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



PPRROOLLOOGG
       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.

NNAAMMEE
       fdatasync -- synchronize the data of a file (RREEAALLTTIIMMEE)

SSYYNNOOPPSSIISS
       #include <unistd.h>

       int fdatasync(int _f_i_l_d_e_s);

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

       The functionality shall be equivalent to _f_s_y_n_c() 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.

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

EERRRROORRSS
       The _f_d_a_t_a_s_y_n_c() function shall fail if:

       EEBBAADDFF  The _f_i_l_d_e_s argument is not a valid file descriptor.

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

       In the event that any of the queued I/O operations fail, _f_d_a_t_a_s_y_n_c()
       shall return the error conditions defined for _r_e_a_d() and _w_r_i_t_e().

       _T_h_e _f_o_l_l_o_w_i_n_g _s_e_c_t_i_o_n_s _a_r_e _i_n_f_o_r_m_a_t_i_v_e_.

EEXXAAMMPPLLEESS
       None.

AAPPPPLLIICCAATTIIOONN UUSSAAGGEE
       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 _f_d_a_t_a_s_y_n_c().

RRAATTIIOONNAALLEE
       None.

FFUUTTUURREE DDIIRREECCTTIIOONNSS
       None.

SSEEEE AALLSSOO
       _a_i_o___f_s_y_n_c(), _f_c_n_t_l(), _f_s_y_n_c(), _o_p_e_n(), _r_e_a_d(), _w_r_i_t_e()

       The Base Definitions volume of POSIX.1-2017, <<uunniissttdd..hh>>

CCOOPPYYRRIIGGHHTT
       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)
