Cron

Cron is a time-based job scheduler in Unix-like operating systems (Linux, macOS) that automatically runs scripts or commands at scheduled intervals. Users define these automated tasks, known as “cron jobs,” in a crontab (cron table) file using a specific 5- or 6-field syntax forMinute, Hour, Day, Month, and Day of Week.

Syntax

• * * * * * command_to_execute

• Minute (0-59), Hour (0-23), Day of Month (1-31), Month (1-12), Day of Week (0-7, 0 and 7 are Sunday).
  Special Characters:

• * (Asterisk): Any value.
• , (Comma): Value list separator (e.g., 1,3,5).
• - (Hyphen): Range of values (e.g., 1-5).
• / (Slash): Step values (e.g., */15 in minute field means every 15 minutes).

Management: Users manage their jobs with crontab -e (edit), crontab -l (list), and crontab -r (remove) commands.

Common Examples:
- 0 0 * * *: Runs at midnight every day.
- 30 8 * * 1-5: Runs at 8:30 AM, Monday through Friday.
- */10 * * * *: Runs every 10 minutes.