IOCTL (2)
control device
SYNOPSIS
#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
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
On success, zero is returned. On error, -1 is returned, and
errno
is set appropriately.
ERRORS
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
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
|
|