“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.” (https://getcomposer.org/doc/00-intro.md)
Para a instalação do Composer no S.O. Ubuntu 18, primeiramente deve-se realizar o download da ferramenta, para isso, executa-se os comandos:
php -r "copy('https://getcomposer.org/installer', 'composer-setup.php');"
php -r "if (hash_file('SHA384', 'composer-setup.php') === '544e09ee996cdf60ece3804abc52599c22b1f40f4323403c44d44fdfdd586475ca9813a858088ffbc1f233e9b180f061') { echo 'Installer verified'; } else { echo 'Installer corrupt'; unlink('composer-setup.php'); } echo PHP_EOL;"
php composer-setup.php
php -r "unlink('composer-setup.php');"
Para tornar o composer um comando global, Acesse https://getcomposer.org/doc/00-intro.md e executar:
$ sudo mv composer.phar /usr/local/bin/composer
Para verificar se a instalação foi realizada com sucesso e exibir a versão instalada:
$ composer -V Composer version 1.8.4
Para mais informações https://getcomposer.org/download/.