LAB
MANUAL
Course: CSC2205-Operating Systems
Department of Computer Science
Learning Procedure
J (Journey inside-out the concept)
Stage a1 (Apply the learned)
Stage v (Verify the accuracy)
Stage a2 (Assess your work)
1) Stage
2)
3)
4)
1
Table of Contents
Lab #
Lab # 01
Topics Covered
Page
#
03
Lab # 02
Operating systems overview
Introduction to Linux (Ubuntu Installation)
Introduction to Basic Shell commands
Lab # 03
Implementation of Linux commands
19
Lab # 04
Inter process communication and implementation through pipes
25
Lab # 05
Multi threading
30
Lab # 06
13
Lab Sessional 1
Lab # 07
Implement Shortest Job First (Non-Preemptive) CPU Scheduling Algorithm
36
Lab # 08
Implement Round Robin CPU Scheduling Algorithm
39
Lab # 09
Simulating Banker’s Algorithm for Deadlock Avoidance
41
Lab # 10
Paging and memory management
44
Lab # 11
Page replacement algorithms
 FIFO algorithm and its implementation
 LRU algorithm and its implementation
 LFU algorithm and its implementation
47
Lab # 12
Lab Sessional 2
Lab # 13
File allocation strategy
 Sequential
61
Lab # 14
File allocation strategy
65

Lab # 15
Indexed
69
File allocation strategy
 Linked
Terminal Examination
2
LAB # 01
Statement Purpose:
This lab will give you the overview of Operating system and introduction to Linux.
Activity Outcomes:
This lab teaches you the following topics:



Operating system overview
Introduction to Linux
Ubuntu Installation
Instructor Note:
Lecture 1,2,3,5
Text book:
Galvin, Peter B., Greg Gagne, and Abraham Silberschatz. Operating system concepts. John
Wiley & Sons, Inc., 2016.
3
1)
Stage J (Journey)
Introduction
Operating System
Operating System is a type of System Software and is a collection (set) of programs, which
performs two specific functions. First, it provides a user interface so that human user can
interact with the machine. Second, the operating system manages computer resources.
Computer Resources
Computer resources are physical devices, which an operating system accesses, and manages.
Printers, memories, input/output devices, files, etc., are examples of computer resources. So
why an operating is called a resource manager.
Some of important tasks, which a typical modern operating system has to perform, are given
below:







Processes Scheduling
Inter-process Communication
Synchronization
Memory Management (physical memory allocation, virtual memory etc.)
Resource Management
Directory and File Management
Communication
Usage share of Operating Systems
Windows, Unix, Linux, DOS are popular operating systems. There usage for personal
computer is given below.
Server Operating Systems
Server-oriented operating systems tend to have certain features in common that
make them more suitable for the server environment, such as
 GUI not available or optional
4
 ability to reconfigure and update both hardware and software to some extent
without restart,
 advanced backup facilities to permit regular and frequent online backups of critical
data... etc. (you may cover it later in the course)
Linux
Linux is an operating system, which is a flavor of Unix. Linux is a multi-user and multitasking operating system. It is a leading operating system on servers and
other big iron systems such as mainframe computers and supercomputers. more than 90%
of today's 500 fastest supercomputers run some variant of Linux, Including the 10 fastest.
The Android system in wide use on mobile devices is built on the Linux kernel.
Since with the likeness with UNIX, all the programs written for UNIX can be compiled and
run under Linux. Linux operating system runes on verity of machines like 486/Pentium, Sun
Sparces, PowerPC, etc.
Linus Torvalds, principal author, at the University of Helsinki, Finland, wrote Linux Kernel.
UNIX programmers around the world in the development of Linux assisted him.
Popular Linux distributions include: Debian (Knoppix, Ubuntu) , Fedora, Gentoo, openSUSE
etc.
Linux System
Linux System can be split into two parts.
i)
ii)
Shell
Kernel
Formally, a Shell is interface between a user and a Linux operating system, i.e. user
interacts with the Linux operating system through the shell. There may be two tasks to be
performed by a shell. First, accepts commands from a user and second, interprets those
commands.
Two shells, which are commonly used, are Bourne shell and C shell. One other shell,
which is rather complex, is Korn shell.
Kernel is the core of Linux Operating System, while the system is operational, it keeps on
running. The kernel is the part of the Linux Operating system which consist of routines,
which interact with underlying hardware, and routines which include system call handling,
process management, scheduling, pipes, signals, paging, swapping, the file system, and highlevel part of the I/O system.
So shell accepts commands from user interpret them and deliver these interpreted
commands to kernel for execution. After execution, the shell displays result of executed
commands.
Shell
Kernel
5
Files
File is a mechanism through which we store information. Normally, there are two modes of
storing information.
i)
ii)
File
Directories
i) File
A simple file stores some type of information. The information it has may be in text format,
or in binary format.
ii) Directories
Directories are special types of files owned the operating system, which contains
information about files, and may contain other directories (called Subdirectories). So
directories are also files, which contains some vital information about the files, and other
directories.
There’s a file (management) system in operating system, which manipulates file and
directories. The major operations, which can be performed on files and directories, are given
below:











Create
Delete
Open
Close
Read
Write
Append
Seek
Rename
Get Attributes
Set Attributes
2)
Stage a1 (apply)
Lab Activities:
Intalling/setting up Ubuntu:
Standard installation
If you are looking to install Ubuntu on your personal desktop/laptop, this is probably what
you are going for, and it has never been easier! The standard Ubuntu desktop installation uses
a Graphical Install, which is meant to cruise you through the installation process in a very
small number of easy steps. To get the installer up and running, you will need to do the
following:
6

Obtain an installation LiveCD. The LiveCD is a fully functional Ubuntu
environment, and it allows you to get a taste of Ubuntu on your machine by using a 'Live'
session! If you downloaded a CD image (.iso file), you can burn it to a standard CD.

