Exercises: Module 02 — Linux and Shell¶

Full exercises will be added when this module's complete content is written. The following are placeholder stubs showing the planned exercise structure.

Instructions¶

Complete each exercise in order. Exercises increase in difficulty.

Easy Exercises (1–3)¶

Exercise 1¶

Difficulty: Easy Objective: Navigate the filesystem hierarchy

List the contents of /etc, /var/log, and /proc/1 and describe what you find in each.

Exercise 2¶

Difficulty: Easy Objective: Basic process management

Find the PID of a running process (nginx, sshd, or any other service), send it a SIGHUP, and verify it handled the signal via journalctl.

Exercise 3¶

Difficulty: Easy Objective: File permissions

Create a directory /tmp/lab-permissions, set its permissions to 750, create a file inside it owned by root, and verify that a non-root user cannot read it.

Medium Exercises (4–6)¶

Exercise 4¶

Difficulty: Medium Objective: Write a bash script with proper error handling

Write a backup script that archives a directory, timestamps the archive, and exits with an appropriate error code if the source directory doesn't exist.

Exercise 5¶

Difficulty: Medium Objective: systemd unit file

Create a systemd unit file for a hypothetical web application. Include: restart policy, resource limits, security hardening directives, and logging configuration.

Exercise 6¶

Difficulty: Medium Objective: Log analysis with standard utilities

Parse /var/log/auth.log (or a similar log file) to find: the top 5 IP addresses with failed SSH login attempts, and the hours with the most login activity.

Hard Exercises (7–8)¶

Exercise 7¶

Difficulty: Hard Objective: Complete deployment script

Write a production-quality bash deployment script that: validates prerequisites, creates a backup, performs the deployment, runs health checks, and rolls back on failure.

Exercise 8¶

Difficulty: Hard Objective: Advanced awk/sed/jq processing

Write a script that parses JSON application logs (one JSON object per line), extracts request duration and status code, and produces a summary report with percentile latencies.

Expert Exercise (9)¶

Exercise 9¶

Difficulty: Expert Objective: Harden a Linux system

Given a fresh Ubuntu 22.04 server, write a hardening script that: disables root SSH login, configures fail2ban, sets up unattended security upgrades, configures auditd, and applies CIS benchmark Level 1 settings. Document each change and the threat it mitigates.