Top 30 Most Common unix interview questions You Should Prepare For

Landing a job that involves Unix systems requires thorough preparation, especially when it comes to unix interview questions. Mastering the most common unix interview questions can dramatically improve your confidence and clarity during the interview process, leading to a better overall performance. This guide covers 30 frequently asked unix interview questions that will help you ace your next Unix interview.

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What are unix interview questions?

Unix interview questions are designed to assess a candidate's knowledge and experience with the Unix operating system, its utilities, and command-line tools. These unix interview questions typically cover a wide range of topics, including file system navigation, process management, shell scripting, system administration, and networking. The purpose of unix interview questions is to determine whether a candidate possesses the practical skills necessary to effectively work in a Unix environment. They are important for job seekers because they provide a structured way to demonstrate their proficiency and understanding of Unix concepts.

Why do interviewers ask unix interview questions?

Interviewers ask unix interview questions to evaluate a candidate's technical proficiency, problem-solving skills, and practical experience in a Unix environment. These unix interview questions help determine if the candidate can effectively manage and troubleshoot Unix-based systems. Interviewers are looking to assess whether you understand fundamental Unix concepts, can use command-line tools efficiently, and can write scripts to automate tasks. They also want to gauge your ability to think critically and solve real-world problems using Unix tools. Ultimately, unix interview questions help interviewers ensure that they hire someone who is capable of contributing to their team and handling the responsibilities of the role.

Here's a quick preview of the 30 questions we'll cover:

1. Name the important standard streams in the UNIX shell scripting.

2. Define a single-user system.

3. List a few significant features of UNIX.

4. Enlist common shells with their indicators.

5. What is Shell?

6. What are the basic responsibilities of a shell?

7. Describe the usage and functionality of the command rm –r *.

8. Differentiate between absolute and relative paths.

9. Which UNIX command lists files/folders in alphabetical order?

10. How do you display manual pages for a command?

11. How do you output text to the screen?

12. Write a command to list all the links from a directory.

13. Create a read-only file in your home directory.

14. Find which operating system your system is running on in UNIX.

15. How to create, mount, and unmount a file system.

16. Explain LVM and its use.

17. How to configure a process to start on boot.

18. How to list all processes running in the system.

19. How to kill a process.

20. Explain how to use find command to search for files.

21. How to use grep command to search for text.

22. How to redirect output to a file.

23. How to use pipes to chain commands.

24. How to use the tar command for archiving files.

25. Explain how to set environment variables.

26. How to use the sed command for text manipulation.

27. How to use awk for data processing.

28. Explain the chown and chmod commands.

29. How to use rsync for file synchronization.

30. How to use cron to schedule jobs.

## 1. Name the important standard streams in the UNIX shell scripting.

Why you might get asked this:

This question assesses your basic understanding of how Unix handles input and output. It's fundamental to scripting and command-line operations. A solid understanding of this concept is critical to answering many other unix interview questions.

How to answer:

Clearly identify the three standard streams: Standard Input (stdin), Standard Output (stdout), and Standard Error (stderr). Explain the purpose of each stream and how they are used in shell scripting.

Example answer:

"The three primary standard streams in Unix are Standard Input, Standard Output, and Standard Error. Standard Input, or stdin, is where a program receives its input, like keyboard input. Standard Output, or stdout, is where a program sends its normal output, usually to the terminal. Standard Error, or stderr, is where a program sends error messages, also typically to the terminal, which allows error messages to be separated from regular output. Understanding these streams is crucial for effective scripting and handling errors."

## 2. Define a single-user system.

Why you might get asked this:

This question checks your understanding of different operating system architectures and their limitations. It also indirectly gauges your knowledge of multi-user systems.

How to answer:

Provide a concise definition of a single-user system and its primary characteristic—designed to support only one user at a time. You can mention typical use cases, such as personal computers.

Example answer:

"A single-user system is an operating system designed to be used by one person at a time. It's typically found on personal computers where the focus is on individual productivity and resource allocation for a single user. This contrasts with multi-user systems that are designed to handle multiple users concurrently. So, when we talk about unix interview questions, this helps set the stage for larger, more complex systems."

