Top 30 Linux Interview Questions and Answers

• 15 September, 2025
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Introduction to Linux Interview Questions

If you want to crack the interview for a job profile related to Linux skills, you are at the right place. Here, we will take a look at the Top 30 Linux interview questions and answers that are specifically prepared for students who are preparing for future interviews.

These questions will give them a clear vision of the actual questions that could arise during a real interview. What are we waiting for? Let’s get straight to the topic!

What is Linux?

The Linux kernel, a key component that controls hardware and software resources, is the foundation of the Linux family of open-source operating systems. Its source code is publicly accessible for anybody to read, use, and alter, as contrasted to proprietary systems like Windows or macOS.

Because of this collaborative methodology, there are now many different Linux distributions (also known as “distros”) that are utilized in anything from servers and cellphones to supercomputers. Let’s talk about the “Top 30 Linux interview questions and answers!”

Top 30 Linux interview questions and answers

1. What is Linux, and how is it different from other operating systems?

Because its source code is publicly available, Linux is an open-source operating system that differs significantly from proprietary ones like Windows and macOS. This allows for extensive customization, community-driven development, and a range of distributions designed for distinct uses.

2. What are the key features of Linux?

The following are the key features of Linux:

1. Open Source,
2. Multi-User & Multitasking,
3. Security & Stability,
4. Flexibility & Customization, and
5. Command-Line Interface (CLI).

3. What is the Linux kernel, and what role does it play?

As the main interface between the computer’s hardware and software (applications and processes), the Linux kernel is the fundamental part of the Linux operating system.

It provides a framework for the execution of applications, controls hardware, and maintains critical system resources.

4. Explain the Linux file system hierarchy.

The Filesystem Hierarchy Standard (FHS) governs the Linux file system hierarchy, which is a tree-like layout with all directories and files branching out from a single top-level directory known as the root directory (/).

By guaranteeing a constant and predictable location for particular file types, this standard facilitates user and program discovery across various Linux distributions.

5. What is a shell in Linux, and what are the different types of shells?

A shell is a command-line interpreter that serves as a conduit between the Linux operating system and the user, converting user-typed commands into kernel instructions.

The two primary families of shells, the Bourne shell family, which includes sh, bash, ksh, and zsh, and the C shell family, which includes csh and tcsh are distinguished by their differences in scripting syntax and characteristics.

6. What are the various file permissions in Linux, and how do they work?

File permissions are assigned to three types of users in Linux: the file’s owner, the group to which the file belongs, and all other users. They regulate who can read, write, or execute a file.

7. How can you check the available disk space in Linux?

In Linux, you can use the df command (which stands for “disk free”) at the terminal to see how much disk space is available.

8. What is the difference between a hard link and a soft link in Linux?

A soft link, also known as a symbolic link, is a pointer to the file’s pathname that functions as a shortcut, whereas a hard link is a direct reference to a file’s inode, sharing the same information and location as the original file.

9. What is the use of the chmod command in Linux?

Linux users can modify a file or directory’s permissions, limiting who can read, write, or execute it, by using the chmod (change mode) command.

10. How would you create and delete files and directories in Linux?

In Linux, the rm command and the rmdir or rm -r command are used to delete files and directories, respectively, while the touch or cat commands and the mkdir command are used to create files and directories, respectively.

11. Explain the concept of a process in Linux. How can you list all running processes?

In Linux, a process is an instance of an active program, a work unit that is controlled by the operating system, which allots memory and CPU time to it. The ps command can be used to list all processes that are currently executing, and the top command can be used for a more dynamic and thorough view.

12. What is the ps command in Linux, and how is it used?

A Linux command-line tool called the ps command (Process Status) is used to display details about the processes that are executing on a system at the moment. It usually displays a quick overview of the processes connected to the current user’s terminal without any settings.

13. How do you find out which processes are using the most CPU in Linux?

The top command, which offers a dynamic, real-time view of system processes arranged by CPU usage by default, can be used to determine which programs in Linux are consuming the most CPU.

