What Is Unix? A Complete Guide

In the digital world we live in, Operating Systems shape our interactions with our computers. One of the most widely used Operating Systems worldwide is UNIX, which is renowned for its simplicity and efficiency. However, if you are still unaware of it and are asking the question, “What is UNIX?” you are at the right place.  

According to W3Techs, UNIX is used by 81.7% of all the websites whose Operating Systems they know. However, despite its widespread use worldwide, it is still growing in popularity – and many people want to know what the OS is all about. In this blog, we will tell you all you need to know about What is UNIX, its core concepts and popular UNIX-based Operating Systems.   

Table of Contents 

1) What is UNIX? A brief introduction 

2) Core concepts of UNIX 

    a) The UNIX philosophy 

    b) The file system 

    c) Shell and commands 

    d )Processes 

    e) Inter-Process Communication (IPC) 

3) Popular UNIX-based Operating Systems 

4) Conclusion 

What is UNIX? A brief introduction    

Before we delve into its core concepts, we will answer What is UNIX Operating System and its full form. UNIX, whose full form is "Uniplexed Information and Computing Service", is a pioneering Operating System developed in the late 1960s at AT&T's Bell Labs. Renowned for its modular design and robustness, UNIX introduced innovative concepts like hierarchical file systems and the use of plain text for storing data.   

With a philosophy centred on simplicity and versatility, Unix advocates the creation of small, single-purpose programs that can work together. The principles and architecture of Unix, alongside resources like the Unix Command Cheat Sheet, have not only stood the test of time but have also become the foundation for a plethora of modern Operating Systems, testifying to its lasting impact on computing.

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Core concepts of UNIX  

This section of the blog will expand on some of the core concepts of UNIX.

The UNIX philosophy  

The UNIX philosophy is an amalgamation of principles aimed at producing simple, robust, and modular software. The main principles are: 

1) Everything is a file: Almost everything is treated as a file in UNIX, from devices to sockets. This abstraction simplifies interaction, as everything can be read from or written in a standard way. 

2) Write programs to do one thing and do it well: Instead of creating multi-functional, complex software; the focus is on developing concise programs. This ensures that each utility remains manageable and comprehensible. 

3) Use plain text for storing data: Plain text is both universal and transparent. UNIX promotes its use because it's easy to read, write, and manipulate without needing specialised tools. 

4) Combine programs to solve bigger tasks: With the ability to connect utilities using pipes (|) and redirections (<, >), users can craft powerful workflows from simple tools. 

The file system  

UNIX introduced a cohesive and hierarchical file system, which became the blueprint for many subsequent OS: 

1) Hierarchical structure: All files and directories stem from the root (/), forming a tree structure that provides an organised approach to data storage. 

2) Everything resides in the file system: Whether it's system configurations, user data, or device references, everything is stored within this tree. 

3) File permissions: Each file or directory possesses permission settings, dictating who can read, write, or execute it. This facilitates a granular security mechanism. 

4) Links: Files can be referenced by multiple names using hard or symbolic links, aiding in data organisation without duplication. 

Shell and commands  

The shell is the Command-Line Interface (CLI) to UNIX, providing an environment for users to interact and execute commands: 

1) Interactive environment: Users input commands into the shell, and it provides output in return, offering a dialogue-like interaction. 

2) Scripting: Beyond one-off commands, users can write shell scripts – sequences of commands stored in files – to automate repetitive tasks. 

3) Job control: Commands can run in the foreground or background. Users can pause, resume, or stop processes directly from the shell. 

4) Built-in and external commands: The shell comes with built-in commands, but users can also execute external programs or scripts. 

Processes  

UNIX views every running program as a process with its own state and memory space: 

1) Unique identification: Each process is given a Unique Process ID (PID), allowing for precise control and monitoring. 

2) Parent-child hierarchy: When a process starts another, it becomes the parent of the new child process. This hierarchy aids in resource management and control. 

3) Life-cycle management: Processes pass through states like start, run, wait, and terminate. The OS provides tools like ps, top, and kill to manage and observe these life cycles. 

Inter-Process Communication (IPC) 

UNIX provides tools for processes to communicate and coordinate tasks, ensuring smooth multitasking: 

1) Pipes (|): These allow for the output of one process to be passed as the input to another. It's a staple of the UNIX philosophy of chaining small tools together. 

2) Signals: Processes can send and receive signals to or from other processes or the system. For instance, the kill command is used to send signals, which can do more than just terminate processes. 

3) Shared memory and semaphores: Shared memory allows multiple processes to access the same memory segment, while semaphore in Operating System ensures safe access to shared resources. 

4) Sockets: For more advanced IPC, particularly over networks, sockets allow processes to communicate by sending and receiving data packets. 

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Popular UNIX-based Operating Systems  

UNIX, the pioneering Operating System, has been the foundation for numerous derivatives that dominate the computing landscape. Solaris, developed by Sun Microsystems, is renowned for its robustness and is favored in enterprise environments. AIX, introduced by IBM, offers superior performance on IBM's proprietary hardware.Both AIX and Solaris have become key players in the enterprise sector, each offering unique strengths tailored to different hardware and application requirements. When choosing a UNIX-based system, a key consideration is the trade-offs between different implementations, such as AIX vs Linux, which offer varying degrees of hardware compatibility, performance characteristics, and cost.  

HP-UX, Hewlett-Packard's contribution, is optimised for HP server platforms and boasts high reliability. Lastly, macOS, Apple's flagship OS, combines UNIX's power with a refined user interface, making it a favourite among professionals and general users alike. These UNIX-based systems underline UNIX's profound and lasting impact on modern computing.

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Conclusion 

UNIX isn't just an Operating System; it's a testament to the power of clear thinking and effective design. Its core principles and concepts have stood the test of time, influencing generations of Software Developers and Systems Designers. As we continue to keep pushing the limits of technology, UNIX serves as a reminder of the enduring values of simplicity, modularity, and efficiency. Hope we could answer all your queries about “What is UNIX”! 

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