composer/doc/00-intro.md

Introduction

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

Dependency management

Composer is not a package manager in the same sense as Yum or Apt are. Yes, it deals with "packages" or libraries, but it manages them on a per-project basis, installing them in a directory (e.g. vendor) inside your project. By default it will never install anything globally. Thus, it is a dependency manager.

This idea is not new and Composer is strongly inspired by node's npm and ruby's bundler.

Suppose:

a) You have a project that depends on a number of libraries.

b) Some of those libraries depend on other libraries.

Composer:

c) Enables you to declare the libraries you depend on.

d) Finds out which versions of which packages can and need to be installed, and installs them (meaning it downloads them into your project).

See the Basic usage chapter for more details on declaring dependencies.

System Requirements

Composer requires PHP 5.3.2+ to run. A few sensitive php settings and compile flags are also required, but when using the installer you will be warned about any incompatibilities.

To install packages from sources instead of simple zip archives, you will need git, svn or hg depending on how the package is version-controlled.

Composer is multi-platform and we strive to make it run equally well on Windows, Linux and OSX.

Installation - Linux / Unix / OSX

Downloading the Composer Executable

Composer offers a convenient installer that you can execute directly from the commandline. Feel free to download this file or review it on GitHub if you wish to know more about the inner workings of the installer. The source is plain PHP.

There are in short, two ways to install Composer. Locally as part of your project, or globally as a system wide executable.

Locally

Installing Composer locally is a matter of just running the installer in your project directory:

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

Note: If the above fails for some reason, you can download the installer with php instead:

php -r "readfile('https://getcomposer.org/installer');" | php

The installer will just check a few PHP settings and then download composer.phar to your working directory. This file is the Composer binary. It is a PHAR (PHP archive), which is an archive format for PHP which can be run on the command line, amongst other things.

Now just run php composer.phar in order to run Composer.

You can install Composer to a specific directory by using the --install-dir option and additionally (re)name it as well using the --filename option:

curl -sS https://getcomposer.org/installer | php -- --install-dir=bin --filename=composer

Now just run php bin/composer in order to run Composer.

Globally

You can place the Composer PHAR anywhere you wish. If you put it in a directory that is part of your PATH, you can access it globally. On unixy systems you can even make it executable and invoke it without directly using the php interpreter.

Run these commands to globally install composer on your system:

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

Note: If the above fails due to permissions, run the mv line again with sudo.

A quick copy-paste version including sudo:

curl -sS https://getcomposer.org/installer | sudo php -- --install-dir=/usr/local/bin --filename=composer

Note: On some versions of OSX the /usr directory does not exist by default. If you receive the error "/usr/local/bin/composer: No such file or directory" then you must create the directory manually before proceeding: mkdir -p /usr/local/bin.

Note: For information on changing your PATH, please read the Wikipedia article and/or use Google.

Now just run composer in order to run Composer instead of php composer.phar.

Installation - Windows

Using the Installer

This is the easiest way to get Composer set up on your machine.

Download and run Composer-Setup.exe. It will install the latest Composer version and set up your PATH so that you can just call composer from any directory in your command line.

Note: Close your current terminal. Test usage with a new terminal: This is important since the PATH only gets loaded when the terminal starts.

Manual Installation

Change to a directory on your PATH and run the install snippet to download composer.phar:

C:\Users\username>cd C:\bin
C:\bin>php -r "readfile('https://getcomposer.org/installer');" | php

Note: If the above fails due to readfile, use the http url or enable php_openssl.dll in php.ini

Create a new composer.bat file alongside composer.phar:

C:\bin>echo @php "%~dp0composer.phar" %*>composer.bat

Add the directory to your PATH environment variable if it isn't already.

Close your current terminal. Test usage with a new terminal:

C:\Users\username>composer -V
Composer version 27d8904

Using Composer

Now that you've installed Composer, you are ready to use it! Head on over to the next chapter for a short and simple demonstration.

Basic usage →