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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