Debian GNU/Linux Introduction Class 1

Debian Linux Evolution.Introduction to GNU-Linux.  Linux Environment in Princess Marina Hospital; Servers, services and workstations.

This post is part of a bigger Debian material that you can access here.

Even when this GNU/Linux Debian classes are for Information Technology personnel if you are starting you might have a lot of question.

What is Debian? What is Linux? What is GNU? What is Debian GNU/Linux? what is a Distrubution? A Kernel? Are they all the same? Is Linus Torvalds the author of every thing?
Not intending to answer all of them I will just quote some clever guys from out there.

The Kernel




“A kernel is the central part of an operating system. It manages the tasks of the computer and the hardware -most notably memory and CPU time. There are two types of kernels:

  1. A microkernel, which only contains basic functionality;
  2. A monolithic kernel, which contains many drivers [Linux].
A computer user never interacts directly with the kernel. It runs behind the scenes and cannot be seen, except for the text logs that it prints.”
Taken from: on 2014-02-12
Nice and simple, so the kernel is the middle man between me and the computer hardware.

Linux – GNU/Linux

  • “Many Linux users are familiar with Linux being called “GNU/Linux”. This means something special. “GNU” refers to the userland and “Linux” refers to the kernel. Now, you may be wondering if these two components can be swapped. Yes, they can.
  • For example, in the beginning of Linux’s history, the GNU community had no kernel at the time and Linux was just a kernel. So, they put the two projects together. Today, the GNU community has a kernel called “Hurd”.
  • They then swapped the Linux kernel with the Hurd kernel to make “GNU/Hurd” systems. For instance, Arch exists as “GNU/Linux” and “GNU/Hurd”.
  • Not only do various userland and kernel combinations exist, there are different Linux kernels. Also, Linux is not the only perating system with a module (obvious, right?).”
Taken from: on 2014/02/11.
Evolution Of Linux

Evolution Of Linux

The fist bullet is very important where he says that a lot of Linux users are aware that the term GNU/Linux.That GNU is the part of the Operating System (OS) that does the direct work with the user (understand that user does not mean only someone who is using a computer). Then Linux refers to the kernel only, that is the part of the OS that interacts with the hardware.

So basically they have joined GNU and Linux and created GNU/Linux. Of course afterwards both projects have evolved and improved their different components. And an other incredible thing that happened was that when people saw that they could take the Software modify it and create their own new code and make it available again, more and more people started to cooperate to create their own versions of GNU/Linux or to contribute to existing ones. Check out the picture to get a rough idea of what I am talking about.


This next picture is a summary of only the most important GNU/Linux distributions created after the code was released for free. What happened at that time was that some distribution appeared and they evolved to our days becoming better and better and better. Also in important to remark that every time that someone does a good contribution this code is free (generally) and it is incorporated again in other distributions making every generally better or at least more updated with the latest free software.

Linux distribution time-line evolution

Linux distribution time-line evolution

The main branches on this graphic are Red Hat from 1994 with child distributions like Mandrake, PCLinux, CentOS, Mandriva, Fedora Core and some other important distributions. Also we have Suse Linux also from 1994 made by Novel Enterprices. An other of the important branches id Debian, it was started back on 1993, for more information read the following paragraph taken from Debian’s project website.

“The Debian Project was officially founded by Ian Murdock on August 16th, 1993. At that time, the whole concept of a “distribution” of Linux was new. Ian intended Debian to be a distribution which would be made openly, in the spirit of Linux and GNU … The creation of Debian was sponsored by the FSF’s GNU project…”

Taken from: on 2014/02/28

Now from Debian we also have a whole lot of good derived distributions, like for instance Knopix,Dam Small Linux or the Ubuntu family that started on 2004.Otherwise along this classes we will be working with Debian mostly. But at the end if you know how to work with one of the distributions. You are very likely to be able to work with other distributions with small or no help.


“The Debian Project (…) is a free operating system. An operating system is the set of basic programs and utilities that make your computer run. At the core of an operating system is the kernel. The kernel is the most fundamental program on the computer and does all the basic housekeeping and lets you start other programs.
  • Debian systems currently use the Linux kernel or the FreeBSD kernel. Linux is a piece of software started by Linus Torvalds and
  • supported by thousands of programmers worldwide. FreeBSD is an operating system including a kernel and other software.
  • However, work is in progress to provide Debian for other kernels, primarily for the Hurd. The Hurd is free software produced by the GNU project.”
Taken from: 2014/02/11.
To get more information about the GNU/Linux and Debian you can go to the official websites:
  • Debian Project:
  • Linux Project:
  • GNU project:


An other of the Linux myths if that Linux has no graphic interface or very rudimentary ones, the true is that there are some very good projects with great future, although there is still a lot to be done. For instance we have Gnome Prject, check out the image, we can get more information about this project here. but Linux has a lot other graphic interfaces among them KDE the closest competitor to gnome or fresh one like LXDE and XFCE. But this classes are not for graphic fans but for Network administrators, so I will not talk to much about graphics any more along the course. We will use the Text Terminal mostly, the scary black Screen that many people are afraid of. The true is that this terminal is very pwoerful and you can perform a lot of activities nicely using it, and also most of the work is not like rocket sciences so we can learn it and that is what we will do along the classes.

Debian and Linux command prompt

We are going to start with real Linux. So if you do not have your Debian GNU/Linux workstation this is the moment to get it. the first thing that we will do is to change to a text terminal you can do that by pressing:

  • CTRL+ALT+(F1 to F6) Opens a Text terminal.

Now to switch back to the graphic terminal you can press:

  • Alt+F7 Opens the graphic terminal.

And you can also open a terminal from the graphic interface of your computer. by going to activities and typing terminal in the search box.

Linux Terminal

Linux Terminal

If you open the you text terminal (black screen) you have to login with a user, because it will prompt you immediately, there you are supposed to put your user and your password. As a curious detail in the Linux terminal when you type a password it does not show the dots that we might be used to in other  systems, so someone might think that is not typing but the terminal is really recording every key that you press. This was done that way for security reasons.

Once you are in you can type commands already, lets do for instance:


It should return your user name.

root@khs01sw10:~# whoami 
Debian man command linux

Debian man command linux

So running commands is simple. But this is not it, if you do not know how to use a command you can use the commandman passing an other command as augment and it will tell you what it does.

man <CommandIDon’tKnow>

for instance:

root@khs01sw10:~# man whoami

And it will show you the Linux manual for the command. the manuals are always something like  the picture. Also if it is not enough you can go to Internet and research about ways of using any command. To get out of the manual you can just press q key and it will exit the manual.

That is what I had prepared for today, let me just add the homework that you can do using the manual and we will met in the next class.

Homework: Explain how to use this commands on a Debian environment.

 ls -la
 passwd user

Thank you for your time.


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