pid3              822 user/usertests.c   int pid1, pid2, pid3;
pid3              844 user/usertests.c   pid3 = fork();
pid3              845 user/usertests.c   if(pid3 < 0) {
pid3              849 user/usertests.c   if(pid3 == 0){
pid3              867 user/usertests.c   kill(pid3);