The Cron Job/Crontab
To have your task run at this frequency, use the following cron:
0 */4 * * *
This cron command translates to the following (in Human-Readable format):
“Every 4 hours.”
What is a Cron Job & Crontab?
A cron job is a time-based task that is typically set up to run automatically at regular intervals. For example, a cron job might be used to send out a daily email report or to back up files every night.
A crontab is a file containing commands and instructions for the cron daemon to execute.
Every cron job uses five fields. Here is an explanation of what each field does in this cron, which runs “every 4 hours“:
FUN FACT: If you want to see what commands are scheduled in your crontab, type: “crontab -l”.
You might want to set up a crontab or cron job to run every 4 hours for several reasons, including:
- run a script to update data in a database
- run a backup script
- send out an email report
Similar Cron Jobs
You might also want to run a crontab:
- every 1 hour
- every 2 hours
- every 5 hours
- every 8 hours
- every 4 hours
- every 6 hours
- every 12 hours at 20 minutes past the hour
- every hour between 6:00 pm and 9:00 pm
FUN FACT: Cron is one of the most powerful tools available on a Linux system – use it wisely!.
In this article, you learned how to set up a cron job that runs every 4 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 cron job cheat sheet for a list of hundreds of popular cron jobs.