UNIX Operating System: Architecture, Features, and Why It Matters 

The UNIX operating system is one of the most important software systems that form the foundation of modern computing. First introduced in the 1960s and 70s by Ken Thompson and Dennis Ritchie at AT&T’s Bell Labs, UNIX has become the foundation for innumerable operating systems, including Linux and macOS. It is and has been a robust, multi-user, multitasking operating system that has heavily influenced the design and development of all other modern operating systems. This guide expands on several features of UNIX, ranging from its early days, architecture, and characteristics to the types of shells, as well as the pros and cons of the system. By the time they finish, readers will have an expert-level grasp of what UNIX is.

Table of Contents:

• What is UNIX Operating System?
• Architecture of UNIX Operating System
• Types of Shell in UNIX Operating System
• Features of UNIX Operating System
• Advantages of UNIX Operating System
• Disadvantages of UNIX Operating System
• UNIX vs LINUX: Key Differences
• Essential UNIX Commands
• Use Cases and Applications
• Career Path with UNIX
• Conclusion

What is UNIX Operating System?

UNIX (short for unix full form: UNiplexed Information and Computing System, originally pronounced U-NICS) is a powerful and flexible operating system that serves as the base for many software development and support systems. Widely regarded as the father of modern operating systems, UNIX laid the groundwork for Linux-based (Ubuntu, Solaris) and POSIX-based platforms.

Initially adopted by government, academic, and research institutions, UNIX was quickly appreciated for its capabilities. Its advanced kernel-centric architecture, which manages hardware, networking, and storage even during active system processes, makes it ideal for high-performance and stable environments.

UNIX features a unique hierarchical file system that organizes files in a tree-like structure, enabling faster indexing, well-arranged storage, and rapid data access. This design inspired many contemporary file systems.

UNIX also pioneered several innovations, such as one of the first full-screen text editors and early online collaboration, long before version control systems became standard. It continues to be used for teaching students the fundamentals while also being used in research, prototyping, and development, thanks to its accessible console and scripting API.

Today, UNIX remains popular in academic, scientific, engineering, and enterprise environments. It’s not just a legacy system but a living foundation of much of today’s digital infrastructure.

Architecture of UNIX Operating System

The UNIX Operating System is split into four major layers. These layers simplify hardware access by presenting an abstract interface to the user. As we proceed from layer 1 up to layer 4, we are moving away from the hardware, and entering into the software domain. The UNIX OS layers include hardware, kernel, shell, and applications. These layers combine to form a multi-user, multi-tasking operating system. The following is a representative diagram on UNIX Operating System layers.

1. Hardware Layer

It is a repository of UNIX OS environment-related data useful for the processing of hardware.

2. Kernel Layer

The ‘ heart ‘ ( as in common use ) of the operating system. It is a program facilitating communication between the hardware and the user. It is the central core of Unix OS, to which is assigned the handling of major operation of the OS such as process, memory, file, network, etc…

Role of the Kernel Layer:

• Ensures that all the system/user operations run concurrently.
• Acts as a device manager, enabling the device driver to have access to the peripheral device connected to the computer.
• Due to this layer, memory is handled in the OS via mechanisms such as paging, swapping, and virtual storage.

3. Shell Layer

The shell in a UNIX operating system is the layer between the user and the kernel, the center of the operating system. It provides a command-line interface (CLI) for users to type in the computer’s operating system.

When a user types a command, the shell interprets the command and sends it in a form that the kernel – the core of the operating system – can understand. This is commonly referred to as command parsing.It translates those commands into instructions that the operating system can execute. A script containing a sequence of one or more such commands is called a shell script.

Did you know? The shell also maintains a history of commands entered by the user. To repeat a previous command, you can simply press the scroll-up key to access older entries.

There are several types of shells in UNIX operating system, including the Bourne Shell (sh), C Shell (csh), and Korn Shell (ksh), to name a few. The shell a user is assigned to upon logging in is typically determined by the system administrator. However, users can change their default shell using the chsh command.

If you are already familiar with Shell, its time to test your skills with Intellipaat’s Shell Scripting Interview Questions!

4. Application Programs Layer

This is the top layer of the operating system (it is the user interface) and it’s made of programs that you run just by typing their name on the bash command. It comprises third-party apps, i.e., word processors, graphic programs, and similar user-level utilities. Although these tools were historically used only in the command line, many of the tools today can also be used with a GUI.

