Top 30 Most Common Linux And Unix Interview Questions You Should Prepare For
Written by
James Miller, Career Coach
Introduction
Preparing for technical interviews can be daunting, especially when roles require proficiency in operating systems like Linux and Unix. These powerful, widely used systems are fundamental to many IT infrastructures, making skills in their administration and usage highly sought after. Interviewers frequently assess candidates' understanding of core concepts, command-line tools, system architecture, and file management. Mastering the common linux and unix interview questions is key to demonstrating your capability and landing your desired position. This guide provides a comprehensive look at 30 essential linux and unix interview questions, offering insights into why they are asked, how to approach them, and example answers to help you confidently navigate your next interview focusing on linux and unix interview questions.
What Are Linux and Unix?
Linux and Unix are both robust, multi-user, multi-tasking operating systems. Unix is the older, foundational system, developed in the 1970s, and is primarily proprietary, with various commercial versions like Solaris, AIX, and HP-UX. Linux, inspired by Unix, is a free and open-source kernel developed by Linus Torvalds. It's available under the GNU General Public License, leading to numerous distributions (like Ubuntu, CentOS, Fedora). While they share many concepts, commands, and the philosophy of using simple tools chained together, Linux is characterized by its widespread adoption on diverse hardware and its community-driven development model. Understanding the basics of both is crucial when tackling linux and unix interview questions.
Why Do Interviewers Ask Linux and Unix Questions?
Interviewers ask linux and unix interview questions to gauge a candidate's foundational knowledge in system administration, command-line operations, scripting capabilities, and troubleshooting skills. Proficiency in these operating systems indicates a candidate can navigate server environments, manage files and processes, understand system architecture, and potentially automate tasks. Since many development, DevOps, and IT support roles involve working with Linux or Unix servers, demonstrating solid knowledge of these systems is essential. The questions test practical skills and theoretical understanding, preparing you for real-world challenges encountered in roles requiring linux and unix interview questions expertise.
Preview List
What is the difference between Linux and Unix?
What are the significant features of Unix?
What is a shell in Unix/Linux?
List common Unix shells and their prompts/indicators.
What is the general format of a Unix command?
Explain what a directory is.
Difference between absolute and relative paths.
What is the use of the
rm -rcommand?How do you list files/folders in alphabetical order in Unix?
What is a kernel in Unix?
What are the different file types in Unix?
What is a single-user system?
What is the meaning and utility of Unix wildcards?
What is the function of the
grepcommand?How do you check your current working directory?
What commands are used to change permissions on files?
How do you list processes in Unix/Linux?
How do you kill a process?
What is a pipe in Unix/Linux?
Explain the concept of a symbolic link (symlink).
How do you check disk usage?
What is the difference between
fork()andexec()in Unix?How do you schedule tasks in Unix/Linux?
What are environment variables?
What is the difference between hard and soft links?
How do you find files in Unix/Linux?
Explain file permissions in Unix/Linux.
What is the use of the
topcommand?How do you redirect output in Unix/Linux?
What are pipes and filters?
1. What is the difference between Linux and Unix?
Why you might get asked this:
Tests fundamental understanding of the core distinction between the two operating systems, which is basic for linux and unix interview questions.
How to answer:
Highlight that Unix is proprietary and the ancestor, while Linux is free, open-source, and based on the Unix philosophy.
Example answer:
Unix is a family of proprietary OS, while Linux is an open-source kernel inspired by Unix. Linux is free, widely ported, and community-developed; Unix variants are typically commercial.
2. What are the significant features of Unix?
Why you might get asked this:
Assesses knowledge of the core design principles and strengths shared by Unix-like systems relevant to linux and unix interview questions.
How to answer:
Mention key features like multi-user, multitasking, hierarchical file system, command-line interface, pipes, and tools.
Example answer:
Key features include multi-user, multi-tasking capabilities, a hierarchical file system, powerful command shells, support for pipes and filters, and a rich set of standard utilities.
