How to Set Up a Cron Job on Ubuntu VPS (Nginx) Print

A cron job is a scheduled task that runs automatically on a Linux server at a specified time or interval.

Cron jobs are commonly used for:

• Running PHP scripts

• Scheduling Laravel commands

• Performing application maintenance

• Sending automated emails

• Processing scheduled tasks

• Running database backups

• Executing system scripts

This guide explains how to create, manage, and troubleshoot cron jobs on an Ubuntu VPS server.

Requirements

Before creating a cron job, you will need:

• An Ubuntu VPS server

• SSH access to your server

• A valid Linux user account

• The script or command you want to execute

• The correct path to the script or executable

Step 1: Connect to Your Ubuntu Server

Connect to your VPS using SSH.

Example:

ssh username@YOUR_SERVER_IP

Replace username with your Linux username and YOUR_SERVER_IP with your server's IP address.

If you are using Windows, you can connect through Windows Terminal, PowerShell, or an SSH client.

Step 2: Check Whether Cron Is Installed

Run the following command:

sudo systemctl status cron

If the cron service is installed and running, you should see an active status.

If it is not installed, install it using:

sudo apt update

sudo apt install cron -y

Enable and start the cron service:

sudo systemctl enable --now cron

Verify the service:

sudo systemctl status cron

Step 3: Open the Crontab Editor

To create a cron job for your current Linux user, run:

crontab -e

If prompted to select an editor, choose your preferred editor.

For example, you can select Nano.

This opens the user's cron configuration file.

Important: If your script needs to run as a specific application user, create the cron job under that user instead of using root unnecessarily.

Step 4: Configure the Cron Schedule

A cron job uses five fields to define when a command should run.

* * * * * command

The five fields represent:

Common Cron Schedules

Use the schedule recommended by your application or script.

Step 5: Add a Cron Job

For example, if you want to execute a PHP script every five minutes:

*/5 * * * * /usr/bin/php /var/www/example.com/public_html/cron.php

Replace:

• /usr/bin/php with the correct PHP executable path.

• /var/www/example.com/public_html/cron.php with the actual script path.

This is only an example. Your application may require a different command.

Example: Laravel Scheduler

For a Laravel application, the scheduler is commonly configured to run every minute:

* * * * * cd /var/www/example.com && /usr/bin/php artisan schedule:run >> /dev/null 2>&1

Replace /var/www/example.com with the actual Laravel project directory.

Example: CodeIgniter Application

For CodeIgniter, the correct command depends on the application and its scheduled tasks.

A CLI command may look like:

* * * * * cd /var/www/example.com && /usr/bin/php spark YOUR_COMMAND

Replace YOUR_COMMAND with the command supported by your application.

Do not use this example unless the application provides a valid Spark command.

Step 6: Save the Cron Job

If you are using Nano:

1. Press CTRL + O to save.

2. Press Enter to confirm.

3. Press CTRL + X to exit.

The cron job will be saved automatically.

Step 7: Verify the Cron Job

To list the current user's cron jobs, run:

crontab -l

You should see the cron job you created.

To check the cron service:

sudo systemctl status cron

To view cron logs:

sudo grep CRON /var/log/syslog

You can also use:

sudo journalctl -u cron

Step 8: Remove or Edit a Cron Job

To edit existing cron jobs:

crontab -e

To remove all cron jobs for the current user:

crontab -r

Warning: The crontab -r command deletes all cron jobs for the current user. Use it carefully.

Troubleshooting

Cron job is not executing

Verify that:

• The cron service is running.

• The cron schedule is correct.

• The script path is correct.

• The command uses the correct PHP or executable path.

• The user has permission to execute the script.

PHP script is not working

Check the PHP executable:

which php

Check the PHP version:

php -v

Your website may use a different PHP version than the command-line PHP version.

Script works manually but not through cron

Cron jobs run in a limited environment.

Use absolute paths and avoid relying on environment variables or the current working directory.

For example:

cd /var/www/example.com && /usr/bin/php script.php

Check cron logs

Run:

sudo grep CRON /var/log/syslog

If the script runs but produces an application error, check the application's own log files.

Important Notes

• Use the correct Linux user for the application.

• Use absolute paths in cron commands.

• Avoid running scripts too frequently unless required.

• Do not run application scripts as root unless necessary.

• Ensure the script is compatible with the installed PHP version.

• Always use the cron command recommended by your application developer.

Need Assistance?

If you need help configuring a cron job on your VPS, contact your hosting provider's support team.

Please provide:

• The application or script name

• The script location

• The required execution frequency

• The cron command, if available

• Any error messages

Our support team will be happy to assist you.