1.\" Copyright (c) 1990, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" Chris Torek and the American National Standards Committee X3, 6.\" on Information Processing Systems. 7.\" 8.\" Redistribution and use in source and binary forms, with or without 9.\" modification, are permitted provided that the following conditions 10.\" are met: 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 2. Redistributions in binary form must reproduce the above copyright 14.\" notice, this list of conditions and the following disclaimer in the 15.\" documentation and/or other materials provided with the distribution. 16.\" 3. All advertising materials mentioning features or use of this software 17.\" must display the following acknowledgement: 18.\" This product includes software developed by the University of 19.\" California, Berkeley and its contributors. 20.\" 4. Neither the name of the University nor the names of its contributors 21.\" may be used to endorse or promote products derived from this software 22.\" without specific prior written permission. 23.\" 24.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 25.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 26.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 27.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 28.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 29.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 30.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 31.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 32.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 33.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 34.\" SUCH DAMAGE. 35.\" 36.\" @(#)fflush.3 8.1 (Berkeley) 6/4/93 37.\" $FreeBSD: src/lib/libc/stdio/fflush.3,v 1.4.2.4 2001/12/14 18:33:57 ru Exp $ 38.\" $DragonFly: src/lib/libc/stdio/fflush.3,v 1.3 2004/06/08 00:29:47 hmp Exp $ 39.\" 40.Dd June 4, 1993 41.Dt FFLUSH 3 42.Os 43.Sh NAME 44.Nm fflush , 45.Nm fpurge 46.Nd flush a stream 47.Sh LIBRARY 48.Lb libc 49.Sh SYNOPSIS 50.In stdio.h 51.Ft int 52.Fn fflush "FILE *stream" 53.Ft int 54.Fn fpurge "FILE *stream" 55.Sh DESCRIPTION 56The function 57.Fn fflush 58forces a write of all buffered data for the given output or update 59.Fa stream 60via the stream's underlying write function. 61The open status of the stream is unaffected. 62.Pp 63If the 64.Fa stream 65argument is 66.Dv NULL , 67.Fn fflush 68flushes 69.Em all 70open output streams. 71.Pp 72The function 73.Fn fpurge 74erases any input or output buffered in the given 75.Fa stream . 76For output streams this discards any unwritten output. 77For input streams this discards any input read from the underlying object 78but not yet obtained via 79.Xr getc 3 ; 80this includes any text pushed back via 81.Xr ungetc 3 . 82.Sh RETURN VALUES 83Upon successful completion 0 is returned. 84Otherwise, 85.Dv EOF 86is returned and the global variable 87.Va errno 88is set to indicate the error. 89.Sh ERRORS 90.Bl -tag -width Er 91.It Bq Er EBADF 92The 93.Fa stream 94argument 95is not an open stream, or, in the case of 96.Fn fflush , 97not a stream open for writing. 98.El 99.Pp 100The function 101.Fn fflush 102may also fail and set 103.Va errno 104for any of the errors specified for the routine 105.Xr write 2 . 106.Sh SEE ALSO 107.Xr write 2 , 108.Xr fclose 3 , 109.Xr fopen 3 , 110.Xr setbuf 3 111.Sh STANDARDS 112The 113.Fn fflush 114function 115conforms to 116.St -isoC . 117