Skip to content

🛠️ Troubleshooting Commands For Linux - CheatSheets

This article combines collection of common Linux commands used while debugging / troubleshooting in production environments.

1. Troubleshooting & Logs 📇

When an application isn't working, these are your first tools:

  • tail -f [filename] : Used to watch logs in real-time.  

  • grep -i "error" [filename] : Used to search for specific keywords like "error" or "failed" within a file.  

  • top or htop : To check CPU and RAM usage to see if a process is crashing the server.

2. Networking & Connectivity 🌐

To find why a service can't talk to a database:

  • curl -v [URL] : Checks if a web service is reachable and shows the headers.

  • netstat -tuln : Shows all active ports to see if your application (like Jenkins or a Flask API) is actually listening.

  • nslookup [domain] : Used to verify if DNS is working correctly.

3. File & Permission Management 🔓

Crucial for Least Privilege and security:

  • chmod : To change file permissions (e.g., making a script executable).

  • chown : To change who owns a file or folder (important for Jenkins access).

  • df -h : To check if your disk is full (a common reason why builds fail).

4. Critical Scenario: "The server is slow. What do you do?" 🧱🔍💿

  • Check Resources: Run top to see if a process is hogging the CPU.

  • Check Disk Space: Run df -h to see if the logs have filled up the storage.

  • Check Logs: Use tail on the application logs to see if it's stuck in a loop.