Top 30 Most Common Linux Operating System Interview Questions You Should Prepare For
Written by
James Miller, Career Coach
Introduction
Preparing for technical interviews can be challenging, especially when the role requires expertise in Linux. The Linux operating system is fundamental to many IT infrastructures, from servers and cloud computing to embedded systems and developer workstations. Hiring managers often assess candidates' understanding of Linux core concepts, commands, and system administration. Mastering common linux operating system interview questions is crucial for demonstrating your proficiency and securing your desired position. This guide compiles 30 essential questions, covering everything from basic definitions to more complex system interactions and security, helping you build confidence and articulate your knowledge effectively. By understanding the underlying principles and practical applications, you can navigate your linux operating system interview with ease.
What Are Linux Operating Systems
Linux refers primarily to the Linux kernel, the core component of a Linux operating system. It's a free and open-source, Unix-like operating system that manages hardware resources and provides essential services for software applications. Unlike proprietary systems, Linux distributions combine the kernel with system libraries, utilities, and software packages (like a graphical interface or command-line tools) to create a complete, usable operating system. Key characteristics include its stability, security, multi-user and multitasking capabilities, vast community support, and the ability to run on a wide range of hardware, making it highly versatile for various computing environments.
Why Do Interviewers Ask Linux Operating System Interview Questions
Interviewers ask linux operating system interview questions to gauge a candidate's foundational knowledge and practical skills. Linux is prevalent in server environments, cloud platforms (AWS, Azure, GCP), DevOps pipelines, and development workflows. Proficiency indicates an ability to navigate, troubleshoot, and manage systems effectively. Questions cover core components like the kernel and shell, essential commands, file systems, permissions, process management, networking basics, and security concepts. Assessing understanding of these areas helps determine if a candidate can perform required tasks, debug issues, and contribute effectively in roles involving Linux administration, development, or system maintenance.
Preview List
What is Linux? Explain its features.
What is the Linux kernel?
Can you edit the Linux kernel?
What is a shell in Linux?
What are the most commonly used shells in Linux?
What is LILO?
What is BASH?
What is swap space?
What is the difference between Unix and Linux?
What are internal commands in Linux?
What are system calls?
How do you rename a file in Linux?
What is a process ID (PID)?
How can a user execute a process at a pre-decided time?
What are hard links and soft links (symlinks)?
What are zombie processes?
Explain the difference between internal and external commands in Linux.
What is the role of system configuration files in Linux?
What is a shell script?
How can you work with Microsoft files on Linux?
How do you connect Linux systems to Microsoft resources?
Explain virtual desktops in Linux.
What are file permissions in Linux?
What is a CLI?
What loader does Linux use?
Discuss the advantages of Linux being open-source.
What are system calls available for process management?
What makes Linux a secure operating system?
Explain the grep command.
What is the standard size for a swap partition in Linux?
1. What is Linux? Explain its features.
Why you might get asked this:
This is a foundational question to assess your basic understanding of what Linux is and its core characteristics.
How to answer:
Define Linux as an OS kernel. Highlight its key features like open-source, Unix-like nature, multi-user/multitasking, stability, and community support.
Example answer:
Linux is an open-source, Unix-like operating system kernel. It manages hardware and resources. Its features include being free and open-source, supporting multiple users and tasks simultaneously, high stability, and strong security features.
2. What is the Linux kernel?
Why you might get asked this:
Tests your knowledge of the core component of any Linux distribution and its function.
How to answer:
Explain that the kernel is the central part of the OS, managing hardware, processes, memory, and acting as the interface between hardware and software.
Example answer:
The Linux kernel is the core of the operating system. It's responsible for managing hardware resources, handling system calls, managing processes, memory, and devices. It's the bridge between the hardware and the applications run by users.
3. Can you edit the Linux kernel?
Why you might get asked this:
Checks your awareness of Linux's open-source nature and its implications for customization.
How to answer:
Yes, explain that due to its open-source nature, the kernel source code is available and can be modified and recompiled.
Example answer:
Yes, you absolutely can. Since Linux is open-source, its kernel's source code is freely available. Users or developers can modify, compile, and customize the kernel for specific needs or hardware.
4. What is a shell in Linux?
Why you might get asked this:
Assesses your understanding of the primary way users interact with the command line in Linux.
