NAME    [Toc]    [Back]

     ioctl -- control device

LIBRARY    [Toc]    [Back]

     Standard C Library (libc, -lc)

SYNOPSIS    [Toc]    [Back]

     #include <sys/ioctl.h>

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

DESCRIPTION    [Toc]    [Back]

     The ioctl() system call manipulates the underlying device parameters of
     special 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.

     The third argument to ioctl() is traditionally named char *argp.  Most
     uses of ioctl() in FreeBSD 3.0 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    [Toc]    [Back]

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

ERRORS    [Toc]    [Back]

     The ioctl() system call will fail if:

     [EBADF]		The d argument is not a valid descriptor.

     [ENOTTY]		The d argument 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]		The request or argp argument is not valid.

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

SEE ALSO    [Toc]    [Back]

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

HISTORY    [Toc]    [Back]

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


FreeBSD 5.2.1		       December 11, 1993		 FreeBSD 5.2.1