ArticlesUnix is more than just an operating system. Rather, it’s a family of different systems that share common principles and architecture.
Originally designed in low-level PDP-7 assembler language, the Unix Operating system was later rewritten in 1972 using the then-new C programming language. This transition enhanced its portability and set a precedent for future operating systems.
One of Unix’s most defining features is its multitasking capability, which remains an important aspect to this day.
Due to its distribution to the government and universities, it was adopted in various hardware components.
This article explains how Unix has shaped the computing world, particularly regarding performance and efficiency. You will also learn about its future. So, without further ado, let’s begin.
Unix is considered and accepted to be the cornerstone of operating systems (OS). Developed at Bell Labs around the late 1960s to early 1970s, it was created by visionaries like Ken Thompson and Dennis Ritchie.
But what makes Unix so enduringly powerful? Fundamentally, Unix operates on some fundamental principles: simplicity, modularity, and interoperability.
The journey from the original Unix to modern derivatives like Linux and Mac OS is fascinating. Initial proprietary versions such as HP-UX and SunOS highlighted the need for standards due to growing incompatibility issues. This led to the development of interoperability standards like POSIX – ensuring different systems could communicate effectively.
Have you ever wondered why Unix remains relevant today? Its robust kernel architecture plays a significant role here. The kernel manages everything from processes and memory to networks and files – ensuring smooth operation across various tasks.
The Unix Philosophy represents a set of software design principles and cultural approaches aimed at writing simple and modular software.
It originated from the early work of Ken Thompson, Dennis Ritchie, and other developers of the Unix operating system at Bell Labs in the early 1970s.
Let us explain this philosophy in simpler terms:
The evolution of Unix operating systems occurred in distinct phases. Let’s look at them:
The architecture of Unix operating system is divided into four layers. All the four layers work in tandem with each other to handle complex tasks efficiently.
Starting with the Hardware layer, it’s the simplest yet least powerful. This layer includes all physical components connected to a Unix-based machine – essentially everything you can touch and see. It forms the foundation upon which all other layers operate.
Next up is the Kernel, which is often considered the powerhouse of Unix architecture. The kernel acts as an intermediary between users and hardware. It ensures efficient utilization through device drivers. Its responsibilities are vast but primarily focus on process management and file management.
Process management involves allocating memory and resources to processes while maintaining synchronization through techniques like paging and context-switching. Meanwhile, file management ensures data stored in files is accessible to processes when needed.
The Shell serves as an interpreter between users and the kernel. When you enter commands into your system, it’s the shell that interprets these instructions for execution by the kernel. Once tasks are completed, it facilitates displaying results back to the user.
There are three main types of shells in Unix:
Finally, we have reached the last shell which is applications or application programs. This outermost layer is responsible for executing various programs that users interact with daily.
Unix operating systems can be categorized into two types: Unix-based systems and Unix-like systems. The names of these systems are quite self-explanatory. Let’s explore them further for a better understanding.
Unix-based systems are developed from the original Unix operating system, meaning they are designed following Unix principles. These systems are commonly utilized in large data centers and for network management because of their robustness and flexibility.
Unix-like systems are not directly derived from Unix but emulate Unix’s behavior and functionality. They follow Unix standards but are developed independently based on the original Unix code. They are not certified as Unix but are generally compatible with Unix software.
Here’s a simple comparison table between Unix-like systems and Unix-based systems:
| Feature | Unix-Based Systems | Unix-Like Systems |
|---|---|---|
| Definition | Directly derived from the original Unix system. | Similar to Unix, but not directly derived from it. |
| Examples | macOS, Solaris, AIX, etc. | Linux, FreeBSD, Android, etc. |
| Source Code | Often proprietary, not always open to the public. | Mostly open-source, freely available to anyone. |
| User Base | Used by large companies and enterprises (servers, workstations). | Used by individuals, developers, and companies (especially for personal computers and servers). |
| Customization | Limited customization, controlled by the vendor (e.g., Apple). | Highly customizable, many different versions (distributions) are available. |
| User Interface | Graphical user interfaces (e.g., macOS’s GUI). | Can have both command-line (CLI) or graphical interfaces (particularly Linux). |
Here are the salient features of Unix operating systems that set it apart:
It is a method for storing and organizing large volumes of data to facilitate better management. A file is the smallest unit in this system where information is stored. Files are organized into directories, which are further structured into a tree-like format known as the file system.