All that remains now is to install Ubuntu by booting from the installation CD.
Alternate Installation

You may not wish to always use the standard LiveCD, because

it may so happen occasionally that your computer is not able to run the standard
Desktop installation CD because it does not meet the hardware requirements, or the required
drivers are missing from the standard LiveCD. The LiveCD is designed to keep most basic
hardware in mind, but there are a few that are bound to be absent from it.

Or, you may simply prefer to install a more customized version of Ubuntu different
from the standard install depending on your taste.

The Alternate CD allows more advanced installation
options which are not available with the Standard LiveCD.
Other ways to get Ubuntu
Direct download and install if you are connected with the
Internet.
Download link:
http://cdimage.ubuntu.com/releases/12.04/release/
Hardware virtualization
[Source: Wikipedia]
Computer hardware virtualization (or hardware virtualisation) is the virtualization
of computer or operating systems. It hides the physical characteristics of a computing
platform from users, instead showing another abstract computing platform. At its origins,
the software that controlled virtualization was called a "control program", but nowadays the
terms “hypervisor” or "virtual machine monitor" are preferred.
7
VMware
VMware, Inc. is a company providing virtualization software, founded in 1998 and based in
Palo Alto, California, USA.
VMware's desktop software runs on Microsoft Windows, Linux, and Mac OS X, while
Vmware's enterprise software hypervisors for servers, VMware ESX and VMware ESXi, are
bare-metal embedded hypervisors that run directly on server hardware without requiring an
additional underlying operating system.
Desktop software
iii)
VMware Workstation (first product launched by VMware in 1999). This software
suite allows users to run multiple instances of x86 or x86-64- compatible operating systems
on a single physical PC.
iv)
VMware Fusion provides similar functionality for users of the Intel Mac platform,
along with full compatibility with virtual machines created by other VMware products.
v)
VMware Player is for users without a license to use VMware Workstation or VMware
Fusion. VMware offers this software as a freeware product for personal use. While initially
not able to create virtual machines, this limitation was removed in version 3.0.1.
VMware Player is a freeware virtualization software package from VMware, Inc.(a
company which was formerly a division of and whose majority shareholder remains EMC
Corporation). VMware Player can run existing virtual appliances and create its own virtual
machines (which require an operating system to be installed to be functional). It
uses the same virtualization core as VMware Workstation, a similar program with more
features, but not free of charge. VMware Player is available for personal non-commercial use,
or for distribution or other use by written agreement. No support is provided by VMWare,
but there is an active community website for discussing and resolving issues.
8
Download Link
https://my.vmware.com/web/vmware/evalcenter?p=vmware-workstation9
How to Share/Access To Partition From Guest Operating Sys. to Host O.S.
Open VMWare, and right click on
the Virtual Machine (recently
created), and click on “virtual
machine settings ...” you will see
the following figure.
Now click on options --> Shared
folders
Then click on Always enable -->
Add
Then Browse to the folder of your
choice, click Next, and follow the on
screen instructions.
Viewing Shared Folders in a
Linux Guest
In a Linux virtual machine, shared folders appear under /mnt/hgfs.
Exercise 1
Install Ubuntu on your system or use 'live' version. You can use any of the methods
discussed above according to your own personal needs or discuss it with your lab Instructor.
Organization of the Linux File System
Unlike DOS, which permits you to organize your disks any way you please. the Linux file
system is organized into a standard directory structure. A portion of the Linux directory
structure is pictured below:
/(Root Directory)
etc/
bin/
usr/
bin/
home/
lib/
div/
info/
lib/
sbin/
tmp/
sbin/
Root Directory
The top most directory is called root directory. The hierarchical structure of directory begins
with a root directory. The name of root directory is /.
Directory
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A file, which holds other files and sub-directories.
Subdirectory
A directory residing within another directory.
Home Directory
The directory selected by Linux as the working directory when a user logs on. When a user
logs on Linux selects home directory (its name usually matches your login name) as
his/her working directory.
Current/Working Directory
The directory currently being used.
Pathname
Pathname is a reference to identify a file within the directory structure.
For example the following file name indicates the file in the hierarchy of directories:
/usr/users/bill/letters/pay
The first slash (/) indicates the root directory (start from root directory), move down to usr,
then users, then bill, then letters and finally to the file. So this pathname is reference to
the file pay with respect to the root directory.
A path may be of two types.
Absolute Pathname
The pathname, which identifies a file or a directory irrespective of the current state of the
user. The user's "current directory" is part of the user's state. The absolute pathname always
starts from the root directory.
For example, to locate file any file in lib directory, the absolute path of the file is:
/usr/local/lib/filename
Relative pathname
The pathname, which identifies a file or a directory in a way that depends on the state of the
user i.e. users current directory. Relative pathname identifies files with respect to user
current directory.
Current Directory (Working Directory)
thesis
chapter4.tex
to refer a file chapter4.tex in the in the subdirectory thesis with respect to the current
directory, we use pathname.
10
thesis/chepter4.tex
Some standard Linux directories are given below:
/home
Users’ home directory
/etc
All system administrator commands, configuration files, and
installation control files.
/bin
The core set of system commands and programs. Most systems cannot
boot (initially start) without executing some of the commands in this directory.
/dev
The device files used to access system peripherals (for example, your
terminal can be accessed from /dev/tty).
/lib
programs.
The standard set of programming libraries linked with Linux
/tmp
Temporary files created and used by many Linux programs.
/sbin
The system program used to boot the system.
/var
Log files(Record of Web activity), spool files(temp files) etc.
/root
The root user’s home directory.
/usr/bin
Common commands and programs.
/usr/doc
Documentation
/usr/games
Games
/usr/include Header files
/usr/info
/usr/lib
Online documentation
Shared libraries
/usr/man
Manual pages (help)
/usr/sbin
All system administration utilities
/usr/share
Shared information
/usr/src
Source code
Elementary File and Directory Commands
The elementary commonly used directory commands are ls, cd, mkdir, pwd and rmdir,
and most elementary file commands includes cat, cp, mv, and rm.
Exploring the File Hierarchy
When you login, there is a special directory associated with your login name called your
home directory. Your home directory is actually your initial current working directory. The
11
simplest way to find out where in the directory hierarchy your home directory is located is
just to use the command pwd straight after you login.
The pwd command tells you your present working directory.
$ pwd
/home/you
Note:- Linux commands are case-sensitive. All standard Linux commands use lower case
letters only.
In order to move your present working directory away from your home directory to
somewhere else in the directory hierarchy, you use the cd (change directory) command. So,
to change directory to the directory hierarchy’s root directory you would use the command.
(Note: Linux directory tree structure is given at the end of handouts).
$ cd /
(we will see the cd command in much detail after a few minutes)
Directory Commands
Command
Description
ls
List the file in the directory, just like dir command in DOS.
Option:
-a
Display all the files, and subdirectories, including
hidden files.
-l
Display detailed information about each file, and
directory.
-r -
Display files in the reverse order.
3) Stage v (verify)
Activity 1:
Install Linux operating system at your home systems.
4)
Stage a2 (assess)
Checking the Ubuntu installation.
12
LAB # 02
Statement Purpose:
This lab will give you the introduction to shell commands.
Activity Outcomes:
This lab teaches you the following topics:


