Originální popis anglicky:
ioctl - control device
Návod, kniha: Linux Programmer's Manual
#include <sys/ioctl.h>
int ioctl(int d, int request, ...);
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.
The second argument is a device-dependent request code. The third argument is an
untyped pointer to memory. It's traditionally
char *argp (from
the days before
void * was valid C), and will be so named for this
discussion.
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>.
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.
- EBADF
- d is not a valid descriptor.
- EFAULT
- argp references an inaccessible memory area.
- EINVAL
- Request or argp is not valid.
- 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.
In order to use this call, one needs an open file descriptor. Often the
open(2) call has unwanted side effects, that can be avoided under Linux
by giving it the O_NONBLOCK flag.
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.
execve(2),
fcntl(2),
ioctl_list(2),
open(2),
mt(4),
sd(4),
tty(4)
