$ uname -r
4.15.0-1019-aws
    

$ uname -s
Darwin

$ uname -r
4.15.0-47-generic

What is an Operating System
One of the first things that we must be sure of before we begin our journey in choosing an operating
system is to understand what we mean by the term. The operating system lies at the heart of your
computer and allows applications to run within and on top of it. Additionally, the operating system
will contain drivers to access the computer’s hardware such as disks and partitions, screens,
keyboards, network cards and so on. We often abbreviate the operating system to simply the OS.
Today there are many operating systems available for both business computer usage as well as for
those looking for something in the home. If we want to simplify the selection available to us, we can
group selections as follows:
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• Linux-based Operating Systems
◦ Enterprise Linux
◦ Consumer Linux
• UNIX
• macOS
• Windows-based Operation Systems
◦ Windows Servers
◦ Windows Desktops
Choosing a Linux Distribution
The Linux Kernel and Linux Distributions
When talking about Linux distributions the operating system is Linux. Linux is the kernel and at the
core of every Linux distribution. The software of the Linux kernel is maintained by a group of
individuals, lead by Linus Torvalds. Torvalds is employed by an industry consortium called The
Linux Foundation to work on the Linux kernel.
NOTE
The Linux kernel was first developed by Linus Torvalds, a student from Finland,
back in 1991. In 1992, the first Kernel release under the GNU General Public
License version 2 (GPLv2) was version 0.12.
Linux Kernel
As we have mentioned, all Linux distributions run the same operating system, Linux.
Linux Distribution
When people talk about Red Hat Linux, or Ubuntu Linux they are referring to the Linux
distribution. The Linux distribution will ship with a Linux kernel and an environment that makes
the kernel useful in a way that we can interact with it. At a minimum we would need a command
line shell such as Bash and a set of basic commands allowing us to access and manage the system.
Often, of course, the Linux distribution will have a full Desktop Environment such as Gnome or
KDE.
Even though each Linux distribution runs the Linux operating system, distributions can and do vary
on the version of the operating system that is used. By this, we mean, the version of the Linux Kernel
that is in use when the distribution boots.
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TIP
If you have access to a Linux command line at the moment, you can easily check the
version of the Linux kernel that you are running by reading the kernel release:
$ uname -r
4.15.0-1019-aws
Types of Linux Distributions
It may seem an obvious choice to always run the latest version of the Linux kernel but it is not quite
as simple as that. We can vaguely categorize Linux distributions into three sets:
• Enterprise Grade Linux Distributions
◦ Red Hat Enterprise Linux
◦ CentOS
◦ SUSE Linux Enterprise Server
◦ Debian GNU/Linux
◦ Ubuntu LTS
• Consumer Grade Linux Distributions
◦ Fedora
◦ Ubuntu non-LTS
◦ openSUSE
• Experimental and Hacker Linux Distributions
◦ Arch
◦ Gentoo
This, of course, is a just a very small subset of possible distributions but the importance is the
difference between enterprise, consumer and experimental distributions and why each exists.

Enterprise Grade Linux
Distributions such as CentOS (Community Enterprise OS) are designed to be deployed within
large organizations using enterprise hardware. The needs of the enterprise are very different
from the needs of the small business, hobbyist or home user. In order to ensure the availability of
their services, enterprise users have higher requirements regarding the stability of their hardand software. Therefore, enterprise Linux distributions tend to include older releases of the
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kernel and other software, which are known to work reliably. Often the distributions port
important updates like security fixes back to these stable versions. In return, enterprise Linux
distributions might lack support for the most recent consumer hardware and provide older
versions of software packages. However, like consumer Linux distributions, enterprises tend to
also choose mature hardware components and build their services on stable software versions.
Consumer Grade Linux
Distributions such as Ubuntu are more targeted for small business or home and hobbyist users.
As such, they are also likely to be using the latest hardware found on consumer grade systems.
These systems will need the latest drivers to make the most of the new hardware but the
maturity of both the hardware and the drivers is unlikely to meet the needs of larger enterprises.
For the consumer market, however, the latest kernel is exactly what is needed with the most
modern drivers even if they are little under tested. The newer Linux kernels will have the latest
drivers to support the very latest hardware that are likely to be in use. Especially with the
development we see with Linux in the gaming market it is tremendously important that the latest
drivers are available to these users.
NOTE
Some distributions like Ubuntu provide both consumer grade versions which
contain recent software and receive updates for a rather small period of time, as
well as so-called Long Term Support versions, LTS for short, which are more suited
for enterprise environments.
Experimental and Hacker Linux Distributions
Distributions such as Arch Linux or Gentoo Linux live on the cutting edge of technology. They
contain the most recent versions of software, even if these versions still contain bugs and
untested features. In return, these distributions tend to use a rolling release model which allows
them to deliver updates at any time. These distributions are used by advanced users who want to
always receive the most recent software and are aware that functionality can break at any time
and are able to repair their systems in such cases.
In short, when considering Linux as your operating system, if you are using enterprise grade
hardware on your servers or desktops then you can make use of either enterprise grade or consumer
grade Linux distributions. If you are using consumer grade hardware and need to make the most of
the latest hardware innovations then you are likely to need a similar Linux distribution to match the
needs of the hardware.
Some Linux distributions are related to each other. Ubuntu, for example, is based on Debian Linux
and uses the same packaging system, DPKG. Fedora, as another example, is a testbed for RedHat
Enterprise Linux, where potential features of future RHEL versions can be explored ahead of their
availability in the enterprise distribution.
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As well as the distributions we have mentioned here there are many other Linux distributions. One
advantage that comes with Linux being open source software is that many people can develop what
they think Linux should look like. As such we have many hundreds of distributions. To view more
Linux distributions you may choose to visit The Distro Watch Web Site, the maintainers of the
website list the top 100 downloads of Linux distributions, allowing you to compare and see what is
currently popular.

