How To Install and Use PHP Composer on Debian 10/9

The PHP Composer is a package management tool. It removes the hassle of maintaining PHP packages for an application manually. You can easily install all the required packages using Composer. It maintains a list of required packages in a JSON file called composer.json.

This tutorial helps you to install and configure PHP composer on Debian 10 Buster, Debian 9 Stretch, and Debian 8 Jessie systems.

1. Prerequsities

Shell access to a running Debian system with sudo privilege.
PHP must be installed and configured, version 5.3 or higher.

2. Install Composer on Debian

You can download the composer script from the getcomposer.org website by running the following command. It will create a composer.phar file in the current directory.

curl -sS https://getcomposer.org/installer | php

Copy composer.phar file under bin directory to make available anywhere in the system. Also, set the execute permission on file. I have changed the filename from composer.phar to the composer for easy use.

mv composer.phar /usr/local/bin/composer 
chmod +x /usr/local/bin/composer

Type composer at the command prompt. This will provide you composer version details along with options available with the composer command.

composer

Output:
   ______
  / ____/___  ____ ___  ____  ____  ________  _____
 / /   / __ \/ __ `__ \/ __ \/ __ \/ ___/ _ \/ ___/
/ /___/ /_/ / / / / / / /_/ / /_/ (__  )  __/ /
\____/\____/_/ /_/ /_/ .___/\____/____/\___/_/
                    /_/
Composer version 2.1.8 2021-09-15 13:55:14

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

3. Upgrade PHP Composer

The composer has the ability to upgrade itself without downloading again. Simply run the below command from the terminal to upgrade compose on Debian.

sudo composer self-update

Working with PHP Composer

Assuming you have been successfully configured PHP composer on your system. That will help you to manage modules for your application. For example, to install a new module for your application.

Switch to the PHP application.

cd /path/to/php-application

Run the following command to install psr/log module in the application.

composer require psr/log

Output:
Using version ^1.1 for psr/log
./composer.json has been created
Running composer update psr/log
Loading composer repositories with package information
Updating dependencies
Lock file operations: 1 install, 0 updates, 0 removals
  - Locking psr/log (1.1.4)
Writing lock file
Installing dependencies from lock file (including require-dev)
Package operations: 1 install, 0 updates, 0 removals
  - Downloading psr/log (1.1.4)
  - Installing psr/log (1.1.4): Extracting archive
Generating autoload files

Composer will automatically create or update composer.json file at application root directory. Now, the application can use the functionality provided by the module.

The above command will install the latest version of the module. You can also define the module version you want to install for your application. If the module is already installed, it will automatically downgrade/upgrade the
package to the specified version.

composer require psr/log=1.0

The module no longer required can be removed with the following command.

composer remove psr/log

All the above commands also update composer.json file accordingly.

Conclusion

In this tutorial, you have found instructions to install composer on a Debian Linux system. You can install composer globally to allow access to all users and applications. Also, you can install composer for a specific directory.