We shall start from Linux Administration ( Fundamentals)
What is Linux
Linux is an operating system, unlike other operating systems.
We shall see how it is different from other operating systems.
- Linux is free
- Linux is portable to any hardware platform
- Linux was made to keep running on and on
- Linux is secure and versatile
- Linux is scalable
- Multitasking ( although other operating systems also are multitasking, but Linux is far ahead of the others in terms of memory management, security etc.
- Multi user
- Text Mode & Graphic Mode (X windows)
- Console & Remote
As we see Linux is a free OS ..what exactly it means
It is free because it is an open source software, well what is open source
Open-source: its source code is freely available to its users. Its users – and anyone else – have the ability to take this source code, modify it, and distribute their own versions of the program. The users also have the ability to distribute as many copies of the original program as they want. there are no licensing fees or other restrictions on the software
The opposite of open-source software is closed-source software, which has a license that restricts users and keeps the source code from them.
Firefox, Chrome, Open Office, Linux, and Android are some popular examples of open-source software, while Microsoft Windows is probably the most popular piece of closed-source software out there.
In 1991 Linux was first created by Linus Torvalds when he was a student at the University of Helsinki. He researched on the kernel and came up with Linux CLI (command line interface) and GUI ( Graphical User Interface) and gave it to the open source foundation (OSS)
In 1992 Suse Linux ( another flavor of Linux) introduced itself to the animation market.
In 1994 Red Hat Linux ( commonly used flavor of Linux) introduced itself to the Corporate market: 90% of Multinational Companies use Red Hat Linux.
The initial version released by red hat as free was red hat Linux 1
Later free versions from red hat were from version 1 till 9 after that red hat released red hat enterprise Linux -1 which was licensed and for commercial use and it continues as commercial so on.. (ie version rhel-2, rhel-3, rhel-4, rhel-5, rhel-6 ).
The Latest Release of Linux to date is Red Hat Enterprise Linux 6.4
Kernel 220.127.116.118 released on 21-feb-2013.
Well we see a term called kernel …so what is a kernel
Linux Kernel :
• In computer science, the kernel is the central component of most computer operating systems (OS). Its responsibilities include managing the system’s resources (the communication between hardware and software components).
A set of functions that make up the heart of an operating system.
In Simple terms : Kernel is an application interface between programs and physical devices ( Hardware)
In this Class we are looking at red hat version 6.4, we shall have a look what has changed from red hat edition 5
We now Compare RHEL6 with red hat enterprise Linux 5 & see what has changed from red hat enterprise Linux 5 (RHEL 5) to red hat enterprise Linux 6 (RHEL 6)
- Major difference between rhel5 and rhel6
- KVM :Kernel based Virtual Machine,
The main advantage of KVM is that it supports the installation of many virtual machines/operating systems like Windows, Linux, Solaris and also it is very easy to manage those virtual machines,
( No kernel compilation needed in rhel6 (KVM), in previos version rhel 5 ( XEN) kernel compilation was needed)
we see in above text that in rhel 5 the virtulisation used terminology used was XEN and in rhel6 the terminology used is KVM.
- Security: RHEL6 has an enhanced version of SELinux(Security Enhanced Linux) now, which also provides security to virtual machines from hackers.
- EXT4: It stands for Extended 4, It has various new advantages then EXT2/3 which were used in earlier version(s) of RHEL. EXT4 is comparatively more faster and easy to manage then previous file systems.
- IPv6: RHEL6 supports IPv6.—ipv4 was the previos version
In rhel6 support for ipv4 along with ipv6 is also there,
Internet Protocol version 6 (IPv6) is the latest revision of the Internet Protocol (IP), the communications protocol that provides an identification and location system for computers on networks across the Internet. IPv6 was developed to deal with the long-anticipated problem of IPv4 address exhaustion.
Every device on the Internet must be assigned an IP address in order to communicate with other devices. With the ever-increasing number of new devices being connected to the Internet, the need arose for more addresses than IPv4 is able to accommodate.
- NFS4: It uses NFSv4 (Network File Transfer) the latest version of NFS for the sharing of files in the network rather than NFSv3.
( We shall discuss nfs3 and nfs version in detail later in the chapters).
- GUI: It has a far better GUI(Graphical User Interface) then RHE5 or any of its prior version(s).
For developers a good site is available you guys can have a look at that too
Before releasing red hat for end users, red hat guys do a test bed on the platform called a fedora project
Various Linux Distributions can be found at
We see red hat is a free OS but the support is subscription based..ie support is paid service.
Identical operating system of red hat is Cent-OS which most of the corporates use:
CentOS is an Enterprise Linux distribution based on a rebuild of the freely available sources from Red Hat Enterprise Linux. Each CentOS version is supported for up to 10 years (by means of security updates A new CentOS version is released approximately every 2 years and each CentOS version is periodically updated (roughly every 6 months) to support newer hardware. This results in a secure, low-maintenance, reliable, predictable and reproducible Linux environment.
Cent-OS is supported by an active user community including system administrators, network administrators, enterprise users, managers, core Linux contributors and Linux enthusiasts from around the world.
CentOS has numerous advantages over some of the other clone projects including: an active and growing user community, quickly rebuilt, tested, an extensive mirror network, developers who are contactable and responsive, multiple free support avenues including IRC Chat, Mailing Lists, Forums, a dynamic FAQ.
In the coming sessions we shall see corporate environment scenarios
- Setup el6 in an enterprise environment
- Basic Linux do it yourself skills
- Shell Usage
- System admin activities, storage management , user management , network management
- Application support
- Security Support ( server Hardening)
You will be able to:
- Install a RedHat-based operating system
- Access the system to perform administration tasks
- Configure the boot and startup sequences of the system
- Shutdown the system with multiple methods
- Install, upgrade, and uninstall software
- Understand the file system organization of Linux
- Partition disks and manage logical volumes (LVM)
and much more in Linux open source..