UNIX and Shell Scripting_Module 2

8/11/2019 UNIX and Shell Scripting_Module 2

1/44

Training Partner

UNIX and Shell Scripting

Module 2: UNIX Operating SystemArchitecture


2/44

Training Partner

Module 2 Objectives

Upon completing this module, the learner will be able to: Describe Onion Architecture of UNIX Operating System

Explain the Interaction of User App with Kernel

Describe the Hierarchical Structure of UNIX File System (VirtualFile System)

Describe the Physical file System

Define a Program

Define a Process

Summarize the difference between Program and Process

Describe working of Shell Describe different flavors of UNIX

List the services offered by UNIX Operating System


3/44

Training Partner

Module 2 Agenda

Topic Name Duration

Introduction to UNIX OS Architecture 30 min

UNIX File System 20 min

Processing Environment 35 minOperating System Services 25 min


4/44

Training Partner 4

Introduction to UNIX OS Architecture

An Operating System (OS)is a software component ofa computer system, which: Shares the limited resources

of the computer

Coordinates and managesthe various activities

Offers a number of servicesto application programs andusers

Acts as a host forApplications that are run onthe machine

Printer

Monitor Applications

DiskDrive

Keyboard

Operat ing

System


5/44

Training Partner

Discussion: Features of UNIX OS (1 of 2)

Discussion topic: What are the features of UNIX OS?

Discussion time:

5 minutes

Instructions: Ask students about their

experience/opinions.

Write them on a flip-chart.


6/44

Training Partner

Features of UNIX OS (2 of 2)

Multi-user, Multi-tasking, Time sharing system File structure

Modularity

Input/Output Redirection and Pipes

Consistent Peripheral Interface Security

Communication and Networking

UNIX Utilities and Software Development Tools


7/44Training Partner 8

UNIX Onion Architecture (1 of 2)

8

Shell

Shell

User Process

Shell

User Process

Shell

Everything below thesystem call interfaceand above thephysical hardware isthe KERNEL.

It provides filesystem, CPUscheduling, memorymanagement, andother OS functions

using system calls.


8/44Training Partner 9

UNIX Onion Architecture (2 of 2)

Shell

Shell

User Process

Shell

User Process

Shell

The system callinterface layerconverts a processrunning in user modeto a protected kernelmode process.

System call provides aprogramming interfacethat allows userprograms to accesskernel functions.


9/44Training Partner

User Application and Kernel Interaction

Kernelcontrols the underlyinghardware. The kernel provideslow-level device, memory, andprocessor management functions.

Shellis a commandinterpreter of UNIX.

Utilities areset of UNIXcommandsand Programs.

Hardware

KernelThe Operating System

ShellUtility

Applications

User

Applications are differentsoftwares run on UNIX.

Usersenter UNIX commands orrun different software applications.


10/44

Training Partner

Knowledge Check (1 of 3)

Which of the following are true about the operatingsystem?

1. It manages memory.

2. It manages processor.3. It manages Input/Output devices.


11/44

Training Partner 12


The operating system comprises a set of softwarepackages that can be used to manage interactions withthe hardware. The elements that are generally included inthis set of software are listed below. Which is the odd oneout?

1. Input/Output Devices

2. Shell

3. File System

4. Kernel


12/44

Training Partner 13


What are system calls? Describe their uses.


13/44

Training Partner 14

Module 2 Agenda

Topic Name Duration

Introduction to UNIX OS Architecture 30 min


Processing Environment 35 minOperating System Services 25 min


14/44

Training Partner

UNIX File System (1 of 3)

What is a file?

A collection of data items stored on a disk

What is a file system? A group of files and relevant information regarding them Each file system is stored in a separate whole disk partition UNIX supports variety of files

Ordinary file Directory file Special files Character special files Block special files


15/44

Training Partner 16

Demonstration: UNIX File System (2 of 3)

For slide 17

This topic includes demonstration related to login to the UNIX systemand files in a directory. It will be conducted in the following manner: Instructions:

Explain the command with demonstration. Ask participants to execute the same. Discuss the related slide.

Note: The commands would be used by the faculty and participantssimultaneously.


16/44

Training Partner 17

UNIX File System (3 of 3)

$ lsl Gives long listing of files

Character In the first column

represents that it is an ordinary file.

