UNIX Operating System I Module 1 Introduction to UNIX/Linux Chapter 1 (and a little extra)

UNIX Operating System I

Module 1Introduction to UNIX/Linux

Chapter 1 (and a little extra)


Objectives• Review of Basic Computer Terminology• What is an Operating System?• Why UNIX?• History of Unix• Different Versions• Linux• Problems with UNIX• Different Versions Note


Objectives (cont.)

• Features of Linux (UNIX)• Let’s Get Started!

– PuTTY– Unix Account– Logged In– The Shell– Prompts– Commands


Review of Basic Computer Terminology

• Please read the “Review of Basic Computer Terminology” under the extra resources area.– Hardware– Software– Operating System– Programming Languages


What is an Operating System?

• Windows 98, Windows NT, Windows XP– These are all operating systems

• Solaris, HP-UX, Linux– These are all different versions of UNIX– These are all operating systems

• Definition: A program that acts as a middle man between the user (you) and the hardware (the computer). It manages your computer’s resources (the disks, applications, loading applications, etc…)


Why UNIX?• Portable Operating System

– Runs on many different machines (from desktop PCs to high end mainframes/servers)

– Hardware Independent.• Open Source OS

– Source Code is Free• Powerful Internet and Network

Capabilities• Based on Standards• Large selection of high-end applications

– Many for scientific and industrial companies• Powerful and Stable Operating System


History of Unix (1)• Bell labs and other companies had a joint

venture in the 60s to develop a new OS, one of the first multi-user operating systems. – Ken Thompson and Dennis Ritchie developed earliest

version– This first OS was called Multics – Was large and slow and not quite what they wanted

• Using what they learned, they created a new OS – UNIX (UNIX is a play on words on multics) – What we call AT&T System V flavor.

• Offered UNIX to universities. UC at Berkeley made some changes and came up with their own flavor of UNIX – What we call the Berkeley BSD flavor.


History of Unix (2)

• There were now two flavors of UNIX– System V– BSD (based on Berkeley’s changes)

– NOTE: Flavors are very similar, but do have differences in some commands, etc…

• Companies who wanted to have Unix run on their computers had to choose from one of the two flavors, change it up for their particular hardware, and sell it with their hardware.


Different Versions

• IBM’s version – AIX• SUN’s version – Solaris• HP’s version – HP-UX• UNIX is a generic term. If someone is

using UNIX, we always have to ask “What version” or “from what vendor”, etc…

• Too many different versions from too many vendors has hurt Unix, for reasons we will mention shortly.


Linux

• Free version of Unix designed to run, among other things, on Intel based PCs

• Developed by Linus Torvalds at the University of Helsinki in Finland. – Linux comes from his name - Linus

• Many versions of Linux are out there.• We are using Red Hat Linux.


Problems with UNIX

• Remember, we mentioned that the OS is responsible for loading applications.

• When a software company writes a program they have to write it for a particular OS. They may choose to write it for Windows 98, or MacOS (Macintosh computers), or Unix, or all.

• If I were writing software for the home user, I would write it for Windows. Why? I like Unix better but I realize that there is a larger market of users running Windows at home.


Different Versions Note– How different is each version (Sun’s vs. HPs

vs. IBM’s vs. Linux)? • Not that much anymore, since they are all based on

similar standards.

– However, some systems might have “extra” commands they have added.

• As a user you might see some differences, but the base commands should all be the same. I will try to point out some differences between Solaris and Linux as the semester goes on.

• There are, however, internal differences, which might effect programmers.

• And of course, there are many differences in installation, which effect Unix administrators.


Features of Linux (UNIX)

• The obvious: multi-user and multitasking

• Portable. Written primarily in C language.It can be changed up slightly to work on different hardware (which is why we have so many versions from the different companies)

• Hierarchical Filesystem: Similar to layout of files/folders on PCs (but yet very different)

• Device-Independent Input and Output: UNIX input/output devices (printers , disks, etc…) are treated as files.

• The Shell: The command line interface. The shell accepts commands and makes sure they are carried out.


Let’s Get Started!

– We will all be using OUR Unix server called redhat9 (its IP address is 192.168.4.21)

• Review (hopefully): every machine is known by their IP address. The name/domain-name (redhat9) is just for our benefit.


PuTTY

• We will be using the PuTTY program to connect to the UNIX server.

• On your PC:– Copy the PuTTY program to your desktop.– Double Click on PuTTY.


PuTTY Screen


PuTTY: Example of Login (graphic)

Note: Enter your UNIX account at the login prompt shown above then press Enter.


PuTTY: Example of Password (graphic)

Note: Next enter your password and then press Enter.


PuTTY: If you have an error you will have to re-enter password.

Note: If you get “Access denied” then it will prompt you to re-enter password again.


Unix Account

• Your UNIX account and password will be the same as the account/password you received during in class.

• After you enter your login account, press return and enter your password.– If you make an error while entering your

password, try to erase and start over. If that doesn’t work, you will be prompted to re-enter.

• Password will not echo at the prompt.


Logged In• After you successfully log in you will see:

– Some welcome messages– The unix shell prompt (shown below):

[terry@redhat9 terry]


The Shell• The shell prompt tells you that UNIX is waiting

and ready for you to enter a UNIX command:– date

[terry@redhat9 terry]$ is the prompt

date is the command entered

You could enter another command at this prompt


Prompts (1)

• Prompts can have many forms:$bash-2.05$%Hello%

• In our class, whenever you see the $ in notes or directions, that will refer to your prompt (unless otherwise instructed).

• Remember, your prompt for now is: [username@redhat9 home]$


Prompts (2)

• When you see a prompt, enter a command (and then press enter)

$ date$ who$ cal

• As shown above, “date” and “who” and “cal” are all commands that can be entered at the prompt. – Remember, you type in the “date” not

the “$”.


Prompts (3)

• I know this sounds silly, but if you do not see a prompt, then you cannot type in a new command.

• If you ever get stuck, and want to break out of the command you entered and start over, press the [Ctrl][c] keys on your keyboard at the SAME TIME.


Commands (1)

• Commands can be as simple as one word, two words, or many words together.

• The following are all UNIX commands:$ date$ ls$ ls –la x*$ tar –cvf text x*$ who$ cal


Commands (2)

• Review: Whenever I want you to enter a command, I will probably use the following notation: $ cal– DO not type the $. That represents the

prompt. The above example means I want you to type: cal


Commands (2)

• There are many commands discussed in each chapter. We will not be covering all of those commands.


The End

Please make sure and review learning module and textbook

for more information on module 1.

UNIX Operating System I Module 1 Introduction to UNIX/Linux Chapter 1 (and a little extra)

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