Overview of shell commands
Practical implementation of shell comands
Instructor Note:
Lecture 4
Text book:
Galvin, Peter B., Greg Gagne, and Abraham Silberschatz. Operating system concepts. John
Wiley & Sons, Inc., 2016.
13
1)
Stage J (Journey)
Introduction
What is a shell program?
Simply put, a shell program (sometimes called a shell script) is a text file that contains
standard UNIX and shell commands. Each line in a shell program contains a single UNIX
command exactly as if you had typed them in yourself. The difference is that you can execute
all the commands in a shell program simply by running the shell program (rather than typing
all the commands within).
Shell programs are interpreted and not compiled programs. This means when you run a shell
program a child shell is started. This child shell reads each line in the shell program and
carries out the command on that line. When it has read all the commands the child shell
finishes.
Support for programming
To be truly useful a programming language must provide the following services




comments,
variables,
conditional commands, and
repeated action commands.
These extra services are provided by the shell. Different shells use different syntax for these
services. This means that a shell program written for the Bourne shell cannot be run by the C
shell (though it can be run by the bash shell.)
For portability, we will use only the Bourne shell syntax.
Creating a shell program
To create a shell program you need to complete the following steps:






create a text file to hold the shell program
decide which shell you will use
add the required commands to the file
save the file
change the permissions on the file so it is executable
run the shell program
2)
Stage a1 (apply)
Lab Activities:
Command: cat ―cat" is short for concatenate. This command is used to create, view and
concatenate files.
14
Example:
o cat>file1
This command creates the file, enter the contents into it and to save the content, press Ctrl+D.
o cat file1
This command shows the content of the file.
o cat file1 file2 > file3
This command combines the contents of the first two files into the third file.
Command: pwd "pwd" stands for print working directory. It displays your current position in the
UNIX/LINUX file system.
Example:
o pwd
It is simply used to report your current working directory.
Command: ls "ls" stands for list. It is used to list information about files and directories.
Example:
o ls
It provides a very basic listing of the files in your current working directory. Filenames beginning
with a decimal are considered hidden files, and they are not shown.
o ls -al
This command provides a long listing of information about all files in the current directory. This
is probably the most used version of the ls command.
Command: mv The "mv" command is used to move and rename files. Examples:
o mv Lab OSLab
This command renames the file "Lab" to the new name "OSLab".
o mv Chapter1 garbage
This command renames the file "Chapter1" to the new name "garbage". (Notice that if "garbage"
is a directory, "Chapter1" would be moved into that directory).
rm -r Labs
This command deletes the directory named "Labs‖. This directory, and all of its' contents, are
erased from the disk, including any sub-directories and files.
Command: cp The "cp" command is used to copy files and directories. When using the cp
command, you must always specify both the source and destination of the file(s) to be copied.
Examples:
o cp /home/Lab1 /home/OSLabs
This command copies the "Lab1" file in "/home" to the directory named "/home/OSLabs".
Command: mkdir The "mkdir" command is used to create new directories (sub-directories).
Examples:
15
o mkdir Lab
This command creates a new directory named "Lab" in your current directory. (This example
assumes that you have the proper permissions to create a new sub-directory in your current
working directory.)
o mkdir memos letters
This command creates two new sub-directories (memos, letters) in the current directory.
o mkdir /home/labb
This command creates a new directory named "labb" in the directory "/home".
Command: rmdir The "rm" command is used to remove files and directories. (Warning - be
very careful when removing files and directories!) Examples:
o rm Lab
This command deletes the file named "Lab" (assuming you have permission to delete this file).
o rm Lab1 Lab2
This command deletes the files named "Lab1","Lab2".
o rm -i Lab1 Lab2
This command prompt you before deleting any of the three files specified. The -i option stands
for inquire. You must answer y (for yes) for each file you really want to delete. This can be a
safer way to delete files.
Command: rm The "rm" command is used to remove files and directories. Examples:
o rm OSLab
This command deletes the file named "OSLab" (assuming you have permission to delete this
file).
o rm Chapter1 Chapter2
This command deletes the files named "Chapter1", "Chapter2"
o rm -r OSLab1
This command will delete the OSLab1(Assume that OSLab1 is a directory).
o rm in*
This command deletes all files in the current directory whose filename begins with the characters
"in".
o rm *.txt
This command deletes all files in the current directory whose filename ends with the characters
".txt".
rm *.txt
This command deletes all files in the current directory whose filename ends with the characters
".txt".
o rm in*
16
This command deletes all files in the current directory whose filename begins with the characters
"in".
o rm -r labb
This command deletes the directory named "labb". This directory, and all of its' contents, are
erased from the disk, including any sub-directories and files.
Command: cd, chdir "cd" stands for change directory. It is the primary command for moving
around the file system. Examples:
o cd /home
This command moves you to the "/home" directory. "/home" becomes your current working
directory.
o cd /h*
Moves you to the "/home" directory - if this is the only directory matching this wildcard pattern.
o cd
Issuing the "cd" command without any arguments moves you to your home directory.
Command: clear ―Clear‖ is used to clear the full screen of text, perhaps garbage on the
terminal. Examples:
o clear
This command clears all text on the terminal.
3) Stage v (verify)
Activity 1:
Verify that you are in your home directory. Make the directory lABS using the following
command.
