pub fn signal_process_group(pid: u32, signal: c_int) -> Result<()>Expand description
Send one signal to the process group led by pid, with no grace and
no escalation: the building block of kill_process_group, for callers
that pick their own signal and timing (the launcher’s teardown backstop).
Same guards: 0, 1 and anything out of range for pid_t are refused
with InvalidInput and nothing is sent. An already-empty group is an
ESRCH error, which callers usually ignore.