have been introduced during the conversion of the source
       files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .



IEEE/The Open Group                  2017                         FDATASYNC(3)
