pid3              825 user/usertests.c   int pid1, pid2, pid3;
pid3              847 user/usertests.c   pid3 = fork();
pid3              848 user/usertests.c   if(pid3 < 0) {
pid3              852 user/usertests.c   if(pid3 == 0){
pid3              870 user/usertests.c   kill(pid3);