Cron Cheatsheet

Edit Crontab

crontab -e

Line format

1 2 3 4 5 command

• 1: Minute (0-59)
• 2: Hour (0-23)
• 3: Day (1-31)
• 4: Month (1-12)
• 5: Day of the week(0-7 [7 or 0 == sunday])

Patterns

Examples

Block reddit using pihole except between 8pm and 10pm daily

0 20 * * * /usr/local/bin/pihole -b -d reddit.com www.reddit.com
0 22 * * * /usr/local/bin/pihole -b reddit.com www.reddit.com

Common problems

• Not including a newline at the end of the last line
• Not using the full path to a command (most environment variables, e.g. path, not available to cron jobs).
• % symbols get converted to newlines. If you actually want a % symbol you need to escape it, %.