1.\" Copyright (c) 1980, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. 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.\" @(#)ioctl.2 8.2 (Berkeley) 12/11/93 33.\" 34.\" $FreeBSD: src/lib/libc/sys/ioctl.2,v 1.7.2.7 2001/12/14 18:34:01 ru Exp $ 35.\" $DragonFly: src/lib/libc/sys/ioctl.2,v 1.4 2008/11/10 23:47:31 swildner Exp $ 36.\" 37.Dd December 11, 1993 38.Dt IOCTL 2 39.Os 40.Sh NAME 41.Nm ioctl 42.Nd control device 43.Sh LIBRARY 44.Lb libc 45.Sh SYNOPSIS 46.In sys/ioctl.h 47.Ft int 48.Fn ioctl "int d" "unsigned long request" ... 49.Sh DESCRIPTION 50The 51.Fn ioctl 52system call manipulates the underlying device parameters of special files. 53In particular, many operating 54characteristics of character special files (e.g.\& terminals) 55may be controlled with 56.Fn ioctl 57requests. 58The argument 59.Fa d 60must be an open file descriptor. 61.Pp 62The third argument to 63.Fn ioctl 64is traditionally named 65.Ar "char *argp" . 66Most uses of 67.Fn ioctl 68however, require the third argument to be a 69.Vt caddr_t 70or an 71.Vt int . 72.Pp 73An 74.Fn ioctl 75.Fa request 76has encoded in it whether the argument is an 77.Dq in 78argument or 79.Dq out 80argument, and the size of the argument 81.Fa argp 82in bytes. 83Macros and defines used in specifying an ioctl 84.Fa request 85are located in the file 86.In sys/ioctl.h . 87.Sh RETURN VALUES 88If an error has occurred, a value of -1 is returned and 89.Va errno 90is set to indicate the error. 91.Sh ERRORS 92.Fn Ioctl 93will fail if: 94.Bl -tag -width Er 95.It Bq Er EBADF 96.Fa d 97is not a valid descriptor. 98.It Bq Er ENOTTY 99.Fa d 100is not associated with a character 101special device. 102.It Bq Er ENOTTY 103The specified request does not apply to the kind 104of object that the descriptor 105.Fa d 106references. 107.It Bq Er EINVAL 108.Fa request 109or 110.Fa argp 111is not valid. 112.It Bq Er EFAULT 113.Fa argp 114points outside the process's allocated address space. 115.El 116.Sh SEE ALSO 117.Xr execve 2 , 118.Xr fcntl 2 , 119.Xr intro 4 , 120.Xr tty 4 , 121.Xr ioctl 9 122.Sh HISTORY 123An 124.Fn ioctl 125function call appeared in 126.At v7 . 127