Introduction

Composer is a popular dependency management tool for PHP, created mainly to facilitate installation and updates for project dependencies. It will check which other packages a specific project depends on and install them for you, using the appropriate versions according to the project requirements. Composer is also commonly used to bootstrap new projects based on popular PHP frameworks, such as Symfony and Laravel.

In this tutorial, you’ll install and get started with Composer on an Ubuntu 20.04 system

Prerequisites

In order to follow this guide, you will need access to an Ubuntu 20.04 server as a non-root sudo user, and a firewall enabled on your server. To set this up, you can follow our initial server setup guide for Ubuntu 20.04.

Step 1 — Installing PHP and Additional Dependencies

In addition to dependencies that should be already included within your Ubuntu 20.04 system, such as git and curl, Composer requires php-cli in order to execute PHP scripts in the command line, and unzip to extract zipped archives. We’ll install these dependencies now.

First, update the package manager cache by running:

sudo apt update

Next, run the following command to install the required packages:

sudo apt install php-cli unzip

You will be prompted to confirm installation by typing Y and then ENTER.

Once the prerequisites are installed, you can proceed to install Composer.

Step 2 — Downloading and Installing Composer

Composer provides an installer script written in PHP. We’ll download it, verify that it’s not corrupted, and then use it to install Composer.

Make sure you’re in your home directory, then retrieve the installer using curl:

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

Next, we’ll verify that the downloaded installer matches the SHA-384 hash for the latest installer found on the Composer Public Keys / Signatures page. To facilitate the verification step, you can use the following command to programmatically obtain the latest hash from the Composer page and store it in a shell variable:

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

If you want to verify the obtained value, you can run:

echo $HASH

Output

756890a4488ce9024fc62c56153228907f1545c228516cbf63f885e036d37e9a59d27d63f46af1d4d07ee0f76181c7d3

Now execute the following PHP code, as provided in the Composer download page, to verify that the installation script is safe to run:

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

You’ll see the following output:

output

Installer verified

If the output says Installer corrupt, you’ll need to download the installation script again and double-check that you’re using the correct hash. Then, repeat the verification process. When you have a verified installer, you can continue.

To install composer globally, use the following command which will download and install Composer as a system-wide command named composer, under /usr/local/bin:

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

You’ll see output similar to this:

output

All settings correct for using Composer Downloading... Composer (version 1.10.5) successfully installed to: /usr/local/bin/composer Use it: php /usr/local/bin/composer

To test your installation, run:

Output
  ______
 / ____/___  ____ ___  ____  ____  ________  _____
/ /   / __ \/ __ `__ \/ __ \/ __ \/ ___/ _ \/ ___/
/ /___/ /_/ / / / / / / /_/ / /_/ (__  )  __/ /
\____/\____/_/ /_/ /_/ .___/\____/____/\___/_/
                   /_/
Composer version 1.10.5 2020-04-10 11:44:22

Usage:
 command [options] [arguments]

Options:
 -h, --help                     Display this help message
 -q, --quiet                    Do not output any message
 -V, --version                  Display this application version
     --ansi                     Force ANSI output
     --no-ansi                  Disable ANSI output
 -n, --no-interaction           Do not ask any interactive question
     --profile                  Display timing and memory usage information
     --no-plugins               Whether to disable plugins.
 -d, --working-dir=WORKING-DIR  If specified, use the given directory as working directory.
     --no-cache                 Prevent use of the cache
 -v|vv|vvv, --verbose           Increase the verbosity of messages: 1 for normal output, 2 for more verbose output and 3 for debug
...

This verifies that Composer was successfully installed on your system and is available system-wide.