Download Ruby on Ubuntu

install.sh

# Ruby 2.6.4

sudo apt update && sudo apt -y upgrade && sudo apt -y install build-essential libpq-dev git memcached cifs-utils nginx redis-server nodejs imagemagick libtiff-dev ghostscript
sudo apt-get install graphicsmagick-imagemagick-compat

## Machine 
sudo apt-get install git 

# ruby-install https://github.com/postmodern/ruby-install
mkdir -p ~/src
cd ~/src
wget -O ruby-install-0.7.0.tar.gz https://github.com/postmodern/ruby-install/archive/v0.7.0.tar.gz
tar -xzvf ruby-install-0.7.0.tar.gz
cd ruby-install-0.7.0/
sudo make install

# chruby https://github.com/postmodern/chruby
cd ~/src
wget -O chruby-0.3.9.tar.gz https://github.com/postmodern/chruby/archive/v0.3.9.tar.gz
tar -xzvf chruby-0.3.9.tar.gz
cd chruby-0.3.9/
sudo make install

# install ruby
ruby-install ruby 2.6.4

echo "It's done......~"

Bunch of basics here, and thanks nick!