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IOCTL(2)                 DragonFly System Calls Manual                IOCTL(2)


NAME

     ioctl -- control device


LIBRARY

     Standard C Library (libc, -lc)


SYNOPSIS

     #include <sys/ioctl.h>

     int
     ioctl(int d, unsigned long request, ...);


DESCRIPTION

     The ioctl() system call 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.

     The third argument to ioctl() is traditionally named char *argp.  Most
     uses of ioctl() however, require the third argument to be a caddr_t or an
     int.

     An ioctl() request has encoded in it whether the argument is an ``in''
     argument or ``out'' argument, 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.

     [EFAULT]           argp points outside the process's allocated address
                        space.


SEE ALSO

     execve(2), fcntl(2), intro(4), tty(4), ioctl(9)


HISTORY

     An ioctl() function call appeared in Version 7 AT&T UNIX.

DragonFly 3.5                  December 11, 1993                 DragonFly 3.5

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