1.\" $NetBSD: fflush.3,v 1.9 2002/02/07 07:00:24 ross Exp $ 2.\" 3.\" Copyright (c) 1990, 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" This code is derived from software contributed to Berkeley by 7.\" Chris Torek and the American National Standards Committee X3, 8.\" on Information Processing Systems. 9.\" 10.\" Redistribution and use in source and binary forms, with or without 11.\" modification, are permitted provided that the following conditions 12.\" are met: 13.\" 1. Redistributions of source code must retain the above copyright 14.\" notice, this list of conditions and the following disclaimer. 15.\" 2. Redistributions in binary form must reproduce the above copyright 16.\" notice, this list of conditions and the following disclaimer in the 17.\" documentation and/or other materials provided with the distribution. 18.\" 3. All advertising materials mentioning features or use of this software 19.\" must display the following acknowledgement: 20.\" This product includes software developed by the University of 21.\" California, Berkeley and its contributors. 22.\" 4. Neither the name of the University nor the names of its contributors 23.\" may be used to endorse or promote products derived from this software 24.\" without specific prior written permission. 25.\" 26.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36.\" SUCH DAMAGE. 37.\" 38.\" @(#)fflush.3 8.1 (Berkeley) 6/4/93 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.Fd #include \*[Lt]stdio.h\*[Gt] 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 92.Fa stream 93is not an open stream, or, in the case of 94.Fn fflush , 95not a stream open for writing. 96.El 97.Pp 98The function 99.Fn fflush 100may also fail and set 101.Va errno 102for any of the errors specified for the routine 103.Xr write 2 . 104.Sh SEE ALSO 105.Xr write 2 , 106.Xr fclose 3 , 107.Xr fopen 3 , 108.Xr setbuf 3 109.Sh STANDARDS 110The 111.Fn fflush 112function 113conforms to 114.St -ansiC . 115