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Here are some key points for troubleshooting common issues in Linux systems:
1. Server Connectivity Issues:
- Ping the server by Hostname and IP Address:
ping example.com ping 192.168.1.1
- Check service availability with telnet command:
telnet example.com 22
- Verify service status, firewall settings, logs, and configuration:
systemctl status sshd sudo ufw status journalctl -xe
2. Disk Space Full Issue:
- Detect system performance degradation:
df -h
- Identify large files/directories:
du -sh * | sort -h
- Check disk health:
sudo badblocks -v /dev/sda
3. Filesystem Corruption:
- Check logs for errors:
cat /var/log/syslog | grep error
- Run fsck to repair filesystem:
sudo fsck /dev/sda1
4. Fstab File Issues:
- Verify fstab entries:
cat /etc/fstab sudo mount -a
5. Memory Issues:
- Monitor memory usage:
free -m top htop
- Kill high-memory processes:
kill -9 $(pidof memory-hog-process)
6. Swap Space Management:
- Create and enable swap file:
sudo fallocate -l 1G /swapfile sudo chmod 600 /swapfile sudo mkswap /swapfile sudo swapon /swapfile
- Make swap persistent:
echo '/swapfile none swap sw 0 0' | sudo tee -a /etc/fstab
You Should Know:
- Check open ports:
sudo netstat -tuln sudo ss -tuln
- Analyze disk I/O:
sudo iotop
- Find and kill zombie processes:
ps aux | grep 'Z'
- Test network speed:
speedtest-cli
- Check CPU load:
uptime mpstat
What Undercode Say:
Linux troubleshooting requires a systematic approach—verify connectivity, disk, memory, and logs before making changes. Always back up critical data before running repairs like fsck. Automation (cron, scripts) helps prevent recurring issues.
Expected Output:
<h1>Example output of `df -h` </h1> Filesystem Size Used Avail Use% Mounted on /dev/sda1 50G 45G 2.0G 96% /
<h1>Example output of `free -m` </h1> total used free shared buff/cache available Mem: 7982 4201 1023 123 2757 3456 Swap: 2047 512 1535
References:
Reported By: Shamseer Siddiqui – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
