#include <unistd.h>
#include <sys/types.h>
#include <errno.h>
#include <stdio.h>
#include <sys/wait.h>
#include <stdlib.h>

int main()
{
    pid_t childpid;
    int retval;
    int status;

    childpid = fork();
    if(childpid >= 0)
    {
        if(childpid == 0)
        {
            printf("CHILD : I am the child process\n");
            printf("CHILD : Here's my PID : %d\n", getpid());
            printf("CHILD : My parent's PID is : %d\n", getppid());
            printf("CHILD : The value of my copy of childpid is : %d\n", childpid);
            printf("CHILD : Sleeping for 1 second...\n");
            sleep(1);
            printf("CHILD : Enter an exit value (0 to 255) : ");
            scanf("%d\n", &retval);
            printf("CHILD : Goodbye\n");
            exit(retval);
        }
        else
        {
            printf("PARENT : I am the parent process\n");
            printf("PARENT : Here's my PID : %d\n", getpid());
            printf("PARENT : The value of my copy of childpid is : %d\n", childpid);
            printf("PARENT : I will now wait for my child to exit\n");
            wait(&status);
            printf("PARENT : Child's exit code is : %d", WEXITSTATUS(status));
            printf("PARENT : Goodbye\n");
            exit(0);
        }
    }
    else
    {
        perror("fork error");
        exit(0);
    }
}