Use code to verify the relationship between a Linux child and its parent

#include "basic.h"
pid_t Fork(void)
{
    pid_t pid = fork();
    if (pid < 0) {
        fprintf(stderr, "Fork error: %sn", strerror(errno));
        exit(0);
    }
    return pid;
}

**********  basic.h  ***********
#ifndef __CSAPP_BASIC_H
#define __CSAPP_BASIC_H
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#include <signal.h>
#include <unistd.h>
#include <string.h>

pid_t Fork();
#endif

*******  fork.c  *********
#include "basic.h"
int main()
{
    int pid = Fork();
    int x = 2;
    if (pid == 0) {
        printf("child: pid = %d, ppid = %d, x = %dn", getpid(), getppid(), ++x);
        sleep(3);

        printf("child: pid = %d, ppid = %d, x = %dn", getpid(), getppid(), ++x);
        exit(0);
    }
    printf("parent: pid = %d, ppid = %d, x = %dn", getpid(), getppid(), --x);
}
 through  gcc fork.c basic.c -o fork  compilable  fork  The program.    run  ./fork
 You can see that the parent process exits first, before exiting child the PPID for 12256 .   Of the post-exit child process PPID Into the  1. Explains the parent process exit by the child process  init  Super process 1 Adoption. And the process is never going away.