Linux Introduction , Unix vs Linux , Linux Advantages

Linux History
• Linus Torvalds was a student in Helsinki, Finland, in 1991, when he started a
project: writing his own operating system kernel.
• In 1992, Linux was re-licensed using the General Public License (GPL) by GNU (a
project of the Free Software Foundation or FSF, which promotes freely available
software), which enabled it to build a worldwide community of developers.
The Linux Operating System
 Linux (pronounced “lih-nucks”)
 operating system that is used today to run a variety of applications on a variety of different
hardware.
 Linux has the ability to manage thousands of tasks at the same time, including allowing
multiple users to access the system simultaneously.
 Linux is referred to as a multiuser and multitasking operating system.

Linux Advantages
 Risk reduction
 Meeting business needs
 Stability and security
 Flexibility for different hardware platforms
 Ease of customization
 Ease of obtaining support
 Cost reduction

1. Kernel:- The kernel is one of the core section of an operating system. It is
responsible for each of the major actions of the Linux OS. This operating system
contains distinct types of modules and cooperates with underlying hardware directly.
The kernel facilitates required abstraction for hiding details of low-level hardware or
application programs to the system. There are some of the important kernel types which
are mentioned below:
 Monolithic Kernel
 Micro kernels
 Exo kernels
 Hybrid kernels
2. System Libraries:- These libraries can be specified as some special functions.
These are applied for implementing the operating system's functionality and don't need
code access rights of the modules of kernel.
3. System Utility Programs:- It is responsible for doing specialized level and individual
activities.
4. Hardware layer:- Linux operating system contains a hardware layer that consists of
several peripheral devices like CPU, HDD, and RAM.

5. Shell:- It is an interface among the kernel and user. It can afford the services of
kernel. It can take commands through the user and runs the functions of the kernel.
The shell is available in distinct types of OSes. These operating systems are
categorized into two different types, which are the graphical shells and command-
line shells.
The graphical line shells facilitate the graphical user interface, while the command line
shells facilitate the command line interface. Thus, both of these shells implement
operations. However, the graphical user interface shells work slower as compared to
the command-line interface shells.
There are a few types of these shells which are categorized as follows:
 Korn shell
 Bourne shell
 C shell
 POSIX shell

Licensing Linux
 Linux is freely developed and continuously improved by a large community of software developers.
 Referred to as Open Source Software (OSS)
Types of Open Source Licenses
 GNU General Public License (GPL), which was developed by the Free Software Foundation (FSF).

 The core component of the Linux operating system is called the Linux kernel.
 The Linux kernel and supporting software (called function libraries) are written almost entirely in the C
programming language,
 Linux kernel is
directly responsible for controlling the computer’s hardware (via device drivers)
 updates in the form of a kernel module or a kernel patch can be used to provide or fix hardware supported
by the kernel.
Identifying Kernel Versions
• Major number
• Minor number
• Revision number
•3 – This is the main kernel version
•.10 – This is the major release version
•.0 – This is the minor revision level
•-957 – This is the level of patches and bug fixes
Developmental kernels are not fully tested and imply instability; they are tested for vulnerabilities by people
who develop Linux software.
Production kernels are developmental kernels that have been thoroughly tested by several Linux developers
and are declared to be stable.
Linux Kernel

Linux Kernel version numbering

Linux Distros Categories
Debian-based
 Examples: Ubuntu, Linux Mint, Kali Linux, Elementary OS
 Package Management: Uses .deb packages with dpkg and apt.
Red Hat-based
 Examples: Fedora, CentOS, RHEL (Red Hat Enterprise Linux), AlmaLinux, Rocky Linux
Arch-based
 Examples: Arch Linux, Manjaro, EndeavourOS
 Package Management: Uses .pkg.tar.zst packages with pacman.
SUSE-based
 Examples: openSUSE, SUSE Linux Enterprise
 Package Management: Uses .rpm packages with zypper.
Gentoo-based
 Examples: Gentoo, Calculate Linux
 Package Management: Uses source packages with portage.
Slackware-based
 Examples: Slackware, Slax, Zenwalk
 Package Management: Uses .tgz packages with pkgtool.

