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IOCTL
!!!IOCTL
NAME
SYNOPSIS
DESCRIPTION
RETURN VALUE
ERRORS
CONFORMING TO
SEE ALSO
----
!!NAME


ioctl - control device
!!SYNOPSIS


#include <sys/ioctl.h>


__int ioctl(int__ ''d''__, int__ ''request''__,...)__


[[The "third" argument is __char *__''argp'', and will be so named for this
discussion.]
!!DESCRIPTION


The __ioctl__ function manipulates the underlying device
parameters of special files. In particular, many operating
characteristics of character special files (e.g. terminals)
may be controlled with __ioctl__ requests. The argument
''d'' must be an open file descriptor.


An ioctl ''request'' has encoded in it whether the
argument is an ''in'' parameter or ''out'' parameter,
and the size of the argument ''argp'' in bytes. Macros
and defines used in specifying an ioctl ''request'' are
located in the file ''''.
!!RETURN VALUE


Usually, on success zero is returned. A few ioctls use the
return value as an output parameter and return a nonnegative
value on success. On error, -1 is returned, and ''errno''
is set appropriately.
!!ERRORS


;__EBADF__: ''d'' is not a valid descriptor.


;__EFAULT__:  ''argp'' references an inaccessible memory area.


;__ENOTTY__:  ''d'' is not associated with a character special device.


;__ENOTTY__: The specified request does not apply to the kind of object that the descriptor ''d'' references.


;__EINVAL__: ''Request'' or ''argp'' is not valid.  This normally happens if you've provided the wrong type of request for the file descriptor you passed to the ioctl

!!CONFORMING TO


No single standard. Arguments, returns, and semantics of ioctl(2) vary according to the device driver in question (the call is used as a catch-all for operations that don't cleanly fit the Unix stream I/O model). See
ioctl_list(2) for a list of many of the known __ioctl__ calls. The __ioctl__ function call appeared in Version 7 AT&T Unix.
!!SEE ALSO


execve(2), fcntl(2), ioctl_list(2), mt(4), sd(4), tty(4), netdevice(7), socket(7)
----

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Last edited on Tuesday, July 9, 2002 9:14:11 pm by "!PerryLorier"

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