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.\" $FreeBSD$ 35.\" 36.Dd December 11, 1993 37.Dt IOCTL 2 38.Os 39.Sh NAME 40.Nm ioctl 41.Nd control device 42.Sh LIBRARY 43.Lb libc 44.Sh SYNOPSIS 45.In sys/ioctl.h 46.Ft int 47.Fn ioctl "int d" "unsigned long request" ... 48.Sh DESCRIPTION 49The 50.Fn ioctl 51system call manipulates the underlying device parameters of special files. 52In particular, many operating 53characteristics of character special files (e.g.\& terminals) 54may be controlled with 55.Fn ioctl 56requests. 57The argument 58.Fa d 59must be an open file descriptor. 60.Pp 61The third argument to 62.Fn ioctl 63is traditionally named 64.Va "char *argp" . 65Most uses of 66.Fn ioctl 67in 68.Fx 3.0 , 69however, require the third argument to be a 70.Vt caddr_t 71or an 72.Vt int . 73.Pp 74An 75.Fn ioctl 76.Fa request 77has encoded in it whether the argument is an 78.Dq in 79argument 80or 81.Dq out 82argument, 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 94The 95.Fn ioctl 96system call 97will fail if: 98.Bl -tag -width Er 99.It Bq Er EBADF 100The 101.Fa d 102argument 103is not a valid descriptor. 104.It Bq Er ENOTTY 105The 106.Fa d 107argument 108is not associated with a character 109special device. 110.It Bq Er ENOTTY 111The specified request does not apply to the kind 112of object that the descriptor 113.Fa d 114references. 115.It Bq Er EINVAL 116The 117.Fa request 118or 119.Fa argp 120argument 121is not valid. 122.It Bq Er EFAULT 123The 124.Fa argp 125argument 126points outside the process's allocated address space. 127.El 128.Sh SEE ALSO 129.Xr execve 2 , 130.Xr fcntl 2 , 131.Xr intro 4 , 132.Xr tty 4 133.Sh HISTORY 134The 135.Fn ioctl 136function appeared in 137.At v7 . 138