Character l in the first column

represents TestFln is link for TestF1.

Character d in the first column represents directory file.


17/44

Training Partner 18

UNIX System Directories (1 of 4)

bin directory contains thecommands and utilities used byuser day to day. These areexecutable binary files

The directory is located at the top ofthe UNIX file system. It is representedby the "/" (forward slash) character.

This directory contains special files used torepresent real physical devices such asprinters and terminals. For non-existentdevice null is used


18/44

Training Partner 19


For systemadministration, thisdirectory containsvarious commands andfiles. One of thesefiles, motd, contains a'message of the day,

which is displayedwhenever we log intothe system.

For each user ofthe system, thisdirectorycontains a homedirectory.

This directorycontains librariesthat are used byvarious programsand languages.


19/44

Training Partner 20


Kernel is loaded in whenever the system is started up called booting ofthe system

It is at the core of each UNIX system It manages the entire resources of the system, presenting them to youand every other user as a coherent system.

This directory acts as aarea to store files ontemporary basis by anyuser.

Typically Application

programs, languagedictionaries, and on-linemanual pages reside in thisdirectory. This also containssystem files and directorieswhich user wants to share

with other users.


20/44

Training Partner 21


Under the root directory, subdirectories organize the filesand subdirectories on the system. These subdirectoriesmight be of any name.

The diagram below represents file structure as invertedtree.

/

etc bin tmp users src

webmin usb tdlibuser User 1 User 2


21/44

Training Partner

Physical File System

Storage space on a computer usually resides on several devices and encompasses

different types of media, including hard drives, CD-ROM drives, and floppy drives.Each of these devices has a distinct physical file system associated with it. There are numerous types of physical file systems found under UNIX, including:

ufs

The standard UNIX File System bffs

The Berkeley Fat Fast File System, an improvement over the original UNIX

file system cd9660 The ISO-9660 file system for CD-ROM drives

The types of file systems available vary from OS to OS and cover a wide variety ofdevices and media.


22/44

Training Partner 23

Module 2 Agenda

Topic Name DurationIntroduction to UNIX OS Architecture 30 min


Processing Environment35 min

Operating System Services 25 min


23/44

Training Partner 24

Discussion: Program in Execution (1 of 3)

Discussion topic: What kind of programs have youwritten?

Discussion time:

5 minutes

Instructions:

Ask students about their

experience/opinions. Write them on a flip-chart.


24/44

Training Partner

Program in Execution (2 of 3)

List of Processes Before Running program

List of Processes After Running program

New process Created for the running program


25/44

Training Partner 26

Demonstration: Program in Execution(3 of 3)

This topic includes demonstration on Program (Focus:Functionality). It will be conducted in the following manner: Instructions:

Explain the command with demonstration.

Ask participants to execute the same.

Discuss the related slide.

Note: The commands would be used by the faculty and participantssimultaneously.


26/44

Training Partner 27

Processing Environment

A program is a set of instructions written to perform aspecific task.

A process is: An operation which takes the instructions given and does the

manipulations or anything that is instructed in the code itself

The single executable module that runs concurrently with otherexecutable modules

A program in execution


27/44

Training Partner 28

Shell as Command Interpreter

Each line that shell reads from standard input is called a pipeline.

Shell as a command interpreter: Reads lines from standard input (each of these line is called pipeline)

Splits the command into tokens

Checks the token to see if its a keyword

Checks the first word for alias

Performs command substitution for any $(string) Performs wildcard expansion

Looks at first word as build-in command

Runs the command

For example, following command on command prompt:

ll $(whence cc) /etc/pass*

will change to lsl /bin/cc /etc/passwd if ll is alias to lsl

cc is in /bin directory

/etc directory has only one file starting with string pass


28/44

Training Partner 29


Find the odd one out:

1. Block Special Files

2. Character Special Files

3. Disk Files

4. Ordinary Files

5. Directory Files


29/44

Training Partner 30


State whether the following statements are True or False:

1. When you log into your UNIX account, you are placed in your pwddirectory.

2. The types of file systems available vary from OS to OS.


30/44

Training Partner 31


Which of the following command should be used to moveto the directory above the current directory?

1. cd

2. cd ..

3. cd..

