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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 <hostname_or_ip>
- Check service availability with telnet command:
telnet <ip> <port>
- Verify service status, firewall settings, logs, and configuration:
systemctl status <service_name> firewall-cmd --list-all journalctl -xe
2. Disk Space Full Issue
- Detect system performance degradation:
df -h
- Identify large files/directories:
du -sh * | sort -h
- Check disk health:
badblocks -v /dev/sdX iotop
3. Filesystem Corruption
- Check log files for errors:
cat /var/log/syslog | grep -i error
- Run fsck to repair filesystem:
fsck /dev/sdX
4. Fstab File Issues
- Verify fstab entries:
cat /etc/fstab mount -a
5. Memory Issues
- Monitor memory usage:
free -m top htop
- Manage high-memory processes:
kill -9 <PID>
6. Swap Space Management
- Create and enable swap file:
sudo fallocate -l 1G /swapfile sudo chmod 600 /swapfile sudo mkswap /swapfile sudo swapon /swapfile echo '/swapfile none swap sw 0 0' | sudo tee -a /etc/fstab
# You Should Know:
Advanced Troubleshooting Commands
- Network Diagnostics:
netstat -tuln ss -tuln
- Check Open Files:
lsof | grep deleted
- System Performance:
vmstat 1 sar -u 1 3
- Kernel Logs:
dmesg | grep -i error
Automated Log Analysis
grep -i "error|fail|critical" /var/log/*.log
### **Recovering Deleted Files**
extundelete /dev/sdX --restore-file /path/to/file
### **Checking for Hardware Failures**
smartctl -a /dev/sdX
# What Undercode Say
Linux troubleshooting requires a systematic approach—check logs, verify configurations, and use the right tools. Key commands like df, du, top, fsck, and `journalctl` are essential. Always monitor system health with vmstat, iostat, and dmesg. For persistent issues, consider rescue mode or live USB diagnostics. Automation with scripts (bash, awk, sed) can streamline debugging.
# Expected Output:
A fully structured troubleshooting guide with verified Linux commands for resolving common system issues.
References:
Reported By: Manoj K – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅
