Manpage of FFLUSH

FFLUSH

Section: Linux Programmer's Manual (3)
Updated: 2015-03-02
Index
 

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 streamvia 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 streamargument is NULL, fflush() flushes allopen output streams.

For a nonlocking counterpart, see unlocked_stdio(3).  

RETURN VALUE

Upon successful completion 0 is returned. Otherwise, EOFis returned and errnois set to indicate the error.  

ERRORS

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

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

ATTRIBUTES

For an explanation of the terms used in this section, see attributes(7).
InterfaceAttributeValue
fflush() Thread safetyMT-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), fopen(3), setbuf(3), unlocked_stdio(3)


 

Index

NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
ATTRIBUTES
CONFORMING TO
NOTES
SEE ALSO

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