Fork system call is used to create a new process. Fork is

called onces and returns twice.It will return 0 to the newly

created process (child process) and process id of child to

the calling process(parent process).

The child process gets copy of parents data, stack and heap

segement.The code segement is common for both.Both the

processes will resume execution from the command next to

fork.Scheduler decide which process to run first.