


      IOCTL(2)                    (UNIX 5.0)                   IOCTL(2)



      NAME
           ioctl - control device

      SYNTAX
           ioctl (fildes, request, arg)

      DESCRIPTION
           Ioctl performs a variety of functions on character special
           files (devices).  The writeups of various devices in Section
           7 discuss how ioctl applies to them.

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

                Fildes is not a valid open file descriptor.  [EBADF]

                Fildes is not associated with a character special
                device.  [ENOTTY]

                Request or arg is not valid.  See Section 7.  [EINVAL]

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

      SEE ALSO
           termio(7).





























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