IOCTL(2)                             BSD                              IOCTL(2)



NAME
     ioctl - control device

SYNOPSIS
     #include <sys/ioctl.h>

     ioctl(d, request, argp)
     int d;
     unsigned long request;
     char *argp;

DESCRIPTION
     ioctl performs a variety of functions on open descriptors.  In
     particular, many operating characteristics of character special files
     (for example terminals) can be controlled with ioctl requests.  The
     write-ups 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
     file <sys/ioctl.h>.

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 references.

     [EINVAL]   request or argp is not valid.

SEE ALSO
     execve(2), fcntl(2), tty(4), intro(4N)

DIAGNOSTICS
     If an error has occurred, a value of -1 is returned and errno is set to
     indicate the error.