//这个程序可以产生僵尸进程#include <stdio.h>#include <unistd.h>#include <sys/types.h>#include<stdlib.h>#include<signal.h>int main(int argc , char **argv){
 //signal(SIGCHLD, SIG_IGN);   如果将这行代码加上将不会产生僵尸进程
 int id; id=fork(); if(id<0)  {  printf("fork error\n");  } else if(id==0)  {   printf("I‘m in child process%d parent process %d\n",getpid(),getppid());   exit(0);   } else if(id>0)   {sleep(20);   printf("I‘m in parent process%d parent process %d\n",getpid(),getppid());   }     return 0;}[root@linux Desktop]# ./a.outI‘m in child process3418 parent process 3417        //这句输出后大概停顿20秒，才输出下面I‘m in parent process3417 parent process 3276[root@linux Desktop]# [root@linux Desktop]# ps aux | grep -w ‘Z‘root      3418  0.0  0.0      0     0 pts/0    Z+   21:27   0:00 [a.out] <defunct>   //产生僵尸进程root      3428  0.0  0.0   4336   796 pts/1    S+   21:27   0:00 grep -w Z[root@linux Desktop]# 

如果将signal(SIGCHLD, SIG_IGN);这行代码加上将不会产生僵尸进程的

[root@linux Desktop]# ps aux | grep -w ‘Z‘
root 3575 0.0 0.0 4336 796 pts/1 S+ 21:36 0:00 grep -w Z
[root@linux Desktop]#