The Cron Job/Crontab
To have your task run at this frequency, use the following cron:
0 0 21 */4 *
This cron command translates to the following (in Human-Readable format):
“Every 4 months on day 21 of the month.”
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 commonly used to automate system maintenance or administration tasks, such as running backups or sending email 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.
Every cron job uses five fields. Here is an explanation of what each field does in this cron, which runs “every 4 months on day 21 of the month“:
FUN FACT: If a cron job is not properly configured, it might never execute – so make sure you double-check your settings before setting one up!.
You might want to set up a crontab or cron job to run every 4 months on day 21 of the month for several reasons, including:
- Updating a blog
- Sending a newsletter
- Checking for software updates
- Generating reports
Similar Cron Jobs
You might also want to run a crontab:
- every 4 months
- every 6 months
- every 5 months
- every 3 months
- every 2 months
- every 1 month
- every 1 month on day 9 of the month
- every 4 months on day 31 of the month
- every 3 months on day 8 of the month
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 months on day 21 of the month. 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.