## 3. List a few significant features of UNIX.

Why you might get asked this:

This question aims to evaluate your familiarity with the core characteristics that define the Unix operating system. It shows your grasp of its design principles.

How to answer:

Mention features such as hardware independence, multi-user capabilities, Unix shells, hierarchical file system, pipes and filters, utilities, and development tools. Briefly explain each feature.

Example answer:

"Unix has several defining features. It's hardware-independent, meaning it can run on different types of hardware. It supports multiple users simultaneously, allowing for efficient resource sharing. The Unix shell provides a powerful command-line interface. It uses a hierarchical file system for organized data storage. Pipes and filters enable chaining commands for complex data processing. It includes a rich set of utilities and development tools. Understanding these features is fundamental when discussing unix interview questions."

## 4. Enlist common shells with their indicators.

Why you might get asked this:

This question tests your awareness of the different shell environments available in Unix and Linux systems. It indicates your familiarity with command-line interfaces.

How to answer:

List several common shells, such as sh, csh, Bash, tcsh, zsh, and ksh. If possible, briefly mention any key differences or unique features.

Example answer:

"Some of the common shells in Unix include sh, which is the original Bourne shell; csh, the C shell; Bash, the Bourne-Again shell, which is widely used today; tcsh, an enhanced version of csh; zsh, a modern shell with many advanced features; and ksh, the Korn shell. Bash is often the default, but knowing the others can be helpful, especially when dealing with different system configurations. These are important foundations that appear often in unix interview questions."

## 5. What is Shell?

Why you might get asked this:

This question checks your understanding of a fundamental component of the Unix operating system and its role in user interaction.

How to answer:

Define the shell as a command-line interface that provides access to the operating system. Explain that it allows users to execute commands and interact with the system.

Example answer:

"The shell is essentially a command-line interpreter that allows users to interact with the Unix operating system. It provides a way to execute commands, run scripts, and manage files. Think of it as the bridge between the user and the kernel. This knowledge helps to understand many unix interview questions about scripting and automation."

## 6. What are the basic responsibilities of a shell?

Why you might get asked this:

This question builds upon the previous one, delving deeper into the shell's functions and capabilities.

How to answer:

Outline the primary responsibilities: reading commands from the user, executing commands, providing output to the user, and supporting scripting and automation.

Example answer:

"The shell has several key responsibilities. It reads commands entered by the user, parses those commands, and then executes them. It also provides output back to the user, whether it's the result of a command or an error message. Importantly, it supports scripting and automation, allowing users to create complex workflows. So many unix interview questions hinge on this core understanding of the shell and what it does."

## 7. Describe the usage and functionality of the command rm –r *.

Why you might get asked this:

This question tests your understanding of a potentially dangerous command and your awareness of its implications.

How to answer:

Explain that rm -r deletes all files and subdirectories in the current directory. Emphasize the -r option for recursive deletion and the wildcard representing all entries. It is very important to explain the potential data loss.

Example answer:

"The command rm -r is used to recursively delete all files and subdirectories within the current directory. The -r option tells rm to operate recursively, meaning it will descend into subdirectories and delete their contents as well. The is a wildcard that matches all files and directories in the current location. It's a powerful command, but extremely dangerous because it can lead to irreversible data loss if used carelessly. Interviewers often ask about this kind of command in unix interview questions to gauge your carefulness and understanding of risks."

## 8. Differentiate between absolute and relative paths.

Why you might get asked this:

This question assesses your understanding of file system navigation and how to specify file locations.

How to answer:

Clearly define absolute paths as starting from the root directory and relative paths as being relative to the current working directory. Provide examples to illustrate the difference.

Example answer:

"An absolute path specifies the exact location of a file or directory, starting from the root directory, which is denoted by a forward slash. For example, /home/user/documents/file.txt is an absolute path. A relative path, on the other hand, specifies the location relative to the current working directory. For instance, if you are in /home/user, then ./documents/file.txt would be the relative path to the same file. This distinction is crucial for many commands, and understanding it shows you're prepared for common unix interview questions."

