Logging and log analysis in Drone Programming - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Drone log filtering command output

You have a drone log file named flight.log containing thousands of lines. You want to extract only the lines that contain the word ERROR. Which command will correctly output these lines?

A grep ERROR flight.log

B cat flight.log | find ERROR

C grep 'error' flight.log

D findstr ERROR flight.log

💡 Hint

Think about the standard Linux command to search text in files, case-sensitive by default.

The grep ERROR flight.log command searches for the exact uppercase word ERROR in the file and outputs matching lines. Option A uses find which is not standard on Linux. Option A searches for lowercase 'error' which won't match uppercase ERROR. Option A is a Windows command.

🧠 Conceptual

intermediate

Purpose of log rotation in drone systems

Why is log rotation important in drone software systems that generate continuous logs?

A To combine all logs into one big file for easier reading

B To delete all logs after every flight automatically

C To prevent log files from growing too large and consuming all disk space

D To encrypt logs for security purposes

💡 Hint

Think about disk space and file management.

Log rotation splits large log files into smaller chunks and deletes or archives old logs. This prevents disk space from filling up and keeps logs manageable. Options B, C, and D do not describe log rotation.

❓ Troubleshoot

advanced

Troubleshooting missing logs in drone system

A drone system is not generating any logs in the expected directory /var/log/drone. Which of the following is the most likely cause?

A The log files are encrypted and hidden

B The logging service is not started or crashed

C The drone is flying too fast to generate logs

D The drone battery is low

💡 Hint

Think about the software responsible for writing logs.

If no logs appear, the logging service or daemon might not be running or has crashed. Flying speed or battery level does not affect log generation directly. Encryption hides logs but does not prevent their creation.

🔀 Workflow

advanced

Analyzing drone logs for flight anomalies

You want to analyze drone flight logs to find all instances where the altitude dropped suddenly by more than 10 meters within 1 second. Which workflow sequence is correct?

A 1,3,2,4

B 3,1,2,4

C 2,1,3,4

D 1,2,3,4

💡 Hint

Think about the logical order of data extraction, calculation, filtering, and reporting.

First extract data (1), then calculate differences (2), filter relevant drops (3), and finally report (4). Other orders skip necessary steps or filter before calculation.

✅ Best Practice

expert

Best practice for secure drone log storage

Which option is the best practice to securely store drone logs containing sensitive flight data?

A Store logs on an encrypted remote server with access control

B Keep logs only on the drone's local storage without backup

C Send logs via unencrypted email to the operator

D Print logs on paper after each flight

💡 Hint

Consider data security and accessibility.

Storing logs on an encrypted remote server with strict access control protects sensitive data from unauthorized access and loss. Local-only storage risks data loss. Unencrypted email and printing are insecure or impractical.

Practice

1. What is the main purpose of logging in drone programming?

easy

A. To reduce the drone's battery usage

B. To speed up the drone's flight

C. To change the drone's hardware settings

D. To record what the drone program does step by step

Solution

1. Step 1: Understand logging basics

   Logging means saving messages about what the program is doing.

2. Step 2: Identify the main goal of logging

   It helps track the program's actions step by step for review or debugging.

3. Final Answer:

   To record what the drone program does step by step -> Option D

4. Quick Check:

   Logging = record steps [OK]

Hint: Logging means writing down program actions stepwise [OK]

Common Mistakes:

• Confusing logging with hardware control
• Thinking logging speeds up the drone
• Assuming logging saves battery

2. Which of the following is the correct syntax to log an info message in a drone program using Python's logging module?

easy

A. log.info("Drone started flying")

B. logging.info("Drone started flying")

C. logging.loginfo("Drone started flying")

D. logging.info: "Drone started flying"

Solution

1. Step 1: Recall Python logging syntax

   The correct method to log info level messages is logging.info(message).

2. Step 2: Check each option

   logging.info("Drone started flying") matches the correct syntax exactly; others have wrong method names or punctuation.

3. Final Answer:

   logging.info("Drone started flying") -> Option B

4. Quick Check:

   logging.info() is correct method [OK]

Hint: Use logging.info("message") to log info level [OK]

Common Mistakes:

• Using wrong method names like log.info or logging.loginfo
• Using colon instead of parentheses
• Missing parentheses around the message

3. Given this Python code snippet for logging in a drone program:

import logging
logging.basicConfig(level=logging.WARNING)
logging.debug("Debug message")
logging.warning("Warning message")
logging.error("Error message")

What will be printed to the console?

medium

A. Warning message\nError message

B. Debug message\nWarning message\nError message

C. Error message only

D. No output

Solution

1. Step 1: Understand logging level setting

   basicConfig sets level to WARNING, so messages with level WARNING and above show.

2. Step 2: Check each log call

   debug is below WARNING, so not shown; warning and error are shown.

3. Final Answer:

   Warning message\nError message -> Option A

4. Quick Check:

   Level WARNING shows warning and error [OK]

Hint: Logs show messages at or above set level [OK]

Common Mistakes:

• Expecting debug messages to appear
• Thinking only error shows at WARNING level
• Confusing logging levels order

4. You see this error in your drone program logs:
AttributeError: 'Logger' object has no attribute 'loginfo'
What is the most likely cause?

medium

A. Setting logging level too high

B. Not importing the logging module

C. Using a wrong logging method name like loginfo instead of info

D. Logging message is empty

Solution

1. Step 1: Analyze the error message

   AttributeError means the Logger object does not have the called method.

2. Step 2: Identify the method name mistake

   loginfo is not a valid method; correct is info.

3. Final Answer:

   Using a wrong logging method name like loginfo instead of info -> Option C

4. Quick Check:

   Method name must be correct [OK]

Hint: Check method names carefully for typos [OK]

Common Mistakes:

• Assuming import error causes AttributeError
• Thinking logging level causes method errors
• Ignoring method name spelling

5. You want to analyze drone logs to find all error messages that happened between 2pm and 3pm. Which approach is best?

hard

A. Filter logs by timestamp and error level using a log analysis tool

B. Manually read the entire log file line by line

C. Change the drone code to print only errors during that hour

D. Delete all logs except those from 2pm to 3pm

Solution

1. Step 1: Understand log analysis goal

   You want to find error messages in a specific time range efficiently.

2. Step 2: Choose best method

   Using a log analysis tool to filter by timestamp and error level is efficient and accurate.

3. Final Answer:

   Filter logs by timestamp and error level using a log analysis tool -> Option A

4. Quick Check:

   Use tools to filter logs by time and level [OK]

Hint: Use tools to filter logs by time and error level [OK]

Common Mistakes:

• Trying to read logs manually which is slow
• Changing code instead of analyzing existing logs
• Deleting logs risks losing data