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Raspberry Piprogramming~10 mins

Scheduled data collection with cron in Raspberry Pi - Step-by-Step Execution

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Concept Flow - Scheduled data collection with cron
Write data collection script
↓
Create cron job entry
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Cron daemon checks schedule
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Run script
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Store data in DB
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Repeat on schedule
The Raspberry Pi runs a script at scheduled times using cron, which collects data and stores it in a database repeatedly.
Execution Sample
Raspberry Pi
#!/bin/bash
# data_collect.sh
python3 /home/pi/collect_data.py

# Cron entry
# * * * * * /home/pi/data_collect.sh
A script runs every minute via cron to collect data and save it to the database.
Execution Table
StepCron Time CheckCondition (Is time to run?)ActionResult
100:00YesRun data_collect.shData collected and stored
200:01YesRun data_collect.shData collected and stored
300:02YesRun data_collect.shData collected and stored
400:03YesRun data_collect.shData collected and stored
500:04YesRun data_collect.shData collected and stored
600:05YesRun data_collect.shData collected and stored
700:06YesRun data_collect.shData collected and stored
800:07YesRun data_collect.shData collected and stored
900:08YesRun data_collect.shData collected and stored
1000:09YesRun data_collect.shData collected and stored
1100:10YesRun data_collect.shData collected and stored
1200:11YesRun data_collect.shData collected and stored
1300:12YesRun data_collect.shData collected and stored
1400:13YesRun data_collect.shData collected and stored
1500:14YesRun data_collect.shData collected and stored
1600:15YesRun data_collect.shData collected and stored
1700:16YesRun data_collect.shData collected and stored
1800:17YesRun data_collect.shData collected and stored
1900:18YesRun data_collect.shData collected and stored
2000:19YesRun data_collect.shData collected and stored
2100:20YesRun data_collect.shData collected and stored
2200:21YesRun data_collect.shData collected and stored
2300:22YesRun data_collect.shData collected and stored
2400:23YesRun data_collect.shData collected and stored
2500:24YesRun data_collect.shData collected and stored
2600:25YesRun data_collect.shData collected and stored
2700:26YesRun data_collect.shData collected and stored
2800:27YesRun data_collect.shData collected and stored
2900:28YesRun data_collect.shData collected and stored
3000:29YesRun data_collect.shData collected and stored
3100:30YesRun data_collect.shData collected and stored
3200:31YesRun data_collect.shData collected and stored
3300:32YesRun data_collect.shData collected and stored
3400:33YesRun data_collect.shData collected and stored
3500:34YesRun data_collect.shData collected and stored
3600:35YesRun data_collect.shData collected and stored
3700:36YesRun data_collect.shData collected and stored
3800:37YesRun data_collect.shData collected and stored
3900:38YesRun data_collect.shData collected and stored
4000:39YesRun data_collect.shData collected and stored
4100:40YesRun data_collect.shData collected and stored
4200:41YesRun data_collect.shData collected and stored
4300:42YesRun data_collect.shData collected and stored
4400:43YesRun data_collect.shData collected and stored
4500:44YesRun data_collect.shData collected and stored
4600:45YesRun data_collect.shData collected and stored
4700:46YesRun data_collect.shData collected and stored
4800:47YesRun data_collect.shData collected and stored
4900:48YesRun data_collect.shData collected and stored
5000:49YesRun data_collect.shData collected and stored
5100:50YesRun data_collect.shData collected and stored
5200:51YesRun data_collect.shData collected and stored
5300:52YesRun data_collect.shData collected and stored
5400:53YesRun data_collect.shData collected and stored
5500:54YesRun data_collect.shData collected and stored
5600:55YesRun data_collect.shData collected and stored
5700:56YesRun data_collect.shData collected and stored
5800:57YesRun data_collect.shData collected and stored
5900:58YesRun data_collect.shData collected and stored
6000:59YesRun data_collect.shData collected and stored
6101:00YesRun data_collect.shData collected and stored
💡 Cron runs the script every minute as scheduled, so it continues indefinitely.
Variable Tracker
VariableStartAfter 1After 2After 3After 4After 5Final
Cron Time00:0000:0100:0200:0300:0400:05continues
Script RunYesYesYesYesYesYesYes
Data StoredYesYesYesYesYesYesYes
Key Moments - 3 Insights
Why does the script run every minute even though the cron entry looks simple?
Because the cron schedule '* * * * *' means run every minute, as shown in execution_table rows where 'Condition' is always Yes.
What happens if the script fails to run at the scheduled time?
Cron will try again at the next scheduled minute; the execution_table shows each minute as a separate check and run.
How does the data get stored in the database?
The script 'data_collect.sh' runs the Python script which collects and stores data; the 'Result' column in execution_table confirms data is stored after each run.
Visual Quiz - 3 Questions
Test your understanding
Look at the execution_table, what is the action taken at step 10?
AWait and do nothing
BRun data_collect.sh script
CStop cron daemon
DDelete stored data
💡 Hint
Check the 'Action' column at row 10 in execution_table.
According to variable_tracker, what is the value of 'Script Run' after the third step?
ANo
BUnknown
CYes
DError
💡 Hint
Look at 'Script Run' row and 'After 3' column in variable_tracker.
If the cron schedule changed to '*/5 * * * *', how would the execution_table change?
AScript runs every 5 minutes only
BScript runs every minute as before
CScript never runs
DScript runs twice every minute
💡 Hint
Understand cron syntax and check the 'Condition' column logic in execution_table.
Concept Snapshot
Cron runs scripts on a schedule.
Use '* * * * *' to run every minute.
Write a script to collect data.
Add script to cron with crontab.
Cron triggers script, data saved in DB.
Runs repeatedly as scheduled.
Full Transcript
This visual execution shows how cron schedules a data collection script on a Raspberry Pi. First, you write a script that collects data and stores it in a database. Then you create a cron job entry with '* * * * *' to run the script every minute. The cron daemon checks the time every minute. If the time matches the schedule, it runs the script. The script collects and stores data. This repeats every minute indefinitely. The execution table shows each minute's check and script run. The variable tracker shows how 'Cron Time', 'Script Run', and 'Data Stored' change over time. Key moments clarify why the script runs every minute and what happens if it fails. The quiz tests understanding of cron timing and script execution. This helps beginners see step-by-step how scheduled data collection works with cron on Raspberry Pi.