Mastering Crontab Syntax: The Complete 5-Part Cron Schedule Reference

Cron is one of the most reliable and battle-tested background scheduling engines in software engineering. Whether you are running nightly database backups, synchronizing third-party APIs, or dispatching customer notification batches, understanding crontab syntax is essential.

The 5 Core Crontab Fields

A standard UNIX cron expression consists of exactly five space-separated fields:

Understanding Special Operators

• Asterisk (*): Matches every possible value within that field.
• Comma (,): Specifies a discrete list of values, e.g., 1,15,30.
• Hyphen (-): Defines an inclusive numerical range, e.g., 1-5 (Monday through Friday).
• Slash (/): Defines step values or recurring intervals, e.g., */15 (every 15 minutes).