Scheduled data collection with cron in Raspberry Pi - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is cron used for on a Raspberry Pi?

Cron is a tool that runs commands or scripts automatically at scheduled times or intervals on a Raspberry Pi.

beginner

How do you edit the cron jobs for the current user?

You use the command crontab -e to open and edit the list of scheduled tasks for the current user.

intermediate

What does the cron time format */5 * * * * mean?

It means the task runs every 5 minutes, every hour, every day, every month, and every weekday.

intermediate

Why is it important to use full paths in cron jobs?

Because cron runs with a limited environment, using full paths ensures the commands and scripts run correctly without missing files or programs.

intermediate

How can you check if your cron job ran successfully?

You can check the cron logs using grep CRON /var/log/syslog or redirect output to a file in your cron job.

Which command opens the cron editor for the current user?

A crontab -e

B cronedit

C cron -open

D editcron

The command crontab -e opens the cron editor for the current user.

What does the asterisk (*) symbol mean in a cron schedule?

A Skip this field

B No value

C Only once

D Every possible value for that time field

An asterisk (*) means the task runs for every possible value of that time field.

If you want a script to run every day at 3 AM, which cron time would you use?

A 0 3 * * *

B 3 0 * * *

C * 3 * * *

D 0 0 3 * *

The format is minute hour day month weekday. So 0 3 * * * runs at 3:00 AM every day.

Why should you use full paths in cron commands?

A To make the command shorter

B Because cron has a limited environment and may not find commands without full paths

C To speed up the cron job

D It is not necessary to use full paths

Cron runs with a limited environment, so full paths ensure commands run correctly.

Where can you find logs to check if cron jobs ran successfully?

A /home/user/cron.log

B /etc/cron.log

C /var/log/syslog

D /var/log/cronjobs

Cron logs are usually found in /var/log/syslog on Raspberry Pi systems.

Explain how to schedule a Python script to run every hour on a Raspberry Pi using cron.

Think about the cron time format and environment paths.

Describe how you would troubleshoot if your scheduled data collection script does not run as expected with cron.

Look for logs and environment issues.