## 9. Which UNIX command lists files/folders in alphabetical order?

Why you might get asked this:

This is a basic question to determine your familiarity with common Unix commands.

How to answer:

State that the ls command lists files and directories, and the output is typically in alphabetical order by default.

Example answer:

"The ls command is used to list files and directories in Unix. By default, the output is usually displayed in alphabetical order. You can also use options like ls -l for a more detailed listing, but the alphabetical order remains unless you specify otherwise. It's a very common command, and knowing it well is essential for tackling unix interview questions effectively."

## 10. How do you display manual pages for a command?

Why you might get asked this:

This question tests your knowledge of how to access documentation and learn about commands within the Unix environment.

How to answer:

Explain that you use the man command followed by the command name, such as man ls.

Example answer:

"To display the manual page for a command, I would use the man command followed by the name of the command. For example, to see the manual page for the ls command, I would type man ls and press Enter. This is incredibly useful for understanding the options and usage of different commands. Knowing this can help you answer other unix interview questions that require specific command knowledge."

## 11. How do you output text to the screen?

Why you might get asked this:

This question checks your basic understanding of how to display information to the user in Unix.

How to answer:

Mention the echo command followed by the text you want to display, such as echo Hello, world!.

Example answer:

"To output text to the screen in Unix, I would use the echo command. For example, if I wanted to display the text 'Hello, world!', I would type echo Hello, world! and press Enter. The text would then be printed to the terminal. It's a fundamental command, and understanding how to use it can give you an edge in unix interview questions."

## 12. Write a command to list all the links from a directory.

Why you might get asked this:

This question tests your ability to combine commands and use filtering to achieve a specific result.

How to answer:

Provide the command ls -lrt | grep ^l and explain that it lists all symbolic links.

Example answer:

"To list all the symbolic links in a directory, I would use the command ls -lrt | grep ^l. The ls -lrt part lists all files and directories in reverse chronological order with detailed information, and then grep ^l filters the output to show only the lines that start with 'l', which indicates a symbolic link. This question shows your understanding of how commands can be chained in unix interview questions."

## 13. Create a read-only file in your home directory.

Why you might get asked this:

This question tests your ability to create files and manipulate their permissions, demonstrating your understanding of file security.

How to answer:

Explain that you would first use touch file to create the file and then chmod 400 file to make it read-only.

Example answer:

"To create a read-only file in my home directory, I would first use the touch command to create the file, like this: touch file. Then, I would use the chmod command to change the file's permissions to read-only for the owner, like this: chmod 400 file. This ensures that only the owner can read the file, and no one can write to or execute it. Questions about file permissions are common in unix interview questions, and this demonstrates a practical understanding."

## 14. Find which operating system your system is running on in UNIX.

Why you might get asked this:

This question checks your knowledge of system information commands and how to identify the operating system.

How to answer:

State that you would use the command uname -a to find detailed information about the operating system.

Example answer:

"To find out which operating system my system is running on in Unix, I would use the command uname -a. This command provides detailed information about the operating system, including the kernel name, network node hostname, kernel release, kernel version, machine hardware name, and the processor type. This command and others like it are commonly tested in unix interview questions."

## 15. How to create, mount, and unmount a file system.

Why you might get asked this:

This question assesses your understanding of file system management and how to make storage devices accessible.

How to answer:

Explain the commands: mkfs (e.g., mkfs.ext4 /dev/sda1) for creating, mount (e.g., mount /dev/sda1 /mnt) for mounting, and umount (e.g., umount /mnt) for unmounting.

Example answer:

"To create, mount, and unmount a file system, I would use the following commands. First, to create a file system, I'd use mkfs, for example: mkfs.ext4 /dev/sda1. Next, to mount the file system, I'd use the mount command, such as: mount /dev/sda1 /mnt. Finally, to unmount the file system, I'd use the umount command, like this: umount /mnt. File system management is a key topic, so be prepared for these types of unix interview questions."

