How to install multiple Drush versions on the account
It requires a lot of resources, so double check if you have enough
The latest dev version to drush/ folder:
mkdir drush
cd drush
curl -sS https://getcomposer.org/installer | php
./composer.phar require drush/drush:dev-master
cd
echo "alias drush='~/drush/vendor/bin/drush'" >> .bashrc
source .bashrc
Drush 9 version
mkdir drush9… Read the rest
cd drush9
curl -sS https://getcomposer.org/installer