killpg - send signal to process group

Syntax	#include <signal.h> int killpg(pid_t pgrp, int sig);
Description	killpg() sends the signal sig to the process group pgrp. The real or effective user ID of the sending process must match the real or saved “set-user- ID“ of the receiving process, unless the effective user ID of the sending process comes from a user with corresponding permission. The only exception is the SIGCONT signal, which can always be sent to any successor of the current process. If pgrp is greater than 1, killpg(pgrp, sig) corresponds to the call of kill(-pgrp,sig). If pgrp is less than or equal to 1, the behavior of killpg() is undefined.
Return val. Errors See also	See kill(). See kill(). getpgid(), getpid(), kill(), raise(), signal.h.