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Manuál Linux
[Linux manuál]

ioctl: ovládací zařízení

Originální popis anglicky: ioctl - control device

Návod, kniha: Linux Programmer's Manual

STRUČNĚ

#include <sys/ioctl.h>
 
int ioctl(int d, int request, ...);

POPIS / INSTRUKCE

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>.

NÁVRATOVÁ HODNOTA

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.

CHYBY / ERRORY

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.

NOTE

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.

ODPOVÍDAJÍCÍ

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.

SOUVISEJÍCÍ

execve(2), fcntl(2), ioctl_list(2), open(2), mt(4), sd(4), tty(4)
2000-09-21 BSD Man Page
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