## 16. Explain LVM and its use.

Why you might get asked this:

This question tests your knowledge of advanced storage management techniques and their benefits.

How to answer:

Explain that LVM (Logical Volume Manager) is used to manage disk space efficiently by creating logical volumes from physical disks, allowing for dynamic resizing and grouping.

Example answer:

"LVM, or Logical Volume Manager, is a method of managing disk space that provides more flexibility than traditional partitioning. It allows you to create logical volumes from physical disks, which can then be resized, grouped, and managed more easily. This is particularly useful for dynamic environments where storage requirements may change over time. Understanding LVM is a sign of advanced knowledge, and it can set you apart in unix interview questions."

## 17. How to configure a process to start on boot.

Why you might get asked this:

This question checks your understanding of system initialization and how to ensure that critical processes are automatically started.

How to answer:

Mention using cron, adding a script to /etc/rc.local or using systemd services if available.

Example answer:

"To configure a process to start on boot, there are several methods. One approach is to use cron with the @reboot option. Another older method is to add a script to /etc/rc.local. However, in modern systems, the preferred method is to use systemd services. You would create a service file and enable it to start on boot. Demonstrating you are aware of more modern approaches to the subject in unix interview questions is highly recommended."

## 18. How to list all processes running in the system.

Why you might get asked this:

This question tests your familiarity with process management commands and how to monitor system activity.

How to answer:

State that you would use ps -ef to list all running processes.

Example answer:

"To list all the processes running in the system, I would use the command ps -ef. This command provides a comprehensive list of all processes, including their user ID, process ID, parent process ID, CPU usage, start time, and the command being executed. Process management is a common topic in unix interview questions."

## 19. How to kill a process.

Why you might get asked this:

This question checks your ability to manage processes and terminate them when necessary.

How to answer:

Explain that you would use kill to terminate a process by its process ID (PID).

Example answer:

"To kill a process, I would use the kill command followed by the process ID, or PID. For example, if the PID of the process I want to terminate is 1234, I would type kill 1234 and press Enter. This sends a termination signal to the process. If the process doesn't terminate, I might use kill -9 to force termination, but that should be a last resort. Showing you understand the proper way of process termination is important in unix interview questions."

## 20. Explain how to use find command to search for files.

Why you might get asked this:

This question assesses your ability to locate files based on various criteria within the file system.

How to answer:

Explain that you use find with options like -name, -type, -size to search for files based on criteria.

Example answer:

"The find command is a powerful tool for searching for files and directories in Unix. You can use it with various options to specify search criteria. For example, find . -name "myfile.txt" searches for a file named 'myfile.txt' in the current directory and its subdirectories. find . -type d searches for directories, and find . -size +10M searches for files larger than 10MB. Knowing these tricks will give you confidence in answering unix interview questions."

## 21. How to use grep command to search for text.

Why you might get asked this:

This question tests your ability to search for specific patterns within files.

How to answer:

Explain that you use grep followed by the text pattern you want to search for, e.g., grep word file.txt.

Example answer:

"The grep command is used to search for text patterns within files. For example, if I wanted to search for the word 'example' in a file named 'file.txt', I would use the command grep example file.txt. This command will print any lines in 'file.txt' that contain the word 'example'. This is a fundamental command, so expect questions about it in unix interview questions."

## 22. How to redirect output to a file.

Why you might get asked this:

This question checks your understanding of input/output redirection and how to save command output for later use.

How to answer:

Explain that you use > to redirect output to a file (e.g., ls > file.txt) or >> to append.

Example answer:

"To redirect output to a file, I would use the > operator. For example, ls > file.txt will redirect the output of the ls command to 'file.txt', overwriting the file if it already exists. To append the output to an existing file, I would use the >> operator, like this: ls >> file.txt. Understanding this simple concept will give you confidence in answering unix interview questions."

## 23. How to use pipes to chain commands.

Why you might get asked this:

This question assesses your ability to combine commands for more complex data processing.

How to answer:

Explain that you use | to pipe output from one command as input to another, e.g., ls | grep file.