Types of Shell in UNIX Operating System

In UNIX OS, a shell is a program that interprets the commands entered by the user to the operating system. In UNIX Operating system, a user is free to take a shell of his or her own choice. Here are some of the often-used shells that you should know:

1. Bourne Shell

Bourne Shell is the original shell for the UNIX operating system and is sometimes referred to as `the’ shell. It is currently the most commonly used shell, all thanks to its high effectiveness. It is represented as sh.

2. C Shell

As the name implies, the C shell from UNIX operating system lets you write scripts in a C-like language. It was created to eliminate the need for the Bourne Shell. It is commonly known as csh.

3. Korn Shell

The solution designed to have the best features of both Bourne and C shell was developed by David Korn, the Korn Shell. It combines all utilities in a single package and enables developers to add new shell commands. It is also known as ksh.

Features of UNIX Operating System

1. Multitasking

UNIX has the ability to launch many jobs or processes on the same terminal, with one running in the background and the other in the foreground.

2. Supports Multi-User Environment

Multiple users can share system resources like CPU, memory, and storage thanks to the UNIX operating system’s support for multiple-users. Every user can function independently and log in from a separate terminal, either locally or remotely. To distribute system resources effectively, UNIX employs time-sharing mechanisms, allocating CPU time to each user’s processes according to a scheduling algorithm. This makes UNIX OS perfect for settings that need multi-user access, such as servers, university labs, and enterprise systems, by guaranteeing that several jobs can run simultaneously without affecting one another.

3. Utilities

There are different kind of tools in UNIX OS. These are: grep, sed, awk command in unix, etc. These values are useful for compiler, network, or remote services.

4. Portability

As much of the UNIX operating system is written in the C language and only a fraction is in the form of machine-dependent code, this guarantees portability of code to other computers. This is why UNIX is extremely portable.

5. File Security and Protection

On a multi-user system like UNIX, the biggest disadvantage is that UNIX is more open to security holes. Hence, security and protection of files is of prime importance in UNIX. UNIX security practices involve issuing user names and passwords, authentication, file access permissions, and file encryption.

6. Command Structure

Commands in UNIX are easy to learn and use. Basic UNIX commands are case-sensitive (i.e. UNIX recognizes capital, small and capitalized letters as different letters) and typically typed in lowercase. Example: cp, mv etc.

7. Communication

The UNIX based operating systems provides the communication through methods like write command, mail command, etc.

8. Accounting

UNIX uses system accounting tools to monitor each user’s activities and resource usage. These tools aid in keeping an eye on system performance, disc space, and CPU utilisation. Administrators have the ability to enforce disc quotas, monitor disc usage by user, and set space limits for each user.For this, commands like quota, df (disk free), and du (disk usage) are frequently used. In order to ensure that users use system resources effectively and fairly, a superuser (like root) can control these resources and enforce regulations.

Advantages of UNIX Operating System

1. Multiple users and multitasking

The UNIX operating system supports more than one user. You also have the privilege of working on several programs simultaneously because they can run concurrently.

2. License-Based Access

UNIX is available under a license and is highly customizable, which makes it one of the preferred operating systems..

3. Portable

As it is implemented in C, the UNIX OS is very portable and easy to use.

4. Less memory usage

The UNIX operating system is highly efficient at managing virtual memory. The memory grows as more programs come into main memory. Here, only minimum resources are required for the tasks that are scheduled.

5. Uniformity

Everything in Unix is treated as a file including devices and terminals.

6. Secure

UNIX is a secure, safe environment for many users. Every user has to log in to get access to the operating system. The documents are kept safe from unauthorized access. Different access rights are assigned to users to prevent misuse of the information. The OS is claimed to be virus-resistant. You do not have to install an antivirus for it.

7. Ideal for web hosting

As an open and stable environment, UNIX OS is ideal for web hosting companies.

8. Modular:

UNIX utilities (programs) are designed to be glue programs i.e. – they break down bigger tasks to smaller ones. These modules are then combined such that they function together seamlessly through out the entire system.

9. Presence of many variants

There are variants such as Ubuntu. RedHat etc.

10. Easy retrieval of files

Hierarchical file systems seemingly make access and retrieval of the files smooth.