Linux Support Lifecycle
As you might expect, enterprise Linux distributions have a longer support life than consumer or
community editions of Linux. For example Red Hat Enterprise Linux has support for 10 years. Red
Hat Enterprise Linux 8 was launched in May 2019, while software updates and support are available
until May 2029.
Consumer editions often will only have community support via forums. Software updates are often
available for 3 releases. If we take Ubuntu as an example, at the time of writing 19.04 is the latest
available having updates through the release of 19.10 and stopping in January 2020. Ubuntu also
supply editions with long term support, known as LTS editions, which have 5 years of support from
the original release. The current LTS version is 18.04 which will have software updates until 2023.
These LTS versions make Ubuntu a possible option for the enterprise with commercial support
available from Canonical (the company behind the Ubuntu brand) or independent consulting firms.
NOTE The Ubuntu distributions use date-based version numbers in the format YY.MM:
For example, version 19.04 was released April 2019.
Linux as Your Desktop
Using Linux as your desktop system may be more challenging in an enterprise where desktop
support focusses on commercial operating system offerings. However it is not only the support that
may prove challenging. An enterprise customer may also have made large investments into software
solutions that tie them into specific desktop operating systems. Having said this, there are many
examples of Linux desktops being integrated into large organizations with companies like Amazon
even having their own Linux distribution Amazon Linux 2. This is used on their AWS cloud platform
but also internally for both servers and desktops.
Using Linux in a smaller business or at home becomes a lot easier and can be a rewarding
experience, removing the need for licensing and opening your eyes to the wealth of free and open
source software that is available for Linux. You will also find that there are many different desktop
environments available. The most common being Gnome and KDE, however many others exists. The
decision comes down to personal preference.
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Using Linux on Servers
Using Linux as your server operating system is common practice in the enterprise sector. Servers are
maintained by engineers who specialize in Linux. So even with thousands of users, the users can
remain ignorant of the servers that they are connecting to. The server operating system is not
important to them and, in general, client applications will not differ between Linux and other
operating systems in the backend. It is also true that as more applications are virtualized or
containerized within local and remote clouds, the operating system is masked even more and the
embedded operating system is likely to be Linux.
Linux in the Cloud
Another opportunity to become familiar with Linux is to deploy Linux within one of the many
public clouds available. Creating an account with one of the many others cloud providers will allow
you to quickly deploy many different Linux distributions quickly and easily.
Non Linux Operating Systems
Yes, incredible as it seems, there are operating systems that are not based on the Linux kernel. Of
course, over the years there have been many and some have fallen by the wayside but there are still
other choices that are available to you. Either at home or in the office.
Unix
Before we had Linux as an operating system there was Unix. Unix used to be sold along with
hardware and still today several commercial Unixes such as AIX and HP-UX are available on the
market. While Linux was highly inspired by Unix (and the lack of its availability for certain
hardware), the family of BSD operating systems is directly based on Unix. Today, FreeBSD, NetBSD
and OpenBSD, along with some other related BSD systems, are available as free software.
Unix was heavily used in the enterprise but we have seen a decline in the fortunes of Unix with the
growth of Linux. As Linux has grown and the enterprise support offerings have also grown, we have
seen Unix slowly start to vanish. Solaris, originally from Sun before moving to Oracle, has recently
disappeared. This was one of the larger Unix Operating Systems used by telecommunication
companies, heralded as Telco Grade Unix.
Unix Operating Systems include:
• AIX
• FreeBSD, NetBSD, OpenBSD
• HP-UX
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• Irix
• Solaris
macOS
macOS (previously OS X) from Apple dates back to 2001. Based very much on BSD Unix, and making
use of the Bash command line shell, it is a friendly system to use if you are used to using Unix or
Linux operating systems. If you’re using macOS you can open the terminal application to access the
command line. Running the same uname command again we can check the reported operating
system:
$ uname -s
Darwin
NOTE We make use of the option -s in this case to return the OS name. We previously
used -r to return the kernel version number.
Microsoft Windows
We can still say that the majority of desktops and laptops out there will be Windows based. The
operating system has been truly successful and has dominated the desktop market for years.
Although it is proprietary software and is not free, often the operating system license is included
when you buy the hardware so it becomes the easy choice to make. There is, of course, wide support
for Windows throughout hardware and software vendors as well of course many open source
applications are also available for Windows. The future for Windows does not seem as bright as it
has been. With fewer desktops and laptops being sold now the focus is on the tablet and phone
market. This has been dominated by Apple and Android and it is hard for Microsoft to gain ground.
As a server platform Microsoft does now allow its customers to choose between a GUI (Graphical
User Interface) and command line only version. The separation of the GUI and the command line is
an important one. Most of the time the GUI of older Microsoft Servers will be loaded but no-one will
use it. Consider an Active Directory Domain Controller… users use it all the time to authenticate to
the domain, but it is managed remotely from administrators’ desktops and not the server.

