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IOCTL(2) System Calls Manual IOCTL(2) NAME ioctl - control device SYNOPSIS #include <sys/types.h> #include <sys/ioctl.h> int ioctl(int d, int request, void *argp) (Minix) int ioctl(int d, ioreq_t request, void *argp) (Minix-vmd) DESCRIPTION Ioctl performs a variety of functions on open descriptors. In particu- lar, many operating characteristics of character special files (e.g. terminals) may be controlled with ioctl requests. The writeups of var- ious devices in section 4 discuss how ioctl applies to them. An ioctl request has encoded in it whether the argument is an "in" pa- rameter 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 VALUE If an error has occurred, a value of -1 is returned and errno is set to indicate the error. ERRORS Ioctl will fail if one or more of the following are true: [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 ob- ject that the descriptor d references. [EINVAL] Request or argp is not valid. SEE ALSO execve(2), fcntl(2), mt(4), tty(4), intro(4). 4th Berkeley Distribution March 4, 1986 IOCTL(2)