3. What is a shell in Unix/Linux?
Why you might get asked this:
Checks understanding of the primary interface users interact with in command-line environments, essential for linux and unix interview questions.
How to answer:
Define it as a command-line interpreter that interacts with the kernel and executes user commands.
Example answer:
A shell is a command-line interpreter acting as an interface between the user and the operating system's kernel, allowing command execution and scripting.
4. List common Unix shells and their prompts/indicators.
Why you might get asked this:
Evaluates familiarity with different shell environments you might encounter when answering linux and unix interview questions.
How to answer:
List popular shells like Bash, sh, csh, ksh, zsh, and briefly mention their typical prompts (e.g., $, #, %).
Example answer:
Common shells include Bash (Bourne Again Shell, often $), sh (Bourne Shell, $), csh (C Shell, %), ksh (Korn Shell, $), and zsh (Z Shell, % or $).
5. What is the general format of a Unix command?
Why you might get asked this:
Confirms basic syntax understanding, crucial for using the command line effectively and answering linux and unix interview questions.
How to answer:
Explain the standard structure: command, followed by options, then arguments.
Example answer:
The general format is command [options] [arguments]. Options modify command behavior, and arguments are the items the command acts upon.
6. Explain what a directory is.
Why you might get asked this:
Tests understanding of the hierarchical file system structure, fundamental to linux and unix interview questions.
How to answer:
Describe it as a special file that organizes other files and directories within the file system tree.
Example answer:
A directory is a special type of file used to group and organize other files and subdirectories, forming the file system's hierarchical structure.
7. Difference between absolute and relative paths.
Why you might get asked this:
Essential for navigating the file system accurately, a common task in linux and unix interview questions.
How to answer:
Explain that absolute paths start from the root (/), while relative paths are relative to the current working directory.
Example answer:
An absolute path starts from the root directory (/). A relative path specifies location relative to the current working directory.
8. What is the use of the rm -r command?
Why you might get asked this:
Assesses knowledge of a powerful command for deleting directories and their contents, relevant for administration linux and unix interview questions.
How to answer:
Explain that the -r option stands for "recursive" and is used to remove directories and everything inside them.
Example answer:
The rm -r command is used to recursively remove a directory and all its contents (files and subdirectories).
9. How do you list files/folders in alphabetical order in Unix?
Why you might get asked this:
Checks basic command-line utility usage, a common element in linux and unix interview questions.
How to answer:
State that the ls command lists files and directories alphabetically by default.
Example answer:
The ls command lists files and directories in alphabetical order by default. Use ls -l for a detailed list.
10. What is a kernel in Unix?
Why you might get asked this:
Tests understanding of the core component of the operating system, fundamental to linux and unix interview questions.
How to answer:
Define it as the central part managing system resources and acting as the bridge between hardware and software.
Example answer:
The kernel is the core of the operating system. It manages hardware resources, process scheduling, memory, and facilitates interaction between hardware and software.
11. What are the different file types in Unix?
Why you might get asked this:
Evaluates knowledge of the various ways Unix/Linux handles data and devices, important for understanding system architecture when facing linux and unix interview questions.
How to answer:
List common types: regular files, directories, symbolic links, device files (character/block), sockets, named pipes.
Example answer:
File types include regular files, directories, symbolic links, hard links, character device files, block device files, sockets, and named pipes.
12. What is a single-user system?
Why you might get asked this:
Checks understanding of multi-user capabilities, a key feature contrasting Unix/Linux from simpler systems, relevant for linux and unix interview questions.
How to answer:
Define it as a system designed for only one user at a time, contrasting with multi-user Unix/Linux.
Example answer:
A single-user system supports only one user session or user account simultaneously, unlike multi-user OS like Unix/Linux.
13. What is the meaning and utility of Unix wildcards?
Why you might get asked this:
Assesses efficiency in command-line usage for file selection and pattern matching, practical knowledge for linux and unix interview questions.
