install composer

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

#The install command (composer require symfony/symfony)
#The current version (3.2.4)
#Create a directory on your server for this project:
sudo mkdir /var/www/html/symfony-test

cd /var/www/html/symfony-test
sudo vim composer.json

{
  "require": {
    "symfony/symfony": "3.2.4"
  }
}
#save and exit and hit the following command
composer install