14. What is the purpose of the grep command in Linux?

A powerful Linux command-line tool for finding a certain pattern (or text) in one or more files and printing the lines that fit the pattern is the grep command.

15. What is a symbolic link in Linux, and how does it differ from a hard link?

A hard link is a direct reference to the original file’s physical data on the disk, while a symbolic link (also known as a soft link) is a file that stores the pathname of another file or directory, serving as a shortcut to it.

16. What is the difference between the kill and killall commands in Linux?

Using its Process ID (PID), the kill command ends a single process, whereas the killall command ends all processes with a specified name.

17. How do you check the status of a service in Linux?

In Linux, the systemctl status command can be used to verify the status of a service. It gives full details on whether the service is operational and active.

18. What is the top command in Linux, and what does it show?

Linux’s top command offers a dynamic, real-time view of an operating system, including system statistics and the programs consuming the most CPU and memory.

19. Explain the difference between the cp and mv commands in Linux.

The main distinction is that while the mv command moves or renames a file by altering its placement on the disk without making a new copy, the cp command copies a file, generating a new, identical file in a new location while leaving the original intact.

20. How do you schedule tasks in Linux using cron?

By creating or modifying a crontab (cron table) file with a certain syntax to specify when and how frequently a command or script should run, you can use the cron program in Linux to schedule operations.

21. What is a Linux daemon, and how is it different from a normal process?

In contrast to a conventional process, which is often initiated by a user and communicates directly with them or a terminal, a Linux daemon is a background process that operates without human intervention. It usually starts at boot and continues continuously to deliver certain functions.

22. What is the sudo command, and when would you use it?

To run a command with the security rights of another user, usually the root user, use the sudo (superuser do) command. It would be used for administrative tasks like software installation, system file modification, and system reboots that are not authorized for a normal user account.

23. How can you view the content of a file without opening it in an editor?

Using a command-line tool like cat, less, more, head, or tail, you can see a file’s contents without opening it in an editor.

24. What is the difference between grep and egrep in Linux?

By treating the search pattern as an extended regular expression by default, the egrep command is a variant of the grep command that lets you utilize more sophisticated and potent matching syntax without having to escape special characters.

25. Explain the concept of virtual memory in Linux.

By temporarily relocating inactive data from RAM to a specific area on the hard drive called swap space, Linux’s virtual memory management approach creates the appearance of having more RAM than is actually available.

26. How do you update or install software packages in Linux using apt or yum?

In Linux, you must first update the package list before managing the packages with apt (for Debian-based systems like Ubuntu) or yum (for Red Hat-based systems like CentOS).

27. What is the role of the /etc/passwd file in Linux?

The /etc/passwd file in Linux is a plaintext file that serves as a database of all user accounts on the system, storing essential information like the username, User ID (UID), Group ID (GID), home directory, and default login shell.

28. How do you check the system uptime in Linux?

In Linux, you can use the uptime command in the terminal to check the system uptime.

29. What is the df command, and how is it used in Linux?

A Linux tool called the df command (short for “disk free”) shows a report of the amount of disk space that has been used, available, and total on all mounted file systems. To make the output easier to read, you use it in the terminal, usually with the -h (human-readable) parameter, as in df -h.

30. How would you troubleshoot performance issues in Linux?

In order to troubleshoot Linux performance issues, you would first use commands like top or htop to check system resource usage and find any processes using excessive amounts of CPU or memory.

Next, you would use specialized tools like df and iostat to look for disk bottlenecks and vmstat to analyze virtual memory.

Benefits of Linux for Organizations

Conclusion

Now that we have talked about the Top 30 Linux interview questions and answers, you might be feeling confident about cracking the interview. Moreover, those who are freshers and want to learn how to use Linux professionally are at the right place.

For that, they can get in contact with Craw Security, offering the Linux Essentials Course in Singapore to IT Aspirants. During the training sessions, students will be able to learn skills remotely via online sessions.

After the completion of the Linux Essentials Course in Singapore offered by Craw Security, students will receive a dedicated certificate validating their honed knowledge & skills during the sessions. What are you waiting for? Contact, Now!