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Mac OS X / Darwin man pages : ioctl (2)
ioctl (2)

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ioctl - control device


#include <sys/ioctl.h>

ioctl(int d, unsigned long request, char *argp);


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 Values

If an error has occurred, a value of -1 is returned and errno is set to indicate the error.


Ioctl() will fail if:

d is not a valid descriptor.

d is not associated with a character special device.

The specified request does not apply to the kind of object that the descriptor d references.

Request or argp is not valid.

See Also

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.

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