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IOCTL(2)		       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  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(), 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"  argu-
     ment 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 in-
     dicate the error.

ERRORS
     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  spe-
			cial device.

     [ENOTTY]		The  specified request does not apply to the kind of ob-
			ject 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
     execve(2), fcntl(2), intro(4), tty(4)

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

FreeBSD 7.0			  July 14, 2007 			IOCTL(2)
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