Disadvantages of UNIX Operating System

1. Not user-friendly

If you’re new to computers, UNIX is awkward. The majority of UNIX work consists of using commands in the CLI, so it will require beginners to commit many commands to memory.

2. The learning curve is high for cryptic commands

Most UNIX commands have obscure names. Commands are inscrutable to the normal human. Some of the instructions are just with funny characters and hard for a novice to understand. If you ever type that wrong letter in a command, your system could start doing some very strange things and that may include deleting or renaming some files.

3. Poor documentation

There is no good UNIX documentation. So when the user runs into a problem, there is no chance he can get online help from the documentation.

Lack of software drivers.

Certain software drivers are inalienable.

4. Unattractive UI

The UNIX interface is NOT the most friendly of that available.

No Games for UNIX – It has less users so most gaming companies don’t make games for it. There is very little selection of games on UNIX.

UNIX vs LINUX: Key Differences

UNIX was powerful, but closed-source, which was holding back people from working. Thus, a student of the University of Helsinki, Linus Torvalds got frustrated with the limitations of Unix, so he decided to make his own kernel as his final year project approached.

He took C and Assembly and made a new kernel and named it Linux. Linux, which was open-source, meant that anyone could look at, edit, or distribute it freely, something that Unix never permitted. The primary use case of Linux is not only limited to computer hardware and software, game development, mainframes, etc. It can execute multiple client programs. It can also provide high configuration and flexibility.

Unix and Linux are the operating systems used by organizations big and small, with both large and small server use. No doubt they have some things in common, but the difference between unix and linux is hard to ignore.

Linux Vs Unix

Linux and Unix are multi-user operating systems, but have differences in their open-source content, license, architecture, community support, utility for operating systems in a network environment, file system, shell, hardware compatibility, and susceptibility to security threats.

Lets have a look at unix and linux difference:

Essential UNIX Commands 

UNIX supports a large variety of commands, and the following are a few of them.

• Programming instructions: These are instructions to create and run Unix programs. This includes ‘ gcc ‘, ‘ make ‘, and ‘ gdb ‘.
• File-management commands: Commands for file management: These commands help you make, remove, copy, move, and work with files and directories. This covers commands like “ls,” “cd,” “pwd,” “cp,” and “rm.”
• Commands for text manipulation: These commands let you edit, search, and work with text files. For instance, cat, grep, sed, awk, etc.
• System Administration Commands: These commands help you to administer and configure the UNIX system and its resources. Such examples are ‘df’, ’du’, ‘top’, and ‘ps’.
• Networking commands: Commands like these let you access and work with other computers over your network. Examples are ‘ping’, ‘telnet’, and ‘ftp.’
• Shell commands: These are the commands used in the UNIX shell, which is the user interface for the operating system. Examples are ‘echo,’ ‘set,’ and ‘alias.’

UNIX (UNiplexed Information Computing System) Commands Example

Some common commands in the Unix operating system include the following:

1. ‘ls’: Lists files and directories in the current directory.
2. ‘cd’: Change the working directory.
3. mkdir: Creates the new directory.
4. ‘rmdir’: Deletes an empty directory.
5. ‘touch’: File creation or modification date manipulation.
6. ‘cp’: Copies a file.
7. ‘mv’: Move a file or rename a file.
8. ‘rm’: Removes a file.
9. ‘cat’: To see the contents of a file.
10. ‘less’: This command is used to open and view the content of the file one page at a time.
11. ‘grep’: Search a file or files for a string or regular expression.
12. ‘find’: Allows you to search files on several conditions, including name, file size, and modified time.
13. ‘sort’: Sorts the lines of a file.
14. ‘uniq’: It is used to remove duplicate lines from a file.
15. ‘wc’: Counts lines, words, and characters of a file.

These are just a couple of the dozens of Unix commands that you can try on online unix compiler. There are many other utilities and programs that you can use to do a lot of different things.

Here’s a complete UNIX shell script that performs the following tasks:

1. Creates a file
   
2. Finds the file
   
3. Renames the file
   
4. Deletes the file
   
5. Creates and changes to a directory
   

You can run this script in a UNIX terminal (e.g., bash shell).

