Cron Jobs Tutorial

Cron jobs are automated tasks scheduled to run at specific times on Unix-like operating systems. They are widely used for system maintenance, backups, and periodic operations.

Basic Syntax

A cron job is defined using a cron expression that specifies the schedule. The format is:

* * * * * command_to_execute

• Minute (0-59)
• Hour (0-23)
• Day of the month (1-31)
• Month (1-12)
• Day of the week (0-6, where 0 is Sunday)

Example:

0 3 * * * /path/to/your/script.sh

This runs script.sh every day at 3:00 AM.

Practical Examples

1. Daily Backup

   0 2 * * * /backup_script.sh
   

   📝 Note: Replace /backup_script.sh with your actual backup command.

2. Weekly Report

   0 0 * * 0 /generate_weekly_report.sh
   

   This executes the script every Sunday at midnight.

3. Monthly System Check

   0 0 1 * * /system_check.sh
   

   Runs on the 1st of every month.

Best Practices

• Use absolute paths for scripts.
• Test commands with crontab -l before saving.
• Redirect output to log files for debugging:

  * * * * * /script.sh >> /var/log/cron.log 2>&1
  

• Avoid spaces in cron expressions.

Related Tutorials

For advanced scheduling techniques, check out our guide on Scheduling Tools.