fork and signal Example

/* fork and signal */
#include<stdio.h>
#include<unistd.h>
#include<signal.h>
#include<sys/wait.h>
#include<sys/types.h>
 
void sig_child(int sig)
{
    pid_t pid;
    int stat;
    puts("signal");
    while((pid=waitpid(-1,&stat,WNOHANG)) > 0)
        printf("child %d terminated\n",pid);
    return;
}
 
void sig_key(int sig)
{
    puts("ctrl + C");
}
 
int main()
{
    signal(SIGINT,sig_key);
    signal(SIGCHLD,sig_child);
    if(fork())
    {
        puts("hello world!!!");
        sleep(5);
    }
    else
    {
        execve("/bin/ls",NULL,NULL);
        puts("after");
    }
    return 1;
}