How to answer:
Define the shell as a command-line interpreter that provides an interface for users to execute commands and scripts.
Example answer:
A shell in Linux is a command-line interpreter. It acts as an interface between the user and the operating system, allowing users to type commands which the shell then interprets and executes. It also handles shell scripting.
5. What are the most commonly used shells in Linux?
Why you might get asked this:
Shows your familiarity with different shell environments available in Linux systems.
How to answer:
List common shells like Bash, Tcsh, Zsh, and Ksh, noting that Bash is the prevalent default.
Example answer:
Several shells are commonly used, including Bash (Bourne Again Shell), which is the default on many distributions, Tcsh, Zsh, and Korn Shell (ksh). Bash is arguably the most widely encountered.
6. What is LILO?
Why you might get asked this:
Tests historical knowledge of Linux boot processes, although GRUB is now more common.
How to answer:
Explain LILO as an older boot loader for Linux systems, responsible for loading the kernel into memory.
Example answer:
LILO stands for Linux Loader. It's a legacy boot loader historically used for Linux. Its main function is to load the Linux kernel into the computer's memory during the startup process so the operating system can begin running.
7. What is BASH?
Why you might get asked this:
Focuses on the most common shell, requiring you to describe its role and features.
How to answer:
Describe Bash as a popular shell and command language, default in many distros, supporting scripting and command execution.
Example answer:
BASH is the Bourne Again Shell. It's a widely used command processor that runs in a text window. It's often the default shell for many Linux distributions and supports scripting, command history, and job control.
8. What is swap space?
Why you might get asked this:
Evaluates your understanding of memory management and handling situations when physical RAM is insufficient.
How to answer:
Define swap space as a disk area used for virtual memory, extending RAM by moving inactive pages to disk.
Example answer:
Swap space is a dedicated area on a hard drive used as virtual memory. When the system runs out of physical RAM, it moves less-used pages from RAM to swap space on the disk, freeing up RAM for active processes.
9. What is the difference between Unix and Linux?
Why you might get asked this:
This is a classic question to check your understanding of the relationship and distinctions between these two OS families.
How to answer:
Explain Unix as the older, proprietary system that inspired Linux. State Linux is a free, open-source, Unix-like kernel developed collaboratively.
Example answer:
Unix is an original operating system developed in the 1970s, often proprietary. Linux is a younger, free, and open-source operating system kernel inspired by Unix. Linux runs on more hardware types and is developed by a global community.
10. What are internal commands in Linux?
Why you might get asked this:
Tests knowledge of how the shell processes commands differently based on their origin.
How to answer:
Explain that internal commands are built directly into the shell executable, executed instantly without searching the file system.
Example answer:
Internal commands are part of the shell itself. When you type an internal command like cd or echo, the shell executes it directly without looking for a separate program file on the disk.
11. What are system calls?
Why you might get asked this:
Assesses understanding of the fundamental interaction layer between user processes and the kernel.
How to answer:
Define system calls as the programmatic way a computer program requests a service from the kernel of the operating system.
Example answer:
System calls are requests made by user-level programs to the operating system's kernel. They provide a standard interface for applications to access kernel services like file I/O, process creation, or inter-process communication.
12. How do you rename a file in Linux?
Why you might get asked this:
A basic command knowledge test, essential for file manipulation.
How to answer:
State the mv command is used for both moving and renaming files. Provide the syntax.
Example answer:
To rename a file in Linux, you use the mv command. The syntax is mv [oldfilename] [newfilename]. For example, mv report.txt final_report.txt.
13. What is a process ID (PID)?
Why you might get asked this:
Fundamental concept in process management and identification.
How to answer:
Explain that a PID is a unique numerical identifier assigned by the kernel to each running process.
Example answer:
A Process ID, or PID, is a unique integer number assigned by the Linux kernel to every running process. It's used by the system and users to identify and manage specific processes.
14. How can a user execute a process at a pre-decided time?
Why you might get asked this:
Tests knowledge of job scheduling utilities for automation.
How to answer:
Mention using cron for recurring tasks and at for one-time future execution.
Example answer:
A user can schedule processes to run at a specific time using job scheduling utilities. The cron utility is used for recurring tasks, while the at command is used for executing a command just once at a specified future time.
15. What are hard links and soft links (symlinks)?
Why you might get asked this:
Common question distinguishing different ways files can be referenced in the file system.
