IOCTL(2) System Calls Manual IOCTL(2) + +NAME + ioctl - control device + +SYNOPSIS + #include <sys/ioctl.h> + + int + ioctl(int d, unsigned long request, ...); + +DESCRIPTION + 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. The third argument is + called arg and contains additional information needed by this device to + perform the requested function. arg is either an int or a pointer to a + device-specific data structure, depending upon the given request. + + An ioctl request has encoded in it whether the argument is an ``in'' + parameter or ``out'' parameter, and the size of the third argument (arg) + 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. + +ERRORS + 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 arg is not valid. + + [EFAULT] arg points outside the process's allocated address + space. + +SEE ALSO + cdio(1), chio(1), mt(1), execve(2), fcntl(2), intro(4), tty(4) + +HISTORY + An ioctl() function call appeared in Version 7 AT&T UNIX. + +BSD December 11, 1993 BSD + |