IOCTL(2) BSD System Calls Manual IOCTL(2)NAMEioctl — control device
ioctl(int d, unsigned long request, char *argp);
The ioctl() function manipulates the underlying device parameters of spe‐
cial 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
If an error has occurred, a value of -1 is returned and errno is set to
indicate the error.
ERRORSIoctl() 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.
SEE ALSOmt(1), execve(2), fcntl(2), tty(4), intro(4)HISTORY
An ioctl function call appeared in Version 7 AT&T UNIX.
4th Berkeley Distribution December 11, 1993 4th Berkeley Distribution