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Cron Jobs

Cron Jobs allow you to schedule commands or scripts to run automatically at defined intervals.
They are a core part of system automation and maintenance in the OS.

Cron Jobs are commonly used for:

  • System maintenance tasks
  • Scheduled backups
  • Log rotation and cleanup
  • Monitoring and health checks
  • Custom automation scripts

The Cron Jobs menu is located under:

Settings → System Configuration → Cron Jobs

Here you can create new cron jobs and manage existing ones.

Example:

Cron Jobs Overview

Creating a New Cron Job​

To create a new cron job, click the Plus Icon and fill in the required fields.

Cron Job Configuration Fields​

Name​

Defines the name of the cron job.

Best practice:

  • Use clear and descriptive names
  • Avoid spaces and special characters
  • Reflect the purpose of the job

Examples:

  • daily_backup
  • log_cleanup
  • update_check
  • media_rescan

Schedule​

Defines when and how often the cron job is executed.

The schedule follows standard cron syntax.

Format:

minute hour day month weekday

Examples:

  • 0 2 * * * → Every day at 02:00
  • */5 * * * * → Every 5 minutes
  • 0 0 * * 0 → Every Sunday at midnight

Tip:
Use fixed schedules for system tasks to avoid unnecessary load.

Command​

Defines the command that will be executed.

Notes:

  • Commands are executed with system privileges
  • Absolute paths are recommended
  • If no command is provided and only a script path is defined, the command is created automatically

Example:

bash /boot/optional/scripts/cron/test_script.sh > /dev/null 2>&1

This ensures:

  • The script is executed reliably
  • No stdout or stderr output is written unless explicitly handled inside the script

Examples:

  • /usr/bin/apt update
  • /usr/local/bin/backup.sh
  • /usr/bin/find /var/log -type f -mtime +7 -delete

Script​

Allows you to select or define a script to be executed instead of a single command.

Use cases:

  • Complex logic
  • Multi-step operations
  • Reusable automation tasks

Notes:

  • Scripts must be executable
  • Ensure proper shebang (#!/bin/sh, #!/bin/bash, etc.)

Managing Existing Cron Jobs​

All created cron jobs are listed in the overview table.

For each cron job, the following actions are available:

Start​

Enables the cron job.

  • The job will run according to its schedule
  • Recommended after creation and testing

Stop​

Disables the cron job without deleting it.

Use cases:

  • Temporary deactivation
  • Troubleshooting
  • Maintenance windows

Edit​

Allows you to modify:

  • Enabled / Disabled state
  • Name
  • Schedule
  • Command

Note:
Changes take effect immediately after saving.

Change Script​

Updates the script path associated with the cron job.

Important:

  • The script itself is not edited here
  • Only the filesystem path to the script is changed
  • Script content must be modified externally (e.g. via shell, editor, or file manager)

Use cases:

  • Switching to a new or updated script version
  • Replacing a script without recreating the cron job
  • Pointing the job to a different script location

Note: Ensure the target script exists and is executable.

Delete​

Permanently removes the cron job.

Warning:
This action cannot be undone.

Best Practices​

  • Test commands and scripts manually before scheduling
  • Avoid overly frequent schedules unless required
  • Log output for debugging and auditing
  • Disable unused cron jobs instead of deleting them

Logging and Output Handling​

By default, cron job output can be suppressed or discarded.
Optionally, you can redirect stdout and stderr to a dedicated log file by defining it directly in the Command field.

Benefits:

  • Easier debugging
  • Better auditing and traceability
  • Persistent access to execution results

Example:

bash /boot/optional/scripts/cron/test_script.sh >> /var/log/cron/test_script.log 2>&1

Notes:

  • Ensure the log directory exists
  • Verify proper file permissions
  • Consider log rotation for frequently running jobs

Summary​

Cron Jobs provide a powerful and flexible way to automate system tasks.

Key points:

  • Create scheduled tasks using commands or scripts
  • Easily start, stop, edit, or delete jobs
  • Use clear naming and predictable schedules
  • Essential for maintenance, backups, and automation

Proper use of cron jobs ensures a reliable and self-maintaining system.

Parts of this documentation were created with the assistance of AI tools. All AI-generated content has undergone review, but it may still contain inaccuracies, omissions, or outdated information.