关于子进程异步等待方式（SIGCHLD信号）

相关博客

Linux下的信号（一）
http://blog.csdn href="http://lib.csdn.net/base/dotnet" target=_blank>.NET/double_happiness/article/details/72848372

Linux下的信号（二）
http://blog.csdn href="http://lib.csdn.net/base/dotnet" target=_blank>.Net/double_happiness/article/details/72897148

僵尸进程
http://blog.csdn.net/double_happiness/article/details/70168897
在上面关于僵尸进程的父进程等待时，父进程有两种等待方式，即阻塞和非阻塞，下面我们来验证一下，子进程退出时的其他情况

验证子进程退出时会给父进程发送信号

#include<stdio.h>
#include<signal.h>
#include<stdlib.h>
#include<sys/types.h>

void handler(int sig){
printf("sig is %d,pid is %d\n",sig,getpid());
}

int main()
{
signal(SIGCHLD,handler);
int id=fork();
if(id<0){
perror("fork");
exit(-1);
}
else if(id==0){
sleep(3);
printf("i am child, my pid is %d\n",getpid());
exit(2);
}
else{
while(1){
printf("i am parent,my pid is %d\n",getpid());
sleep(1);
}
}
return 0;
}


运行结果：



父进程等待子进程的异步版本代码实现：

#include<stdio.h>
#include<signal.h>
#include<stdlib.h>
#include<sys/types.h>

void handler(int sig){
printf("sig is %d,pid is %d\n",sig,getpid());
}

int main()
{
int id=fork();
if(id<0){
perror("fork");
exit(-1);
}
else if(id==0){
sleep(3);
printf("i am child, my pid is %d\n",getpid());
exit(2);
}
else{
struct sigaction act;
act.sa_handler = handler;
sigemptyset(&act.sa_mask);
act.sa_flags = 0;
sigaction(SIGCHLD, &act, NULL);
while(1){
printf("i am parent,my pid is %d\n",getpid());
sleep(1);
}
}
return 0;
}

运行结果：