4. None


31/44

Training Partner


What is the command used to see all the processesrunning currently?

1. ps2. ls

3. cd4. lsl


32/44

Training Partner 33



1. Basic and other commands are available in bin directory.2. Shell is also a program which keeps on running till user login.3. Every word written on command line is command for shell.

4. UNIX allows other processes to run while running one.5. Process is an executable module.


33/44

Training Partner 34

Module 2 Agenda

Topic Name DurationIntroduction to UNIX OS Architecture 30 min


Processing Environment 35 min

Operating System Services 25 min


34/44

Training Partner 35

Discussion: UNIX Variants (1 of 3)

Discussion topic: How many different UNIX variants have

you heard of?

Discussion time:

5 minutes

Instructions: Ask students about their

experience/opinions.

Write them on a flip-chart.


35/44

Training Partner 36

UNIX Variants (2 of 3)

UNIX VariantsYear UNIX Variant Features

1957 BESYS At Bell Labs

To run batch jobs

1965 MULTICS(Multiplexed Information andComputing Service)

Adopted third generation computerequipments

1969 UNICS

(UNiplexed Information andComputing Service)

To play space travel on anothersmaller machine (DEC PDP-7)

1971 UNIX The first edition of the "UNIXPROGRAMMER'S MANUAL

By K. Thompson [and] D. M. Ritchie;included over 60 commands


36/44

Training Partner 37

UNIX Variants (3 of 3)

UNIX Popular VariantsUNIX Variant FeaturesAIX

(Advanced Interactive eXecutive)

Developed By IBM in 1990

Shells available (Korn, Bourne, C)

Default Korn shell

BSD(Berkeley Software Distribution)

Developed at the Computer SystemResearch Group (CSRG)

Sun Solaris Sun company's UNIX variant operatingsystem

MINIX A free UNIX clone written from scratchSmall size

Micro kernel-based design and simpledocumentation

Suited for personal computer


37/44

Training Partner

LINUX

Developed by Linus Torvalds

Freely available multitasking and multi-user operating system

Placed under General Public License

Variants Caldera Linux Debian Linux Kondara Linux Red Hat Linux

Mandrake Linux SuSE Linux


38/44

Training Partner 39

UNIX Flavors

All proprietary UNIX flavors and their names are respective

trademarks of the originating entity/vendor.

Originator Proprietary Name

U. Cal. Berkley BSD

Sun SolarisIBM AIX

HP HP - UX

SGI IRIX

Digital Equipment2 DEC UNIXCompaq Tru64 UNIX3

Apple MacOS X4

L. Torvalds/GNU5 Linux6


39/44

Training Partner

Kernel (1 of 2)

Kernel is the heart of OS and performs various operations on

behalf of the user processes, like: Permitting process controlled access

Devices like terminals

Disk and tape drives

Network drives Controlling the process execution

Creation

Termination

Suspension

Communication


40/44

Training Partner 41

Kernel (2 of 2)

Efficient retrieval and storage of user data

By allocating storage

By reclaiming unused storage

Protecting Time sharing

Suspending the process

Rescheduling the processes Sharing of main memory

Swapping system


41/44

Training Partner


Which one from the following service support more thanone user to use the UNIX system at the same time?

1. Modularity

2. File Structure

3. Multitasking

4. Input-Output Redirections and Pipes


42/44

Training Partner 43



1. Portability is the ability of software to operate on different types ofmachines (often called platforms).

2. In UNIX systems, a user can initiate more than one task to run at atime from the same terminal.

3. UNIX has a hierarchical file structure. It is like an inverted tree,having the Child at the top.

4. A UNIX system consists of various tools that help the programmersto develop different applications.


43/44

Training Partner

Module 2 Summary

Upon completing this module, you should now be able to: Describe Onion Architecture of UNIX Operating System

Explain the Interaction of User App with Kernel

Describe the Hierarchical Structure of UNIX File System (Virtual File System)

Describe the Physical file System

Define a Program

Define a Process Summarize the difference between Program and Process

Describe working of Shell

Describe different flavors of UNIX

List the services offered by UNIX Operating System


44/44

Questions and Comments

What questions orcomments do you have?

UNIX and Shell Scripting_Module 2

Documents

Transcript of UNIX and Shell Scripting_Module 2