#!/bin/bash

# Step 1: Create a directory and navigate into it
echo "Creating a directory named 'Intellipaat_dir'"
mkdir intellipaat_dir
cd intellipaat_dir || exit

# Step 2: Create a file
echo "Creating a file named 'Intellipaat.txt'"
touch intellipaat.txt

# Step 3: Find the file
echo "Finding 'intellipaat.txt'"
find . -name "intellipaat.txt"

# Step 4: Rename the file
echo "Renaming 'intellipaat.txt' to 'renamed_intellipaatian.txt'"
mv intellipaat.txt renamed_intellipaatian.txt

# Step 5: Delete the renamed file
echo "Deleting 'renamed_intellipaatian.txt'"
rm renamed_intellipaatian.txt

# Step 6: Go back and remove the directory
cd ..
echo "Removing directory 'test_dir'"
rmdir intellipaat_dir

echo "All operations completed successfully."

Output:

Creating a directory named 'Intellipaat_dir'
Creating a file named 'Intellipaat.txt'
Finding 'intellipaat.txt'
./intellipaat.txt
Renaming 'intellipaat.txt' to 'renamed_intellipaatian.txt'
Deleting 'renamed_intellipaatian.txt'
Removing directory 'test_dir'
All operations completed successfully.

script.sh: line 2: $'r': command not found
script.sh: line 6: cd: intellipaat_dir: No such file or directory
script.sh: line 6: $'exitr': command not found
script.sh: line 7: $'r': command not found
script.sh: line 11: $'r': command not found
script.sh: line 15: $'r': command not found
mv: cannot stat 'intellipaat.txt': No such file or directory
script.sh: line 19: $'r': command not found
rm: cannot remove 'renamed_intellipaatian.txt'$'r': No such file or directory
script.sh: line 23: $'r': command not found
script.sh: line 25: cd: $'..r': No such file or directory
script.sh: line 28: $'r': command not found

Use Cases and Applications

Usage statistics and market shares of operating systems for websites!

This diagram shows the percentages of various operating systems used by almost all websites.

1. How to read the diagram: 

Of the known operating system users, those who use UNIX account for 89.3% of all these large-set websites.

2. Usage and Changing Rankings

This diagram shows the percentages of selected technologies being used by websites; the statistics only speak about the last year.

3. How to read the diagram:

Of those sites ranked in the top 1,000,000 that also use UNIX as their operating system, 80.4% fall under this percentage range.

UNIX and its relatives, like Linux, are the foundation of much of today’s computing. Packed with tools and features and with integration for support across most servers, embedded systems, and development environments, they are a favorite in many circles. Web servers, database servers, and even large scientific computation sites are built on top of UNIX-based systems.

But now consider where UNIX is seen:

1. Servers:

• Web Servers: Web servers tend to run on UNIX. Its resiliency and ability to gracefully handle high-traffic patterns make it an essential tool for hosting websites and applications.
• Database Servers: The beauty of the UNIX platform is its ability to handle hundreds or even thousands of concurrent connections from large data tables found in Oracle, MySQL, and MongoDB.
• File Servers: The UNIX system maintains files and has good and reasonably safe facilities for sharing files.
• Network Servers: These are key utilities for managing network structures like e-mail servers and collaborative systems.

2. Development Environments:

• Command-line Interface: First of all, UNIX-based systems are well-known for their strong command-line interface. Developers love this because you can script the crap out of it.
• Stability and Reliability: UNIX-based systems are stable and do provide a dependable environment for software development, where high computer performance is available at all times of programming.

3. Embedded Systems:

• Routers and Network Devices: UNIX-based systems power a lot of the routers and network gear you rely on, managing everything from data flow to communication channels, keeping your network running smoothly.
• Smart TVs and IoT Devices: UNIX is also used in a number of embedded systems, e.g., smart TVs and IoT devices.
• Scientific Computing: High-Performance Computing (HPC): UNIX is the in thing in HPC, and some of the supercomputers used today run on UNIX-based platforms.
• Big Data Processing: Databases in the tens of terabytes, regular file servers, and even the research on the bleeding edge of artificial intelligence development; work on a big scale like this requires UNIX-based systems like nothing else can deliver.

4. Desktops:

• Linux Distributions: Dozens of friendly Linux distributions for desktop computing (like Ubuntu and Fedora) come from the UNIX tradition and provide the user with a happy GUI environment.
• MacOS: As is Apple’s macOS, another UNIX operating system known for its UI and stability.

