IOCTL(2)	    UNIX Programmer's Manual		 IOCTL(2)


NAME
     ioctl - control device

SYNOPSIS
     #include <sys/ioctl.h>

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

DESCRIPTION
     Ioctl performs a variety of functions on open descriptors.
     In particular, many operating characteristics of character
     special files (e.g. terminals) may be controlled with ioctl
     requests.	The writeups of various devices in section 4 dis-
     cuss how ioctl applies to them.

     An  ioctl request has encoded in it whether the argument is
     an "in" parameter or "out" parameter, and the size of the
     argument argp in bytes.  Macros and defines used in specify-
     ing an ioctl request are located in the file <sys/ioctl.h>.

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

ERRORS
     Ioctl will fail if one or more of the following are true:

     [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 refer-
		    ences.

     [EINVAL]	    Request or argp is not valid.

SEE ALSO
     execve(2), fcntl(2), mt(4), tty(4), intro(4N)


Printed 11/26/99	  March 4, 1986                         1


 
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