Entware is a software package installer. It allows you to install programs that can't be included into FreshTomato itself, mainly due to most routers' limited flash RAM size. This example assumes you have a USB flash drive mounted under /mnt/sda1. If you need more details about configuring USB storage before reading this, see the USB Support page.
First, create the opt folder and mount it:
mkdir /mnt/sda1/opt mount -o bind /mnt/sda1/opt /opt
Then, you can run the installation command:
Finally, you can install the packages you want, for example:
opkg update opkg upgrade opkg install htop