The top-level directory of the file system is called “root” and is represented by a “/”. All other files are referred to as the “descendants” of the root.
UNIX file systems are divided into six files, each with its purpose, location, and unique identification.
These are the most common files you will come across. They store data, text, or program instructions and reside within directories. However, they cannot contain other files themselves. When you list them using the `ls -l` command, they’re marked with a “-” symbol.
These are the folders that organize both files and other directories. They maintain a hierarchical structure with the root directory (/) at the top. Each entry within a directory has its filename and unique ID known as an inode number. In `ls -l` output, directories are identified by a “d” symbol.
These exist for hardware devices such as I/O, like printers or drives. They come in two varieties:
Character Special Files (character devices, marked “c”) transfer one character at a time
Block Special Files (block devices, marked “b”) deal with larger amounts of data
Pipes are used to pass data and transfer output from one command to another. The syntax for pipes is the “|” symbol. For example – who | wc -l. They are denoted by “p” when listed.
Sockets facilitate communication between programs on the same system, akin to network sockets but localized within the file system itself. They are often used in client-server applications and identified by an “s” symbol in listings.
These act as shortcuts pointing to other files. When accessed, they redirect operations to their target file unless it’s moved or deleted at which point the link breaks down. They are marked with an “l” symbol in `ls -l`.
The Unix operating system has widespread applications across various sectors and industries. Here are the common uses:
In the banking sector, Unix is indispensable for mission-critical applications. Trading systems and risk management platforms rely heavily on Unix due to its high availability and uptime. These systems demand reliability, and Unix delivers just that.
Many telecom switches and transmission systems are managed by administration tools based on Unix. Its proficiency in handling real-time operations makes it ideal for managing complex telecommunications tasks efficiently.
UNIX-based systems are favored for their support of high-performance computing environments. They excel at running complex simulations required in research settings.
Unix operating systems have powered mission-critical applications worldwide for more than four years. But as technology evolves the future of Unix is at a crossroads. Today, it is a story of continuity and adaptability.
Unix has diversified into various flavors, many tailored for proprietary hardware like RISC architectures. A significant portion of the Unix market has transitioned to Linux—a system initially deemed “Unix-like.”
High-performance hardware manufacturers have also embraced Linux. Notable examples include SGI’s shift from IRIX to Linux and Cray’s preference for Linux over UNICOS.
On consumer platforms, Unix endures through descendants like Android (Linux) and MacOS (BSD). But in enterprise computing, Windows engineers far outnumber their Unix counterparts. This disparity stems from the deeper expertise required for managing Unix systems – skills that come at a premium.
In the future, if you are not running a mission-critical Unix application, part of an academic institution, or are involved in fields like visual effects or lab research, you will probably have little interaction with Unix.
While Unix still powers mission-critical applications, many enterprises face a significant challenge: the application is still indispensable for business operations, but the hardware is causing a serious threat to businesses. Keeping the hardware is expensive. It is also a threat to business continuity.
But there’s no need to worry about losing access to these vital applications. Stromasys offers an innovative solution with its Charon emulator, that allows you to run your legacy Unix applications seamlessly on modern hardware or on the cloud.
By doing so, you can maintain the functionality and performance of your essential applications without expensive application rewrites.
This lift and shift emulation protects your investment in current software and keeps your business running smoothly.
Want peace of mind knowing your vital applications are strong and reliable with modern infrastructure?
1. Are Linux and Unix the same?
No. But they are very similar in design philosophy as well as functionality. Speaking about differences, actually Unix is the proprietary operating system while Linux is an open-source Unix-like operating system.
2. What is the full form of Unix?
While most assume it is an abbreviation, that is not the case. Even though, sometimes it is written in capital letters as UNIX, causing people to think it is an acronym. In fact, that name pun on “Multics”. Also, UNIX was originally called UNICS that is – Uniplexed Information Computing System.
3. Who Invented Unix?
Ken Thompson, Dennis Ritchie, and others.
4. What is Multics in Unix Operating Systems?
Multics was a complex, early multi-user OS that inspired Unix’s development and simpler design.
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