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NAME    [Toc]    [Back]

       ioctl - control device

SYNOPSIS    [Toc]    [Back]

       #include <sys/ioctl.h>

       int ioctl(int d, int request, ...)

       [The "third" argument is traditionally char *argp, and will be so named
       for this discussion.]

DESCRIPTION    [Toc]    [Back]

       The ioctl function 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.

       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 specifying an ioctl request are located in
       the file <sys/ioctl.h>.

RETURN VALUE    [Toc]    [Back]

       Usually, on success zero is returned.  A  few  ioctls  use  the	return
       value as an output parameter and return a nonnegative value on success.
       On error, -1 is returned, and errno is set appropriately.

ERRORS    [Toc]    [Back]

       EBADF  d is not a valid descriptor.

       EFAULT argp references an inaccessible memory area.

       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 argp is not valid.

CONFORMING TO    [Toc]    [Back]

       No single standard.  Arguments, returns, and semantics of ioctl(2) vary
       according to the device driver in question  (the  call  is  used  as  a
       catch-all  for  operations  that  don't cleanly fit the Unix stream I/O
       model). See ioctl_list(2) for a list of many of the known ioctl	calls.
       The ioctl function call appeared in Version 7 AT&T Unix.

SEE ALSO    [Toc]    [Back]

       execve(2), fcntl(2), ioctl_list(2), mt(4), sd(4), tty(4)

BSD Man Page			  1993-07-23			      IOCTL(2)
[ Back ]
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