Linux Troubleshooting Cheat Sheet

Linux Troubleshooting Cheat Sheet | Essential Commands for Production Environments

Linux is easy to manage — until something breaks in production! 😄
A server won't boot, CPU usage suddenly spikes, disk space runs out, SSH stops responding, or a critical service refuses to start.

That's why systematic troubleshooting is essential for every Linux System Administrator and IT Infrastructure Engineer.

🔍 What's Covered in This Linux Troubleshooting Guide?
🔴 Boot Issues: systemctl, journalctl, dmesg, grub
📈 CPU & Performance: top, htop, uptime, ps
💾 Disk & Storage: df -h, du -sh, lsblk, mount
⚙️ Service Failures: systemctl status, systemctl restart
🌐 Network Issues: ip addr, ip route, ping, ss -tulnp
🔐 Permission Errors: chmod, chown, ls -l
💻 SSH Troubleshooting: systemctl status sshd, ssh -vvv, journalctl -u sshd
📦 Package Management: apt, dnf, rpm
❌ Process & Memory Issues: free -h, vmstat, kill, ps aux
🔥 Firewall & Ports: firewall-cmd, ufw, iptables, ss
🕐 Time Synchronization: timedatectl, chronyc
📋 Log Analysis: /var/log/messages, /var/log/syslog, /var/log/secure, journalctl
🛠️ Production Troubleshooting Workflow
1️⃣ Check system status and symptoms.
2️⃣ Review logs and identify errors.
3️⃣ Analyze CPU, memory, disk, and network resources.
4️⃣ Identify the root cause before applying changes.
5️⃣ Implement the fix safely.
6️⃣ Verify service recovery and monitor system stability.

💡 A Golden Rule for Production Engineers:
Don't restart first. Don't guess. Check the logs, investigate the root cause, fix it, and verify the result.
Troubleshoot systematically. Resolve confidently. Keep production stable.