1.\" Copyright (c) 1980, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" %sccs.include.redist.man% 5.\" 6.\" @(#)ioctl.2 8.2 (Berkeley) 12/11/93 7.\" 8.Dd 9.Dt IOCTL 2 10.Os BSD 4 11.Sh NAME 12.Nm ioctl 13.Nd control device 14.Sh SYNOPSIS 15.Fd #include <sys/ioctl.h> 16.Ft int 17.Fn ioctl "int d" "unsigned long request" "char *argp" 18.Sh DESCRIPTION 19The 20.Fn ioctl 21function manipulates the underlying device parameters of special files. 22In particular, many operating 23characteristics of character special files (e.g. terminals) 24may be controlled with 25.Fn ioctl 26requests. 27The argument 28.Fa d 29must be an open file descriptor. 30.Pp 31An ioctl 32.Fa request 33has encoded in it whether the argument is an 34.Dq in 35parameter 36or 37.Dq out 38parameter, and the size of the argument 39.Fa argp 40in bytes. 41Macros and defines used in specifying an ioctl 42.Fa request 43are located in the file 44.Ao Pa sys/ioctl.h Ac . 45.Sh RETURN VALUES 46If an error has occurred, a value of -1 is returned and 47.Va errno 48is set to indicate the error. 49.Sh ERRORS 50.Fn Ioctl 51will fail if: 52.Bl -tag -width [ENOTTY] 53.It Bq Er EBADF 54.Fa d 55is not a valid descriptor. 56.It Bq Er ENOTTY 57.Fa d 58is not associated with a character 59special device. 60.It Bq Er ENOTTY 61The specified request does not apply to the kind 62of object that the descriptor 63.Fa d 64references. 65.It Bq Er EINVAL 66.Fa Request 67or 68.Fa argp 69is not valid. 70.El 71.Sh SEE ALSO 72.Xr mt 1 , 73.Xr execve 2 , 74.Xr fcntl 2 , 75.Xr tty 4 , 76.Xr intro 4 77.Sh HISTORY 78An 79.Nm 80function call appeared in Version 7 AT&T UNIX. 81