To install htop on a pfSense firewall, you will need to use the pfSense Package Manager.
Here are the steps to install htop using the Package Manager:
Log in to the pfSense web interface and go to System > Package Manager.
In the "Available Packages" tab, search for "htop" using the search box.
Select the htop package and click the "Install" button.
Review the package details and click the "Confirm" button to begin the installation.
Wait for the installation to complete, which may take a few minutes.
Once the installation is complete, click the "Close" button to return to the Package Manager.
To launch htop, go to the Services menu and select the "System: Shell" option. This will open a terminal window where you can enter the htop command.
It's important to note that htop is a resource-intensive application and may not be suitable for use on low-powered devices or devices with limited memory. It is also recommended to use caution when using htop or other system utilities on a production firewall, as improper use can potentially disrupt the operation of the firewall.