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IOCTL(2) BSD System Calls Manual IOCTL(2)
ioctl -- control device
ioctl(int d, unsigned long request, char *argp);
The ioctl() function manipulates the underlying device parameters of special files. In par-
ticular, 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 specify-
ing an ioctl request are located in the file <sys/ioctl.h>.
If an error has occurred, a value of -1 is returned and errno is set to indicate the error.
Ioctl() will fail if:
[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.
mt(1), cdio(1), chio(1), execve(2), fcntl(2), tty(4), intro(4)
An ioctl() function call appeared in Version 7 AT&T UNIX.
4th Berkeley Distribution December 11, 1993 4th Berkeley Distribution
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