Activity 2:
List the files in the current directory to verify that the directory LABS has been made correctly.
Change directories to LABS.
Activity 3:
Create the file named file1. List the contents of the file file1 to the screen. Make a copy of the file
file1 under the name file2. Verify that the files file1 and file2 both exist.
Activity 4:
List the contents of both file1 and file2 to the monitor screen. Then delete the file file1. Clear the
window. Rename file2 to thefile.
Activity 5:
17
Copy thefile to your home directory.
Activity 6:
Remove thefile from the current directory.
Activity 7:
Copy thefile from your home directory to the current directory. Change directories to your home
directory. Remove thefile from your home directory and from directory LABS. Verify thefile is
removed from the directory LABS. Remove the directory LABS from your home directory with
the following command. Verify that thefile and LABS are gone from your home directory.
4)
Stage a2 (assess)
Through viva or practical demonstration of running commands
18
LAB # 03
Statement Purpose:
This lab will give you the implementation of Linux commands.
Activity Outcomes:
This lab teaches you the following topics:


Login to Linux
Implement linux commands
Instructor Note:
Lecture 6,7,8
Text book:
Galvin, Peter B., Greg Gagne, and Abraham Silberschatz. Operating system concepts. John
Wiley & Sons, Inc., 2016.
19
1)
Stage J (Journey)
Introduction
Linux Terminal
Now we are going to start Linux. As a first step we will do Linux commands. You must have
used DOS commands copy, format, dir etc. Similarly Linux has such type of commands but
with different syntax and format. You have to remember these commands because you will
be using these commands frequently, and these commands will become base for your next
practice. There is syntax for each command, using wrong syntax the command will not
execute. As a first step we look how a user log in Linux OS. Then we go to Linux commands,
and see their general syntax for all Linux commands.
2)
Stage a1 (apply)
Lab Activities:
Logging In
As you must have known that shell is interface between a user and Linux kernel. The first
step you must accomplish before you can use Shell is to log in to your machine. This is
usually a very straightforward process provided that you have a login ID and a password.
If you enters a correct password, the system will return with a prompt inviting you to enter
commands.
When you login successfully, for an ordinary user account, the system will execute a program
called the shell. Any program, while it is executing within the system is called a process.
And it is your shell process that is responsible for giving you a command prompt.
Logging out
Logging out of Linux system is done by pressing control-D (^D).
Command
A request from a programmer, an operator, or a user to Linux operating system asking that a
specific function be performed; for example, a request to list all files in your current
directory. Shell commands operate on files, directories, and various devices – disk, printers,
etc.
Command
mkdir directory-name
Description
Creates a new directory.
Directory-name specifies the name of the new
directory. If the name doesn’t begin with a
slash, the new directory is created as a
subdirectory of the current working directory.
If the name begins with a slash, the name
20
defines the path from the root directory to the
new directory.
Example
Try to use the following command first because this will bring you back to your home
directory.
$ cd
(this command will bring you to the home directory) now try mkdir command
user@ubuntu:~$ mkdir books
This command will create a new directory under the home directory.
user@ubuntu
books
Though you have created a sub-directory books, but you are still in the home (parent
directory of books) directory i.e. user@ubuntu:~$
How would you go to the directory books?
Command
Description
cd
Change to another directory.
For Example:
$cd dir-name
To change to any sub-directory under the current directory.
Example
user@ubuntu:~$ cd books
(when enter is pressed the prompt becomes)
user@ubuntu:~/books $
What are you feeling differences between two prompts?
Now you are in books directory, a step down to home. How will you go up?
user@ubuntu:~/books $ cd .. (there’s space between cd and ..)
Now you will again in your parent directory. And the prompt becomes:
user@ubuntu:~ $
Example
Create other directory chemistry under books, and move to chemistry directory.
user@ubuntu:~/books $ mkdir chemistry
user@ubuntu:~/books $ cd chemistry
user@ubuntu:~/chemistry $
Now you are quite away from your home directory. How would you go to your home
directory? Your current location is
user@ubuntu:~$  books  chemistry
To go to your home directory:
user@ubuntu:~/chemistry $ cd (enter)
The prompt will become:
user@ubuntu:~ $
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Example
Now you are in your home directory. How will you go directly to chemistry directory?
user@ubuntu:~$ cd books/chemistry (enter)
3) Stage v (verify)
What do you think books/chemistry is relative or absolute path?
Activity 1:
Make the following directory hierarchy:
math
books
physics
trigonometry
calculus
quantum
computer
classical
nuclear
Example
If I’m in directory classical, how would I find where I am? The command used for the
purpose is pwd (covered in previous lab).
When I entered this command when I was in directory classical the following information
was printed on my screen. The path printed was absolute path.
So when you lost in directory structure you could find the way to your current directory by
command pwd.
For Example:
user@ubuntu:~/classical $ pwd
/home/staff/uzair/books/physics/classical (for example)
Activity 2:
How will you add a directory graphics under the directory computer while you are in
physics’ sub-directory classical?
Now you can create directories. What is the way removing them?
Command
Description
rmdir
(‘remove directory”) Deletes a directory. For example
$rmdir
dirname
Note:rmdir will only work if the directory you are trying to remove does not
contain any file. So first remove all files from the directory.
Activity 3:
(Note: First complete part a from this exercise and then move activity. 4)
22
a)
You are in books directory, from here try to remove sub-directory quantum under
the directory physics.