Example answer:

"Pipes are used to chain commands together, allowing the output of one command to be used as the input for another command. The pipe symbol is |. For example, ls | grep file will list all files in the current directory and then filter the output to show only the lines that contain the word 'file'. This is a powerful way to combine simple commands to perform complex tasks. Being able to explain this well is a big win in unix interview questions."

## 24. How to use the tar command for archiving files.

Why you might get asked this:

This question tests your knowledge of archiving and compression techniques.

How to answer:

Explain that you use tar with options like -cvf to create an archive or -xvf to extract.

Example answer:

"The tar command is used for archiving files. To create an archive, I would use the -cvf options, where c stands for create, v stands for verbose (optional), and f specifies the archive file name. For example, tar -cvf archive.tar file1 file2 file3 creates an archive named 'archive.tar' containing 'file1', 'file2', and 'file3'. To extract the files, I would use the -xvf options, where x stands for extract. For example, tar -xvf archive.tar extracts the files from 'archive.tar'. Archiving is a crucial part of system administration, and understanding it will impress interviewers in unix interview questions."

## 25. Explain how to set environment variables.

Why you might get asked this:

This question checks your understanding of environment configuration and how to make variables accessible to processes.

How to answer:

Explain that you use export VARIABLE=value to set environment variables.

Example answer:

"To set an environment variable, I would use the export command followed by the variable name, an equals sign, and the value. For example, export MYVARIABLE=myvalue sets the environment variable MYVARIABLE to 'myvalue'. This variable is then available to any processes run in that shell or any child processes. You can also set variables permanently by adding them to the shell's configuration file, such as .bashrc or .zshrc. Explaining the permanence will help you in your unix interview questions."

## 26. How to use the sed command for text manipulation.

Why you might get asked this:

This question tests your ability to perform text editing and substitution using a powerful command-line tool.

How to answer:

Explain that you use sed with commands like sed 's/old/new/g' file.txt to replace text.

Example answer:

"The sed command is a powerful tool for text manipulation. For example, to replace all occurrences of 'old' with 'new' in a file named 'file.txt', I would use the command sed 's/old/new/g' file.txt. The s command stands for substitute, and the g flag means to replace all occurrences on each line. Sed is very flexible and can be used for more complex operations like inserting lines, deleting lines and more. This is one of the most common tools tested in unix interview questions."

## 27. How to use awk for data processing.

Why you might get asked this:

This question assesses your ability to extract and process data from structured text files.

How to answer:

Explain that you use awk with patterns like awk '{print $1}' file.txt to print data.

Example answer:

"The awk command is used for data processing, particularly for extracting and manipulating data from structured text files. For example, to print the first field of each line in a file named 'file.txt', I would use the command awk '{print $1}' file.txt. Awk can also perform calculations, conditional operations, and more, making it a versatile tool for data analysis. You are highly likely to be askded about awk and sed in unix interview questions."

## 28. Explain the chown and chmod commands.

Why you might get asked this:

This question checks your understanding of file ownership and permissions, which are crucial for system security.

How to answer:

Explain that chown changes ownership of a file or directory, e.g., chown user:group file.txt, and chmod changes permissions of a file or directory, e.g., chmod 755 file.txt.

Example answer:

"chown and chmod are fundamental commands for managing file ownership and permissions. chown is used to change the owner and group of a file or directory. For example, chown user:group file.txt changes the owner to 'user' and the group to 'group' for the file 'file.txt'. chmod is used to change the permissions of a file or directory. For example, chmod 755 file.txt sets the permissions to read, write, and execute for the owner, and read and execute for the group and others. Without a good understanding of these commands, unix interview questions can be tough."

## 29. How to use rsync for file synchronization.

Why you might get asked this:

This question tests your knowledge of file synchronization techniques and tools.

How to answer:

Explain that you use rsync followed by source and destination paths to synchronize files, e.g., rsync -avz source/ destination/.

