Linux nload command

Filed Under: UNIX/Linux
Linux Nload Command

nload is a Linux command-line tool used to monitor network traffic and bandwidth usage in real time, using insightful graphs and traffic statistics.

In this article, we shall take a quick look at what the nload command can do for us.


Installing nload Command

If nload is not installed on your system, try typing the below command and examine the output.

nload --help

Based on the ouput, we can check if we have nload installed.

Linux Nload Command Not Found
Linux Nload Command Not Found

In my case (Ubuntu), I do not have it installed yet. So install it using your package manager (apt in my case).

Now, on typing nload --help, a suitable help prompt will appear, indicating that it is now installed on your system.


Using nload Command

There are different ways of invoking nload command to perform and show the required statistics as per the option given. Let us understand that one by one.


Default config: No options

We can directly call nload command using default settings by simply typing:

nload

This will now take you to another screen, which will show you the network visualizations in real-time, coming from various devices.

Nload Command Default
Nload Command Default 1

Here, as you can see, there are 3 pages available; One for each device. A device is anything which sends and/or receives internet packets on the same network, but usually, it represents a network interface device. It does not necessarily need to be a separate physical device, but can even be on the same machine!

In my case, my first device is Docker, which is not a physical device, but rather just a service which sends packets through the network. Since it is present locally, it is also listed as a device on nload command.

The statistics for this device show that currently, Docker is not sending or receiving any types of packets across a network connection, which is to be expected, as we are not running any Docker Container,

Key Shortcuts for navigation

When the statistics window is open, the following key bindings serve as navigation within the window.

KeybindingFunction
Left and Right arrow keysSwitch the display to the next network device/page
Enter / TabSwitch the display to the next network device/page
F2Display the options window
F5Save current settings to the user config file
F6Reload settings from the configuration file
q / Ctrl + CQuit nload command

Now that we know how we can navigate the screen in nload, let us move to our next device, which we can examine by pressing the right arrow key.

Nload Command Page Two
Nload Command Page Two

This shows that the second device is ens3, which is a network interface. This is the primary means through which my system is communicating with the internet, and therefore, this roughly shows the bandwidth of my network via the ens3 interface. Since there are no packets actively being transferred via this interface, there is no traffic graph.

Now that we understand the basics of using nload, let us understand some more options for this command.


Display multiple devices

To display multiple network interfaces at the same time without the graphs, use the -m option. This offers a view of all the interfaces in one screen.

nload -m
Nload Multiple Network Interfaces
Nload Multiple Network Interfaces

This makes it easier to monitor the whole network more easily, using a minimal display screen without traffic graphs.


Set a time window

We can use the -a option to set the length in seconds of the time window for average calculation. By default, nload sets this to be 300 seconds.

Syntax:

nload -a DURATION

Where DURATION is the number of seconds used for calculation.

An example invocation can be:

nload -a 100

Set the refresh rate

The -t interval flag sets the refresh interval of the display in milliseconds. By default, nload sets this to be 500 seconds.

nload -t 600

Use a specific network device

We can specify network devices to use with the devices flag. The default option is set to “all”, so to change this, we need to explicitly specify the network device to the devices flag.

nload devices ens3

The above command analyses network packet statistics in the ens3 interface.


Putting them together – Using multiple options

As for other commands, we can invoke nload using multiple options to analyze the network traffic according to our needs.

For, example, the below command will display multiple devices across all available interfaces with a time window of 400 seconds and a refresh rate of 600 milliseconds.

nload -m -a 400 -t 600

Output

Linux Nload Multiple Options
Linux Nload Multiple Options

Configuration files for nload command

The nload command can take advantage of some special configuration files to specify the command invocation, instead of using the command options all the time.

Such configuration files can specify the options with which nload starts up by default. There are 2 configuration files, one for the current user, and a global system-wide configuration.

The system configuration for nload is located at /etc/nload.conf. It is generally advised to not tamper with this file, as we have a separate user config file for user specific settings.

The user configuration file is located at $HOME/.nload, where $HOME is the Home Environment Variable, that mentions your home directory. This file may not exist by default, but nload creates this automatically for us when we save the settings using F5. These settings will then be used by default if we type nload, since a configuration file exists!

We can first check if the user config file exists, using this script:

#!/bin/sh

if test -f $HOME/.nload; then
    echo "Found"
else
    echo "Not Found"
fi
Nload Check Cofig File 1
Nload Check Cofig File 1

There is no such file in my system, so let’s create it using nload with the previous set of options and saving it by F5.

nload -m -a 400 -t 600

After saving it, and exiting the window, run the script again. nload must have automatically created a config file and saved settings related to our options.

Let’s examine it using any text editor.

vi $HOME/.nload

Indeed, an existing file opens for us.

Nload Config Options
Nload Config Options

This is more or less some of the options which we specified, so this indeed works.

Now, if you want to invoke nload with the same options, you can simply type nload, and the options will be automatically specified in the configuration file!


Conclusion

In this tutorial, we learned about how we can use the nload command to monitor network traffic. We also learned various options which can be used to set custom monitoring options and analyze our network bandwidth and traffic accordingly, and to also work with configuration files for reusability.

Hope this tutorial serves to be helpful for you to use this useful tool!


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