Perl Programming/Keywords/ioctl

The ioctl keyword
ioctl implements the UNIX function ioctl(2) that manipulates the underlying device parametres of special files. Many operating characteristics of character special files (like terminals) can be controlled with ioctl requests. The argument FILEHANDLE must be an open file descriptor.

To run this function, one may first request "sys/ioctl.ph";. SCALAR is read or written, depending on the FUNCTION.

The function returns undef, if the operating system returns -1; if the OS returns 0, this function returns the string <tt>"0 but true"</tt>, and the returned number from the OS otherwise.