1. Installation - Linux / Unix / OSX
The first step is to download Composer, which will effectively create a Phar (PHP Archive) file called composer.phar. From your terminal, run the following command:
curl -sS https://getcomposer.org/installer | php
1.1. Installation Errors
In some cases, you might receive the following error:
Some settings on your machine make Composer unable to work properly. Make sure that you fix the issues listed below and run this script again: The detect_unicode setting must be disabled. Add the following to the end of your `php.ini`: detect_unicode = Off A php.ini file does not exist. You will have to create one. If you can not modify the ini file, you can also run `php -d option=value` to modify ini values on the fly. You can use -d multiple times.
For OS X 10.8, the php.ini file should be located in /private/etc/. If you don't have one already, you can copy the default one:
sudo cp /private/etc/php.ini.default php.ini
Then, edit the file and append the following to it:
detect_unicode = Off
Save the file and rerun the curl command above.
1.2. Running Composer
The resulting file will be called composer.phar, a PHP Archive that can be executed directly via PHP. However, in my case, I want Composer to be accessible globally by simply typing composer. To do this, move it to /usr/bin/ and create an alias:
sudo mv composer.phar /usr/local/bin/composer nano ~/.bash_profile
Add this to your .bash_profile. It may be empty or non-existent, so go ahead and create it:
alias composer="php /usr/local/bin/composer"
Now, relaunch your terminal and you'll be able to access Composer simply by calling composer.
2. Installation - Windows
2.1. 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 call composer from any directory in your command line.
2.2. Manual Installation
Change to a directory on your PATH and run the installer following the Download page instructions to download composer.phar.
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. For information on changing your PATH variable, please see this article and/or use Google.