IOCTL(2) System Calls IOCTL(2)
ioctl - control device
int ioctl (int d, unsigned long request, void *argp);
The ioctl function manipulates the underlying device parameters of spe-
cial 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 <sys/ioctl.h>.
The writeups of various devices in chapter 4 discuss how ioctl applies
If an error has occurred, a value of -1 is returned and errno is set to
indicate the error.
Ioctl will fail if:
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.
mt(1), execve(2), fcntl(2), tty(4), intro(4)
An ioctl function call appeared in Version 7 AT&T UNIX.
GNO 16 January 1997 IOCTL(2)
Man(1) output converted with