IOCTL(2) BSD System Calls Manual IOCTL(2)
NAME
ioctl -- control device
SYNOPSIS
#include <sys/ioctl.h>
int
ioctl(int d, unsigned long request, char *argp);
DESCRIPTION
The ioctl() function manipulates the underlying device parameters of special files. In particular, many operating characteristics of charac-
ter 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>.
RETURN VALUES
If an error has occurred, a value of -1 is returned and errno is set to indicate the error.
ERRORS
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.
SEE ALSO
mt(1), cdio(1), chio(1), execve(2), fcntl(2), tty(4), intro(4)
HISTORY
An ioctl() function call appeared in Version 7 AT&T UNIX.
4th Berkeley Distribution December 11, 1993 4th Berkeley Distribution