Guided Exercises
1. Which project makes up the common component of all Linux distributions?
CentOS
Red Hat
Ubuntu
Linux Kernel
CoreOS
2. Which operating system is reported in use for macOS from Apple?
OS X
OSX
Darwin
MacOS
3. How does a Linux distribution differ from the Linux kernel?
The kernel is part of a distribution, the
distribution as applications to surround the
kernel to make it useful
The kernel is the Linux distribution
All distributions that use the same kernel are
the same
4. Which of the following is a desktop environment in Linux?
Mint
Elementary
Zorin
Wayland
5. Which component of an operating system allows access to hardware?
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Drivers
Shells
Service
Application
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Explorational Exercises
1. Retrieve the current Kernel release of your Linux system if you have access to the command
line.
2. Using your preferred search engine locate and identify public cloud providers available to you.
These could include AWS, Google Cloud, Rackspace and many more. Choose one and see which
operating systems are available to deploy.
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Summary
In this section you have learned how to differentiate between different operating systems commonly
available. We discussed:
• Linux Based Operating Systems
• UNIX
• macOS
• Windows Based Operation Systems
Within the Linux category we could further break the selection down into distributions with long
term support and those with a shorter support cycle. LTS versions being more suited to the
Enterprise and shorter term support being targeted toward home and hobby users.
• Enterprise Grade Linux Distributions
◦ Red Hat Enterprise Linux
◦ CentOS
◦ SUSE Linux Enterprise Server
◦ Debian GNU/Linux
◦ Ubuntu LTS
• Consumer Grade Linux Distributions
◦ Fedora
◦ Ubuntu non-LTS
◦ openSUSE
• Experimental and Hacker Linux Distributions
◦ Arch
◦ Gentoo
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Answers to Guided Exercises
1. Which project makes up the common component of all Linux distributions?
CentOS
Red Hat
Ubuntu
Linux Kernel X
CoreOS
2. Which operating system is reported in use for OS X from Apple?
OS X
OSX
Darwin X
MacOS
3. How does a Linux distribution differ from the Linux kernel?
The kernel is part of a distribution, the
distribution as applications to surround the
kernel to make it useful
X
The kernel is the Linux distribution
All distributions that use the same kernel are
the same
4. Which of the following is a desktop environment in Linux?
Mint
Elementary
Zorin
Wayland X
5. Which component of an operating system allows access to hardware?
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Drivers X
Shells
Service
Application
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Answers to Explorational Exercises
1. Retrieve the current kernel release of your Linux system if you have access to the command line.
$ uname -r
4.15.0-47-generic
2. Using your preferred search engine locate and identify public cloud providers available to you.
These could include AWS, Google Cloud, Rackspace and many more. Choose one and see which
operating systems are available to deploy.
AWS, as an example, allows you to deploy many Linux distributions such as Debian, Red Hat,
SUSE or Ubuntu as well as Windows.
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