what is Linux..?

*LINUX:

Linux is an operating system's kernel. You might have heard of UNIX. Well, Linux is a UNIX clone. But it was actually created by Linus Torvalds from Scratch. Linux is free and open-source, that means that you can simply change anything in Linux and redistribute it in your own name! There are several Linux Distributions, commonly called “distros”.

Some of the popular Linux flavours are:
● Ubuntu Linux
● Fedora Linux
● Linux Mint
● OpenSUSE
● Debian Linux
● Mandriva Linux
● Kali Linux
● Puppy Linux
● Sabayon Linux
● RedHat Linux
● Mandrake Linux
● CentOS
● BOSS Linux



 LINUX COMMANDS:-

i) touch — The touch command is used to create a file. It can be anything, from an empty txt file to an empty zip file. For example, “touch new.txt”.

ii) ls⇒ Use the "ls" command to know what files are in the directory you are in. You can see all the hidden files by using the command “ls -a”.

iii)mkdir⇒ This command is used to create a new folder or directory.

iv) cd⇒ To change the directory
$cd foldername
cd .. To go back to the parent directory

v) pwd⇒ To display present working directory

vi) cat⇒ This command is used to create or display the content of a given file.
cat abc.txt ⇒ This will display the content of abc.txt
cat > xyz.txt ⇒This will create a file named xyz.txt. Type your content. At last
press Ctrl+D.

vii) cal⇒ To display the the current month calendar.

viii) mv⇒ To rename a file or directory

ix) date⇒ To display OS date and time.

x) uname⇒ To display OS name.

* Linux  console terminal:-

A Linux console terminal is one of the system consoles provided in the Linux kernel.The Linux console terminal acts as the medium for input and output operations for a Linux system. A Linux console terminal is similar to command line in Microsoft Windows but it differs in that it can perform any operation on the system.

* Explain Linux console Terminal:

The architecture in Linux does not require the graphical interface for system operation. The Linux console terminal is usually used to provide text user interface applications and important kernel messages. In many Linux distributions, the default user interface is the real terminal, though virtual consoles are also provided. The console terminal has its own terminal screen, unlike the virtual console terminal, which needs to share the monitor screen.

Some of the functions possible through the Linux console terminal are:

Extensive, system-wide configuration and administration

File and folder administration The ability to access, transfer and share data between machines Extensive system monitoring Most consider the Linux console terminal to be faster and more efficient as compared to the graphical user interface mode.

Why use Linux?

This is the one question that most people ask. Why bother learning a completely different computing environment, when the operating system that ships with most desktops, laptops, and servers works just fine?

To answer that question, I would pose another question. Does that operating system you?re currently using really work ?just fine?? Or, do you find yourself battling obstacles like viruses, malware, slow downs, crashes, costly repairs, and licensing fees?

If you struggle with the above, Linux might be the perfect platform for you. Linux has evolved into one of the most reliable computer ecosystems on the planet. Combine that reliability with zero cost of entry and you have the perfect solution for a desktop platform.

That’s right, zero cost of entry… as in free. You can install Linux on as many computers as you like without paying a cent for software or server licensing.

Let’s take a look at the cost of a Linux server in comparison to Windows Server 2016. The price of the Windows Server 2016 Standard edition is $882.00 USD (purchased directly from Microsoft). That doesn’t include Client Access License (CALs) and licenses for other software you may need to run (such as a database, a web server, mail server, etc.). For example, a single user CAL, for Windows Server 2016, costs $38.00. If you need to add 10 users, for example, that’s $388.00 more dollars for server software licensing.  With the Linux server, it?s all free and easy to install. In fact, installing a full-blown web server (that includes a database server), is just a few clicks or commands away (take a look at ?Easy LAMP Server Installation? to get an idea how simple it can be).

If zero cost isn’t enough to win you over? what about having an operating system that will work, trouble free, for as long as you use it? I’ve used Linux for nearly 20 years (as both a desktop and server platform) and have not had any issues with ransomware, malware, or viruses. Linux is generally far less vulnerable to such attacks. As for server reboots, they’re only necessary if the kernel is updated. It is not out of the ordinary for a Linux server to go years without being rebooted. If you follow the regular recommended updates, stability and dependability are practically assured.

Open source:-

Linux is also distributed under an open source license. Open source follows these key tenants:

The freedom to run the program, for any purpose.

The freedom to study how the program works, and change it to make it do what you wish.

The freedom to redistribute copies so you can help your neighbor.

The freedom to distribute copies of your modified versions to others.

These points are crucial to understanding the community that works together to create the Linux platform. Without a doubt, Linux is an operating system that is ?by the people, for the people?. These tenants are also a main factor in why many people choose Linux. It?s about freedom and freedom of use and freedom of choice.

What is a “distribution?”

Linux has a number of different versions to suit any type of user. From new users to hard-core users, you’ll find a “flavor” of Linux to match your needs. These versions are called distributions (or, in the short form, “distros”). Nearly every distribution of Linux can be downloaded for free, burned onto disk (or USB thumb drive), and installed (on as many machines as you like).

Popular Linux distributions include:

LINUX MINT

MANJARO

DEBIAN

UBUNTU

ANTERGOS

SOLUS

FEDORA

ELEMENTARY OS

OPENSUSE

Each distribution has a different take on the desktop. Some opt for very modern user interfaces (such as GNOME and Elementary OS’s Pantheon), whereas others stick with a more traditional desktop environment (openSUSE uses KDE).

You can check out the top 100 distributions on the Distrowatch.

And don’t think the server has been left behind. For this arena, you can turn to:

Red Hat Enterprise Linux

Ubuntu Server

Centos

SUSE Enterprise Linux

Some of the above server distributions are free (such as Ubuntu Server and CentOS) and some have an associated price (such as Red Hat Enterprise Linux and SUSE Enterprise Linux). Those with an associated price also include support.

