htop / System Monitoring

Overview

htop is an interactive process viewer for Linux. Combined with other CLI tools (top, vmstat, iostat, iotop, nethogs), it provides comprehensive real-time system monitoring without installing external agents.

Instructions

Step 1: Process Monitoring

htop                      # interactive process viewer
htop -u deploy            # filter by user
htop -p 1234,5678         # monitor specific PIDs

# Inside htop:
# F5 = tree view (parent/child processes)
# F6 = sort by column
# F9 = kill process
# / = search
# Space = tag process

Step 2: Resource Analysis

# CPU and memory overview
free -h                    # memory usage (human-readable)
uptime                     # load average (1, 5, 15 min)
nproc                      # number of CPU cores

# Disk I/O
iostat -x 1                # disk I/O stats, 1 second interval
iotop                      # top for disk I/O (shows which process reads/writes)

# Network
nethogs                    # bandwidth per process
ss -tulnp                  # listening ports with process names
iftop                      # bandwidth per connection

Step 3: Quick Diagnostics Script

#!/bin/bash
# scripts/server-status.sh — Quick health check
echo "=== CPU Load ==="
uptime

echo -e "\n=== Memory ==="
free -h

echo -e "\n=== Disk ==="
df -h /

echo -e "\n=== Top 5 CPU Processes ==="
ps aux --sort=-%cpu | head -6

echo -e "\n=== Top 5 Memory Processes ==="
ps aux --sort=-%mem | head -6

echo -e "\n=== Listening Ports ==="
ss -tulnp | grep LISTEN

Guidelines

• Load average > number of CPU cores = system is overloaded.
• free -h: look at "available" column, not "free" (Linux uses free RAM for cache).
• Use dstat for combined CPU/disk/net stats in one view.
• For historical monitoring, pair with Prometheus + Grafana or Netdata.