Installing Composer on Debian, Ubuntu, and Derivatives

Composer is a dependency manager for PHP that allows you to install and manage packages easily. Below are the steps to install Composer on Debian, Ubuntu, and derived distributions.

1. Update the system

Before installing Composer, it is recommended to update the system:

sudo apt update

sudo apt upgrade

2. Install necessary dependencies

Composer requires PHP and some additional modules. Install them with:

sudo apt install php-cli php-zip php-curl

3. Download the Composer installer

Navigate to the user's home directory and download the installer:

cd ~

curl -sS https://getcomposer.org/installer -o /tmp/composer-setup.php

4. Verify the installer's integrity

To ensure that the installer has not been altered, we obtain the official hash and compare it with the downloaded file:

HASH=`curl -sS https://composer.github.io/installer.sig`

Run the following command to obtain the hash:

echo $HASH

With the following PHP command, we verify the integrity of the installation script by matching the hash of the downloaded file with the obtained hash. If the output indicates "Installer verified," the file is safe, and we can proceed with the installation:

php -r "if (hash_file('SHA384', '/tmp/composer-setup.php') === '$HASH') { echo 'Installer verified'; } else { echo 'Installer corrupt'; unlink('/tmp/composer-setup.php'); } echo PHP_EOL;"

5. Install Composer

Run the following command to install Composer in /usr/local/bin/ and make it globally accessible:

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

If the installation is successful, you will see a message similar to:

        All settings correct for using Composer
        Downloading...
        Composer (version x.x.x) successfully installed to: /usr/local/bin/composer
    

6. Verify the installation

To check that Composer is installed correctly, run:

composer

Composer is an essential tool for PHP developers. By following these steps, you can easily install it on Debian, Ubuntu, and their derivatives. Now you are ready to manage dependencies and develop applications efficiently.