fflush - flush a stream


SYNOPSIS

       #include <stdio.h>

       int fflush(FILE *stream);


DESCRIPTION

       The  function  fflush  forces  a  write  of all user-space
       buffered data for the given output or  update  stream  via
       the  stream's  underlying write function.  The open status
       of the stream is unaffected.

       If the stream argument is NULL, fflush  flushes  all  open
       output streams.


RETURN VALUE

       Upon  successful completion 0 is returned.  Otherwise, EOF
       is returned and the global variable errno is set to  indi­
       cate the error.


ERRORS

       EBADF  Stream  is  not  an open stream, or is not open for
              writing.

       The function fflush may also fail and set errno for any of
       the errors specified for the routine write(2).


NOTES

       Note  that fflush only flushes the user space buffers pro­
       vided by the C library.  To ensure that the data is physi­
       cally  stored  on  disk the kernel buffers must be flushed
       too, e.g. with sync(2) or fsync(2).


CONFORMING TO

       The fflush function conforms to ANSI  X3.159-1989  (``ANSI
       C'').


SEE ALSO

       write(2),    fclose(3),   fopen(3),   fsync(2),   sync(2),
       write(2), setbuf(3)


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