Introduction to Unix - The Basics

The History of Unix


Basic Computer Components:

What does it all do? How does it all work together?

Have you ever built your own computer? If you have not and you're going into Computer Science, I highly suggest it (It's like legos for grown-ups!). There are different pieces and parts of your computer that all work together to form one working machine. The key parts are listed below: All of the items above are hardware components of the computer. Luckily for the user, normally they do not give commands directly to the pieces of hardware. This is where the idea of an Operating System comes in. The operating system is not only a middle-man between the user and the hardware, but also between the software (programs on the computer) and the hardware. The user can interact directly with the operating system which will in turn "talk" to the hardware, or the user can interact with software that is installed to work properly with the appropriate operating system (which in turn then talks to the hardware if needed).

Vareties of Unix

Ever used a unix based machine before? I'll bet you have...

There are many current commercial usages, personal usages, and deployments of unix based Operating Systems used today. Some popular and widely used systems that run unix/linux variants are: There are other distributions of Unix based Operating systems that are available for your computer system like: Ubuntu, Debian, Fedora, etc.

Shells vs. Machines

What's the difference?

In this class, we will be accessing unix based machines (physical computers) that are located in Carothers hall. You'll use your ssh software (like ssh secure shell or another client if you choose) to log into these machines. Examples of some machines that the FSU computer science department has that are available for use are: When you log on to any of these machines, you'll then be utilizing a SHELL to interact with the machine you're logged in to. A SHELL is the middle-man between you (the user) and the kernel of the machine you're logged in to.
By DEFAULT, when you log into any of the above machines, you'll be placed into the TCSH (pronounced T C Shell, aka, the Tenex shell). Some other shells that are available to you are: So the idea is:
Log into a MACHINE of choice --> Use a SHELL to interact with the KERNEL of that machine.

When you use a shell, you'll notice there are some aspects that can change based on what shell you're currently using. You'll see that the prompt changes as we move from shell to shell. To change your shell, simply type the name of the new shell you'd like to use. If you'd like to go back to the previous shell, type exit. Starting in TCSH:
bash-4.1$ sh
sh-4.1$ csh
sh-4.1$ exit
bash-4.1$ exit
You'll notice in the TCSH, we see that the prompt ends in the >, while in bash and sh, it ends in $. The style of the prompt changes from shell to shell. Certain shells have better capabilities over others to perform certain tasks. We'll see some of this later in the class. For now, the TCSH is fine for our needs. We'll utilize bash or sh later when we get to shell scripting.

Major Components of the Unix Operating System

Some Definitions of common Terms Relating to the file system

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(c) Melina Vastola, 2015