Red Hat Enterprise Linux (RHEL) heads the family that includes CentOS, CentOS
Stream, Fedora and Oracle Linux.
Red Hat Family
 Fedora serves as an upstream testing platform for RHEL.
 CentOS is a close clone of RHEL; in fact, CentOS has been part of Red Hat since
2014.
 A heavily patched version 4.18 kernel is used in RHEL/CentOS 8 Stream, while
version 5.14 is used in RHEL/CentOS 9 Stream.
 It supports multiple hardware platforms.
 It uses dnf, the RPM-based package manager (covered in detail later) to install,
update, and remove packages in the system.
 RHEL is widely used by enterprises which host their own systems.

The relationship between SUSE (SUSE Linux Enterprise Server, or SLES) and
openSUSE is similar to the one described between RHEL, CentOS, and Fedora.
Some of the key facts about the SUSE family are listed below:
 SUSE Linux Enterprise Server (SLES) is upstream for openSUSE.
 Kernel version 5.14 is used in openSUSE Leap 15.4.
 It uses the RPM-based zypper package manager (we cover it in detail later) to
install, update, and remove packages in the system.
 It includes the YaST (Yet Another Setup Tool) application for system
administration purposes.
 SLES is widely used in retail and many other sectors.
SUSE Family

Some key facts about the Debian family are listed below:
 The Debian family is upstream for Ubuntu, and Ubuntu is upstream for Linux Mint
and others.
 Kernel version 5.19 is used in Ubuntu 22.04 LTS.
 It uses the DPKG-based APT package manager (using apt, apt-get, apt-cache, etc.,
which we cover in detail later) to install, update, and remove packages in the
system.
 Ubuntu has been widely used for cloud deployments.
 While Ubuntu is built on top of Debian and is GNOME-based under the hood, it
differs visually from the interface on standard Debian, as well as other distributions.
Debian family

LTS stands for long term support. Here, support means that throughout the lifetime of a release
there is a commitment to update, patch and maintain the software.
Ubuntu Distro

Ubuntu version Code name Linux kernel version
24.04 Noble Numbat 6.6
23.10 Mantic Minotaur 6.5
23.04 Lunar Lobster 6.2
22.10 Kinetic Kudu 5.19
22.04 Jammy Jellyfish 5.15
21.10 Impish Indri 5.13
21.04 Hirsute Hippo 5.11
20.10 Groovy Gorilla 5.8
20.04 Focal Fossa 5.4
19.10 Eoan Ermine 5.3
19.04 Disco Dingo 5.0
18.10 Cosmic Cuttlefish 4.18
18.04 Bionic Beaver 4.15
17.10 Artful Aardvark 4.13
17.04 Zesty Zapus 4.10
16.10 Yakkety Yak 4.8
16.04 Xenial Xerus 4.4
15.10 Wily Werewolf 4.2
15.04 Vivid Vervet 3.19
14.10 Utopic Unicorn 3.16
14.04 Trusty Tahr 3.13
13.10 Saucy Salamander 3.11
13.04 Raring Ringtail 3.8
12.10 Quantal Quetzal 3.5
12.04 Precise Pangolin 3.2+
11.10 Oneiric Ocelot 3.0
11.04 Natty Narwhal 2.6.38
10.10 Maverick Meerkat 2.6.35
10.04 Lucid Lynx 2.6.32
09.10 Karmic Koala 2.6.31
09.04 Jaunty Jackalope 2.6.28
08.10 Intrepid Ibex 2.6.27
08.04 Hardy Heron 2.6.24
07.10 Gutsy Gibbon 2.6.22
07.04 Feisty Fawn 2.6.20
06.10 Edgy Eft 2.6.17
06.06 Dapper Drake 2.6.15
05.10 Breezy Badger 2.6.12
05.04 Hoary Hedgehog 2.6.10
04.10 Warty Warthog 2.6.8
Ubuntu Distro Version History

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