Sends a break signal of the specified type to the specified process group.
type can be one of
signaling, respectively, the pressing of CTRL + Break and of CTRL + C. If not
specified, type defaults to
processgroup is the PID of a process sharing the same console. If omitted,
it defaults to 0 (the current process), which is also the only meaningful
value that you can pass to this function.
undef on error, a nonzero value on success.