How to Install and Use Nmon to Monitoring Tool System and Network on Linux

Nmon short for (Ngel’s Monitor), is a fully interactive Linux system performance monitoring command-line utility that was originally developed by IBM for the AIX systems and later ported to the Linux platform.

The important benefit of the nmon tool is that it allows you to monitor the performance of your Linux system aspects such as CPU utilization, memory usage, disk space, network utilization, top processes, virtual machine stats, file systems, resources, power micro-partition and more, in a single, concise view.

In addition to monitoring your Linux system interactively, nmon can also be used in batch mode to gather and save performance data for later analysis.

Installing Nmon Monitoring Tool in Linux

For Debian/Ubuntu:

apt update
apt-get install nmon

For CentOS: AlmaLinux 9

dnf install https://dl.fedoraproject.org/pub/epel/epel-release-latest-9.noarch.rpm
yum install nmon

How to use Nmon to Monitor Linux Performance

Once the installation of Nmon has been finished and you launch it from the terminal by typing the ‘nmon‘ command you will be presented with the following output.

nmon

As you guys can see from the above screenshot, the nmon command-line utility runs completely in interactive mode and it presents the user with the keys to toggle statistics.

Monitor Linux CPU Utilisation

For example, if you want to collect some statistics about CPU performance, you should press the ‘c‘ key on the keyboard of the system you are using. After pressing the ‘c‘ key on the keyboard, we will get the output information about CPU usage.

The following are the keys you can use with the utility to get information on other system resources present in your machine.

• m – Memory
• j – Filesystems
• d – Disks
• n – Network
• V – Virtual Memory
• r – Resource
• N – NFS
• k – kernel
• t – Top-processes
• . – only busy disks/procs
• U – Utilisation

Monitor Linux Top Processes Statistics

To get stats on top processes running on your Linux system press the key ‘t‘ on your keyboard and wait for the information to show up.

Monitor Linux Network Statistics

How about some network stats? Just press ‘n‘ on your keyboard.

Monitor Linux Disk I/O Graphs

Use the ‘d‘ key to get information on disks.

Check Linux Kernel Information

A very important key to use with this tool is ‘k‘, it is used to display some brief information on the kernel of your system.

Check Linux System Information

A very useful key is the key ‘r‘ which is used to give information on different resources such as machine architecture, operating system version, Linux version, and CPU. You can get an idea of the importance of the key ‘r‘ by looking at the following screenshot.

Monitor Linux File System Statistics

To get stats on the file systems press ‘j‘ on your keyboard.

As you can see from the above screenshot, we get information on the size of the file system, used space, free space, type of file system, and the mount point.

Check Linux Memory Information

Use the ‘m‘ key to get information on Memory

Check NFS Data

The key ‘N‘ can help to collect and display data on NFS.

Many tools can do the job of the Nmon utility but none of them is so easy to use and friendly to a Linux beginner. Unfortunately, the tool does not have as many features as other tools such as collect and it can not provide in-depth stats to the user.

You can see How to Setup Collectl – Linux Performance Monitoring here if you want to know more features and information

Conclusion

That’s all the features of Nmon, we hope this article will be useful for you. Good luck!