Cron Job

A cron job is a scheduled task that runs automatically at predefined times or intervals on Unix-based systems.

It is commonly used for repetitive operations such as backups, system maintenance, script execution, and server-side automation. Cron jobs rely on the cron scheduler and use a time-based expression to define when a command or script should run.

Also known as: Scheduled task, automated job.

How Does a Cron Job Work?

Cron checks scheduled tasks in the background and executes them when their configured time is reached.

Cron jobs are typically defined in a crontab file. A standard cron expression contains five time fields followed by the command to execute:

* * * * * command
│ │ │ │ │
│ │ │ │ └─ Day of week
│ │ │ └─── Month
│ │ └───── Day of month
│ └─────── Hour
└───────── Minute

For example:

0 2 * * * /path/to/script.sh

This expression runs the specified script every day at 2:00 AM.