Unix vs. Linux: Understanding the Core Differences and Similarities

Operating systems are computer programs. An operating system is the first piece of software that the computer executes when you turn the machine on.

The operating system loads itself into memory and begins managing the resources available on the computer. It then provides those resources to other applications that the user wants to execute. Typical services that an operating system provides include:

An operating system normally also provides the default user interface for the system. The standard "look" of Windows 98 includes the Start button, the task bar, etc. The Mac OS provides a completely different look and feel for Macintosh computers.

Linux is as much a phenomenon as it is an operating system. To understand why Linux has become so popular, it is helpful to know a little bit about its history.

Unix originated in the late 1960s as a project at Bell Labs [source: University of Colorado Boulder]. Developed by Ken Thompson, Dennis Ritchie, and others, Unix was designed to be a portable, multi-tasking, and multi-user system in an era dominated by proprietary operating systems. It's was designed with simplicity in ming, and uses small, modular utilities that could be combined in any number of ways.

The first version of UNIX was used primarily as a research operating system in universities. High-powered desktop workstations from companies like Sun proliferated in the 1980s, and they were all based on UNIX.

A number of companies entered the workstation field to compete against Sun: HP, IBM, Silicon Graphics, Apollo, etc. Unfortunately, each one had its own version of UNIX and this made the sale of software difficult. Windows NT was Microsoft's answer to this marketplace.

NT provides the same sort of features as UNIX operating systems — security, support for multiple CPUs, large-scale memory and disk management, etc. — but it does it in a way that is compatible with most Windows applications.

The entry of Microsoft into the high-end workstation arena created a strange dynamic. The proprietary operating systems owned by separate companies and the lack of a central authority in the UNIX world weaken UNIX, but many people have personal problems with Microsoft. Linux stepped into this odd landscape and captured a lot of attention.

The Linux kernel, created by Linus Torvalds, was made available to the world for free. Torvalds then invited others to add to the kernel provided that they keep their contributions free [source: Love]. Thousands of programmers began working to enhance Linux, and the operating system grew rapidly. Because it is free and runs on PC platforms, it gained a sizeable audience among hard-core developers very quickly. Linux has a dedicated following and appeals to several different kinds of people:

In general, Linux is harder to manage than something like Windows, but offers more flexibility and configuration options.

While the the Unix operating system and Linux operating systems enjoy an intertwined history, there are indeed differences. From licensing models and availability to kernel design and system architectures, these differences not only define them but also influence their adoption and application [source: Schulze].

Licensing and Availability

One of the most significant differences between Unix and Linus is their licensing and availability. Unix, historically commercial and proprietary, is owned and sold by various companies. Each version of Unix (AIX, HP-UX, and Solaris) is developed and licensed by a different company, leading to a variety of Unix flavors with distinct characteristics.

In contrast, Linux is a free, open source operating system, allowing users to modify, distribute, and use the software without hefty licensing fees. This has led to the creation of numerous Linux distributions (Ubuntu, Fedora, and Debian) each catering to different needs and preferences.

Kernel and System Design

The kernel is the core part of any operating system. The Unix kernel is proprietary and varies between the versions mentioned above. On the other hand, the Linux kernel was developed from scratch by Torvalds and the ever-growing Linux community. This means that while both systems share similar concepts and commands, they aren't compatibile.

User Community and Support

As mentioned multiple times above, Unix has traditionally been used in enterprise environments, with support and maintenance provided by the respective vendor. Linux benefits from a vast, global community of developers and users. As such, support for Linux can come from various sources, including community forums, professional support services, and in-house IT teams.

Understanding these differences is more than academic. It's a practical way to differentiate and choose the right system. Still, despite these differences, Unix and Linux both continue to make significant contributions to the evolution of computing, each from its own unique vantage point.

At the heart of both systems lies a shared philosophy that prioritizes efficiency, modularity, and the power of the command line interface. These core similarities reflect the foundational lineage that has profoundly influenced the design and development of both interfaces.

Philosophy and Design

Both Unix and Linux adhere to the philosophy of providing a simple, modular operating system where small, single-purpose programs can be combined to perform complex tasks. This design principle has contributed to the flexibility, power, and reliability of both systems.

Command Line Interface (CLI)

At their core, both Unix and Linux offer a powerful command line interface (CLI), allowing users to perform tasks by typing commands. Many of these commands are common between the two.

POSIX Compliance

Most Unix variants and many Linux distributions adhere to the Portable Operating System Interface (POSIX) standards. This ensures a degree of compatibility and interoperability between different Unix-like operating systems, making it easier for software to be ported across them.

While Unix and Linux have their distinct paths and philosophies, they also share a significant common ground that has contributed to their enduring legacy in the computing world. The choice between the Unix OS and the Linux OS often comes down to specific needs, preferences, computer hardware, and philosophies regarding open-source software and proprietary solutions. Regardless of the choice, understanding the core differences and similarities between Unix and Linux is essential for anyone navigating the complex landscape of modern operating systems.