The Cron Job/Crontab
To have your task run at this frequency, use the following cron:
40 */3 * * *
This cron command translates to the following (in Human-Readable format):
“Every 3 hours at 40 minutes past the hour.”
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 (also known as a “cron table”) is a file that contains a list of commands that are executed at specified times.
Every cron job uses five fields. Here is an explanation of what each field does in this cron, which runs “every 3 hours at 40 minutes past the hour“:
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)..
You might want to set up a crontab or cron job to run every 3 hours at 40 minutes past the hour for several reasons, including:
- To run a backup of all new and changed files every 3 hours
- To check for new messages in a mailbox every 3 hours
- To rotate log files every 3 hours
Similar Cron Jobs
You might also want to run a crontab:
- every 5 hours
- every 10 hours
- every 7 hours
- every 2 hours
- every 11 hours at 1 minutes past the hour
- every hour between 4:00 pm and 8:00 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 3 hours at 40 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.