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man:fflush

FFLUSH(3) Linux Programmer's Manual FFLUSH(3)

NAME

     fflush - flush a stream

SYNOPSIS

     #include <stdio.h>
     int fflush(FILE *stream);

DESCRIPTION

     For  output streams, fflush() forces a write of all user-space buffered
     data for the given output or update stream via the stream's  underlying
     write function.
     For input streams associated with seekable files (e.g., disk files, but
     not pipes or terminals), fflush() discards any buffered data  that  has
     been fetched from the underlying file, but has not been consumed by the
     application.
     The open status of the stream is unaffected.
     If the stream argument  is  NULL,  fflush()  flushes  all  open  output
     streams.
     For a nonlocking counterpart, see unlocked_stdio(3).

RETURN VALUE

     Upon  successful  completion 0 is returned.  Otherwise, EOF is returned
     and errno is set to indicate 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 write(2).

ATTRIBUTES

     For   an   explanation   of   the  terms  used  in  this  section,  see
     attributes(7).
     +----------+---------------+---------+
     |Interface | Attribute     | Value   |
     +----------+---------------+---------+
     |fflush()  | Thread safety | MT-Safe |
     +----------+---------------+---------+

CONFORMING TO

     C89, C99, POSIX.1-2001, POSIX.1-2008.
     POSIX.1-2001 did  not  specify  the  behavior  for  flushing  of  input
     streams, but the behavior is specified in POSIX.1-2008.

NOTES

     Note  that fflush() flushes only the user-space buffers provided by the
     C library.  To ensure that the data is physically stored  on  disk  the
     kernel  buffers  must  be  flushed  too,  for  example, with sync(2) or
     fsync(2).

SEE ALSO

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

COLOPHON

     This  page  is  part of release 4.16 of the Linux man-pages project.  A
     description of the project, information about reporting bugs,  and  the
     latest     version     of     this    page,    can    be    found    at
     https://www.kernel.org/doc/man-pages/.

GNU 2017-09-15 FFLUSH(3)

/data/webs/external/dokuwiki/data/pages/man/fflush.txt · Last modified: 2019/05/17 09:32 by 127.0.0.1

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