Linux & DevOps Troubleshooting Blog
Practical guides for Linux engineers — NGINX debugging, process troubleshooting, CIS hardening, and production incident response.
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79 posts · page 4 of 9
Linux Check Open Connections: ss, netstat, lsof Examples
Check open network connections in Linux using ss, netstat, and lsof — see established connections, connection counts by state, and find which process owns each connection.
Linux Check Memory Usage: free vs top Explained
Check memory usage in Linux using free, top, and /proc/meminfo — understand available vs free, detect memory pressure, and identify memory-hungry processes.
Linux Check Listening Ports with ss: Complete Guide
Check listening ports in Linux with ss — see TCP and UDP listeners, find which process owns each port, filter by interface binding, and detect unexpected services.
Linux Check Last Login Users: last, lastlog, who
Check last login history in Linux using last, lastlog, and who — find recent logins, failed attempts, and suspicious access patterns for security audits.
Linux Check File Size: ls, du, stat Command Examples
Check file size in Linux using ls -lh, du, and stat — understand apparent size vs disk usage, find files by size, and script size checks with real examples.
Linux Check Disk Usage by Folder: du Command Guide
Check disk usage by folder in Linux with du — sort directories by size, drill down to find what's consuming space, and use ncdu for interactive exploration.
Linux Check Disk I/O Usage: iostat Examples
Check disk I/O usage in Linux using iostat — read utilization, throughput, and latency metrics, identify saturated disks, and correlate I/O with application slowdowns.
journalctl Filter by Time Range: Real Examples
Filter journalctl output by time range, unit, priority, and keyword — with real command examples for production incident investigation and log triage.
iptables Block IP: Practical Examples for Linux
Block IPs with iptables — block single IP, IP range, port-specific rules, make rules persistent, and use ipset for large block lists. Real production examples.