Install drush 8 without uninstalling older drush

I have been struggling since past hour for installing drush 8 without uninstalling drush7.

Here are the steps i followed:
Open your terminal

1. Get latest drush

cd /usr/local/lib/
git clone --branch master https://github.com/drush-ops/drush.git

2. Get composer

curl -sS https://getcomposer.org/installer | php
mv composer.phar /usr/local/bin/composer

3. Install Drush

cd drush
composer install

4. Create an alias for Drush 8

vi ~/.bashrc (ubuntu)

Add this line to file

alias drush8='/usr/local/lib/drush/drush'
source ~/.bashrc

Run Drush 8

Now it’s time to test that everything we did works well. Type:

drush8 version

Thanks for reading it.