How to answer:
Explain hard links as pointing to the same inode (the actual file data), and soft links (symlinks) as pointing to a file path name.
Example answer:
A hard link is essentially another name for an existing file, pointing directly to the same inode. A soft link, or symbolic link, is a special file that contains a path to another file or directory; it's like a shortcut.
16. What are zombie processes?
Why you might get asked this:
Evaluates understanding of process states and parent-child process interaction issues.
How to answer:
Define a zombie process as a child process that has finished execution but its entry remains in the process table because the parent hasn't read its exit status.
Example answer:
A zombie process is a process that has completed its execution but still has an entry in the process table. This occurs when the parent process hasn't yet called wait() or waitpid() to collect the child's exit status, leaving the entry 'defunct'.
17. Explain the difference between internal and external commands in Linux.
Why you might get asked this:
Reinforces the concept introduced earlier, asking for a clearer distinction.
How to answer:
Reiterate that internal commands are built into the shell binary, while external commands are standalone executable programs found in directories like /bin or /usr/bin.
Example answer:
Internal commands are compiled directly into the shell program itself and run instantly. External commands are separate executable files located in system directories. When you run an external command, the shell searches for the file and then executes it.
18. What is the role of system configuration files in Linux?
Why you might get asked this:
Tests knowledge of how system and application settings are stored and managed.
How to answer:
Explain they store settings for the OS and applications, typically located in /etc, controlling system behavior, services, and user environments.
Example answer:
System configuration files store settings for the operating system and installed applications. They are mostly located in the /etc directory and control how services run, define network settings, user configurations, and many other system behaviors.
19. What is a shell script?
Why you might get asked this:
Assesses understanding of basic automation capabilities using the shell.
How to answer:
Define it as a text file containing a sequence of shell commands, executed by the shell to automate tasks.
Example answer:
A shell script is a plain text file containing a series of commands that the shell executes sequentially. They are used for automating repetitive tasks, managing files, running programs, and performing system administration chores.
20. How can you work with Microsoft files on Linux?
Why you might get asked this:
Relevant for environments requiring interoperability between Linux and Windows.
How to answer:
Mention support for file systems like NTFS (via drivers like ntfs-3g) and compatibility layers or applications (like LibreOffice) for document formats.
Example answer:
Linux systems can work with Microsoft files. For file systems like NTFS used on Windows drives, Linux uses drivers such as ntfs-3g to mount and access them. For document formats (like .docx, .xlsx), applications like LibreOffice provide compatibility.
21. How do you connect Linux systems to Microsoft resources?
Why you might get asked this:
Evaluates knowledge of interoperability tools, particularly for file/print sharing.
How to answer:
Mention Samba as the primary tool for integrating Linux into Windows networks for file and print sharing (SMB/CIFS protocol).
Example answer:
Connecting Linux systems to Microsoft resources, such as file and print shares, is typically done using Samba. Samba is a suite of programs that allows Linux to act as a file and print server or client using the SMB/CIFS protocol that Windows uses.
22. Explain virtual desktops in Linux.
Why you might get asked this:
Relevant if the role involves using a graphical Linux environment or helping users with desktop features.
How to answer:
Describe virtual desktops as multiple independent workspaces available on a single physical display, helping organize open applications.
Example answer:
Virtual desktops, also known as workspaces, allow users to have multiple independent desktop environments on one physical screen. This helps organize open applications by spreading them across different workspaces, reducing clutter and improving multitasking.
23. What are file permissions in Linux?
Why you might get asked this:
Essential security and access control concept in Unix-like systems.
How to answer:
Explain they control who (owner, group, others) can do what (read, write, execute) with a file or directory. Mention the chmod command.
Example answer:
File permissions in Linux determine the access rights for files and directories. They specify who (the owner, the group, or others) has permission to read (r), write (w), or execute (x) a file or directory. These are set using commands like chmod.
24. What is a CLI?
Why you might get asked this:
Basic terminology for interacting with the system without a graphical interface.
How to answer:
Define CLI as the Command-Line Interface, a text-based way to interact with the OS using commands.
Example answer:
CLI stands for Command-Line Interface. It's a text-based way to interact with the operating system. Users type commands into a terminal, and the shell interprets and executes them, as opposed to using a graphical interface (GUI).
