fflush — flush a stream
#include <stdio.h>
int
fflush( |
FILE *stream); |
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).
Upon successful completion 0 is returned. Otherwise,
EOF is returned and
errno is set to indicate the
error.
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).
For an explanation of the terms used in this section, see attributes(7).
| Interface | Attribute | Value |
fflush() |
Thread safety | MT-Safe |
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.
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).
fsync(2), sync(2), write(2), fclose(3), fileno(3), fopen(3), fpurge(3), setbuf(3), unlocked_stdio(3)
This page is part of release 5.13 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/.
|
Copyright (c) 1990, 1991 The Regents of the University of California. All rights reserved. This code is derived from software contributed to Berkeley by Chris Torek and the American National Standards Committee X3, on Information Processing Systems. %%%LICENSE_START(BSD_4_CLAUSE_UCB) Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. 3. All advertising materials mentioning features or use of this software must display the following acknowledgement: This product includes software developed by the University of California, Berkeley and its contributors. 4. Neither the name of the University nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. %%%LICENSE_END (#)fflush.3 5.4 (Berkeley) 6/29/91 Converted for Linux, Mon Nov 29 15:22:01 1993, faithcs.unc.edu Modified 2000-07-22 by Nicolás Lichtmaier <nickdebian.org> Modified 2001-10-16 by John Levon <mozcompsoc.man.ac.uk> |