1.\" $OpenBSD: ioctl.2,v 1.11 2001/07/30 01:12:43 deraadt Exp $ 2.\" $NetBSD: ioctl.2,v 1.5 1995/02/27 12:33:47 cgd Exp $ 3.\" 4.\" Copyright (c) 1980, 1991, 1993 5.\" The Regents of the University of California. All rights reserved. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. All advertising materials mentioning features or use of this software 16.\" must display the following acknowledgement: 17.\" This product includes software developed by the University of 18.\" California, Berkeley and its contributors. 19.\" 4. Neither the name of the University nor the names of its contributors 20.\" may be used to endorse or promote products derived from this software 21.\" without specific prior written permission. 22.\" 23.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33.\" SUCH DAMAGE. 34.\" 35.\" @(#)ioctl.2 8.2 (Berkeley) 12/11/93 36.\" 37.Dd December 11, 1993 38.Dt IOCTL 2 39.Os 40.Sh NAME 41.Nm ioctl 42.Nd control device 43.Sh SYNOPSIS 44.Fd #include <sys/ioctl.h> 45.Ft int 46.Fn ioctl "int d" "unsigned long request" "..." 47.Sh DESCRIPTION 48The 49.Fn ioctl 50function manipulates the underlying device parameters of special files. 51In particular, many operating 52characteristics of character special files (e.g., terminals) 53may be controlled with 54.Fn ioctl 55requests. 56.Pp 57The argument 58.Fa d 59must be an open file descriptor. The third argument is called 60.Fa arg 61and contains additional information needed by this device 62to perform the requested function. 63.Fa arg 64is either an 65.Li int 66or a pointer to a device-specific data structure, depending upon 67the given 68.Fa request . 69.Pp 70An 71.Nm 72.Fa request 73has encoded in it whether the argument is an 74.Dq in 75parameter 76or 77.Dq out 78parameter, and the size of the third argument 79.Pq Fa arg 80in bytes. 81Macros and defines used in specifying an ioctl 82.Fa request 83are located in the file 84.Ao Pa sys/ioctl.h Ac . 85.Sh RETURN VALUES 86If an error has occurred, a value of \-1 is returned and 87.Va errno 88is set to indicate the error. 89.Sh ERRORS 90.Fn ioctl 91will fail if: 92.Bl -tag -width Er 93.It Bq Er EBADF 94.Fa d 95is not a valid descriptor. 96.It Bq Er ENOTTY 97.Fa d 98is not associated with a character 99special device. 100.It Bq Er ENOTTY 101The specified request does not apply to the kind 102of object that the descriptor 103.Fa d 104references. 105.It Bq Er EINVAL 106.Fa request 107or 108.Fa arg 109is not valid. 110.It Bq Er EFAULT 111.Fa arg 112points outside the process's allocated address space. 113.El 114.Sh SEE ALSO 115.Xr cdio 1 , 116.Xr chio 1 , 117.Xr mt 1 , 118.Xr execve 2 , 119.Xr fcntl 2 , 120.Xr intro 4 , 121.Xr tty 4 122.Sh HISTORY 123An 124.Fn ioctl 125function call appeared in 126.At v7 . 127