1. Unix / Linux Fundanmetals

2. Linux Ideas and History
• Linux originated at 1991 at the Helsinki university by a
student named Linus Torvalds with the intention of
developing an open-source kernel to run on Intel-compatible
hardware. Linus used the GNU project’s software under his
kernel.
• The GNU project’s beginning goes back almost 10 years prior
to Linus’ kernel development, its father is Richard Stallman
and it was designed create open-source alternatives to all
utilities and applications that run under UNIX.
• The GNU project has brought forth highly known and used
software such as the BASH shell and the “gcc” compiler
however the most important thing it brought was the GPL
(General Public License) which legally defines and secures a
software as being “open-source”.

3. What is Linux?
• Linux is a UNIX-based operating system originally designed to
function on Intel-based hardware. Today, Linux can be found
on many different hardware platforms such as: Cell-phones
and Tablets (Google’s Android OS), various vendor specific
server-hardware, x86/x86_64 based hardware and there was
even a wristwatch developed by IBM at 2001 which ran Linux.
• Linux is a modern OS, meaning uses features such as virtual
memory, memory protection and preemptive multitasking.
• The development of Linux goes on by a large community of
users and developers worldwide. These people see Linux as
an alternative to proprietary systems such as MS Windows /
Apple Macintosh / UNIX.

4. Why Use Linux?
• Some of the reasons to use Linux are:
– Configurability
– Convenience
– Stability
– Community
– Freedom
Let’s break down and explain these advantages:

5. Configurability
• Linux gives the end-user full access to configure just about
any aspect of their system; Customization options range from
simple actions such as changing the background image in a
graphical desktop environment to some more esoteric
actions, such as making the "Caps Lock" key behave as the
“CTRL” key.
• Linux allows the user to automate just about any task using its
advanced scripting and programming capabilities, which are
standard features.
• Linux, being an open-source system, offers the source-code of
its software and even of the kernel itself so that users can
modify them to fit their own specific needs.

6. Convenience
• While Linux may require a little bit of work to initially set-up a
flowing and working environment, it is a very low-
maintenance system after finishing the set-up process.
• Package management is as simple as running a few single
commands in the shell or point-and-click if using a graphical
desktop environment.
• Linux offers a complete suite of remote-access options which
allow access to the system’s shell (over SSH) or the graphical
desktop environment, if using one, via VNC; There are
numerous additional advanced methods of gaining access to a
Linux system.

7. Stability
• Linux is based on the UNIX kernel which include features such
as preemptive multitasking and protected memory.
– Preemptive Multitasking: prevents applications from “stealing” all of
the CPU and causing the system to lock-up.
– Protected Memory: Prevents applications from interfering with each
others’ memory thus preventing them from crashing each other.
• Linux and its related tools are, as said before, open-source
programs and as such the code is available to the public to
further develop. There are many developers worldwide who
keep working on that code, whether they are the original
creators of it or not, resulting in bugs being fixed very quickly
by those who find them instead of waiting to the next release
or hotfix of the software in order to repair its bugs.

8. Community
• Linux is part of a greater open-source community, consisting
of thousands of developers and many more users worldwide.
These people, who make the community, are also its
technical support force.
• There are mailing lists to just about any open-source project
out there where users can communicate with each other and
the project’s developers.
• There are many open-source and Linux related forums, where
problems and their solutions and/or workarounds are posted.
One of the bigger forums is: www.linuxquestions.org
• Free Linux tutorials, step-by-step guides and information is
available online to all user proficiency levels.

9. Freedom
• Linux is completely free, that means more than just the
system not costing money but also that you can do with it
whatever you like.
• There is one restriction: even if one does sell a Linux
distribution, the same way RedHat, SuSE and Mandrake do,
they must grant full access to the source codes used by them,
which also include the kernel sources; This restriction
prevents a corporation from using the Linux kernel as a base
to a proprietary operating-system of their own.

10. Generic Public License
• As many other ‘Open Source’ projects, Linux is registered
under the Generic Public License (GPL), which includes the
following rules and restrictions
– You can review, modify and use the source code in any way
– In case you choose to change the code and publish a modified
application (commercial or public) you must provide the source code
for the Entire application, both the original GPL and the newly added
features
– You can sell, distribute or give any GPL application, as long as you
provide the source code of that application with it

11. Distribution
• Linux has many distributions. Distribution refers to an
open-source project that includes a full featured operating
system based on the Linux Kernel
• These distributions usually make a vast use of the GNU tool
kit and other open-source project such as:
– X.org
– Apache
– GIMP
– BIND
• Each distribution is intended for a certain audience, several are for IT
professionals, other for Developers and many are for general or specific
usage users (Audio/Video Editors, Graphic Editors, etc)

12. Distribution
• Red Hat and SuSe are two of the oldest distributions for IT
general purposes.
Currently both groups are commercial companies, which
provides support services for Linux and sell Licensed
Enterprise Linux Editions
Both companies have a free version of their distributions
(Fedora and openSuSe)
• Debian is a distribution vastly used by Developers.
Being an open-source project, several ‘child’ distributions
have appeared during the years such as Ubuntu which targets
home / desktop users