A Guide to Unix Using Linux, Fourth Edition 1-1
Chapter 1
The Essence of UNIX and Linux
At a Glance
Instructor’s Manual Table of Contents
• Overview
• Objectives
• Teaching Tips
• Quick Quizzes
• Class Discussion Topics
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Lecture Notes
Overview
Chapter 1 begins with an introduction to basic operating systems concepts. Students are
then provided with some details on UNIX and Linux systems, such as shells, user
Chapter Objectives
• Explain operating systems, including PC and server operating systems
• Describe the UNIX and Linux operating systems
• Explain the purpose of UNIX/Linux shells
• Understand how to select user names and passwords
• Connect to UNIX/Linux using Telnet or SSH
• Use basic UNIX/Linux commands and command-line editing features
• Explain the role of a system administrator
• Change your password for security
• Use multiple commands to view the contents of files
• Redirect output to a file
Teaching Tips
Share the following Web sites for Linux vendors with your students so that they
Understanding Operating Systems
1. Use Figure 1-1 to describe the relationship between an operating system and other parts
of a computer system.
PC Operating Systems
2. Figure 1-2 identifies some popular PC operating systems.
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Server Operating Systems and Networks
1. Use Figure 1-3 to introduce the following terms: network, server, server operating
system, host, client, and server-based network.
3. Contrast peer-to-peer networks with server-based networks.
Introducing the UNIX and Linux Operating Systems
2. Make sure students understand the concepts of multitasking and multiuser.
3. Stress that many organizations choose UNIX and Linux because these operating
systems:
a. Enable employees to work on a range of computers (portability).
b. Are stable, reliable, and versatile.
A Brief History of UNIX
1. Provide a brief history of the evolution of UNIX systems. Remember to introduce the
term POSIX.
At the time of this writing, Bell Labs is now part of Alcatel Lucent. To share a
review of the Bell Labs inventions that have had a profound impact on the world,
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UNIX Concepts
2. Emphasize the importance of layering in software design.
Linux and UNIX
1. Explain why we say that Linux is a UNIX-like operating system:
a. It is not written from traditional UNIX code.
2. You have already introduced your students to some Linux distributions (see first
Introducing UNIX/Linux Shells
2. Briefly describe the Bourne, Korn, C, and Bash shells.
1. Explain that a default shell is associated with your account when it is created.
2. Note that many users prefer the Bash shell.
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Switching from Shell to Shell
1. Explain how you can switch to another shell. Note that you work in a shell until you:
2. Note that users often use one shell for writing shell scripts and another shell for
interacting with a program.
Choosing User Names and Passwords
1. Describe the role of user names and passwords. Note that some restrictions may apply
when choosing a user name and a password.
2. Explain that you may use your user name and password to log in to a UNIX/Linux
system in any of the following ways:
a. Telnet or SSH.
Appendix A, “How to Access a UNIX/Linux Operating System,” describes
b. Through client software.
c. On a stand-alone PC.
d. Through a dumb terminal connected to a communications port on a UNIX/Linux
host.
Connecting to UNIX/Linux Using Telnet or SSH
2. Explain the difference between Telnet and SSH, and briefly indicate how to use these
programs to connect to a remote host.
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Teaching
To use Telnet or SSH, you need to enable them on your system. See the note
Logging In to UNIX/Linux
1. Use Figure 1-6 to describe how you log in to a UNIX/Linux system.
2. When describing the login process in GUI environments, note that in UNIX/Linux, the
foundation of a GUI is called the X Window interface.
Teaching
To learn more about the GNOME Project, visit the Web site at www.gnome.org.
Quick Quiz 1
1. The ____________________ is the base operating system, and it interacts directly with
the hardware, software services, application programs, and user-created scripts.
2. ____________________ is the default shell in Linux, and it is the shell many users
prefer.
3. An IP address is a set of ____________________ numbers (in the commonly used IP
version 4) separated by periods.
4. ____________________ (SSH) was developed for UNIX/Linux systems to provide
authentication security for TCP/IP applications, such as FTP and Telnet.
Using Commands
2. Stress that in UNIX/Linux, commands are case sensitive.
4. Explain that you must know a command’s syntax (including options and arguments) to
enter it properly.
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The date Command
1. Use Figure 1-7 to describe the use of the date command.
The cal Command
1. Use Figure 1-8 to describe the use of the cal command (the -j option was used in the
example shown).
The who Command
1. Describe the use and syntax of the who command. Discuss the importance of this
command for system administrators.
The clear Command
1. Explain that the clear command, which is used to clear your screen, has no options or
arguments.
The man Program
1. Use Figures 1-9 and 1-10 to describe the use of the man command to view the man
pages.
info pages provide more information about commands, and sometimes the man
Many systems also offer info pages in addition to the man pages. Sometimes the
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The whatis Command
1. Use Figure 1-11 to describe the use of the whatis command.
The whatis command relies on information stored in a database. On some
UNIX/Linux systems, the administrator must execute the whatis command,
Command-line Editing
1. Use Table 1-1 to explain that shells support certain keystrokes for performing
command-line editing.
Multiple Command Entries
1. Use one or more examples to explain how to use “;” to type multiple commands on the
command line.
The Command-line History
1. Explain how you can navigate through the command-line history. Stress that this feature
is very important in saving time and decreasing frustration.
2. Emphasize that not all shells provide this feature.
Logging Out of UNIX/Linux
1. Explain that once you are done, it is important to log out of the UNIX/Linux system to
ensure security. Describe how this is done in different shells.
