:sig
int task_kill(pid_t pid, s32 sig = 0)

:params
pid : PID of the process
sig : signal number
return value : 0 if signal was sent, -1 otherwise

:see
>task
task
task_pid
task_repeat

:content
Wraps the standard POSIX `kill()` function for positive process IDs.

`task_kill()` rejects `pid <= 0` and returns `-1`, so callers cannot accidentally use POSIX process-group or broadcast semantics through this helper.

`sig` may be any supported POSIX signal, including values such as `SIGTERM`, `SIGKILL`, `SIGINT`, `SIGUSR1`, `SIGUSR2`, `SIGCHLD`, `SIGCONT`, and related process-control signals.

Passing `0` as the signal performs an existence and permission check without actually delivering a signal.

:example
task("doc-demo-kill", []() { usleep(3000000); });
pid_t pid = task_pid("doc-demo-kill");
print(pid > 0 && task_kill(pid) == 0 ? "task signalled to stop" : "no task to kill", "\n");