Setup a cron job that runs on every 15 minute using Crontab in Ubuntu 16.04

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In a Ubuntu-powered VPS, there was requirement to run a PHP script on every 15 minute. So, I fire up Google, search in ubuntu-related resources and setup it a cron job that run on every 15 minutes. This article is a ready-reference for me and, of course, for the rest of the world who runs into similar scenario.

Cron jobs are executed by www-data user.

I used Crontab and below is the command that I issue to start new cron job:

crontab -u www-data -e

My VPS server was new and there was nothing in the list of jobs. Empty file. So, I wrote the following line of code to start a new cron job.

*/15 * * * * /usr/bin/php /your/path/to_the_folder_of/php_script/your-script-filename.php

Code Dissection

1. */15 - tell Ubuntu to run the script on EVERY 15 MINUTE
2. * - 2nd asterisk tells OS to run on EVERY HOUR
3. * - 3rd asterisk tells OS to run on EVERY DAY
4. * - 4th asterisk tells OS to run on EVERY MONTH
5. * - 5th asterisk tells OS to run on EVERY DAY OF THE WEEK
6. /usr/bin/php - indicates that PHP is running from "/usr/bin/php" folder
7. /your/path/to_the_folder_of/php_script/your-script-filename.php - tells the OS about the actual path of your PHP script.

Crontab Options:

To view www-data user's current jobs, use -l (small L) switch:

crontab -u www-data -l

To delete www-data user's current jobs, use -r switch:

crontab -u www-data -r

Helpful resources

To help you learn about more variant of possible setup on crontab, I have compiled some useful resources on this topic below.

• Linux Crontab: 15 Awesome Cron Job Examples
• Running PHP with CRON on Ubuntu
• Official documentation
• How To Use Cron To Automate Tasks On a VPS

I hope that this article will give you a head start and guide you to setup your first cron job in your Ubuntu server.