You can use cron to run repeated tasks on your server. Cron jobs are defined in a file, known as a 'crontab', and run as often as you specify. A cron entry looks like this:
5 * * * * curl https://lasershark.uk
The crontab line is broken down into these parts:
Just specify the number that represents the time you want the task to run, for example
5 * * * * for every hour at :05. You can separate multiple values with commas, so
1,31 * * * * will run the task at :01 and :31 past every hour.
You can also use a divisor. For example, instead of configuring a job to run at :00, :15, :30 and :45, you can just type
*/4 * * * *. You can also use a range, such as
0 9-17 * * *, to make a job run every hour between 09:00 and 17:00.
Adding a cron task
To add a task to your crontab, type
crontab -e at the command line. This will open your crontab in your default editor—if it's the first time you've done this, on some systems you might be asked to choose a default editor (we recommend
nano)—and you can add your cron jobs to the end of this file.
Remember, your crontab will run as the currently logged-in user, so if you need a task to run as root, log in as root or run
sudo crontab -e.