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CS 476/576
Systems
Programming
Fall
2006
Midterm
Exam
Time
2 & 1/2 hours
Open
Book & Notes
Name:
Login:
A
total of five questions, each question
is 20 points
Ø
Do
not use networked computer.
Ø To make it easy to read your answer, please
do NOT write:
·
include statements
·
error checking statements
·
comment statements
Question
1:
Write a shell script that
have the following description:
RunAndMail <cmd>
The
program runs the <cmd> then email to the user the message:
You have run:
<cmd>
Example:
% RunAndMail ls -lt
If the user is cs476, then he will get the following email
message:
From cs476@cs.odu.edu Sat
Date: Sat, 14 Oct 2006 00:45:00 -0400 (EDT)
From: cs476 grader <cs476@cs.odu.edu>
To: cs476@cs.odu.edu
You have run:
ls -lt
Question
2:
Write a shell script with following description:
getnames <file>
where the <file> is a file contains a list of emails.
The program produces another
file called: <file>_Names that maps each email to one name.
Example:
% cat FacultyEmails
wahab
maly
ajay
% getnames FacultyEmails
% cat FacultyEmails_Names
wahab :
Dr. wahab
maly :
Kurt Maly
ajay :
Ajay Gupta
Question
3:
Write a Motif program with following
description:
q3 cm1 cmd2 …. cmdN
to create an interface with N+1
push buttons, where button i,
<= i <=N, is
labeled with cmdi and button N+1 is labeled quit.
Clicking on
cmdi button executes cmdi and displays its output to stdout.
The program exits by clicking on the quit button.
Example:
% q3 ls date who ps date
Creates the following interface:
For example clicking on date produces the
following on the stdout:
Mon
Question 4:
Consider the
following program where the parent creates two children processes.
Modify this program
such that:
The parent create a file specified as argv[1]
and write the message: “Hello Kids” in that file.
It then sends SIGUSR1 to child1 and SIGUSR2
to child2 and exits.
When a child receives
signal from the parent, it reads the line from the file, prints it to the stdout and exits.
Example:
% q4 q4file
% cat q4file
Hello Kids
----------------q4.c
---------------------------------
int main (int argvc, char **argv)
{
pid_t pid1=0,
pid2=0;
pid1 = fork();
if (pid1 ==
0) {
printf("First Child: pid %d\n", getpid());
pause();
}
else {
pid2 =
fork();
if ( pid2
== 0 ) {
printf("Second Child: pid %d\n", getpid());
pause();
}
else {
printf("Parent: pid %d, pid1 %d, pid2 %d\n",
getpid(), pid1, pid2);
pause();
}
}
}
Question 5:
Like Question 4, in
the following program, the parent creates two children processes.
Modify this program
such that:
1.
The parent dies after a random amount of time T
between 1 and 100 seconds.
2.
Each child sleeps a random amount of time T between
1-10 seconds and then checks to see if the parent is dead.
3.
When a child discovers that the parent is dead, it
kills the other child (may be to inherit all the wealth!), and then exits.
You may assume that the PIDs of the two children are
consecutive.
int main (int argvc, char **argv)
{
pid_t pid1=0,
pid2=0;
pid1 = fork();
if (pid1 ==
0) {
printf("First Child: pid %d\n", getpid());
pause();
}
else {
pid2 =
fork();
if ( pid2
== 0 ) {
printf("Second Child: pid %d\n", getpid());
pause();
}
else {
printf("Parent: pid %d, pid1
%d, pid2 %d\n",
getpid(), pid1, pid2);
pause();
}
}
}