Unix System Calls like fork,wait,execlp,sleep for Process Management...

************************ Instructions how to make program ****************************

(1) Open Terminal.

(2) type  vi <prog-name>.<extension> & then Press Enter...

(3) whenever you want to insert code or statements press i.

(4) Save program bye typing this :-   Press Esc key then Shift + ;  then wq & then Press Enter...

(5) How to compile :- just enter this :- cc <prog-name>.<extension> & pres Enter...

(6) How To Run :- just enter this :- ./a.out & press Enter...

*********************************** final.c **************************************

#include<stdio.h>

#include<stdlib.h>

#include<unistd.h>

#include<sys/types.h>

int main()

{

pid_t gp,p,c;

printf("\n Gramd Parent Executing...");     

gp=fork();

printf("Grand Parent's pid => %d",gp);

if(gp==0) // its Child executes...

{

printf("\n Parent Executing...");     

p=fork();

printf("Parent's pid => %d",p);

if(p==0) // its Child executes...

{

printf("\n Child Executing...");     

c=fork();

sleep(10);

printf("Child's pid => %d",c);

printf("\n Child after execution...");

}

printf("\n Parent after execution...");

execlp("/bin/ls/","ls",NULL);

printf("\n execlp() Completed...");

}

gp=wait();

printf("\n After Waiting Grant Parent's Process id = > %d",gp);

exit(0);

}

*******************************************************************************

For this Program You can refer following links :- 

       http://linux.about.com/library/cmd/blcmdl3_execlp.htm

       http://linux.about.com/od/commands/l/blcmdl.htm