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. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" @(#)ioctl.2 8.2 (Berkeley) 12/11/93 29.\" 30.\" $FreeBSD: src/lib/libc/sys/ioctl.2,v 1.7.2.7 2001/12/14 18:34:01 ru Exp $ 31.\" $DragonFly: src/lib/libc/sys/ioctl.2,v 1.4 2008/11/10 23:47:31 swildner Exp $ 32.\" 33.Dd December 11, 1993 34.Dt IOCTL 2 35.Os 36.Sh NAME 37.Nm ioctl 38.Nd control device 39.Sh LIBRARY 40.Lb libc 41.Sh SYNOPSIS 42.In sys/ioctl.h 43.Ft int 44.Fn ioctl "int d" "unsigned long request" ... 45.Sh DESCRIPTION 46The 47.Fn ioctl 48system call manipulates the underlying device parameters of special files. 49In particular, many operating 50characteristics of character special files (e.g.\& terminals) 51may be controlled with 52.Fn ioctl 53requests. 54The argument 55.Fa d 56must be an open file descriptor. 57.Pp 58The third argument to 59.Fn ioctl 60is traditionally named 61.Ar "char *argp" . 62Most uses of 63.Fn ioctl 64however, require the third argument to be a 65.Vt caddr_t 66or an 67.Vt int . 68.Pp 69An 70.Fn ioctl 71.Fa request 72has encoded in it whether the argument is an 73.Dq in 74argument or 75.Dq out 76argument, and the size of the argument 77.Fa argp 78in bytes. 79Macros and defines used in specifying an ioctl 80.Fa request 81are located in the file 82.In sys/ioctl.h . 83.Sh RETURN VALUES 84If an error has occurred, a value of -1 is returned and 85.Va errno 86is set to indicate the error. 87.Sh ERRORS 88.Fn Ioctl 89will fail if: 90.Bl -tag -width Er 91.It Bq Er EBADF 92.Fa d 93is not a valid descriptor. 94.It Bq Er ENOTTY 95.Fa d 96is not associated with a character 97special device. 98.It Bq Er ENOTTY 99The specified request does not apply to the kind 100of object that the descriptor 101.Fa d 102references. 103.It Bq Er EINVAL 104.Fa request 105or 106.Fa argp 107is not valid. 108.It Bq Er EFAULT 109.Fa argp 110points outside the process's allocated address space. 111.El 112.Sh SEE ALSO 113.Xr execve 2 , 114.Xr fcntl 2 , 115.Xr intro 4 , 116.Xr tty 4 , 117.Xr ioctl 9 118.Sh HISTORY 119An 120.Fn ioctl 121function call appeared in 122.At v7 . 123