How to answer:
Explain they are special characters (*, ?, []) used for pattern matching filenames or strings in commands.
Example answer:
Wildcards (*, ?, []) are used to match patterns in filenames or strings. They help select multiple files easily for commands.
14. What is the function of the grep command?
Why you might get asked this:
A ubiquitous tool; understanding its function is crucial for text processing and log analysis in linux and unix interview questions.
How to answer:
Explain it searches for patterns (using regular expressions) within files and prints lines containing matches.
Example answer:
grep searches for lines matching a specified pattern (regular expression) within input files or streams and prints the matching lines.
15. How do you check your current working directory?
Why you might get asked this:
Tests knowledge of a fundamental command for navigating the file system, common in entry-level linux and unix interview questions.
How to answer:
State the command pwd.
Example answer:
You check your current working directory using the pwd command, which stands for "print working directory".
16. What commands are used to change permissions on files?
Why you might get asked this:
Tests essential knowledge of file security and access control in Unix/Linux, vital for administration linux and unix interview questions.
How to answer:
Identify the chmod command and mention it uses numeric or symbolic modes.
Example answer:
The chmod command is used to change file permissions. You can use either numeric mode (e.g., 755) or symbolic mode (e.g., u+rwx).
17. How do you list processes in Unix/Linux?
Why you might get asked this:
Assesses understanding of process management basics, important for troubleshooting and system monitoring linux and unix interview questions.
How to answer:
Mention the ps command and common options like aux or ef for detailed listings.
Example answer:
You list processes using the ps command. Common variations are ps aux or ps -ef to show all processes with detailed information.
18. How do you kill a process?
Why you might get asked this:
Tests ability to terminate unresponsive or unwanted processes, a necessary administration skill covered in linux and unix interview questions.
How to answer:
State the kill command and explain it uses the process ID (PID), mentioning kill -9 for force termination.
Example answer:
You kill a process using the kill command followed by its Process ID (PID). kill -9 PID sends a SIGKILL signal for forceful termination.
19. What is a pipe in Unix/Linux?
Why you might get asked this:
Evaluates understanding of command chaining for efficient data processing, a core Unix philosophy feature common in linux and unix interview questions.
How to answer:
Explain it connects the standard output of one command to the standard input of another using the | symbol.
Example answer:
A pipe (|) redirects the standard output of one command to become the standard input of another command, allowing command chaining.
20. Explain the concept of a symbolic link (symlink).
Why you might get asked this:
Tests knowledge of file linking, which is important for file system flexibility and organization, relevant for linux and unix interview questions.
How to answer:
Describe it as a pointer or shortcut to another file or directory by name/path.
Example answer:
A symbolic link (symlink) is a special file that contains a reference to another file or directory, acting like a shortcut or pointer.
21. How do you check disk usage?
Why you might get asked this:
Assesses knowledge of system monitoring tools, crucial for managing system resources when handling linux and unix interview questions.
How to answer:
Mention the du command for directory usage and df for filesystem usage.
Example answer:
You check disk usage using du to estimate file/directory space usage and df to display filesystem disk space usage.
22. What is the difference between fork() and exec() in Unix?
Why you might get asked this:
Tests understanding of how processes are created and managed programmatically, a deeper topic in linux and unix interview questions.
How to answer:
Explain that fork() creates a child process (a copy), while exec() replaces the current process's code with a new program.
Example answer:
fork() creates a new process by duplicating the calling process. exec() replaces the current process image with a new process.
23. How do you schedule tasks in Unix/Linux?
Why you might get asked this:
Evaluates knowledge of automation tools, a common requirement for administration and scripting linux and unix interview questions.
How to answer:
Identify cron and crontab as the primary tools for scheduling recurring tasks.
Example answer:
Tasks are scheduled using cron jobs, typically configured via crontab files which specify commands and execution times.
24. What are environment variables?
Why you might get asked this:
Tests understanding of how shell and program settings are stored and accessed, relevant for scripting and configuration linux and unix interview questions.