25. What loader does Linux use?
Why you might get asked this:
Tests knowledge of the boot process step immediately preceding the kernel.
How to answer:
Identify GRUB (GRand Unified Bootloader) as the most common boot loader used by modern Linux distributions.
Example answer:
Modern Linux distributions primarily use GRUB, the GRand Unified Bootloader. GRUB is responsible for loading the operating system kernel into memory after the BIOS or UEFI completes its initial hardware checks during boot.
26. Discuss the advantages of Linux being open-source.
Why you might get asked this:
Evaluates understanding of the benefits of open-source software development and distribution.
How to answer:
Highlight benefits like cost (free), transparency (code visible), security (community review), flexibility (customization), and community support/rapid development.
Example answer:
Being open-source means the source code is freely available. Advantages include no licensing costs, greater security due to community review, rapid development and bug fixes, flexibility for customization, and strong community support.
27. What are system calls available for process management?
Why you might get asked this:
Checks understanding of how processes are created, controlled, and terminated programmatically.
How to answer:
List key system calls like fork() (create child), exec() (replace process image), wait()/waitpid() (wait for child), and exit() (terminate process).
Example answer:
Several system calls manage processes. Key ones include fork() to create a new child process, exec() to replace the current process image with a new program, wait() or waitpid() to wait for a child process to terminate, and exit() to terminate the current process.
28. What makes Linux a secure operating system?
Why you might get asked this:
Tests knowledge of Linux security features and philosophy.
How to answer:
Mention features like multi-user architecture with file permissions, strong user/group management, built-in firewall (iptables/nftables), SELinux/AppArmor, regular updates, and the open-source scrutiny.
Example answer:
Linux is considered secure due to its robust multi-user design, fine-grained file permission system, effective user and group management, strong firewall capabilities, mandatory access control systems like SELinux, frequent security updates, and the transparency provided by open source.
29. Explain the grep command.
Why you might get asked this:
A fundamental and widely used command for text processing.
How to answer:
Describe grep as a command-line utility used for searching plain-text data sets for lines that match a regular expression.
Example answer:
grep is a command-line utility used to search for patterns in text. It scans input files or data streams line by line and prints any lines that contain a match for the specified pattern, often using regular expressions.
30. What is the standard size for a swap partition in Linux?
Why you might get asked this:
Evaluates practical knowledge of system setup and memory configuration.
How to answer:
Explain it's variable. Historically twice RAM for small RAM, but for larger RAM systems, equal to RAM or a fixed small size (e.g., 2GB) is common.
Example answer:
The standard size for a swap partition has changed over time. Historically, it was recommended to be twice the amount of physical RAM. For systems with larger amounts of RAM today, a size equal to RAM or simply a smaller fixed size like 2GB is often sufficient.
Other Tips to Prepare for a Linux Operating System Interview
Beyond memorizing answers to specific linux operating system interview questions, focus on demonstrating your problem-solving skills and practical experience. Practice using the commands discussed and explore related concepts like process signals, networking tools (ping, traceroute, netstat), and package management (apt, yum, dnf). As the famous saying goes, "Theory is when you know everything but nothing works. Practice is when everything works but nobody knows why." Aim for a balance! Be ready to discuss real-world scenarios where you've used Linux. Consider using an AI tool like the Verve AI Interview Copilot (https://vervecopilot.com) to practice your responses and get feedback. The Verve AI Interview Copilot can help you refine your explanations and improve your delivery for common linux operating system interview questions. Using the Verve AI Interview Copilot provides valuable practice in a simulated environment.
Frequently Asked Questions
Q1: What's the difference between a process and a thread? A1: A process is an instance of a program running, with its own memory space; a thread is a path of execution within a process, sharing memory.
Q2: How do you check disk space in Linux? A2: You typically use the df command (disk free) to see mounted filesystems and their usage.
Q3: What is an inode? A3: An inode is a data structure in the Linux file system that stores information about a file, except its name and actual data.
Q4: How do you list files in a directory? A4: Use the ls command. ls -l provides a long listing with permissions, owner, size, etc.
Q5: What is the root directory? A5: The root directory (/) is the top-level directory in the Linux file system hierarchy, from which all other directories branch.
Q6: What is the difference between sudo and su? A6: su switches to another user (often root, requiring root password), while sudo executes a single command as another user (default root) using the user's own password for authentication.
