Linux was first developed by Linus Torvalds in 1991 as an open source alternative to Unix. Since it is open source, developers can code the kernel, the utilities, and the applications without being under any overriding corporate entity overseeing development, and this also often resulted in lack of conventions and standardization.
Kali Linux was developed by Offensive Security as a hacking operating system built on a distribution of Linux called Debian. There are many other distribution of Linux which includes Ubuntu, Red Hat, CentOS, Mint etc. Although they all share the same Linux kernel(the heart of the OS that controls the CPU, RAM, and so on), each has it’s own utilities, applications, and choice of GUI(GNOME, KDE, etc) for different purposes.
Kali was designed for penetration testers & hackers & comes with a significant complement of hacking tools.

A tour of Kali Linux
Here we will try to understand about the terminal and file system.

The Terminal
Terminal or CLI(Command Line Interface) is one the important tool to get familiar with if someone wants to master Linux. In Kali Linux we can open the terminal by double-clicking the terminal icon or by pressing Ctrl+Alt+T.



The terminal open the command line environment, known as the shell, which enables us to run commands on the underlying OS and write scripts. Bash shell is the default shell in Kali Linux and it’s one of the most popular shell in Linux world.


The Linux File System
The filesystem structure of Linux is somewhat different from of Windows, Linux doesn’t have a physical drive(such as C: drive) at the base of the filesystem. At the very top of the filesystem structure is /, which is often referred to as the root of the filesystem, as if it were an upside-down tree. root directory is different from the root user.

The root(/) of the filesystem is at the top of the tree, &  following are the most important sub directories to know.



/root – The home directory of the all-powerful root user.
/etc – Generally contains the Linux configuration files(files that control when & how the programs start up).
/home – The user’s home directory.
/mnt – Where other filesystem are attached or mounted to the filesystem.
/media – Where CDs & USB devices are usually attached or mounted to the filesystem.
/bin – Where application binaries(the equivalent of executables in Microsoft Windows) reside.
/lib – Where we fill find libraries(shared programs that are similar to Windows DLLs).