PHP Composer PHP 5.6でDrushをインストールしません：phpunit/phpunit 4.8.xにはext-domが必要

Question

CentOS 7で作業しています。作業用のDrupal Composerテンプレート（https://github.com/drupal-composer/drupal-project）を作成しようとしていますサイトローカルのDrush install（http://docs.drush.org/en/master/install/）。私たちのプロジェクトでは、PHP 5.6とDrupal 8.2を使用する必要があります。私はきれいなのVirtualBox上で次のことを行っている上記の手順パー

はCentOSののインストール：

インストール済みのgitを。

インストールされているPHP 5.6：

rpm -Uvh https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm 
rpm -Uvh https://mirror.webtatic.com/yum/el7/webtatic-release.rpm 

yum install php56w php56w-opcache 

今、私は作曲をダウンロードして、世界的にインストールします。

php -r "copy('https://getcomposer.org/installer', 'composer-setup.php');" 
php -r "if (hash_file('SHA384', 'composer-setup.php') === '669656bab3166a7aff8a7506b8cb2d1c292f042046c5a994c43155c0be6190fa0355160742ab2e1c88d40d5be660b410') { echo 'Installer verified'; } else { echo 'Installer corrupt'; unlink('composer-setup.php'); } echo PHP_EOL;" 
php composer-setup.php 

mv composer.phar /usr/local/bin/compose 

私は作曲を実行することができ、正常に動作するようです。

composer create-project drupal-composer/drupal-project:8.x-dev some-dir --stability dev --no-interaction 

プロジェクトテンプレートのビルド：我々は使用して作曲家とのDrupalのプロジェクトを作成することができますDrupalの作曲からの指示に従って今

。

Your requirements could not be resolved to an installable set of packages. 

Problem 1 
    - phpunit/phpunit 4.8.x-dev requires ext-dom * -> the requested PHP extension dom is missing from your system. 
    - phpunit/phpunit 4.8.9 requires ext-dom * -> the requested PHP extension dom is missing from your system. 
    - phpunit/phpunit 4.8.8 requires ext-dom * -> the requested PHP extension dom is missing from your system. 
    - phpunit/phpunit 4.8.7 requires ext-dom * -> the requested PHP extension dom is missing from your system. 
    - phpunit/phpunit 4.8.6 requires ext-dom * -> the requested PHP extension dom is missing from your system. 
    - phpunit/phpunit 4.8.5 requires ext-dom * -> the requested PHP extension dom is missing from your system. 
    - phpunit/phpunit 4.8.4 requires ext-dom * -> the requested PHP extension dom is missing from your system. 
    - phpunit/phpunit 4.8.35 requires ext-dom * -> the requested PHP extension dom is missing from your system. 
    - phpunit/phpunit 4.8.34 requires ext-dom * -> the requested PHP extension dom is missing from your system. 
    - phpunit/phpunit 4.8.33 requires ext-dom * -> the requested PHP extension dom is missing from your system. 
    - phpunit/phpunit 4.8.32 requires ext-dom * -> the requested PHP extension dom is missing from your system. 
    - phpunit/phpunit 4.8.31 requires ext-dom * -> the requested PHP extension dom is missing from your system. 
    - phpunit/phpunit 4.8.30 requires ext-dom * -> the requested PHP extension dom is missing from your system. 
    - phpunit/phpunit 4.8.3 requires ext-dom * -> the requested PHP extension dom is missing from your system. 
    - phpunit/phpunit 4.8.29 requires ext-dom * -> the requested PHP extension dom is missing from your system. 
    - phpunit/phpunit 4.8.28 requires ext-dom * -> the requested PHP extension dom is missing from your system. 
    - phpunit/phpunit 4.8.27 requires ext-dom * -> the requested PHP extension dom is missing from your system. 
    - phpunit/phpunit 4.8.26 requires ext-dom * -> the requested PHP extension dom is missing from your system. 
    - phpunit/phpunit 4.8.25 requires ext-dom * -> the requested PHP extension dom is missing from your system. 
    - phpunit/phpunit 4.8.24 requires ext-dom * -> the requested PHP extension dom is missing from your system. 
    - phpunit/phpunit 4.8.23 requires ext-dom * -> the requested PHP extension dom is missing from your system. 
    - phpunit/phpunit 4.8.22 requires ext-dom * -> the requested PHP extension dom is missing from your system. 
    - phpunit/phpunit 4.8.21 requires ext-dom * -> the requested PHP extension dom is missing from your system. 
    - phpunit/phpunit 4.8.20 requires ext-dom * -> the requested PHP extension dom is missing from your system. 
    - phpunit/phpunit 4.8.2 requires ext-dom * -> the requested PHP extension dom is missing from your system. 
    - phpunit/phpunit 4.8.19 requires ext-dom * -> the requested PHP extension dom is missing from your system. 
    - phpunit/phpunit 4.8.18 requires ext-dom * -> the requested PHP extension dom is missing from your system. 
    - phpunit/phpunit 4.8.17 requires ext-dom * -> the requested PHP extension dom is missing from your system. 
    - phpunit/phpunit 4.8.16 requires ext-dom * -> the requested PHP extension dom is missing from your system. 
    - phpunit/phpunit 4.8.15 requires ext-dom * -> the requested PHP extension dom is missing from your system. 
    - phpunit/phpunit 4.8.14 requires ext-dom * -> the requested PHP extension dom is missing from your system. 
    - phpunit/phpunit 4.8.13 requires ext-dom * -> the requested PHP extension dom is missing from your system. 
    - phpunit/phpunit 4.8.12 requires ext-dom * -> the requested PHP extension dom is missing from your system. 
    - phpunit/phpunit 4.8.11 requires ext-dom * -> the requested PHP extension dom is missing from your system. 
    - phpunit/phpunit 4.8.10 requires ext-dom * -> the requested PHP extension dom is missing from your system. 
    - phpunit/phpunit 4.8.1 requires ext-dom * -> the requested PHP extension dom is missing from your system. 
    - phpunit/phpunit 4.8.0 requires ext-dom * -> the requested PHP extension dom is missing from your system. 
    - Installation request for phpunit/phpunit ~4.8 -> satisfiable by phpunit/phpunit[4.8.0, 4.8.1, 4.8.10, 4.8.11, 4.8.12, 4.8.13, 4.8.14, 4.8.15, 4.8.16, 4.8.17, 4.8.18, 4.8.19, 4.8.2, 4.8.20, 4.8.21, 4.8.22, 4.8.23, 4.8.24, 4.8.25, 4.8.26, 4.8.27, 4.8.28, 4.8.29, 4.8.3, 4.8.30, 4.8.31, 4.8.32, 4.8.33, 4.8.34, 4.8.35, 4.8.4, 4.8.5, 4.8.6, 4.8.7, 4.8.8, 4.8.9, 4.8.x-dev]. 

