simple program to create Orphan process

shiv@ubuntu:~/ds/unix$ cat  orp.c
/*
 * Program to create orphan process @ Linux

 * getpid() gives process PID and 

 * getppid() gives process's parent ID 

 * here main() process ID is parent id is current shells PID

 * once process becomes orphan it is adopted by init process(it's PID is 1)

 */

 
#include<stdio.h>
#include<unistd.h>
int main()
{

 pid_t p;

/* create child process */
 p=fork();

 if(p==0) {
    /* fork() returns Zero to child */
    sleep(10);
 }
 printf("The child process pid is %d parent pid %d\n", getpid(), getppid());
/*parent/child waits for 20 secs and exits*/
 sleep(20);
 printf("\nProcess %d is done its Parent pid %d...\n", getpid(), getppid());

 return 0;
}

O/p
shiv@ubuntu:~/ds/unix$ ./a.out
The child process pid is 2575 parent pid 1922
The child process pid is 2576 parent pid 2575

Process 2575 is done its Parent pid 1922...
shiv@ubuntu:~/ds/unix$
Process 2576 is done its Parent pid 1...