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ioctl(2)
NAME
  ioctl - Controls devices

SYNOPSIS
  #include <stropts.h>

  int ioctl(
	  int fildes,
	  int request,
	  ... /* arg */);

STANDARDS
  Interfaces documented on this reference page conform to industry standards
  as follows:

  ioctl():  XPG4-UNIX

  Refer to the standards(5) reference page for more information about
  industry standards and associated tags.

PARAMETERS
  fildes    Specifies the file descriptor of the requested device.

  request   Specifies the ioctl command to be performed on the device.

  arg	    Specifies parameters for this request.  The type of arg is
	    dependent on the specific ioctl() request and device to which the
	    ioctl is targeted.	See the appropriate Section 7 reference page
	    or the documentation accompanying the device for more
	    information.

DESCRIPTION
  The ioctl() function performs a variety of control functions on devices and
  STREAMS.  For non-STREAMS files, the functions performed by this call are
  device-specific control functions.  The request and arg parameters are
  passed to the file designated by fildes and are interpreted by the device
  driver.  This control is occasionally used on non-STREAMS devices, with the
  basic input/output functions performed through the read() and write()
  system calls.

  An ioctl() request has encoded in it whether the parameter is an "in"
  parameter or "out" parameter, and the size of the arg parameter in bytes.
  Macros and defines used to specify an ioctl() request are located in the
  <stropts.h> header file.

  For STREAMS files, specific functions are performed by the ioctl() function
  as described in streamio(7).

  STREAMS errors are described in streamio(7).

RETURN VALUES
  Upon successful completion, the ioctl() function returns a value other than
  -1 that depends upon the STREAMS device control function.

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

ERRORS
  The ioctl() function sets errno to the specified values for the following
  general conditions:

  [EBADF]   The fildes parameter is not a valid open file descriptor.

  [EINTR]   A signal was caught during the ioctl() operation.

  [EINVAL]  The STREAM or multiplexer referenced by fildes is linked
	    (directly or indirectly) downstream from a multiplexer.

  If an underlying device driver detects an error, errno may be set to one of
  the following values:

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

  [EIO]	    Some physical I/O error has occurred.

  [ENOTTY]  [XPG4-UNIX]	 The fildes parameter is not associated with a
	    STREAMS device that accepts control functions.

  [ENOTTY]  [Digital]  The fildes parameter is not associated with a
	    character special device, or the specified request does not apply
	    to the kind of object that the fildes parameter references.

  [ENXIO]   The request and arg parameters are valid for this device driver,
	    but the service requested cannot be performed on the particular
	    subdevice.

  [ENODEV]  The fildes parameter refers to a valid STREAMS device, but the
	    corresponding device driver does not support the ioctl()
	    function.

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

  Files: tty(7), lvm(7), streamio(7)

  Standards: standards(5)