Now move to directory computer, from here remove sub-directory calculus under
the directory math.
Now create again both removed directories.

You can, remove directories, now look at how to create and delete files.
Creating file through pico editor
There are number of editors (e.g. Gedit-GUI based) through which files can be created, but
easiest way to use is through pico editor in shell.
Example
$ pico notes
With this command an editor will be opened. Enter text into the file.
Press Ctrl-O to save the file, and Ctrl-X to exit from the editor.
In order to view an existing file use cat command.
Activity 4:
Create a file using “pico” editor and save it with your name.
Removing/Deleting files
Command
Description
rm
(‘remove’) Removes a file permanently. For example,
$rm
filename
Options
-r
-i
Deletes an entire directory, and all the files it
contains.
This option puts the rm command into interactive
mode and prompts you before it removes it
Activity 5:
Try to remove a directory having some files in it, and observe the response of system.
$rm
directoryname
Note:- To remove all files from a directory use
$ rm dirname/*
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Command
Description
date
The date command displays the current date and time on the
screen. The system administrator sets the date
users cannot change them.
Example
$date
Wed Feb 7 10:35:41 PKT 2006
There are number of options in which date can be displayed. If you want to see
only date, you can do this like this:
$ date +”%d”
07
for time only
$date +”%r”
10:38:11 AM
%Y = Year. %H = Hour(00..23), %I = Hour (01..12), %m = Month
Command
Description
clear
Clears the screen.
Command
Description
echo
Echoes back whatever you type on the command line after
echo.
Options
-n
information.
doesn’t begin a new line after echoing the
Example
echo Hello there
Example
echo -n
4)
Hello
Stage a2 (assess)
Through viva or practical demonstration
24
LAB # 04
Statement Purpose:
This lab will give you the overview of Inter-process Communication and Implement the
Inter-process Communication using pipes
Activity Outcomes:
This lab teaches you the following topics:


Inter process communication
Its implementation through pipes
Instructor Note:
Lecture 9
Text book:
Galvin, Peter B., Greg Gagne, and Abraham Silberschatz. Operating system concepts. John
Wiley & Sons, Inc., 2016.
25
1)
Stage J (Journey)
Introduction
Interprocess communication (IPC) is a mechanism for processes to communicate and to
synchronize their actions. It is a set of programming interfaces that allows a programmer to
coordinate activities among different program processes that can run concurrently in an
operating system. This allows a program to handle many user requests at the same time. Since
even a single user request may result in multiple processes running in the operating system on the
user's behalf, the processes need to communicate with each other. The IPC interfaces make this
possible. Each IPC method has its own advantages and limitations so it is not unusual for a single
program to use all of the IPC methods.
Pipes:
A pipe is a communication channel between two ends. It is mostly used to communicate between
processes running within a computer. It is a communication device that permits unidirectional
communication. Data written to the ―write end‖ of the pipe is read back from the ―read end‖.
Pipes are serial devices; the data is always read from the pipe in the same order it was written. A
pipe‘s data capacity is limited. If the writer process writes faster than the reader process
consumes the data, and if the pipe cannot store more data, the writer process blocks until more
capacity becomes available. If the reader tries to read but no data is available, it blocks until data
becomes available. Thus, the pipe automatically synchronizes the two processes.
2)
Stage a1 (apply)
Lab Activities:
Creating Pipes:
To create a pipe, invoke the pipe command. Supply an integer array of size 2.The call to pipe
stores the reading file descriptor in array position 0 and the writing file descriptor in position
1. For example, consider the code:
int pipe_fds[2];
int read_fd;
int write_fd;
pipe (pipe_fds);
read_fd = pipe_fds[0];
write_fd = pipe_fds[1];
Data written to the file descriptor read_fd can be read back from write_fd.
To create a simple pipe with C, we make use of the pipe () system call. It takes a single
argument, which is an array of two integers. If successful, the array will contain two new file
descriptors to be used for the pipeline.
System call: pipe ();
Prototype: int pipe (int fd[2] );
It returns 0 on success, -1 on error.
26
NOTE:
o fd[0] is set up for reading
o fd[1] is set up for writing
The first integer in the array (element 0) is set up and opened for reading, while the second
integer (element 1) is set up and opened for writing. Visually speaking, the output of fd1
becomes the input for fd0.
27
printf("End!\n");
}
return(0);
}
3) Stage v (verify)
Activity 1:
Compute the Factorial of a number using IPC (PIPE implementation).
28
o Parent creates pipe
o Forks a child
o Parent writes into pipe (the number whose factorial is to be calculated, take the number from
the user)
o Child reads from pipe and compute the Factorial of a number written by Parent
Activity 2:
Using pipes, parent read data from one file, and child write data into another file.
4)
Stage a2 (assess)
Through viva or practical demonstration
29
LAB # 05
Statement Purpose:
This lab will give you the concepts of multi threading.
Activity Outcomes:
This lab teaches you the following topics:


Overview of multithreading
Thread programming
Instructor Note:
Lecture 9
Text book:
Galvin, Peter B., Greg Gagne, and Abraham Silberschatz. Operating system concepts. John
Wiley & Sons, Inc., 2016.
30
1)
Stage J (Journey)
Introduction
A thread is a single sequence stream within in a process. Threads have some of the properties of
processes; they are sometimes called lightweight processes. In a process, threads allow multiple
executions of streams. In many respect, threads are popular way to improve application through
parallelism. The CPU switches rapidly back and forth among the threads giving illusion that the
threads are running in parallel. Like a traditional process i.e., process with one thread, a thread
can be in any of several states (Running, Blocked, Ready or Terminated). Each thread has its own
stack. Since thread will generally call different procedures and thus a different execution history.
This is why thread needs its own stack. An operating system that has thread facility, the basic unit
of CPU utilization is a thread. A thread has or consists of a program counter (PC), a register set,
and a stack space. Threads are not independent of one other like processes as a result threads
shares with other threads their code section, data section, OS resources also known as task, such
as open files and signals.
Multithreading is the ability of a program or an operating system process to manage its use by
more than one user at a time and to even manage multiple requests by the same user without
having to have multiple copies of the programming running in the computer. Each user request
for a program or system service (and here a user can also be another program) is kept track of as a
thread with a separate identity. As programs work on behalf of the initial request for that thread
and are interrupted by other requests, the status of work on behalf of that thread is kept track of
until the work is completed.
Thread Programming: Some of the basic thread routines are as follows:
Creation:
int pthread_create(pthread_t * thread, const pthread_attr_t * attr, void * (*start_routine)(void *),
void *arg);
o Analogous to a combined fork and exec routine
o Returns a thread id in thread.
o When attr is NULL the default thread attributes are used.
Pthread_t: It is defining a thread pointer. When a thread is created identifier is written into the
variable to which the pointer points. This identifier helps to refer to thread.
Pthread_attr_t: It is used to set the thread attributes. If attr is NULL, the default attributes are
used.
Name of function: The name of the function to be started by the thread for execution.
Arguments to be passed to the function: When a new thread is created it executes the function
pointed by the function variable name.
On success, pthread_create ( ) returns 0, and on error, it returns an error number.
Termination
void pthread_exit(void * return_value);
31
o
o
o
o
o
Analogous to exit
The exit routine kills all threads and exits the process
If the current thread is the last thread then the process terminates
Returning from the start_routine is equivalent to calling pthread_exit
Returning from the initial thread main is the equivalent to calling exit
Detach and Join
int pthread_detach(pthread_t thread); int pthread_join(pthread_t thread, void ** status);
o Analogous to wait
o Must specify thread. There is no wait any.
o Current thread blocks until thread terminates
o The return value of thread is returned in status
o All threads must be detached or joined with.
pthread_join: It is used to wait for the thread represented in the thread_join call. It waits for the
thread represented in the call to finish executing. It waits for the specified thread to complete, and
gathers information about the thread's exit status.
Self and Equal
pthread_t pthread_self(void); int pthread_equal(pthread_1 t1, pthread_t t2);
2)
Stage a1 (apply)
Lab Activities:
32
33
/* sleep() causes the current thread to suspend execution for a specified period. This is an
efficient means of making processor time available to the other threads of an application or other
applications that might be running on a computer system. */
sleep(1);
}}
34
3) Stage v (verify)
Activity 1:
Write a program for matrix addition, subtraction and multiplication using
multithreading.
4)
Stage a2 (assess)
Through viva or practical demonstration
35
LAB # 07
Statement Purpose:
This lab will give you the concept of implementing Shortest Job First (Non-Preemptive) CPU
Scheduling Algorithm
Activity Outcomes:
This lab teaches you the following topics:


CPU scheduling algorithm
Implementation of shortest job first algorithm
Instructor Note:
Lecture 15
Text book:
Galvin, Peter B., Greg Gagne, and Abraham Silberschatz. Operating system concepts. John
Wiley & Sons, Inc., 2016.
36
1)
Stage J (Journey)
Introduction
Associate with each process the length of its next CPU burst. Use these lengths to schedule the
process with the shortest time.
Two schemes:
Non preemptive: Once CPU given to the process it cannot be preempted until completes its CPU
burst
Preemptive: If a new process arrives with CPU burst length less than remaining time of current
executing process, preempt. This scheme is known as the Shortest-Remaining-Time-First (SRTF)
SJF is optimal gives minimum average waiting time for a given set of processes
Suppose that there are four processes P1, P2, P3, P4
The Gantt chart for the Schedule is:
Average waiting time: (0+6+3+7)/4=4
2)
Stage a1 (apply)
Algorithm:
1)
2)
3)
4)
Take total no. of processes from user.
Take Name, Arrival Time and Burst Time for each process.
Select the process which have shortest burst will execute first.
If all processes arrive at 0 time interval than process with the smallest CPU Burst will
execute first.
37
5) If processes arrive at different time intervals than CPU will be given to the process that
will arrive first and let the other processes to be in queue.
6) If two processes have same burst length then FCFS scheduling algorithm will be used.
7) Sort the processes in ascending order of their CPU Burst.
8) Compute Waiting Time & Turnaround Time for each process.
9) Compute Average Waiting Time & Turnaround Time of processes.
10) Display Average Waiting and Turnaround Time of processes.
11) Display the Gantt chart.
3) Stage v (verify)
Activity 1:
Implement Shortest Job First (Non-Preemptive) CPU Scheduling Algorithm.
Output:
4)
Stage a2 (assess)
Through viva or practical demonstration
38
LAB # 08
Statement Purpose:
This lab will give you the concept of implementing Round Robin CPU Scheduling Algorithm
Activity Outcomes:
This lab teaches you the following topics:


CPU scheduling algorithm
Implementation of Round Robin algorithm
Instructor Note:
Lecture 15
Text book:
Galvin, Peter B., Greg Gagne, and Abraham Silberschatz. Operating system concepts. John
Wiley & Sons, Inc., 2016.
39
1)
Stage J (Journey)
Introduction
The round-robin (RR) scheduling algorithm is designed especially for time-sharing systems. It is
similar to FCFS scheduling, but pre-emption is added to switch between processes. A small unit
of time called time slice or quantum is defined. All runable processes are kept in a circular queue.
The CPU scheduler goes around this queue, allocating the CPU to each process for a time interval
of one quantum. New processes are added to the tail of the queue. Every time a process is granted
the CPU, a context switch occurs, which adds overhead to the process execution time.
2)
Stage a1 (apply)
Algorithm for Round Robin:










Get total no. of processes from user.
Get Name, Arrival Time and Burst Time for each process.
Get the Quantum/Time Slice.
Maintain a circular ready queue.
Make the CPU scheduler goes around the ready queue allocating CPU to each process for
the time slice specified.
Make the CPU scheduler picks the first process and after quantum expired, dispatches the
process.
 If the process have burst less than the time quantum then:
The process releases the CPU.
The scheduler will then proceed to the next process in the ready queue.
 If the CPU burst of the currently running process is longer than 1 time quantum
then:
 The process will be executed for quantum time and then the process will
be put at the tail of the ready queue.
 The CPU scheduler will then select the next process in the ready queue.
Compute Waiting Time & Turnaround Time for each process.
Calculate Average Waiting Time & Average Turnaround Time of processes.
3) Stage v (verify)
Activity 1:
Implement Round Robin CPU Scheduling Algorithm.(Time quantum should be entered by user)
4)
Stage a2 (assess)
Through viva or practical demonstration
40
LAB # 09
Statement Purpose:
This lab will give you the concept of Simulating Banker’s Algorithm for Deadlock
Avoidance.
Activity Outcomes:
This lab teaches you the following topics:


Deadlock Avoidance
Simulating Banker’s algorithm
Instructor Note:
Lecture 17, 18, 19
Text book:
Galvin, Peter B., Greg Gagne, and Abraham Silberschatz. Operating system concepts. John
Wiley & Sons, Inc., 2016.
41
1)
Stage J (Journey)
Introduction
The Banker‘s Algorithm is a resource allocation that tests the safety by simulating the allocation
of predetermined maximum possible amounts of all resources, and then makes "s-state" check to
test for possible deadlock conditions for all other pending activities, before deciding whether
allocation should be allowed to continue. When a new process enters the system, it declares the
maximum number of instances that are needed. This number cannot exceed the total number of
resources in the system. If the process can be accommodated based upon the needs of the system,
then resources are allocated, otherwise the process must wait. The algorithm is actually made up
of two separate algorithms: the safety algorithm and the resource allocation algorithm. Data
Structures for the Banker’s Algorithm
o p = number of processes
o r = number of resource types
o Available: Vector of length r. If available[j] = k, there are k instances of resource type R j
available.
o Max: p x r matrix. If Max [i,j] = k, then process Pi may request at most k instances of resource
type Rj.
o Allocation: p x r matrix. If Allocation [i,j] = k then Pi is currently allocated k instances of Rj.
o Need: p x r matrix. If Need [i,j] = k, then Pi may need k more instances of Rj to complete its
task.
Need [i,j] = Max[i,j] – Allocation [i,j]
2)
Stage a1 (apply)
Steps for Banker’s (Safety) Algorithm:
1)
2)
3)
4)
5)
6)
7)
Get total no. of processes from user.
Get total no. of resources.
Get the values for Max Matrix.
Get the values for Allocation Matrix.
Get maximum instances of each resource type.
Find Need Matrix.
Find Available Vector.
1. Let Finish be vector of length p. Initially Finish[i] = false; i = 1, 2, …, p.
2. Find and i such that both:
a. Finish[i] = false
b. Needi ≤ Availbale
If no such i exists, go to step 4.
3. Available = Available + Allocationi
8) Finish[i] = true
9) Go to step 2.
a) If Finish [i] == true for all i, then the system is in a safe state.
10) Display the result.
42
3) Stage v (verify)
Activity 1:
Implement Banker‘s Algorithm.
4)
Stage a2 (assess)
Through viva or practical demonstration
43
LAB # 10
Statement Purpose:
This lab will give you the concept of paging and memory management.
Activity Outcomes:
This lab teaches you the following topics:


