Unix Network Programming Assignment-2
Winter Semester,Department of Computer Science
University of Hyderabad
Max.Marks : 10					    	Deadline : 10-02-05.

Note : Answer All Questions , Precise Answers will be appreciated.


1. Can a process send a signal to  another process that is not in its process 
group? why or why not?



2.The Canteen at "Gopes", has four employees : (1) Hanuma, who 
takes customers' orders ; (2)  PushpaKumar.SP, who prepares the food;
(3) Subhash , who stuffs the food into bags; and (4) Suresh, who gives
the bags to the customers and take their money. Each employee can be
regarded as a communicating sequential process. What form of interprocess
communication do they use? Relate this model to processes in UNIX.



3.When a new process is forked off, it must be assigned a unique integer as 
its PID. Is it sufficient to have a counter in the kernel that is incremented 
on each process creation, with the counter used as the new PID? Discuss
your answer.


4.program :  Parent-child.c
#include <stdlib.h>
#include <stdio.h>
#include <signal.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
volatile unsigned long loop = 10000000;

void
handler (int n){
  if (loop > 0)
    --loop;
}

static int
child (void)
{
  pid_t ppid = getppid ();

  sleep (1);
  while (1)
    kill (ppid, SIGUSR1);
  return 0;
}

int
main (void)
{
  pid_t child_pid;
  int r;
if ((child_pid = fork ()) == 0)
    exit (child ());

  signal (SIGUSR1, handler);
  while (loop)
    sleep (1);
  r = kill (child_pid, SIGTERM);
  waitpid (child_pid, NULL, 0);
  return 0;
}

 a)Explain the above program?
 b)This program forks a process ,now there are two processes.

Changing the priorities of the processes may affect the execution time of the program.  So find-out   the probable priorities which could result in least execution time.

Hint : use nice() system call  time and top  commands.