Why Linux Monitoring Tools Matter for Hosting

If you’re running anything on Linux—cloud VMs, Docker containers, VPS, or a beefy dedicated server—you need to know what’s happening under the hood. Whether you’re chasing down a performance bottleneck, keeping tabs on resource usage, or just want to make sure your shiny new server isn’t melting, monitoring tools are your best friend. But with so many options, which one do you pick? Today, we’re putting two of the most popular real-time monitoring tools—Glances and nmon—head to head.

Let’s break down how they work, how to get them running in minutes, and which one might be the right fit for your next project (or fire-fighting session).

The Big Question: Glances vs nmon

Both Glances and nmon are lightweight, terminal-based monitoring tools for Linux (and other *nix systems). They’re designed to give you a quick, at-a-glance overview of your system’s health—CPU, memory, disk, network, and more. But they take different approaches, and each has its own strengths and quirks.

Three Main Questions to Ask

• How do they work? What’s under the hood—what do they monitor, and how do they show it?
• How easy are they to set up and use? Can you get started in five minutes, or will you be reading man pages all afternoon?
• Which one fits your workflow? Are you a sysadmin, a developer, or just someone who wants to keep their server humming along?

How Does It Work? Algorithms, Structure, and Philosophy

Glances: The Swiss Army Knife

Glances is written in Python and uses the psutil library to gather system stats. It’s all about giving you a broad overview—CPU, memory, disk I/O, network, sensors, processes, Docker containers, and even RAID status. The UI is colorful, dynamic, and can be accessed via the terminal or a web browser (yep, it has a built-in web server!).

• Real-time dashboard: Everything you need is on one screen, updated every second.
• Auto-scaling: Glances adjusts what it shows based on your terminal size and available sensors.
• Extensible: Plugins for Docker, RAID, sensors, and more.
• Client/server mode: Monitor remote servers from your laptop.

nmon: The No-Nonsense Performance Monitor

nmon (short for Nigel’s Monitor) is a C-based tool originally built for AIX, now ported to Linux. It’s fast, efficient, and a bit old-school—think less “dashboard,” more “engineer’s toolkit.” nmon focuses on raw performance stats, with lots of toggles to show/hide different data sets. It can also capture stats to CSV for later analysis (perfect for troubleshooting or capacity planning).

• Interactive display: Toggle CPU, memory, disk, network, processes, and more with single keypresses.
• Data capture: Run in background mode to log stats for later graphing.
• Minimal dependencies: No Python, no fancy libraries—just a single binary.
• Super lightweight: Practically zero impact on system resources.

Quick & Easy Setup: Get Monitoring in Minutes

Installing Glances

Glances is available in most Linux repos, or you can install it via pip for the latest version.

# On Ubuntu/Debian
sudo apt update
sudo apt install glances

# Or, for the latest version via pip
pip install glances

# Run it!
glances

Want to monitor remotely? Start the web server:

glances -w
# Then visit http://your-server-ip:61208 in your browser

Installing nmon

nmon is even simpler—just install and run.

# On Ubuntu/Debian
sudo apt update
sudo apt install nmon

# On CentOS/RHEL
sudo yum install nmon

# Run it!
nmon

To capture data for later analysis:

nmon -f -s 10 -c 360
# -f: output to file
# -s 10: sample every 10 seconds
# -c 360: 360 samples (1 hour)

Comparison Table: Glances vs nmon

Feature	Glances	nmon
Language	Python	C
UI	Colorful, dashboard, web UI	Text-based, toggles, no web UI
Remote Monitoring	Yes (client/server, web)	No (but can log data for remote analysis)
Resource Usage	Low (but higher than nmon)	Ultra-low
Extensibility	Plugins (Docker, RAID, sensors)	No plugins
Data Logging	Yes (CSV, JSON, InfluxDB, etc.)	Yes (CSV)
Best For	All-in-one dashboard, remote monitoring, containers	Performance analysis, scripting, minimalism

Examples & Real-World Cases

Case 1: Docker Host Monitoring

• Glances: With the Docker plugin, you can see container stats right in the dashboard. Super handy for devs running lots of microservices.
• nmon: No native Docker support. You’ll see overall system usage, but not per-container stats.

Case 2: Performance Troubleshooting on a VPS

• nmon: Perfect for this! Fire up nmon, toggle to CPU, memory, and disk stats, and watch for spikes. Capture a log for later analysis if the issue is intermittent.
• Glances: Also great, but the dashboard can feel a bit busy if you just want raw numbers.

Case 3: Remote Monitoring for Multiple Servers

• Glances: Run in server mode on each box, then connect from your laptop. Or use the web UI for a quick peek from anywhere.
• nmon: Not built for this. You’d need to collect logs and analyze them elsewhere.

Positive Example: Automation & Scripting

• nmon: Its CSV output is perfect for feeding into scripts, Grafana, or Excel for graphing. Great for scheduled reports or capacity planning.
• Glances: Can output to JSON, InfluxDB, or even MQTT—awesome for IoT or custom dashboards.

Negative Example: Beginner Mistakes

• Glances: Some users forget to install Python dependencies, leading to missing features (like sensors or Docker stats).
• nmon: Easy to forget to toggle the right stats on/off, or to set the correct sample interval for logging.

Beginner Mistakes & Common Myths

• “nmon is outdated!” Nope—it’s still actively maintained and widely used, especially in enterprise environments.
• “Glances is heavy because it’s Python.” It’s heavier than nmon, but still very lightweight compared to full-blown monitoring stacks.
• “I need a full monitoring suite like Nagios or Zabbix.” Not always! For quick troubleshooting or resource checks, Glances or nmon are way faster to deploy.

Similar Solutions & Alternatives

• htop: Great for process monitoring, but less info on disk/network.
• bpytop/btop: Eye-candy terminal dashboards, more interactive but less extensible than Glances.
• Netdata: Gorgeous web-based monitoring, but heavier and more complex to set up.
• Dockbix: For Docker + Zabbix fans.

Interesting Facts & Non-Standard Usage

• Glances can be run as a REST API server—you can pull stats into your own tools or dashboards.
• nmon’s CSV logs are so popular that there are entire ecosystems of tools (like nmon Analyser) built just to parse and graph them.
• Glances can send alerts (via email, Slack, etc.) if resource usage crosses thresholds—handy for lightweight automation.

Automation, Scripting, and New Opportunities

• Glances: Use its REST API or MQTT output to feed stats into home automation, custom dashboards, or even trigger scripts (e.g., auto-scale your VPS when memory is low).
• nmon: Schedule regular nmon runs via cron, collect logs, and generate performance reports automatically. Perfect for compliance, audits, or just keeping your boss happy.

Conclusion: Which Should You Use?

Both Glances and nmon are fantastic tools, and honestly, you can’t go wrong with either. Here’s the TL;DR:

• Choose Glances if: You want a modern, all-in-one dashboard, need remote or web access, or want to monitor Docker containers and sensors.
• Choose nmon if: You want raw speed, minimal dependencies, or need to capture performance data for later analysis (especially for scripting or automation).

For most VPS, cloud, or dedicated server users, Glances is the friendlier option—especially if you’re juggling multiple servers or containers. If you’re a performance geek or need to script/report, nmon is a classic for a reason.

Ready to try it out? Spin up a new VPS or dedicated server, and see which tool fits your workflow. Happy monitoring!

• Official Glances: https://nicolargo.github.io/glances/
• Official nmon: http://nmon.sourceforge.net/pmwiki.php

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