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System Monitoring: Know What's Happening

System monitoring shows what's happening. CPU. Memory. Disk. Network.

Here's the thing: Monitoring shows problems before they become disasters. Learn it. Use it.

Real-Time Monitoring​

top: Process Monitor​

top                               # Interactive monitor

Navigation:

  • q = Quit
  • M = Sort by memory
  • P = Sort by CPU
  • 1 = Show all CPUs

My take: top is basic. But it works. Use it.

htop: Better top​

htop                              # Better version

My take: Install htop. It's better than top. More colorful. Easier.

iotop: I/O Monitor​

sudo iotop                         # Monitor disk I/O

My take: iotop shows disk I/O. Useful when disk is slow.

nethogs: Network Monitor​

sudo nethogs                       # Monitor network by process

My take: nethogs shows network by process. Useful for network issues.

Resource Monitoring​

CPU Usage​

top
htop
mpstat                            # CPU statistics

My take: Monitor CPU. High usage means problems.

Memory Usage​

free -h                           # Memory usage
top
htop

My take: Monitor memory. Low memory causes problems.

Disk Usage​

df -h                             # Disk space
du -sh *                          # Directory sizes
iotop                             # Disk I/O

My take: Monitor disk. Full disk breaks things.

Network Usage​

ifstat                            # Network statistics
nethogs                           # By process

My take: Monitor network. High usage means traffic.

Common Monitoring Patterns​

Quick System Check​

# CPU and memory
top

# Disk space
df -h

# Disk I/O
sudo iotop

Continuous Monitoring​

# Watch disk space
watch -n 5 df -h

# Watch processes
watch -n 2 'ps aux | head -20'

My take: watch monitors continuously. Useful for tracking changes.

Common Mistakes (I've Made These)​

  1. Not monitoring: Monitor systems. Find problems early.

  2. Only checking CPU: Check CPU, memory, disk, network. All matter.

  3. Not using htop: Install htop. It's better than top.

  4. Ignoring I/O: Disk I/O can be the problem. Check it.

  5. Not setting up alerts: Manual monitoring is tedious. Automate it.

Real-World Examples​

Monitor System​

# CPU and memory
htop

# Disk
df -h
sudo iotop

# Network
sudo nethogs

Find Resource Hogs​

# Top CPU
ps aux --sort=-%cpu | head -10

# Top memory
ps aux --sort=-%mem | head -10

What's Next?​

Now that you can monitor systems, let's talk about Performance Tools for detailed analysis.

Personal note: I used to ignore monitoring. Then systems broke. Now I monitor everything. It prevents problems. Monitor your systems.