IP Networking

void main()
{
int pid;

pid=fork();

switch(pid)
{
case -1: printf("\n THE PROCESS HAS NOT BEEN CREATED \n");
break;
case 0: printf("\n I HAVE ENTERED IN THE CHILD PROCESS \n");
printf("\n THE CHILD PID IN CHILD PROCESS IS %d",getpid());
printf("\n THE PARENT PID IN CHILD PROCESS IS %d",getppid());
break;
default: printf("\n I AM NOW IN THE PARENT PROCESS \n");
printf("\n THE CHILD PID IN PARANT PROCESS IS %d",getpid());
printf("\n THE PARENT PID IN PARENT PROCESS IS %d",getppid());

break;
}
}

Hi,

The program u have given itself gives the answer .. rite ...

When we fork a new child process from a parent process like pid=fork(); the fork function returns the process id of the child process spawned ....

getpid returns the process id of the process which calls this function and getppid gives the process id of its parent process ...

C the output I got :

#include <unistd.h>
#include <iostream.h>
int main()
{
int pid;

pid=fork();

switch(pid)
{
case -1: printf("\n THE PROCESS HAS NOT BEEN CREATED \n");
break;
case 0: printf("\n I HAVE ENTERED IN THE CHILD PROCESS \n");
printf("\n THE pid returned by fork to me is %d",pid);
printf("\n THE CHILD PID IN CHILD PROCESS IS %d",getpid());
printf("\n THE PARENT PID IN CHILD PROCESS IS %d",getppid());
break;
default: printf("\n I AM NOW IN THE PARENT PROCESS \n");
printf("\n THE pid returned by fork to me is %d",pid);
printf("\n THE CHILD PID IN PARANT PROCESS IS %d",getpid());
printf("\n THE PARENT PID IN PARENT PROCESS IS %d \n",getppid());

break;
}
}

Output:
--------

I HAVE ENTERED IN THE CHILD PROCESS

THE pid returned by fork to me is 0
THE CHILD PID IN CHILD PROCESS IS 25524
THE PARENT PID IN CHILD PROCESS IS 25521

I AM NOW IN THE PARENT PROCESS

THE pid returned by fork to me is 25524
THE CHILD PID IN PARANT PROCESS IS 25521
THE PARENT PID IN PARENT PROCESS IS 10024

Explanation:
-------------

Here if u chk, we can c that the getpid result of the parent process and getppid result of child process are same (25521)

Again the process 10024 which is the parent of the parent process is nothing but the shell .. ;-)

$ ps -eaf | grep 10024
appsuser 10024 9343 0 08:08:19 pts/60 0:01 -ksh

Hope its clear now ....