NAME
	  ioctl	- Controls devices

     SYNOPSIS
	  #include <sys/ioctl.h>

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

     PARAMETERS
	  d    Specifies the file descriptor of	the requested device.

	  request
	       Specifies the ioctl command to be performed on the dev-
	       ice.

	  argp Points to an parameter array for	the request.

     DESCRIPTION
	  The ioctl() function performs	a variety of operations	on
	  open descriptors.  In	particular, many operating charac-
	  teristics of character special files (for example, termi-
	  nals)	may be controlled with ioctl() requests.

	  An ioctl() request has encoded in it whether the parameter
	  is an	"in" parameter or "out"	parameter, and the size	of the
	  argp parameter in bytes.  Macros and defines used in speci-
	  fying	an ioctl() request are located in the sys/ioctl.h
	  file.

     RETURN VALUES
	  If an	error occurs, a	value of -1 is returned	and errno is
	  set to indicate the error.

     ERRORS
	  If the ioctl() function fails, errno may be set to one of
	  the following	values:

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

	  [ENOTTY]	 The d parameter is not	associated with	a
			 character special device.

	  [ENOTTY]	 The specified request does not	apply to the
			 kind of object	that the descriptor d refer-
			 ences.

	  [EINVAL]	 Either	the request or argp parameter is not
			 valid.

     RELATED INFORMATION
	  Functions: exec(2), fcntl(2)

	  Files: tty(7)	lvm(7)