The Cron Job/Crontab
To have your task run at this frequency, use the following cron:
0 0 */3 * *
This cron command translates to the following (in Human-Readable format):
“Every 3 days at 12:00 am.”
What is a Cron Job & Crontab?
A cron job is a task that is scheduled to run at a specific time or interval. Cron jobs are typically used for maintenance or administrative tasks, such as backing up data or updating software.
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.
Every cron job uses five fields. Here is an explanation of what each field does in this cron, which runs “every 3 days at 12:00 am“:
FUN FACT: When troubleshooting issues with cron jobs, it can be helpful to run them manually from the command line – this will allow you to see any error messages that might be generated..
You might want to set up a crontab or cron job to run every 3 days at 12:00 am for several reasons, including:
- Checking for updates to a software program
- Generating reports
- Deleting temporary files
- Sending reminder emails
Similar Cron Jobs
You might also want to run a crontab:
- every 2 days
- every 1 day
- every 7 days
- every 3 days
- every 8 days
- every 6 days
- every 8 days at 1:30 am
- every 2 days at 12:30 am
- every 7 days at 1:00 am
FUN FACT: When editing your crontab, it is important to use a text editor that supports Unix-style line endings (LF), as opposed to Windows-style line endings (CRLF)..
In this article, you learned how to set up a cron job that runs every 3 days at 12:00 am. 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.