Stage 1: Curious Solver

Introduce learners to Linux troubleshooting scenarios. Build confidence in identifying problems, applying commands, and explaining solutions clearly — exactly the kind of skill interviewers test with “what would you do if…” questions.

Hackbook Overview

• Troubleshooting Mindset: Break problems into smaller steps, check logs, verify configs.
• Common Issues: Permission errors, missing configs, service failures, network connectivity.
• Tools to Use: ls -l, systemctl, journalctl, ping, grep.
• Why It Matters: Scenario questions test practical thinking, not memorization.

Hands‑On Practice

• Simulate a “Permission denied” error by removing execute permission from a script, then fix it.
• Stop a service (e.g., nginx) and practice diagnosing why it won’t start.
• Disconnect network temporarily and troubleshoot connectivity with ping and ip addr.
• Search logs for errors using journalctl -xe | grep error.

Interview Question Bank

Conceptual

• Q1. What’s your first step when troubleshooting a Linux issue?
  A1. Identify the problem clearly, reproduce it if possible, and check logs or error messages.
• Q2. Why are logs important in troubleshooting?
  A2. Logs provide detailed system and application events, helping pinpoint the root cause.

Practical

• Q3. A script fails with “Permission denied.” How do you fix it?
  A3. Grant execute permission: chmod +x script.sh.
• Q4. A service won’t start. How do you investigate?
  A4. Run systemctl status <service> and check logs with journalctl -u <service>.
• Q5. How do you test if a server has network connectivity?
  A5. Use ping <IP> or curl <URL> to verify connectivity.

Scenario‑Based

• Q6. You log in and find the disk is full. What do you do?
  A6. Run df -h to check usage, then clean logs or remove unnecessary files.
• Q7. A user cannot access a file they should. How do you troubleshoot?
  A7. Check permissions with ls -l filename and adjust using chmod or chown.
• Q8. A web server is running but inaccessible externally. What’s your approach?
  A8. Verify firewall rules, confirm port 80/443 is open, and check service status.

Behavioral Based

• Q9. Tell me about a time you solved a tricky Linux issue.
  A9. Example: “I once resolved a deployment failure by tracing logs with journalctl and fixing a missing config file.”

Cheatsheet (Quick Notes)

• Permissions: chmod, chown.
• Services: systemctl status, journalctl -u.
• Networking: ping, ip addr, curl.
• Disk Usage: df -h, du -sh.
• Logs: journalctl -xe, /var/log/.