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 1.3 2006/05/26 19:39:37 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 52function 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.Nm 64is traditionally named 65.Ar "char *argp" . 66Most uses of 67.Nm 68in 69.Fx 3.0 70however, require the third argument to be a 71.Ar caddr_t 72or an 73.Ar int . 74.Pp 75An ioctl 76.Fa request 77has encoded in it whether the argument is an 78.Dq in 79parameter 80or 81.Dq out 82parameter, and the size of the argument 83.Fa argp 84in bytes. 85Macros and defines used in specifying an ioctl 86.Fa request 87are located in the file 88.In sys/ioctl.h . 89.Sh RETURN VALUES 90If an error has occurred, a value of -1 is returned and 91.Va errno 92is set to indicate the error. 93.Sh ERRORS 94.Fn ioctl 95will fail if: 96.Bl -tag -width Er 97.It Bq Er EBADF 98.Fa d 99is not a valid descriptor. 100.It Bq Er ENOTTY 101.Fa d 102is not associated with a character 103special device. 104.It Bq Er ENOTTY 105The specified request does not apply to the kind 106of object that the descriptor 107.Fa d 108references. 109.It Bq Er EINVAL 110.Fa request 111or 112.Fa argp 113is not valid. 114.It Bq Er EFAULT 115.Fa argp 116points outside the process's allocated address space. 117.El 118.Sh SEE ALSO 119.Xr execve 2 , 120.Xr fcntl 2 , 121.Xr intro 4 , 122.Xr tty 4 123.Sh HISTORY 124An 125.Fn ioctl 126function call appeared in 127.At v7 . 128