Monitoring your system is important. Through system monitoring we can find problems on the server, hopefully before they impact performance. Today we will examine the following tools:

• top
• htop
• ps
• kill
• nice / renice
• uptime
• vmstat

top

top is a real-time system monitoring tool.

Basic Usage:

top

top has several flags which alter output; be sure to become familar with them.

Top will show the follwing information:

• CPU
• memory usage
• active processes

Key Interactions:

• q to quit
• k to kill a process
• 1 to display per-core CPU usage

htop

Htop is like top, but is more visual & interactive. It allows scrolling, and color coded resource tracking.

Basic Usage:

htop

Key Features:

• Navigate with arrow keys
• Press F9 to kill a process
• Press F6 to sort columns

ps

Ps displays a snapshot of currently running processes.

Basic Usage:

ps aux

You can filter by username:

ps aux -u username

You can also search by process name:

ps aux | grep process_name

kill

Kill terminates processes by PID:

kill PID

To force kill a process:

kill -9 PID

You can find the PID with the ps command:

ps aux | grep process_name

nice & renice

Adjusts process priority (lower = higher priority)

Start a process with priority:

nice -n 10 command

Change priority of an existing process:

renice 5 -p PID   

uptime

Displays system uptime, number of users, and load averages

Usage:

uptime   

vmstat

Reports system performance metrics (CPU, memory, I/O)

Usage:

vmstat 2 5 

(updates every 2 seconds, 5 times)

Final Thoughts

Use htop over top for a more intuitive process view

If kill doesn’t work, escalate to kill -9 PID

Monitor load averages in uptime—high values indicate potential slowdowns

Use vmstat to detect memory swapping and disk I/O bottlenecks

Always check ps aux before terminating processes to avoid killing critical system tasks

Regular use of these commands hones your ability to react swiftly and effectively.