linux-crashcourse

DFG - Linux Hands-on Homework

Linux Learning Tasks

Install Linux on a virtual machine (VM) or physical device.

Install flog to generate fake logs.

Install stress to simulate CPU and memory load.

Task 1.1: Create a directory structure as follows:

project/ |-- reports/ | |-- 2024/ | |-- 2025/ |-- scripts/ |-- data/

Task 1.2: Create three empty files in the reports/2024 directory: q1.txt, q2.txt, and q3.txt.

Task 1.3: Move q1.txt to the 2025 directory.

Task 1.4: Copy q2.txt to the scripts directory and rename it as analysis.txt.

Task 1.5: List all files in the reports/2025 directory using ls and log the output to file_list.log.

Task 1.6: Display the contents of q3.txt using cat and append "Task Completed" to the file.

Task 1.7: Use tree to display the directory structure of the project directory and save the output to structure.log.

Task 1.8: Remove the scripts/analysis.txt file and confirm its deletion by listing the contents of the scripts directory.

Task 1.9: Copy the entire project directory to a new directory named project-old.

Task 1.10: Delete the original project directory.

Task 1.11: Create a large file (5GB) in the data directory using dd or truncate. Name it large_file.dat.

Task 2.1:Use flog to generate a fake log file named access.log with 2000 entries.

flog --entries 2000 > access.log

Task 2.2: Extract and display all unique IP addresses from the access.log file using awk or cut.

Task 2.3: Count how many times each IP address appears in the log file and save the results to ip_counts.txt.

Task 2.4: Use grep to filter all log entries containing the status code 404 and save them to errors.log.

Task 2.5: Replace all occurrences of the user agent string "Mozilla" with "BrowserX" in the access.log file and save the modified log as access_modified.log.

Task 2.6: Extract all log entries from a specific date (e.g., "2025-01-01") using grep and save them into specific_date.log.

Task 2.7: Use awk to calculate the total number of bytes transferred (from a specific column in the log) and output the result.

Task 2.8: Combine grep and awk to find the IP address with the highest number of 404 errors and save the result in top_404_ip.txt.

Task 2.9: Use sed to anonymize all IP addresses in the access.log file, replacing them with "ANONYMIZED_IP" and save it as access_anonymized.log.

Task 2.10: Use pipes (|) to combine grep and wc commands to count the number of log entries with a 500 status code.

Task 3.1: Start a long-running process using the command sleep 500 & and note its PID.

Task 3.2: Run stress in a separate terminal tab to simulate light CPU and memory usage: stress --cpu 1 --vm 1 --vm-bytes 512M --timeout 30s.

Task 3.3: Use top or htop to monitor the system and identify resource usage by processes.

Task 3.4: Use ps to verify the sleep process is running.

Task 3.5: Use df and du to check disk space usage, particularly focusing on large files in the system.

Task 3.6: Use free to monitor memory usage while stress is running.

Task 3.7: Use ps -aux and awk to log processes consuming more than 10% CPU into a file high_cpu.log every 5 seconds.

Task 3.8: Kill the long-running process started in Task 3.1 using its PID.

Task 4.1: Use ping to check the connectivity to google.com and log the output into ping_output.txt.

Task 4.2: Use ping to check the connectivity to google.com with 10 packets, logging the output into ping_10_packets.txt.

Task 4.3: Use ping to check the connectivity to google.com with a packet size of 1000 bytes, and log the output into ping_large_packet.txt.

Task 4.4: Use telnet to test the connectivity to port 80 on discord.com.

Task 4.5: Use telnet to check the connection to the SMTP server at smtp.gmail.com on port 25.

Task 4.6: Use curl to fetch the content of https://discord.com and save it to a file discord.html.

Task 4.7: Use curl to fetch the content of https://google.com and add a custom header User-Agent: MyBrowser.

Task 4.8: Use netstat to list all active TCP connections on your system.

Task 4.9: Use netstat to display all ports that are in the listening state on your system.

Task 4.10: Use iperf in client mode to test the network bandwidth to a remote server (iperf-server.google.com).

Task 4.11: Use iperf in server mode to listen for incoming connections on a remote machine (iperf-server.discord.com).

Task 4.12: Use nc (Netcat) to check if port 443 is open on discord.com.

Task 4.13: Use nc to send the message "Hello, Server!" to google.com on port 12345.

Task 4.14: Use nc to start a simple HTTP server on port 8080 and serve a static HTML file.

Task 4.15: Use telnet to connect to port 53 (DNS) on 8.8.8.8 and manually query for the domain discord.com.

Document all tasks in this homework, including steps taken and command outputs, in a Notion or document file. Include relevant screenshots of terminal outputs.

Include a brief summary of challenges encountered and how they were resolved.