Linux Interview Questions For DevOps With Answers Explained

Here are Linux interview questions for DevOps with answers. These are commonly asked in real interviews and explained clearly.

Linux interview questions for DevOps with answers

1. What is Linux?

Linux is an open-source operating system based on the Unix architecture. It is widely used in servers, cloud platforms, and DevOps environments because of its stability, security, and flexibility.

2. What are the main components of Linux?

• Kernel – Core part that manages hardware and processes
• Shell – Interface to interact with the system
• File System – Organizes data
• Utilities – Commands and tools for daily operations

3. What is the difference between Linux and Unix?

Unix is a proprietary operating system, while Linux is open-source and freely available. Linux is inspired by Unix but developed independently.

4. What is a shell?

A shell is a command-line interface that allows users to communicate with the operating system using commands.

5. What are some common Linux distributions?

• Ubuntu
• CentOS / Rocky Linux
• Debian
• Red Hat Enterprise Linux (RHEL)

File System & Commands

6. What is the Linux file system structure?

Linux follows a hierarchical structure starting from / (root directory). Important directories:

• /home – User files
• /etc – Configuration files
• /var – Logs and variable data
• /bin – Essential commands

7. Difference between cp, mv, and rm?

• cp → Copy files
• mv → Move or rename files
• rm → Delete files

8. How do you check disk usage?

• df -h → Shows disk space
• du -sh → Shows folder size

9. What is an inode?

An inode stores metadata about a file, such as size, permissions, and ownership, but not the file name.

10. What is the use of grep?

grep is used to search for patterns in files or output.

Example:

bash

grep "error" logfile.txt

Permissions & Users

11. What are file permissions in Linux?

There are three types:

• Read (r)
• Write (w)
• Execute (x)

For:

• Owner
• Group
• Others

12. What is chmod?

Used to change file permissions.

Example:

bash

chmod 755 file.sh

13. What is chown?

Used to change file ownership.

Example:

bash

chown user:group file.txt

14. How do you create a user?

bash

useradd username
passwd username

Process & System Management

15. How do you check running processes?

bash

ps -ef
top

16. What is PID?

Process ID – a unique number assigned to each running process.

17. How do you kill a process?

bash

kill PID
kill -9 PID

18. What is a daemon?

A daemon is a background service (e.g., SSH, cron).

Networking (Important for DevOps)

19. How to check the IP address?

bash

ip a

20. What is the difference between ping and curl?

• ping → Checks connectivity
• curl → Fetches data from a URL

21. How do you check open ports?

bash

netstat -tuln
ss -tuln

22. What is SSH?

Secure Shell is used to connect to remote servers securely.

Storage & Disk Management

23. What is LVM?

Logical Volume Manager allows flexible disk management (resize, snapshots).

24. Difference between a hard link and a soft link?

• Hard link → Points to the same inode
• Soft link → Shortcut to file

DevOps-Focused Linux Questions

25. What is cron?

Cron is used to schedule tasks.

Example:

bash

* * * * * /script.sh

26. What is systemd?

systemd is a system and service manager used to start and manage services.

27. How do you check logs?

bash

/var/log/
journalctl

28. What is a package manager?

A tool used to install and manage software.

Examples:

• apt (Ubuntu)
• yum / dnf (RHEL)

29. What is an environment variable?

A variable that defines system behavior.

Example:

bash

echo $PATH

30. What is a pipeline in Linux?

It allows passing the output of one command to another.

Example:

bash

cat file.txt | grep "error"

Also read about Unix Operating System Commands For Interview With Examples

Scenario-Based Questions (Very Important)

31. Disk is full. What will you do?

• Check usage (df -h)
• Find large files (du -sh *)
• Clean logs (/var/log)
• Remove unused files

32. Service is not starting. How to troubleshoot?

• Check status (systemctl status)
• View logs (journalctl -xe)
• Verify config files

33. Server is slow. What will you check?

• CPU (top)
• Memory (free -m)
• Disk (iostat)
• Processes

34. How do you monitor logs in real time?

bash

tail -f logfile

35. How do you find a file in Linux?

bash

find / -name filename

DevOps Real-World Scenarios

36. Application is slow. What will you check?

• CPU → top
• Memory → free -m
• Disk I/O → iostat
• Logs

37. Server is unreachable. What will you do?

• Check network
• Ping server
• Check the SSH service
• Verify firewall rules

38. Disk suddenly full. Root cause?

• Logs growing
• Large files
• Docker images
• Temporary files

39. How do you find large files?

bash

du -ah / | sort -rh | head -20

40. How do you handle zombie processes?

• Identify using ps aux
• Kill the parent process

Containers & DevOps Integration

41. How does Linux support Docker?

• Namespaces → isolation
• Cgroups → resource limits
• Union FS → layered filesystem

42. What are namespaces?

They isolate:

• Processes
• Network
• Filesystem
• Users

43. What are cgroups?

Control CPU, memory, and I/O usage of processes.

Advanced Troubleshooting

44. What tools do you use for debugging?

• strace → system calls
• lsof → open files
• netstat → network
• tcpdump → packet capture

45. How do you debug a crashed service?

• Check logs
• Run in debug mode
• Check dependencies
• Use journalctl

Also read about Linux Shell Scripting For DevOps Interview Questions Guide