homeworkb2.c

用系统调用signal()让父进程捕捉键盘上来的中断信号（按Ctrl-C键）；当捕捉到中断信号后

#include <stdio.h>
#include <signal.h>
#include <unistd.h>
void killchild(int);
main()
{
     static a,b,c;
     int pid0,pid1,pid2;
     pid1=fork();
     if(pid1==0){
            for(;;){
             printf("child 1 is alive\n");
             sleep(1);
             b=(int)getpid();
             printf("%d\n",b);
            }
     }
           pid2=fork(); 
           if(pid2==0)
           {
            for(;;)
            {
            printf("child 2 is alive\n");
            sleep(2);
            c=(int)getpid();
            printf("%d\n",c);
            }
           }
       // printf("%d  %d\n,a,b");
         a=(int)getpid();
         printf("%d\n",a);
         void(* old_handler)(int);
       //  printf("%d\n",old_handler);
         old_handler=signal(SIGINT,killchild);
         wait();
         wait();
 //  while((c=getchar())!='\n')
         //    ;  
         printf("Parent Process is Killed!\n");
         signal(SIGKILL,old_handler);
}
void killchild(int dump)
{
     int i,j;
     i=(int)getpid()-1;
     j=i-1;
     printf("%d   %d\n",i,j);
     kill(i,SIGKILL);
     kill(j,SIGKILL);
     printf("Child Process 1 is Killed by Parent!\n");
     printf("Child Process 2 is Killed by Parent!\n");
}