1.\" $NetBSD: fd.4,v 1.4 2001/09/11 22:52:52 wiz Exp $ 2.\" 3.\" Copyright (c) 1990, 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. All advertising materials mentioning features or use of this software 15.\" must display the following acknowledgement: 16.\" This product includes software developed by the University of 17.\" California, Berkeley and its contributors. 18.\" 4. Neither the name of the University nor the names of its contributors 19.\" may be used to endorse or promote products derived from this software 20.\" without specific prior written permission. 21.\" 22.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32.\" SUCH DAMAGE. 33.\" 34.\" @(#)fd.4 8.1 (Berkeley) 6/9/93 35.\" 36.Dd June 9, 1993 37.Dt FD 4 38.Os 39.Sh NAME 40.Nm fd , 41.Nm stdin , 42.Nm stdout , 43.Nm stderr 44.Nd file descriptor files 45.Sh DESCRIPTION 46The files 47.Pa /dev/fd/0 48through 49.Pa /dev/fd/# 50refer to file descriptors which can be accessed through the file 51system. 52If the file descriptor is open and the mode the file is being opened 53with is a subset of the mode of the existing descriptor, the call: 54.Bd -literal -offset indent 55fd = open("/dev/fd/0", mode); 56.Ed 57.Pp 58and the call: 59.Bd -literal -offset indent 60fd = fcntl(0, F_DUPFD, 0); 61.Ed 62.Pp 63are equivalent. 64.Pp 65Opening the files 66.Pa /dev/stdin , 67.Pa /dev/stdout 68and 69.Pa /dev/stderr 70is equivalent to the following calls: 71.Bd -literal -offset indent 72fd = fcntl(STDIN_FILENO, F_DUPFD, 0); 73fd = fcntl(STDOUT_FILENO, F_DUPFD, 0); 74fd = fcntl(STDERR_FILENO, F_DUPFD, 0); 75.Ed 76.Pp 77Flags to the 78.Xr open 2 79call other than 80.Dv O_RDONLY , 81.Dv O_WRONLY 82and 83.Dv O_RDWR 84are ignored. 85.Sh FILES 86.Bl -tag -width /dev/stderr -compact 87.It Pa /dev/fd/# 88.It Pa /dev/stdin 89.It Pa /dev/stdout 90.It Pa /dev/stderr 91.El 92.Sh SEE ALSO 93.Xr tty 4 94