🐧 Linux Interview Questions Every DevOps Engineer Must Know

🔰 Beginner-Level Linux Interview Questions

1️⃣ What is Linux?

Linux is an open-source, Unix-like operating system kernel used to manage hardware resources and provide services to applications.

📌 Examples:

• Ubuntu

• CentOS

• Amazon Linux

• Red Hat Enterprise Linux (RHEL)

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2️⃣ What is the Linux Kernel?

The kernel is the core of the operating system that:

• Manages CPU, memory, and devices

• Handles process scheduling

• Acts as a bridge between hardware and software

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3️⃣ Difference between Linux and Unix?

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4️⃣ What is a Shell?

A shell is a command-line interface that allows users to interact with the Linux OS.

Popular shells:

• bash

• zsh

• sh

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5️⃣ Common Linux Commands

ls      # list files
pwd     # current directory
cd      # change directory
mkdir   # create directory
rm      # delete file
cp      # copy file
mv      # move/rename file

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⚙️ Intermediate-Level Linux Interview Questions

6️⃣ What is the difference between rm and rm -r?

• rm file → deletes a file

• rm -r dir → deletes a directory recursively

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7️⃣ What are Linux file permissions?

Linux permissions are:

• Read (r) – 4

• Write (w) – 2

• Execute (x) – 1

Example:

chmod 754 file.sh

Meaning:

• Owner: rwx

• Group: r-x

• Others: r--

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8️⃣ What is a process in Linux?

A process is a running instance of a program.

Commands:

ps
top
htop
kill

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9️⃣ Difference between ps and top?

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🔟 What is a daemon?

A daemon is a background process that runs continuously.

Examples:

• sshd

• cron

• systemd

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🧠 Advanced Linux Interview Questions

1️⃣1️⃣ What is the difference between Soft link and Hard link?

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1️⃣2️⃣ What is inode?

An inode stores metadata about a file:

• File size

• Permissions

• Owner

• Disk location

📌 File name is not stored in inode.

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1️⃣3️⃣ What is swap space?

Swap is disk space used as virtual memory when RAM is full.

Commands:

free -h
swapon -s

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1️⃣4️⃣ What is cron?

cron is a job scheduler used to run tasks automatically.

Example:

0 2 * * * backup.sh

➡ Runs daily at 2 AM

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1️⃣5️⃣ Explain booting process in Linux

1. BIOS/UEFI

2. Bootloader (GRUB)

3. Kernel

4. init/systemd

5. User space

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🚀 Linux + DevOps Interview Questions

1️⃣6️⃣ How Linux is used in DevOps?

• Running Docker containers

• Managing Kubernetes nodes

• CI/CD pipelines

• Cloud servers (AWS EC2, GCP, Azure)

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1️⃣7️⃣ Difference between systemctl and service?

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📝 Final Tips for Linux Interviews

✔ Practice commands daily
✔ Understand why, not just how
✔ Use real-world examples
✔ Learn Linux from a DevOps perspective

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📌 Conclusion

Linux is not just an operating system — it’s a core skill for DevOps engineers. Mastering Linux fundamentals gives you confidence in interviews and real production environments.