Linux Interview Questions: Guide for Job Seekers

If you’re preparing for a job interview in the Linux domain, understanding the most commonly asked Linux interview questions can give you a competitive edge. Linux is a widely used operating system in servers, cloud computing, and cybersecurity, making it essential for IT professionals to have a strong grasp of Linux fundamentals. This guide covers essential Linux interview questions along with their answers to help you ace your interview.

Basic Linux Interview Questions

1. What is Linux?

Linux is an open-source, Unix-like operating system based on the Linux kernel. It is widely used in various computing environments, including servers, desktops, and embedded systems.

2. What are the advantages of using Linux?

• Open-source and free to use
• Highly secure and stable
• Multi-user and multitasking support
• Large community support and extensive documentation

3. What is the Linux kernel?

The Linux kernel is the core component of the Linux operating system. It manages hardware resources, system processes, and security features.

4. What are the different types of Linux distributions?

Some of the popular Linux distributions include:

• Ubuntu
• Debian
• Fedora
• CentOS
• Arch Linux
• Red Hat Enterprise Linux (RHEL)

5. What is the difference between Linux and Unix?

• Linux is an open-source operating system inspired by Unix.
• Unix is a proprietary OS developed by AT&T Bell Labs.
• Linux is free, whereas Unix is mostly commercial.

6. What is the default shell in Linux?

The default shell in most Linux distributions is Bash (Bourne Again Shell), though others like Zsh, Fish, and KornShell are also used.

7. How do you check the Linux version?

Use the following command:

uname -a

Or for a more detailed version:

lsb_release -a

Intermediate Linux Interview Questions

8. What are inodes in Linux?

Inodes are data structures that store metadata about files, such as permissions, ownership, and timestamps, but they do not store the actual file content or name.

9. How do you check system uptime in Linux?

You can use the following command:

uptime

It displays the system’s uptime, current time, number of users, and load average.

10. How do you change file permissions in Linux?

The chmod command is used to change file permissions. For example:

chmod 755 filename

This grants read, write, and execute permissions to the owner and read/execute permissions to others.

11. What are Linux runlevels?

Runlevels define different states of a Linux system. Common runlevels include:

• 0 – Halt
• 1 – Single-user mode
• 3 – Multi-user mode with networking
• 5 – Graphical user interface (GUI) mode
• 6 – Reboot

12. How do you list all running processes in Linux?

You can use:

ps -aux

Or

top

Advanced Linux Interview Questions

13. What is the difference between a hard link and a soft link?

• Hard Link: A direct reference to the file’s inode, making it indistinguishable from the original file.
• Soft Link (Symbolic Link): A shortcut pointing to the original file.

14. How do you find large files in Linux?

Use the following command:

find / -type f -size +100M

This finds files larger than 100MB on the system.

15. How do you check CPU usage in Linux?

You can use:

top

OR

htop

These commands provide real-time CPU usage information.

16. What is the difference between TCP and UDP?

• TCP (Transmission Control Protocol): Reliable, connection-oriented protocol.
• UDP (User Datagram Protocol): Faster, connectionless protocol but less reliable.

17. What is the difference between grep and awk?

• grep: Used for searching and filtering text.
• awk: More advanced; used for pattern scanning and processing.

Scenario-Based Linux Interview Questions

18. How would you troubleshoot a slow Linux system?

• Use top or htop to check running processes
• Check disk usage with df -h
• Monitor memory usage with free -m
• Investigate logs using journalctl or /var/log/syslog

19. How do you create a user in Linux?

Use the following command:

sudo useradd -m username

To set a password for the user:

sudo passwd username

20. How do you schedule a cron job?

Edit the crontab file using:

crontab -e

Add a job, for example, to run a script every day at 5 AM:

0 5 * * * /path/to/script.sh

Final Thoughts

Mastering these Linux interview questions will prepare you for both beginner and advanced job roles in Linux system administration, DevOps, and cybersecurity. Since Linux is widely used in enterprise environments, having a deep understanding of these topics will significantly boost your chances of landing a great job.

Additionally, practicing Linux commands and troubleshooting real-world scenarios will enhance your confidence during interviews. Keep exploring Linux documentation, join Linux forums, and work on hands-on projects to strengthen your skills. With the right preparation, you can excel in your next Linux interview and secure your dream job.

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