Raspberry Pi - Data Logging and Databases
You want to schedule a data cleanup script to run at 11:30 PM on the last day of every month. Which cron entry achieves this?
You want to schedule a data cleanup script to run at 11:30 PM on the last day of every month. Which cron entry achieves this?
hard🚀 Application Q9 of 15
Step-by-Step Solution
Solution:
Step 1: Understand last day of month scheduling
Cron alone cannot detect last day; a conditional check is needed.Step 2: Analyze 30 23 28-31 * * [ "$(date -d tomorrow +\%d)" = "01" ] && /home/pi/cleanup.sh
Runs 11:30 PM on days 28-31, but only executes script if tomorrow is day 1 (last day).Step 3: Check other options
30 23 31 * * /home/pi/cleanup.sh runs only on 31st (fails for months with fewer days), C runs Sundays, D uses unsupported 'L'.Final Answer:
30 23 28-31 * * [ "$(date -d tomorrow +\%d)" = "01" ] && /home/pi/cleanup.sh -> Option BQuick Check:
Last day needs date check in script [OK]
Quick Trick: Use date check for last day, cron alone can't detect it [OK]
Common Mistakes:
MISTAKES- Using 31 only (misses shorter months)
- Using weekday for last day
- Assuming 'L' works in standard cron
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