To enable extensions, verify that they are enabled in your .ini files: 
    - /etc/php.ini 
    - /etc/php.d/bz2.ini 
    - /etc/php.d/calendar.ini 
    - /etc/php.d/ctype.ini 
    - /etc/php.d/curl.ini 
    - /etc/php.d/exif.ini 
    - /etc/php.d/fileinfo.ini 
    - /etc/php.d/ftp.ini 
    - /etc/php.d/gettext.ini 
    - /etc/php.d/gmp.ini 
    - /etc/php.d/iconv.ini 
    - /etc/php.d/json.ini 
    - /etc/php.d/opcache.ini 
    - /etc/php.d/phar.ini 
    - /etc/php.d/shmop.ini 
    - /etc/php.d/simplexml.ini 
    - /etc/php.d/sockets.ini 
    - /etc/php.d/tokenizer.ini 
    - /etc/php.d/xml.ini 
    - /etc/php.d/zip.ini 
You can also run `php --ini` inside terminal to see which files are used by PHP in CLI mode. 

Composerは、更新することを拒否：

しかし、私の問題は、私はこれらのエラーを取得するので、私は

composer require drush/drush 

または

composer update 

を実行することはできませんということです。 数日のグーグル・グーグルで、私は迷うようです。私はこれらのファイルを正確に変更する必要があるかどうか分からず、作曲者のダウンロードで同じエラーが発生する人はいません（ほとんどの投稿は年月を過ぎているようです）。

私がここで紛失しているものについて、誰でも洞察力を提供することはできますか？

ありがとうございます。

EDIT：

sudo yum install php56w-xml 

拡張機能は、彼のコメント内のリンクで見つけることができます：私は、問題は私が使用してphp5.6ためにインストールのphp-xmlのを必要としてい@Oliverに感謝します。

私はdrupal/coreまたはeasyrdfがそのサイトに掲載されていないため、何をすべきかを考え出しています。私の新しいエラーはここにあります：

DrupalProject\composer\ScriptHandler::checkComposerVersion 
    Loading composer repositories with package information 
    Updating dependencies (including require-dev) 
    Your requirements could not be resolved to an installable set of packages. 