5. Other Applications:

• Game Consoles: A few game console systems are based on UNIX.
• CGI Movie Scene Rendering: Large-scale rendering for the CGI scenes in motion pictures frequently uses high-power UNIX systems.
• Banking and Finance: Sensitive applications such as bank account handling, interbank transfers, and online retail sales are well suited for UNIX.
• Medicine: UNIX is operating on medical machinery used in crucial operations, among other things.

Combined, UNIX’s flexibility, reliability, and security provide the foundation of today’s computing. It drives everything from infrastructure to the everyday devices and applications that surround us.

Career Path with UNIX

A UNIX-based career can include positions like Unix/Linux Systems Administrator or different type of engineers (e.g., DevOps), with particular emphasis on cloud computing and cybersecurity. Specialized roles also exist, such as Red Hat Linux Engineer and Unix Application Engineer/Tester.

System Administration

• Unix/Linux System Administrator: People in this position are responsible for those tasks that are part of establishing or maintaining a Unix/Linux system, such as installing the operating system and software, setting up network configurations, and troubleshooting problems that arise in these systems.
• Linux Engineer: Specializing in Linux server hardware and software.
• Red Hat Linux Engineer: Dealing exclusively with Red Hat systems, often calling for Red Hat certification.
• Senior Unix Systems Admin: A further step up from Unix System Administrator, this role includes managing, directing, and automating complex environments.

DevOps and Cloud:

• DevOps Engineer: Bringing together technology development and operation roles, this position applies Unix scripting skills to deliver software more quickly.
• Cloud Architect: Using Unix know-how to design clouds and build resources there.

Development and Testing:

• Unix Developer: Developing applications on Unix systems, often requiring strong programming skills.
• Unix Application Engineer/Tester: Managing and testing applications running on Unix machines.

Other Related Roles:

• Network Engineer: The professional develops, configures, and maintains the company’s network infrastructure (with responsibilities in areas such as switches, routers, firewalls). In many cases underpinning these activities will be Unix-based systems.
• Cybersecurity/Penetration Tester: Drawing on a deep grounding in Unix to probe and assess security vulnerabilities.

Essential Skills:

• Basics of Unix/Linux: Excellent understanding of OS, command line, and system admin.
• Scripting: Knowledge of automation using Bash, Python, or Perl.
• Network: You should have a strong understanding of the concepts of network, protocols, and diagnosis.
• Cloud Computing: Experience with infrastructure that is related to AWS, Azure, or Google Cloud.
• Security: Unix security architecture and tools.
• Troubleshooting: You should be able to troubleshoot and solve problems with your Unix system immediately.

Progression:

Junior System Administrator, Unix/Linux support positions, and Junior DevOps Engineer would be good entry-level positions.

• Intermediate: System Administrator, Network Engineer, Software Engineer, Cloud Engineer
• Senior: Senior SysAdmin, Senior DevOps, Cloud Architect, Team Lead

Career Growth:

There is much need in the world for Unix/Linux administrators, especially those who work in cloud computing and DevOps. Specialized skills and certifications can make a big difference in your earnings and may even be the promotion or career jump you are looking for!

Education:

A minimum of a degree in computer science, information technology, or a relevant field is necessary.

• Certifications: Common options are Red Hat Certified System Administrator (RHCSA) and LPI (Linux Professional Institute) certs.
• Online classes: There are many online courses like UNIX network programming-type courses from Yellow Tail Tech, and Intellipaat does it in their Courses and Certifications.
• Networking: Professionals need to both get involved in related professional communities and meet others who share their same interest, as well as attend conferences that showcase technology being built on these platforms today.

Conclusion

As an OS, UNIX is famous for its stability, its ability to multitask, and its robust security system. Because of its design and its strong command-line interface, developers, system administrators, and any business that needs stability, performance, and high availability employ it.

If you are attracting a scene of servers, coding your own software, or just want to be a world-class security expert, learning UNIX implications is definitely a way to start. Instead, doing UNIX has been passed down to modern systems as if it were genetic.

To the IT tech worker human being, UNIX is a wonderful treasure. Learning UNIX is not a strictly academic exercise; it is also an exercise in understanding more closely what computers do on a low level.

Begin your journey today—your tech career starts here!

UNIX OS: Architecture, Features, and Why It Matters- FAQs