2. Explain that logging out is performed differently when using a GUI.
Quick Quiz 2
1. Use the ____________________ command to show the system calendar.
2. To determine information about who is logged in, use the ____________________
command.
3. The man program in UNIX/Linux displays this online manual, called the
____________________, for command-line assistance.
4. You can type more than one command on the command line by separating commands
with a(n) ____________________.
Understanding the Role of the UNIX/Linux System Administrator
1. Describe the role of the UNIX/Linux system administrator and introduce the following
The System Administrator’s Command Line
1. Use an example to show students the system administrator’s command line. Make sure
students understand how to interpret the prompt.
When you use the GNOME terminal window in SUSE, the user’s prompt is a
(for the current directory), and the pound sign, such as aspen: ~ #.
The Ordinary User’s Command Line
1. Use an example to show students an ordinary user’s command line.
2. Note that ~ refers to the user’s home directory.
Changing Passwords
1. Stress that it is crucial to keep passwords secure.
2. Use an example to show how to use the passwd command to change a password. Note
that if an account does not have a password, you can use this command to create one.
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Remind your students to remember their passwords! They need your password
Viewing Files Using the cat, more, less, head, and tail Commands
1. Briefly describe the use of the following commands: cat, more, less, head, and tail.
3. Note that the number of lines shown by default with head and tail is 10.
Redirecting Output
1. Use a couple of examples to explain how to use the output redirection operator (>).
Explain to your class that the output redirection operator (>) sends output to a
Quick Quiz 3
1. The system administrator has a unique user name: ____________________.
2. The system administrator’s prompt is the ____________________ symbol.
3. If your account does not have a password, you can use the ____________________
command to create one.
4. In UNIX/Linux, the greater-than sign (>) is called a(n) ____________________
redirection operator.
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Class Discussion Topics
1. Form groups of four or five students and ask them to discuss their experiences with the
UNIX/Linux operating systems. Which distribution is the most popular in your class?
2. If students have previous experience with UNIX/Linux systems, they may be familiar
Additional Projects
2. Ask students to do some research on the differences between four UNIX/Linux shells.
They should summarize their findings in a table.
Additional Resources
2. Which Shell Is Right for You? Shell Comparison:
5. LinuxQuestios.org Man Pages Online:
Key Terms
➢ argument — Text that provides UNIX/Linux with additional information for executing
in 1975.
➢ Bourne shell — The first UNIX/Linux command interpreter, developed at AT&T Bell
Labs by Stephen Bourne.
➢ C shell — A UNIX/Linux command interpreter designed for C programmers.
➢ case sensitive — A property that distinguishes uppercase letters from lowercase letters;
➢ File Transfer Protocol (FTP) — An Internet protocol for sending and receiving files.
➢ graphical user interface (GUI) — Software that transforms bitmaps into an infinite
variety of images, so that when you use an operating system you see graphical images.
➢ host — See server.
➢ Internet Protocol (IP) address — A set of four numbers (for the commonly used IP
each user to type a user name and password before using the system.
➢ mainframe — A large computer that has historically offered extensive processing,
mass storage, and client access for industrial-strength computing. Mainframes are still
in use today, but many have been replaced by PC-type computers that are designed as
servers with powerful processing and disk storage capabilities.
superuser.
➢ output redirection operator — The greater-than sign (>) is one example of a
redirection operator. Typing > after a command that produces output creates a new file
or overwrites an existing file and then sends output to a disk file, rather than to the
monitor.
experts from industry, academia, and government through the Institute of Electrical and
Electronics Engineers (IEEE) for the portability of applications, including the
standardization of UNIX features.
➢ root — The system administrator’s unique user name; a reference to the system
administrator’s ownership of the root account and unlimited system privileges. Also,
➢ server operating system — An operating system that controls the operations of a
server or host computer, which accepts and responds to requests from user programs
running on other computers (called clients) on the network.
➢ shell — An interface between the user and the operating system.
➢ superuser — See system administrator.
and keyboard and has no CPU. Sometimes called a dumb terminal.
➢ terminal window — A special window that is opened from a UNIX or Linux GUI
desktop and that enables you to enter commands using a shell, such as the Bash shell.
➢ User mode — A means of accessing the areas of a system where program software
resides.
Technical Notes for Hands-On Projects
For these projects, students need their own user account. A few projects require access to the
root account. Some projects have additional requirements that are listed below.
Hands-On Project 1-1:
In this project, students use a Windows computer to remotely access a UNIX/Linux computer.
Firewall software should be configured to enable Telnet (on both computers).
Telnet is disabled by default in Windows Vista. To enable Telnet in Windows
On the UNIX/Linux host server, Telnet should also be enabled, such as by
editing the /etc/xinetd.d/telnet file and changing disable=yes to disable=no. On
many UNIX/Linux systems, you can also log in to the root and enter ~/.telnetrc
menu, point to Administration, click Security Level and Firewall, enter the root
password (if requested) and click OK, check the boxes for Telnet and SSH, click
OK, and click Yes. If you are using SUSE Linux 10.0 or earlier (with GNOME),
click the Desktop menu, click Yast, enter the root password (if requested) and
click Continue, click Security and Users in the left pane, click Firewall in the
select SSH (Telnet is not listed as an option), click the Add button, click Next,
and click Accept. If none of these steps work, consult Appendix A.
Hands-On Project 1-2:
This project requires SSH to be enabled via the Fedora, Red Hat Enterprise Linux, or SUSE
firewall software.