PHP Composer не будет устанавливать Drush с php 5.6: phpunit / phpunit 4.8.x требует ext-dom

поэтому я работаю над CentOs 7 и пытаюсь создать работающий шаблон Drupal Composer (https://github.com/drupal-composer/drupal-project), которая включает локальную установку Drush (http://docs.drush.org/en/master/install/). Для нашего проекта нам нужно использовать PHP 5.6 и Drupal 8.2.

В соответствии с приведенными выше инструкциями, я сделал следующее на моей чистой установке CentOS в виртуальной коробке:

Установил мерзавец.

Установил 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

Теперь я загружаю composer и устанавливаю глобально:

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

Я могу запустить композитор, и, кажется, работает нормально.

Теперь, следуя инструкциям Drupal Composer, мы можем создать наш проект drupal с помощью composer, используя:

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

Шаблон проекта строится.

Однако моя проблема в том, что я не могу бежать

composer require drush/drush

или же

composer update

потому что я получаю эти ошибки:

  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.

Композитор отказывается обновляться.
После нескольких дней поиска, я, кажется, в растерянности. Я не знаю, что именно мне нужно изменить в этих файлах, и я не вижу, чтобы кто-то сталкивался с такой же ошибкой при загрузке композитора (и большинство сообщений кажутся устаревшими по годам).

Может ли кто-нибудь предложить какое-либо понимание того, что мне здесь не хватает?

Спасибо.

РЕДАКТИРОВАТЬ: Благодаря @Oliver я обнаружил, что проблема в том, что мне нужен php-xml, который я установил для php5.6, используя:

sudo yum install php56w-xml

Расширения можно найти по ссылке в его комментарии.

Теперь я выясняю, что делать, так как я не вижу drupal / core или easyrdf в списке на этом сайте. Моя новая ошибка здесь:

  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.

Выложу обновление, когда разберусь.

ЗАКЛЮЧИТЕЛЬНОЕ РЕДАКТИРОВАНИЕ: выяснилось, что easyrdf нужны ext-mbstring и ext-pcre. ext-pcre поставляется с общим пакетом php, поэтому все, что мне нужно, это ext-mbstring:

sudo yum install php56w-mbstring

Теперь при вызове composer update все мои зависимости были загружены! Теперь я могу запустить vender / bin / drush и команда работает, подтверждая, что моя локальная установка завершена!

sudo yum install php56w-xml