Linux Interview Guide for DevOps Engineers with Pooja Daga

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Linux for DevOps: 75 Interview Questions

Preparing for a DevOps, Cloud, SRE or Platform Engineering interview? This practical handbook helps you revise Linux fundamentals, practise essential commands and build a structured approach to real-world troubleshooting.

📚 What Topics Are Covered?

1. Linux Fundamentals & Commands

1. Linux architecture, kernel, shell and system calls
2. Linux distributions: Ubuntu vs RHEL
3. File operations, paths, environment variables and command lookup
4. Standard input/output, pipes and redirection

2. Files, Text Processing & Permissions

1. Inodes, hard links and symbolic links
2. grep, find, locate, awk, sed and log analysis
3. Linux permissions, ownership, umask, SUID, SGID and ACLs

Troubleshooting permission-denied errors, including SELinux .

3. Processes, CPU & Memory

1. Processes, threads, signals, zombies and orphan processes
2. CPU utilisation, load average, memory and swap
3. Diagnosing slow servers and resource-intensive processes
4. File descriptor limits and “Too many open files” errors

4. Storage, Filesystems, LVM & RAID

1. Disks, partitions, MBR vs GPT and filesystem formatting
2. ext4 vs XFS, mounting and /etc/fstab
3. Disk-space and inode exhaustion
4. LVM: PV, VG and LV creation and expansion
5. RAID levels, disk failures and safe recovery
6. Troubleshooting filesystems that become read-only

5. Boot Process & systemd

1. BIOS/UEFI, GRUB, kernel and initramfs
2. systemd units, targets and service dependencies
3. systemctl and journalctl
4. Failed services, emergency mode and rescue mode

6. Networking & Port Troubleshooting

1. IP addresses, subnetting, TCP vs UDP and common ports
2. Listening vs established connections
3. Port conflicts and applications that aren't listening
4. Firewall, DNS, connection-refused and timeout troubleshooting
5. End-to-end endpoint debugging: DNS, TCP, TLS and HTTP

7. Logs, Troubleshooting & Bash Scripting

1. Linux system, kernel and authentication logs
2. Log rotation and safe disk-space recovery
3. Hung applications, unexpected reboots and OOM-killer events
4. Bash variables, positional parameters, exit codes, conditionals and loops
5. Script error handling, cron jobs and systemd timers

8. Practical Production Scenarios

1. SSH key authentication failures
2. Granting users safe, least-privilege sudo access
3. Container isolation using namespaces and cgroups
4. Diagnosing container exit code 137
5. Investigating why the same deployment works on one host but fails on another

🎯 What Will You Get?

1. 75 interview questions with detailed explanations
2. Practical Linux commands, examples and expected-output interpretation
3. Step-by-step troubleshooting sequences and prevention techniques
4. Interview-ready answers to practise explaining concepts aloud
5. Likely follow-up questions to prepare for deeper technical discussions
6. A Linux Commands Quick Reference for fast revision
7. A Practical Interview Revision Checklist for the final week before your interview

👨‍💻 Who Is This For?

1. DevOps and Cloud engineers preparing for interviews
2. SRE, Platform and Infrastructure engineers
3. IT professionals transitioning into DevOps
4. Working professionals who want to strengthen their Linux troubleshooting skills

📥 Format

A 209-page downloadable PDF handbook designed for structured learning, hands-on practice and interview revision.

How to get the most out of it: Attempt each question before reading the answer, practise commands on a lab VM, and use the revision checklist to identify areas that need more work.

Educational and interview-preparation resource. Validate commands in a test environment before using them in production.