Paging technique
Memory management
Instructor Note:
Lecture 22, 23
Text book:
Galvin, Peter B., Greg Gagne, and Abraham Silberschatz. Operating system concepts. John
Wiley & Sons, Inc., 2016.
44
1)
Stage J (Journey)
Introduction
Logical address space of a process can be noncontiguous; process is allocated physical
memory whenever the latter is available
Divide physical memory into fixed-sized blocks called frames (size is power of 2, between
512 bytes and 8,192 bytes)
Divide logical memory into blocks of same size called pages
Keep track of all free frames
To run a program of size n pages, need to find n free frames and load program
ALGORITHM:
1. Start
2. Read the number of pages
3. Read the page size
4. Allocate the memory to the pages dynamically in non contiguous locations.
5. Display the pages and their addresses.
6. Stop
2)
Stage a1 (apply)
45
3) Stage v (verify)
Activity 1:
Implement paging having the number of pages =10, and page size =4.
4)
Stage a2 (assess)
Through viva or practical demonstration
46
LAB # 11
Statement Purpose:
This lab will give you the concept of page replacement algorithms
Activity Outcomes:
This lab teaches you the following topics:




Page replacement algorithms
FIFO
LRU
LFU
Instructor Note:
Lecture 25
Text book:
Galvin, Peter B., Greg Gagne, and Abraham Silberschatz. Operating system concepts. John
Wiley & Sons, Inc., 2016.
47
1)
Stage J (Journey)
Introduction
1) FIFO:
2)
Stage a1 (apply)
Code:
48
49
Output:
3) Stage v (verify)
Activity 1:
Implement the FIFO algorithm.
4)
Stage a2 (assess)
Through viva or practical demonstration
50
1)
Stage J (Journey)
Introduction
b) LRU:
2)
Stage a1 (apply)
Code:
51
52
53
Output:
54
3) Stage v (verify)
Activity 1:
Implement LRU algorithm.
4)
Stage a2 (assess)
Through viva or practical demonstration
55
1)
Stage J (Journey)
Introduction
c) LFU:
2)
Stage a1 (apply)
Code:
56
57
58
Output:
enter the number of frames:5
enter the page size2
59
3) Stage v (verify)
Activity 1:
Implement LFU algorithm.
4)
Stage a2 (assess)
Through viva or practical demonstration
60
LAB # 13
Statement Purpose:
This lab will give you the concept of file allocation strategy through sequential method.
Activity Outcomes:
This lab teaches you the following topics:


File allocation strategy
Sequential
Instructor Note:
Lecture 26, 28, 29
Text book:
Galvin, Peter B., Greg Gagne, and Abraham Silberschatz. Operating system concepts. John
Wiley & Sons, Inc., 2016.
61
1)
Stage J (Journey)
Introduction
2)
Stage a1 (apply)
Code:
62
Output:
63
3) Stage v (verify)
Activity 1:
Implement file allocation algorithm through sequential method.
4)
Stage a2 (assess)
Through viva or practical demonstration
64
LAB # 14
Statement Purpose:
This lab will give you the concept of file allocation strategy through Indexed method.
Activity Outcomes:
This lab teaches you the following topics:


File allocation strategy
Indexed
Instructor Note:
Lecture 26, 28, 29
Text book:
Galvin, Peter B., Greg Gagne, and Abraham Silberschatz. Operating system concepts. John
Wiley & Sons, Inc., 2016.
65
1)
Stage J (Journey)
Introduction
2)
Stage a1 (apply)
Code:
66
Output:
67
3) Stage v (verify)
Activity 1:
Implement File allocation algorithm through Indexed method.
4)
Stage a2 (assess)
Through viva or practical demonstration
68
LAB # 15
Statement Purpose:
This lab will give you the concept of file allocation strategy through Linked method.
Activity Outcomes:
This lab teaches you the following topics:


File allocation strategy
Linked
Instructor Note:
Lecture 26, 28, 29
Text book:
Galvin, Peter B., Greg Gagne, and Abraham Silberschatz. Operating system concepts. John
Wiley & Sons, Inc., 2016.
69
1)
Stage J (Journey)
Introduction
2)
Stage a1 (apply)
Code:
70
}
71
Output:
3) Stage v (verify)
Activity 1:
Implement File allocation algorithm through Linked method.
4)
Stage a2 (assess)
Through viva or practical demonstration
72