FFLUSH
Section: Linux Programmer's Manual (3)
Updated: 2013-07-15
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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,
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
Multithreading (see pthreads(7))
The
fflush()
function is thread-safe.
CONFORMING TO
C89, C99, POSIX.1-2001, POSIX.1-2008.
The standards do not specify the behavior for input streams.
Most other implementations behave the same as Linux.
NOTES
Note that
fflush()
only flushes 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),
fopen(3),
setbuf(3),
unlocked_stdio(3)
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- ATTRIBUTES
-
- Multithreading (see pthreads(7))
-
- CONFORMING TO
-
- NOTES
-
- SEE ALSO
-
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