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IOCTL(2)		    BSD	System Calls Manual		      IOCTL(2)

NAME
     ioctl -- control device

SYNOPSIS
     #include <sys/ioctl.h>

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

DESCRIPTION
     The ioctl() function manipulates the underlying device parameters of spe-
     cial 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 is
     called arg	and contains additional	information needed by this device to
     perform the requested function.  arg is either an int or a	pointer	to a
     device-specific data structure, depending upon the	given request.

     An	ioctl request has encoded in it	whether	the argument is	an "in"	param-
     eter or "out" parameter, and the size of the third	argument (arg) in
     bytes.  Macros and	defines	used in	specifying an ioctl request are	lo-
     cated in the file <sys/ioctl.h>.

GENERIC	IOCTLS
     Some ioctls are applicable	to any file descriptor.	 These include:

     FIOCLEX
	     Set close-on-exec flag.  The file will be closed when exec(3) is
	     invoked.

     FIONCLEX
	     Clear close-on-exec flag.	The file will remain open across
	     exec(3).

     Some generic ioctls are not implemented for all types of file descrip-
     tors.  These include:

     FIONREAD int *
	     Get the number of bytes that are immediately available for	read-
	     ing.

     FIONBIO int *
	     Set non-blocking I/O mode if the argument is non-zero.  In	non-
	     blocking mode, read(2) or write(2)	calls return -1	and set	errno
	     to	EAGAIN immediately when	no data	is available.

     FIOASYNC int *
	     Set asynchronous I/O mode if the argument is non-zero.  In	asyn-
	     chronous mode, the	process	or process group specified by
	     FIOSETOWN will start receiving SIGIO signals when data is avail-
	     able.  The	SIGIO signal will be delivered when data is available
	     on	the file descriptor.

     FIOSETOWN,	FIOGETOWN int *
	     Set/get the process or the	process	group (if negative) that
	     should receive SIGIO signals when data is available.

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 arg is not valid.

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

SEE ALSO
     cdio(1), chio(1), mt(1), execve(2), fcntl(2), intro(4), tty(4)

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

BSD				 June 27, 2014				   BSD

NAME | SYNOPSIS | DESCRIPTION | GENERIC IOCTLS | RETURN VALUES | ERRORS | SEE ALSO | HISTORY

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