forktree.c

#include <stdio.h>
#include <unistd.h>

void main()
{
    int pId1;
    pId1 = fork();
    if (pId1 < 0)
    {
        printf("Process creation is Unsuccessful!");
    }
    // The return value is 0 for a child process
    else if (pId1 == 0)
    {
        printf("Child process:");
        printf("\nChild : Child’s PID: %d", getpid());
        printf("\nChild : Parent’s PID: %d\n", getppid());
        int pId2;
        pId2 = fork();
        if (pId2 < 0)
   	 {
       	 	printf("Process creation is Unsuccessful!");
   	 }
   	 // The return value is 0 for a child process
   	 else if (pId2 == 0)
    	{
    	    printf("Child process:");
    	    printf("\nChild : Child’s PID: %d", getpid());
   	     printf("\nChild : Parent’s PID: %d\n", getppid());
   	 }
   	 // The return value is positive for a parent process
   	 else if (pId2 > 0)
   	 {
     	   printf("Parent process:");
     	   printf("\nParent : Parent’s PID: %d", getpid());
     	   printf("\nParent : Child’s PID: %d\n", pId2);
    	}
    }
    // The return value is positive for a parent process
    else if (pId1 > 0)
    {
        printf("Parent process:");
        printf("\nParent : Parent’s PID: %d", getpid());
        printf("\nParent : Child’s PID: %d\n", pId1);
    }
}