ioctl - control device
int ioctl(int d, int request, void *argp) (Minix)
int ioctl(int d, ioreq_t request, void *argp) (Minix-vmd)
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 discuss 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 specifying an ioctl request are located in the
If an error has occurred, a value of -1 is returned and errno is set to
indicate the error.
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 references.
[EINVAL] Request or argp is not valid.
execve(2), fcntl(2), mt(4), tty(4), intro(4).