Atualizar versão do compositor
composer self-update
Chris
composer self-update
brew install composer
#mac
composer self-update
composer global update
php composer.phar self-update
#Ubuntu-Download Composer and create a Phar (PHP Archive) file
$ curl -s https://getcomposer.org/installer | php
#Move it to bin directory
$ sudo mv composer.phar /usr/local/bin/composer