The Cron Job/Crontab
To have your task run at this frequency, use the following cron:
0 21 */9 * *
This cron command translates to the following (in Human-Readable format):
“Every 9 days at 9:00 pm.”
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 emails.
A crontab is a table or list of commands that are scheduled to run at specified times. The commands in a crontab file (also called a “cron table”) are normally executed by the cron daemon, which runs in the background and executes these commands automatically.
Every cron job uses five fields. Here is an explanation of what each field does in this cron, which runs “every 9 days at 9:00 pm“:
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 9 days at 9:00 pm for several reasons, including:
- Checking for updates to a software package
- Generating reports
- Running a backup script
Similar Cron Jobs
You might also want to run a crontab:
- every 3 days
- every 5 days
- every 8 days
- every 6 days
- every 4 days
- every 9 days
- every 5 days at 9:30 pm
- every 9 days at 8:00 am
- every 5 days at 3:30 am
FUN FACT: Cron jobs can be set up to run at specific times, or they can be configured to run periodically (e.g., every hour)..
In this article, you learned how to set up a cron job that runs every 9 days at 9:00 pm. 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.