Step 1: Install Composer

Composer is a dependency manager for PHP. It allows you to declare the libraries your project depends on and it will manage (install/update) them for you.

Install dependencies

 $ sudo apt-get update
 $ sudo apt-get install php-cli unzip

Download the installer

 $ cd ~
 $ curl -sS https://getcomposer.org/installer -o composer-setup.php

Verify the installer

 $ HASH=`curl -sS https://composer.github.io/installer.sig`
 $ php -r "if (hash_file('SHA384', 'composer-setup.php') === '$HASH') { echo 'Installer verified'; } else { echo 'Installer corrupt'; unlink('composer-setup.php'); } echo PHP_EOL;"

Output

Installer verified

If you get the message Installer corrupt then delete the composer-setup.php file and try again.

Install Composer

 $ sudo php composer-setup.php --install-dir=/usr/local/bin --filename=composer

Test the installation

 $ composer --version

Step 2: Install PHP

Installing dependencies

 $ sudo apt update
 $ sudo apt install -y lsb-release ca-certificates apt-transport-https software-properties-common gnupg2