$ curl -sS https://getcomposer.org/installer | php
$ sudo mv composer.phar /usr/local/bin/composer
Install drush globally (for your user), you can specify the version:
$ composer global require drush/drush:8.*
This will install in the directory: ~/.composer/vendor/drush/drush, so we will have to set path.
sudo ln -s /home/<linux user name>/.composer/vendor/drush/drush /usr/bin/drush
export PATH="$PATH:/home/<linux user name>/.composer/vendor/drush/drush:/usr/local/bin"
Run "drush status" to see if drush has been installed.