Example answer:

"The rsync command is used for file synchronization. It efficiently copies files between two locations, minimizing the amount of data transferred by only copying the differences between files. For example, rsync -avz source/ destination/ synchronizes the 'source' directory with the 'destination' directory, preserving permissions, ownership, and timestamps. The -a option stands for archive, -v for verbose, and -z for compress during transfer. If you know this command well, answering unix interview questions will be a breeze."

## 30. How to use cron to schedule jobs.

Why you might get asked this:

This question assesses your ability to automate tasks and schedule them to run at specific times.

How to answer:

Explain that you use crontab -e to edit cron jobs, specifying the timing and command to run, e.g., 0 0 * command for daily execution at midnight.

Example answer:

"The cron utility is used to schedule jobs to run automatically at specific times. To edit the cron table, I would use the command crontab -e. Each line in the cron table represents a job and consists of five time-related fields (minute, hour, day of month, month, day of week) followed by the command to execute. For example, 0 0 * command runs the 'command' at midnight every day. Knowing how to automate things with cron is valuable for anyone, but critical to answering advanced unix interview questions."

Other tips to prepare for a unix interview questions

Preparing for unix interview questions requires more than just memorizing commands. It involves understanding the underlying concepts and gaining practical experience. Here are some tips to help you prepare:

• Practice Regularly: Use Unix-based systems regularly to gain hands-on experience with the commands and utilities discussed above.

• Review Documentation: Familiarize yourself with the official documentation for Unix commands and utilities.

• Solve Problems: Work through practical problems and exercises that require you to use Unix tools to solve real-world scenarios.

• Mock Interviews: Conduct mock interviews with friends or colleagues to simulate the interview experience and get feedback on your performance.

• Study Plans: Create a structured study plan to cover all the essential topics and allocate time for practice.

• Utilize resources such as Verve AI, which provides role-specific mock interviews.

Want to simulate a real interview? Verve AI lets you rehearse with an AI recruiter 24/7. Try it free today at https://vervecopilot.com.

Quotes to Inspire:

• "The only way to do great work is to love what you do." - Steve Jobs

• "The future belongs to those who believe in the beauty of their dreams." - Eleanor Roosevelt

• "Success is not final, failure is not fatal: It is the courage to continue that counts." - Winston Churchill

Frequently Asked Questions

Q: What is the best way to learn Unix commands?
A: The best way is through hands-on practice. Set up a Unix environment (like a virtual machine with Linux), and start using the commands. Refer to the man pages for detailed information and try to solve practical problems using the commands.

Q: How important is shell scripting for a Unix interview?
A: Shell scripting is very important. Interviewers often ask questions about writing simple scripts to automate tasks. Being proficient in shell scripting demonstrates your ability to solve real-world problems using Unix tools.

Q: Should I memorize all the Unix commands?
A: It's not necessary to memorize every single command, but you should be familiar with the most common ones, such as ls, cd, mkdir, rm, cp, mv, grep, sed, awk, find, and tar. Focus on understanding how these commands work and how to use them effectively.

Q: What if I don't know the answer to a question during the interview?
A: It's okay not to know everything. If you don't know the answer, be honest and explain your thought process. If possible, offer a related concept or approach that you do know. It's better to show your problem-solving skills than to try to bluff your way through.

Q: How can Verve AI help me prepare for my Unix interview?
A: Verve AI provides AI interviewers, an extensive company-specific question bank, and real-time support during the interview to help you practice and refine your skills. This can greatly enhance your preparation for unix interview questions.

Q: Is there a free plan available on Verve AI?
A: Yes, Verve AI offers a free plan that allows you to start practicing immediately and get a feel for how the platform can help you prepare for your Unix interview.

Conclusion

Preparing for unix interview questions can seem daunting, but with the right approach and resources, you can significantly increase your chances of success. By understanding the common questions, practicing regularly, and utilizing tools like the Verve AI Interview Copilot , you'll be well-equipped to impress your interviewer and land your dream job. From resume to final round, Verve AI supports you every step of the way. Try the Interview Copilot today—practice smarter, not harder: https://vervecopilot.com.