Verifying the relationship between a Linux subprocess and a parent process using code _c language

Copy Code code as follows:

/******** BASIC.C ********/
#include "basic.h"

pid_t Fork (void)
{
pid_t pid = fork ();
if (PID < 0) {
fprintf (stderr, "Fork Error:%s\n", Strerror (errno));
Exit (0);
}

return PID;
}

Copy Code code as follows:

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>
/* Function definition concerned with BASIC.C * *
pid_t Fork ();

#endif

Copy Code code as follows:

FORK.C *********

#include "basic.h"

int main ()
{
int pid = Fork ();
int x = 2;

if (PID = = 0) {
printf ("Child:pid =%d, Ppid =%d, x =%d\n", Getpid (), Getppid (), ++x);
Sleep (3);

printf ("Child:pid =%d, Ppid =%d, x =%d\n", Getpid (), Getppid (), ++x);
Exit (0);
}

printf ("Parent:pid =%d, Ppid =%d, x =%d\n", Getpid (), Getppid (),--x);

}

Through GCC fork.c basic.c-o Fork Compile-ready fork program. Run./fork

You can see that the parent process exits first, the ppid of the child before exiting is 12256, and the ppid of the subprocess becomes 1. The child process after the parent process exits is adopted by the INIT super Process 1. And the process is not going to quit.