Top 19 Linux & DevOps Interview Questions You Must Master

Part 1: Linux Basics

Question 1: There are 100 image files with URLs ranging from http://down.xiaomi.com/img/1.png to http://down.xiaomi.com/img/100.png. Write a script to batch download these images and identify the files larger than 500KB.

Question 2: Given a text file info.txt containing lines like "aa,201", "zz,502", "bb,1", "ee,42", sort the file in descending order based on the numeric second column.

Question 3: Check whether the current Linux server is listening on port 80; if it is, find the process ID and terminate that process.

Question 4: Use curl or wget to retrieve the HTTP header information of a web service.

Question 5: Which statements about Linux user accounts are correct? A. Passwords are stored in plain text in /etc/passwd. B. Passwords are stored in encrypted form in /etc/passwd. C. Passwords are stored in encrypted form in /etc/shadow. D. During login, the plain‑text password is compared with the stored password.

Question 6: For a RAID array composed of N disks, which of the following statements is false? A. Compared with RAID1, RAID5 reads data faster. B. RAID5 has higher disk‑space utilization than RAID1. C. RAID1 can tolerate (N‑1) disk failures without data loss. D. RAID0 offers the fastest read/write speed among RAID0, RAID1, and RAID5.

Question 7: List at least three common load‑balancing software solutions and discuss the drawbacks of each.

Question 8: After running time sleep 2, the output shows real, user, and sys times. Explain what each of these three values represents and how they differ.

Question 9: In an Nginx rewrite rule, explain the meanings of the flags last, break, redirect, and permanent.

Question 10: Describe the differences between web service cookies and sessions.

Question 11: Compare HTTP/1.0 and HTTP/1.1, and outline the main changes or advantages introduced in HTTP/2.0.

Part 2: Security

Question 12: List at least three common web security issues, explaining their principles and potential impact.

Question 13: Enumerate common DoS attack types, describing the principle behind each and possible mitigation strategies.

Question 14: If a server is compromised, what steps should a security administrator take to respond and remediate?

Part 3: Networking

Question 15: Briefly describe the three‑way handshake process of TCP.

Question 16: A system shows a large number of TIME_WAIT sockets. Analyze the cause and propose at least three optimization suggestions.

Part 4: Python

Question 17: Compare and contrast xrange and range in Python.

Question 18: Given two lists A and B, write a Python snippet to quickly obtain their common elements.

Question 19: You have 20 servers and need to execute echo "123" on all of them, but only run commands on 5 servers in parallel at any time. Provide a Python or shell script to achieve this.