NAME
ioctl - control device
SYNOPSIS
#include <sys/types.h>
#include <sys/ioctl.h>
int ioctl(int d, int request, void *argp) (Minix)
int ioctl(int d, ioreq_t request, void *argp) (Minix-vmd)
DESCRIPTION
Ioctl performs a variety of functions on open descriptors.
In particular, many operating characteristics of character
special files (e.g. terminals) may be controlled with ioctl
requests. The writeups of various devices in section 4 dis-
cuss how ioctl applies to them.
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 specify-
ing an ioctl request are located in the file <sys/ioctl.h>.
RETURN VALUE
If an error has occurred, a value of -1 is returned and
errno is set to indicate the error.
ERRORS
Ioctl will fail if one or more of the following are true:
[EBADF] D is not a valid descriptor.
[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 refer-
ences.
[EINVAL] Request or argp is not valid.
SEE ALSO
execve(2), fcntl(2), mt(4), tty(4), intro(4).