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5 Must-Know Linux Troubleshooting Techniques

Linux Troubleshooting

As a Linux user or system administrator, troubleshooting is an essential skill. Whether you're dealing with a misbehaving web server, connectivity issues, or configuration problems, knowing the right commands can save you hours of debugging. Here are 5 must-know Linux troubleshooting techniques that will help you quickly identify and fix common issues.

1. Verify Your Environment Variables

Many applications rely on environment variables to function correctly. Before diving into complex debugging, make sure all required environment variables are loaded. You can do this by:

  • Checking your .env file exists and has correct values.
  • Exporting variables in your shell, or setting them in .bashrc / .zshrc.
# Load variables from .env file
export $(cat .env | xargs)

Ensuring your environment is properly configured can prevent a lot of runtime errors.

2. Test Nginx Configuration

Nginx is a popular web server, but even small syntax errors in configuration files can break your setup. Always test your Nginx configuration after changes:

sudo nginx -t

If there are any errors, this command will highlight them, allowing you to fix them before restarting the service.

3. Check DNS Resolution

Sometimes, issues are not with your server but with DNS. The dig command helps you see where a domain is pointed:

dig example.com

Look for the ANSWER SECTION in the output to verify that your domain points to the correct IP address.

4. Inspect Service Status

System services may fail to start or crash unexpectedly. Use systemctl to check the status of any service:

systemctl status nginx
systemctl status <service-name>

This will show logs, errors, and the current state of the service, helping you pinpoint the problem.

5. Check Firewall Rules

Network issues can often be caused by misconfigured firewall rules. Check whether your firewall is blocking the required ports:

sudo ufw status
sudo iptables -L

Ensure that ports like 80 and 443 for web servers are open and accessible.

Conclusion

By mastering these five techniques—checking environment variables, testing Nginx configurations, verifying DNS, inspecting service status, and checking firewall rules—you can quickly identify the root cause of most Linux issues. Keep these commands handy and incorporate them into your troubleshooting workflow to save time and headaches.