Problem 1 
    - drupal/core 8.0.0 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.0.0-beta10 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.0.0-beta11 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.0.0-beta12 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.0.0-beta13 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.0.0-beta14 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.0.0-beta15 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.0.0-beta16 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.0.0-beta6 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.0.0-beta7 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.0.0-beta8 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.0.0-beta9 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.0.0-rc1 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.0.0-rc2 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.0.0-rc3 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.0.0-rc4 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.0.1 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.0.2 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.0.3 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.0.4 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.0.5 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.0.6 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.0.x-dev requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.1.0 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.1.0-beta1 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.1.0-beta2 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.1.0-rc1 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.1.1 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.1.10 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.1.2 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.1.3 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.1.4 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.1.5 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.1.6 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.1.7 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.1.8 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.1.9 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.1.x-dev requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.2.0 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.2.0-beta1 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.2.0-beta2 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.2.0-beta3 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.2.0-rc1 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.2.0-rc2 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.2.1 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.2.2 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.2.3 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.2.4 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.2.5 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.2.6 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.2.7 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.2.x-dev requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.3.0-alpha1 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.3.0-beta1 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.3.0-rc1 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.3.0-rc2 requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.3.x-dev requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - drupal/core 8.4.x-dev requires easyrdf/easyrdf 0.9.* -> satisfiable by easyrdf/easyrdf[0.9.0, 0.9.0-rc.1, 0.9.0-rc.2, 0.9.0-rc.3, 0.9.0-rc.4, 0.9.0-rc.5, 0.9.1, 0.9.x-dev]. 
    - easyrdf/easyrdf 0.9.x-dev requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system. 
    - easyrdf/easyrdf 0.9.1 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system. 
    - easyrdf/easyrdf 0.9.0-rc.5 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system. 
    - easyrdf/easyrdf 0.9.0-rc.4 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system. 
    - easyrdf/easyrdf 0.9.0-rc.3 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system. 
    - easyrdf/easyrdf 0.9.0-rc.2 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system. 
    - easyrdf/easyrdf 0.9.0-rc.1 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system. 
    - easyrdf/easyrdf 0.9.0 requires ext-mbstring * -> the requested PHP extension mbstring is missing from your system. 
    - Installation request for drupal/core ~8.0 -> satisfiable by drupal/core[8.0.0, 8.0.0-beta10, 8.0.0-beta11, 8.0.0-beta12, 8.0.0-beta13, 8.0.0-beta14, 8.0.0-beta15, 8.0.0-beta16, 8.0.0-beta6, 8.0.0-beta7, 8.0.0-beta8, 8.0.0-beta9, 8.0.0-rc1, 8.0.0-rc2, 8.0.0-rc3, 8.0.0-rc4, 8.0.1, 8.0.2, 8.0.3, 8.0.4, 8.0.5, 8.0.6, 8.0.x-dev, 8.1.0, 8.1.0-beta1, 8.1.0-beta2, 8.1.0-rc1, 8.1.1, 8.1.10, 8.1.2, 8.1.3, 8.1.4, 8.1.5, 8.1.6, 8.1.7, 8.1.8, 8.1.9, 8.1.x-dev, 8.2.0, 8.2.0-beta1, 8.2.0-beta2, 8.2.0-beta3, 8.2.0-rc1, 8.2.0-rc2, 8.2.1, 8.2.2, 8.2.3, 8.2.4, 8.2.5, 8.2.6, 8.2.7, 8.2.x-dev, 8.3.0-alpha1, 8.3.0-beta1, 8.3.0-rc1, 8.3.0-rc2, 8.3.x-dev, 8.4.x-dev]. 

To enable extensions, verify that they are enabled in your .ini files: 
    - /etc/php.ini 
    - /etc/php.d/bz2.ini 
    - /etc/php.d/calendar.ini 
    - /etc/php.d/ctype.ini 
    - /etc/php.d/curl.ini 
    - /etc/php.d/dom.ini 
    - /etc/php.d/exif.ini 
    - /etc/php.d/fileinfo.ini 
    - /etc/php.d/ftp.ini 
    - /etc/php.d/gettext.ini 
    - /etc/php.d/gmp.ini 
    - /etc/php.d/iconv.ini 
    - /etc/php.d/json.ini 
    - /etc/php.d/opcache.ini 
    - /etc/php.d/phar.ini 
    - /etc/php.d/shmop.ini 
    - /etc/php.d/simplexml.ini 
    - /etc/php.d/sockets.ini 
    - /etc/php.d/tokenizer.ini 
    - /etc/php.d/xml.ini 
    - /etc/php.d/xml_wddx.ini 
    - /etc/php.d/xmlreader.ini 
    - /etc/php.d/xmlwriter.ini 
    - /etc/php.d/xsl.ini 
    - /etc/php.d/zip.ini 
You can also run `php --ini` inside terminal to see which files are used by PHP in CLI mode. 

もし考えられたらアップデートを投稿します。

最終編集：easyrdfにext-mbstringとext-pcreが必要であることがわかりました。

sudo yum install php56w-mbstring 

今、作曲はすべて私の依存関係がダウンロードされたアップデート呼び出すとき：EXT-PCREはので、私は必要なすべてがEXT-MBSTRINGし、共通のPHPパッケージにインストールされています！vender/bin/drushを実行すると、コマンドが動作し、ローカルインストールが完了したことを確認できます。

Answer 1

これはコンポーザー関連ではありません。あなたはちょうどPHPの拡張機能が不足しています。 私はどのPHPバージョンを持っているのか、あなたのサーバー上のオペレーションシステムが何か分かりません。私はbashのためのいくつかの例を投稿：

EDIT：あなたがここに5.6をPHP用のパッケージのリストを見つけることができます

sudo yum install php56w-xml 

：

のCentOS-例：NOW私はバージョンを発見したhttps://webtatic.com/packages/php56/