Linux is a free and open Source Operating System developed by Linus Torvalds and came into existence in the year 1991, at AT & T’s Bell Laboratories, released under the GPL (General Public License).  As any other OS main function of Linux OS is to manage the system resources (Hardware). We can refer it as an interface between the user and the computer system. GNU Linux has received lots of success and popularity in the last 2 decades with most of the commercial servers now using GNU Linux. Recently home users also started using Linux as their day to day OS, and popular Laptop and PC manufactures also giving GNU Linux as a pre-installed OS on their systems as its free and helps in cutting overall cost.

A brief history of Linux Development

Linus Torvalds was a student at the University of Helsinki, he was using a version of the UNIX operating system called ‘Minix‘. When Linus and other users found that some modifications can make the OS even better he and the other users sent requests for modifications and improvements to Minix’s creator, Andrew Tanenbaum, but Andrew felt that these changes are not necessary and didn’t make the changes. That was the time when Linus decided to create his own operating system that would take into account user’s comments and suggestions for improvements.

As Linus was a student of C Language he started writing the codes in C, around 95% of the Linux was written in C, and 2nd most used language for the Linux development was ‘Assembly‘ language i.e. around 2.8%.

What type of OS is Linux?

Linux falls under the category of the Layered Architecture OS, consists of following layers:

• Hardware layer - Hardware consists of all peripheral devices (RAM/ HDD/ CPU etc.).
• Kernel - Core component of Operating System, for all basic input/output management it interacts directly with the hardware.
• Shell/GCC - An interface between the user & the kernel, hiding the complexity of the kernel’s functions from users. Takes command from user and executes kernel’s functions.
• Application Software - Utility programs giving user most of the functionality of an operating system.
• Users - System users, who intracts directly with the system and application softwares.

Basic Features of Linux OS

Linux is fast, free and easy to use, power laptops and servers around the world. Linux has many more features to amaze its users such as:

• Live CD/USB: Almost all Linux distributions have Live CD/USB feature by which user can run/try the OS even without installing it on the system.
• Graphical user interface (X Window System): People think that Linux is a command line OS, somewhere its true also but not necessarily, Linux have packages which can be installed to make the whole OS graphics based as Windows.
• Support’s most national or customized keyboards: Linux is used worldwide and hence available in multiple languages, and supports most of their custom national keyboards.
• Application Support: Linux has its own software repository from where users can download and install thousands of applications just by issuing a command in Linux Terminal or Shell. Linux can also run Windows applications if needed.

Characteristics of Linux OS

Linux has several silent features, some of the important ones are:

Multiuser Capability: This is a capability of Linux OS where, the same computer resources – hard disk, memory, etc. are accessible to multiple users. Of course, not on a single terminal, they are given different terminals to operate from. A terminal will consist of at least a Monitor/VDU, keyboard and mouse as input devices. All the terminals are then connected to the main Linux Server or Host Machine, whose resources and connected peripheral devices such as printer, can be used.

Client/Server Architecture is an example of multiuser capability of Linux, where different clients are connected to a Linux server. The client sends request to the server with a particular data and server requests with the processed data or the file requested, client terminal is also known as a Dumb Terminal.

Multitasking: Linux has the ability to handle more than one job at a time, say for example you have executed a command for sorting for a huge list and simultaneously typing in a notepad. This is managed by dividing the CPU time intelligently by the implementation of scheduling policies and the concept of context switching.

Portability: Portability was the one of the main features that made Linux so popular among the users, but portability doesn’t mean that it is smaller in file size and can be carried on pen drive, CDs and memory cards. Instead, here portability means that Linux OS and its application can work on different types of hardwares in the same way. Linux kernel and application programs support their installation even on very least hardware configuration.

Security: Security is a very important part of any OS, for the organizations/user who is using the system for their confidential works, Linux does provide several security concepts for protecting their users from unauthorized access of their data and system.

Linux provide 3 main security concepts are:

• Authentication: This simply implies claiming the person whom you are by assigning passwords and login names to individual users, ensuring that nobody can gain access to their work.
• Authorization: At the file level Linux has authorization limits to users, there are read, write and execute permissions for each file which decide who can access a particular file, who can modify it and who can execute it.
• Encryption: This feature encodes your files into an unreadable format that is also known as ‘cyphertext‘, so that even if someone succeeds in opening it your secrets will be safe.

Communication: Linux has an excellent feature for communicating with the fellow users, it can be within the network of a single main computer, or between two or more such computer networks. The users can easily  exchange mail, data,  program through such networks.

Argument on Linux is ‘Kernel‘ not an ‘OS‘

Later on when different Linux distros like Arc Linux, Ubuntu, Debian and Fedora started to come into existence with better GUI (Graphical User Interface) and system softwares, which were basically customized versions of the Linux, users started to say that Linux is a Kernel not an operating system. Which has been now proved to be true :

For those who are still confused between Linux being an OS or kernel, Linux in true sense as written by Linus was a kernel that was written by referring to book on Unix internals (Though the Linux kernel has adopted best features from many other Unix like kernels too) while the commercially available distributions that contain utilities like graphical desktop, text editors, compilers etc. on top of the Linux kernel are complete operating systems.