cd ~/
wget https://github.com/underdarkskies/Ravencoin/releases/download/v2.1.1/raven-2.1.1-arm-linux-gnueabihf.tar.gz
gunzip ./raven-2.1.1-arm-linux-gnueabihf.tar.gz
gunzip didn't work for me just left me with raven-2.1.1-arm-linux-gnueabihf.tar
I ended up using: tar -xvzf raven-2.1.1-arm-linux-gnueabihf.tar.gz
