Cron Job Every 3 Hours (Crontab)

This page will help you quickly and easily set up a cron job to run every 3 hours.

The Cron Job/Crontab

To have your task run at this frequency, use the following cron:

0 */3 * * *

This cron command translates to the following (in Human-Readable format):

“Every 3 hours.”

What is a Cron Job & Crontab?

A cron job is a scheduled task that is typically executed automatically at a predetermined time or interval. Cron jobs are often used to perform routine system maintenance tasks, such as backing up files or databases, deleting temporary files, or sending email notifications.

Crontab is a file that contains commands and instructions for the cron daemon to execute. The crontab file is usually located in the /etc/cron directory. Each user on a system can have their own crontab file. The commands in the crontab files are executed by the cron daemon at the specified times.

Cron Fields

Every cron job uses five fields. Here is an explanation of what each field does in this cron, which runs “every 3 hours“:

  • Field 1: (0) indicates that the task will be run at minute 0.
  • Field 2: (*/3) indicates that the task will be run every 3 hours.
  • Field 3: (*) indicates that the task will be run every day of the month.
  • Field 4: (*) indicates that the task will be run every month.
  • Field 5: (*) indicates that the task will be run every day of the week.
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    FUN FACT: Cron jobs are often used to perform regular maintenance tasks, such as running backups or sending out reports..

    Use Cases

    You might want to set up a crontab or cron job to run every 3 hours for several reasons, including:

    • To run a backup every 3 hours
    • To check for new emails every 3 hours
    • To generate reports every 3 hours

    Similar Cron Jobs

    You might also want to run a crontab:

    FUN FACT: If you need to temporarily disable a cron job, you can simply comment out the line in the crontab file that corresponds to that particular task..

    Wrapping Up

    In this article, you learned how to set up a cron job that runs every 3 hours. Please share this page with friends and colleagues if you find it useful.

    If you have any questions, please don’t hesitate to comment below.

    If you are looking for cron jobs that run at certain minutes, hours, days, weekdays, or months, or if you are looking for miscellaneous cron jobs, then check out our relevant sections, or visit our crontab cheat sheet for a list of hundreds of popular cron jobs.

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