drush-composer.sh

#!/usr/bin/env bash
rm -rf composer.phar*
rm -rf composer*
rm -rf drush*

echo "Check out Composer"
git clone git@github.com:composer/composer composer

echo "Install Composer"
wget http://getcomposer.org/composer.phar
cd composer && php ../composer.phar install
cd ..

echo "Check out Drush 7"
git clone -b 7.x git@github.com:drush-ops/drush.git drush

echo "Install Drush dependencies"
cd drush
php ../composer/bin/composer install
cd ..
chmod +x drush/drush

drush/drush status