The Cron Job/Crontab
To have your task run at this frequency, use the following cron:
20 */3 * * *
This cron command translates to the following (in Human-Readable format):
“Every 3 hours at 20 minutes past the hour.”
What is a Cron Job & Crontab?
A cron job is a time-based task that is set to run at specific intervals. This can be anything from running a script every hour to backing up a database every day. Cron jobs are typically used for maintenance tasks or tasks that need to be performed regularly, such as checking for updates or sending out reports.
A crontab is a file that contains a list of commands that are to be executed at specified times. The commands in the crontab are executed by the cron daemon, which runs in the background.
Every cron job uses five fields. Here is an explanation of what each field does in this cron, which runs “every 3 hours at 20 minutes past the hour“:
FUN FACT: Cron is one of the most versatile tools in a Linux administrator’s toolbox..
You might want to set up a crontab or cron job to run every 3 hours at 20 minutes past the hour for several reasons, including:
- clear cache
- take backups
- send email notifications
- run a script
Similar Cron Jobs
You might also want to run a crontab:
- every 12 hours
- every 9 hours
- every 2 hours
- every 4 hours
- every 10 hours
- every 6 hours
- every hour between 11:00 am and 2:00 pm
- every 4 hours at 1 minutes past the hour
- every hour between 6:00 am and 8:00 am
FUN FACT: If you want to see what commands are scheduled in your crontab, type: “crontab -l”.
In this article, you learned how to set up a cron job that runs every 3 hours at 20 minutes past the hour. 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 cron job cheat sheet for a list of hundreds of popular cron jobs.