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. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)fflush.3 8.1 (Berkeley) 6/4/93 33.\" $FreeBSD: src/lib/libc/stdio/fflush.3,v 1.11 2007/01/09 00:28:06 imp Exp $ 34.\" $DragonFly: src/lib/libc/stdio/fflush.3,v 1.3 2004/06/08 00:29:47 hmp Exp $ 35.\" 36.Dd June 4, 1993 37.Dt FFLUSH 3 38.Os 39.Sh NAME 40.Nm fflush , 41.Nm fpurge 42.Nd flush a stream 43.Sh LIBRARY 44.Lb libc 45.Sh SYNOPSIS 46.In stdio.h 47.Ft int 48.Fn fflush "FILE *stream" 49.Ft int 50.Fn fpurge "FILE *stream" 51.Sh DESCRIPTION 52The function 53.Fn fflush 54forces a write of all buffered data for the given output or update 55.Fa stream 56via the stream's underlying write function. 57The open status of the stream is unaffected. 58.Pp 59If the 60.Fa stream 61argument is 62.Dv NULL , 63.Fn fflush 64flushes 65.Em all 66open output streams. 67.Pp 68The function 69.Fn fpurge 70erases any input or output buffered in the given 71.Fa stream . 72For output streams this discards any unwritten output. 73For input streams this discards any input read from the underlying object 74but not yet obtained via 75.Xr getc 3 ; 76this includes any text pushed back via 77.Xr ungetc 3 . 78.Sh RETURN VALUES 79Upon successful completion 0 is returned. 80Otherwise, 81.Dv EOF 82is returned and the global variable 83.Va errno 84is set to indicate the error. 85.Sh ERRORS 86.Bl -tag -width Er 87.It Bq Er EBADF 88The 89.Fa stream 90argument 91is not an open stream, or, in the case of 92.Fn fflush , 93not a stream open for writing. 94.El 95.Pp 96The function 97.Fn fflush 98may also fail and set 99.Va errno 100for any of the errors specified for the routine 101.Xr write 2 . 102.Sh SEE ALSO 103.Xr write 2 , 104.Xr fclose 3 , 105.Xr fopen 3 , 106.Xr setbuf 3 107.Sh STANDARDS 108The 109.Fn fflush 110function 111conforms to 112.St -isoC . 113