ioctl(2) - NetBSD Manual Pages

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IOCTL(2)                  NetBSD Programmer's Manual                  IOCTL(2)

ioctl - control device
Standard C Library (libc, -lc)
#include <sys/ioctl.h> int ioctl(int d, unsigned long request, void *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'' 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>.
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), execve(2), fcntl(2), intro(4), tty(4)
An ioctl() function call appeared in Version 7 AT&T UNIX. NetBSD 1.6.2 December 11, 1993 1
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