Linux Distributions List

There are on an average six hundred Linux distributors providing different features. Here, we'll discuss about some of the popular Linux distros today.

1) Ubuntu

It came into existence in 2004 by Canonical and quickly became popular. Canonical wants Ubuntu to be used as easy graphical Linux desktop without the use of command line. It is the most well known Linux distribution. Ubuntu is a next version of Debian and easy to use for newbies. It comes with a lots of pre-installed apps and easy to use repositories libraries.

Earlier, Ubuntu uses GNOME2 desktop environment but now it has developed its own unity desktop environment. It releases every six months and currently working to expand to run on tablets and smartphones.

2) Linux Mint

Mint is based on Ubuntu and uses its repository software so some packages are common in both.

Earlier it was an alternative of Ubuntu because media codecs and proprietary software are included in mint but was absent in Ubuntu. But now it has its own popularity and it uses cinnamon and mate desktop instead of Ubuntu's unity desktop environment.

3) Debian

Debian has its existence since 1993 and releases its versions much slowly then Ubuntu and mint.

This makes it one of the most stable Linux distributor.

Ubuntu is based on Debian and was founded to improve the core bits of Debian more quickly and make it more user friendly. Every release name of Debian is based on the name of the movie Toy Story.

4) Red Hat Enterprise / CentOS

Red hat is a commercial Linux distributor. There products are red hat enterprise Linux (RHEL) and Fedora which are freely available. RHEL is well tested before release and supported till seven years after the release, whereas, fedora provides faster update and without any support.

Red hat uses trademark law to prevent their software from being redistributed. CentOS is a community project that uses red hat enterprise Linux code but removes all its trademark and make it freely available. In other words, it is a free version of RHEL and provide a stable platform for a long time.

5) Fedora

It is a project that mainly focuses on free software and provides latest version of software. It doesn't make its own desktop environment but used 'upstream' software. By default it has GNOME3 desktop environment. It is less stable but provides the latest stuff.

6) Kali Linux

kali linux is a Debian-based Linux distribution aimed at advanced Penetration Testing and Security Auditing. Kali contains several hundred tools which are geared towards various information security tasks, such as Penetration Testing, Security research, Computer Forensics and Reverse Engineering. Kali Linux is developed, funded and maintained by offensive security, a leading information security training company.

Kali Linux was released on the 13th March, 2013 as a complete, top-to-bottom rebuild of BackTrack linux, adhering completely to Debian  development standards.

More than 600 penetration testing tools included: After reviewing every tool that was included in BackTrack, we eliminated a great number of tools that either simply did not work or which duplicated other tools that provided the same or similar functionality. Details on what’s included are on the kali tools  site.

Free (as in beer) and always will be: Kali Linux, like BackTrack, is completely free of charge and always will be. You will never, ever have to pay for Kali Linux.

Open source Git tree: We are committed to the open source development model and our devlopment tree is available for all to see. All of the source code which goes into Kali Linux is available for anyone who wants to tweak or rebuild packages to suit their specific needs.

FHS compliant:  Kali adheres to the Filesystem Hirerchy standered, allowing Linux users to easily locate binaries, support files, libraries, etc.

Wide-ranging wireless device support: A regular sticking point with Linux distributions has been supported for wireless interfaces. We have built Kali Linux to support as many wireless devices as we possibly can, allowing it to run properly on a wide variety of hardware and making it compatible with numerous USB and other wireless devices.

Custom kernel, patched for injection: As penetration testers, the development team often needs to do wireless assessments, so our kernel has the latest injection patches included.

Developed in a secure environment: The Kali Linux team is made up of a small group of individuals who are the only ones trusted to commit packages and interact with the repositories, all of which is done using multiple secure protocols.

GPG signed packages and repositories:  Every package in Kali Linux is signed by each individual developer who built and committed it, and the repositories subsequently sign the packages as well.

Multi-language support: Although penetration tools tend to be written in English, we have ensured that Kali includes true multilingual support, allowing more users to operate in their native language and locate the tools they need for the job.

Completely customizable: We thoroughly understand that not everyone will agree with our design decisions, so we have made it as easy as possible for our more adventurous users to customize kali linux  to their liking, all the way down to the kernel.

ARMEL and ARMHF support: Since ARM-based single-board systems like the Raspberry Pi and BeagleBone Black, among others, are becoming more and more prevalent and inexpensive, we knew that Kali's Arm support would need to be as robust as we could manage, with fully working installations for both ARMEL AND ARMHF systems. Kali Linux is available on a wide range of ARM  devices and has ARM repositories integrated with the mainline distribution so tools for ARM are updated in conjunction with the rest of the distributions.

7) Puppy Linux

-> Puppy Linux is an operating system and family of light weight linux distributions that focus on ease of use and minimal memory footprint. The entire system can be run from random-access memory  with current versions generally taking up about 210 MB. allowing the boot medium to be removed after the operating systems has started. Applications such as Abiword, Gnumeric and Mplayer are included, along with a choice of lightweight web browsers and a utility for downloading other packages. The distribution was originally developed by Barry Kauler and other members of the community, until Kauler retired in 2013. The tool woof can build a Puppy Linux distribution from the binary packages of other Linux distributions.

8) Boss Linux

BOSS (Bharat Operating System Solutions) is a GNU/Linux distribution developed by C-DAC, Chennai in order to benefit the usage of Free/Open Source Software in India. BOSS GNU/Linux is a key deliverable of NRCFOSS. It has enhanced Desktop Environment integrated with Indian language support and other softwares.