4.3BSD - /usr/man/cat2/ioctl.0

IOCTL(2)                                                              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 particu‐
       lar, many operating characteristics of character  special  files  (e.g.
       terminals) may be controlled with ioctl requests.  The writeups of var‐
       ious devices in section 4 discuss 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  specifying  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 references.

       [EINVAL]       Request or argp is not valid.

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


4th Berkeley Distribution        March 4, 1986                        IOCTL(2)