How to answer:
Describe them as dynamic variables holding values that affect how processes and the shell run.
Example answer:
Environment variables are dynamic named values that store system-wide or user-specific configuration settings accessible by processes and the shell.
25. What is the difference between hard and soft links?
Why you might get asked this:
A common question distinguishing file system concepts, relevant for file management linux and unix interview questions.
How to answer:
Explain hard links point to the same inode (data), while soft links (symlinks) point to the file name/path.
Example answer:
A hard link points directly to the inode of a file. A soft link (symbolic link) points to the filename of another file or directory.
26. How do you find files in Unix/Linux?
Why you might get asked this:
Tests practical command-line utility knowledge for searching the file system, a frequent task addressed by linux and unix interview questions.
How to answer:
State the find command and mention its capability to search based on various criteria.
Example answer:
You find files using the find command, which can search directories recursively based on criteria like name, type, size, or permissions.
27. Explain file permissions in Unix/Linux.
Why you might get asked this:
Crucial for security and access control; demonstrates fundamental administrative knowledge when discussing linux and unix interview questions.
How to answer:
Explain the rwx (read, write, execute) permissions for user, group, and others.
Example answer:
File permissions define access rights for the owner, group, and others: read (r), write (w), and execute (x). They can be represented numerically or symbolically.
28. What is the use of the top command?
Why you might get asked this:
Tests familiarity with system monitoring tools, vital for performance analysis and troubleshooting, often part of linux and unix interview questions.
How to answer:
Describe it as a tool for monitoring processes and system resources (CPU, memory) in real-time.
Example answer:
The top command displays a dynamic, real-time view of system processes and resource usage, showing CPU, memory, swap usage, and running tasks.
29. How do you redirect output in Unix/Linux?
Why you might get asked this:
Assesses command-line fluency and ability to manage input/output streams, useful for scripting and utility usage when tackling linux and unix interview questions.
How to answer:
Explain the use of >, >>, and < operators for redirecting standard output and input.
Example answer:
Output is redirected using > (write/overwrite file), >> (append to file), and < (redirect input from a file).
30. What are pipes and filters?
Why you might get asked this:
Reinforces understanding of the Unix philosophy of combining simple tools, a key concept covered in linux and unix interview questions.
How to answer:
Define pipes as connectors between commands and filters as commands that process input to produce output.
Example answer:
Pipes (|) connect the output of one command to the input of another. Filters are commands that read standard input, perform operations, and write to standard output.
Other Tips to Prepare for a Linux and Unix Interview
Beyond mastering these common linux and unix interview questions, consider these tips. Practice using the command line extensively on a Linux virtual machine or server. Familiarize yourself with different distributions if possible. Understand key configuration files and basic networking concepts. "Practice does not make perfect. Only perfect practice makes perfect," said Vince Lombardi. Use mock interviews to simulate the pressure and structure of answering linux and unix interview questions. The Verve AI Interview Copilot (https://vervecopilot.com) can provide realistic interview simulations, allowing you to practice answering typical linux and unix interview questions and get feedback on your responses. As Colin Powell noted, "There are no secrets to success. It is the result of preparation, hard work, and learning from failure." Leverage tools like Verve AI Interview Copilot to refine your answers to linux and unix interview questions and build confidence. Consistent preparation, perhaps guided by Verve AI Interview Copilot, is your best strategy.
Frequently Asked Questions
Q1: What is the difference between grep and egrep? A1: egrep is equivalent to grep -E and supports extended regular expressions.
Q2: How do you view manual pages for a command? A2: Use the man command followed by the command name (e.g., man ls).
Q3: What is the purpose of the /etc directory? A3: It contains system-wide configuration files.
Q4: How do you switch users in Unix/Linux? A4: Use the su command (switch user) or sudo (execute command as another user).
Q5: What is an inode? A5: An inode is a data structure storing metadata about a file in the filesystem.
Q6: How do you create an empty file? A6: Use the touch command (e.g., touch myfile.txt).
