yum --enablerepo=remi,remi-php71 install composer
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Loading mirror speeds from cached hostfile
 * base: ftp.sjtu.edu.cn
 * epel: fedora.cs.nctu.edu.tw
 * extras: mirrors.shu.edu.cn
 * updates: ftp.sjtu.edu.cn
 * webtatic: uk.repo.webtatic.com

--> 
--->  composer.noarch.0.1.8.0-1.el7  
-->  php-composer(composer/ca-bundle) < 2 composer-1.8.0-1.el7.noarch 
-->  php-composer(composer/semver) < 2 composer-1.8.0-1.el7.noarch 
-->  php-composer(composer/spdx-licenses) < 2 composer-1.8.0-1.el7.noarch 
-->  php-composer(composer/xdebug-handler) < 2 composer-1.8.0-1.el7.noarch 
-->  php-composer(psr/log) < 2 composer-1.8.0-1.el7.noarch 
-->  php-composer(seld/jsonlint) < 2 composer-1.8.0-1.el7.noarch 
-->  php-composer(seld/phar-utils) < 2 composer-1.8.0-1.el7.noarch 
-->  php-PsrLog >= 1.0.0-8 composer-1.8.0-1.el7.noarch 
-->  php-composer(composer/ca-bundle) >= 1.0 composer-1.8.0-1.el7.noarch 
-->  php-composer(composer/semver) >= 1.0 composer-1.8.0-1.el7.noarch 
-->  php-composer(composer/spdx-licenses) >= 1.2 composer-1.8.0-1.el7.noarch 
-->  php-composer(composer/xdebug-handler) >= 1.1 composer-1.8.0-1.el7.noarch 
-->  php-composer(psr/log) >= 1.0 composer-1.8.0-1.el7.noarch 
-->  php-composer(seld/jsonlint) >= 1.4 composer-1.8.0-1.el7.noarch 
-->  php-composer(seld/phar-utils) >= 1.0 composer-1.8.0-1.el7.noarch 
-->  php-seld-phar-utils >= 1.0.1 composer-1.8.0-1.el7.noarch 
-->  php-composer(fedora/autoloader) composer-1.8.0-1.el7.noarch 
-->  php-intl composer-1.8.0-1.el7.noarch 
-->  php-justinrainbow-json-schema5 composer-1.8.0-1.el7.noarch 
-->  php-symfony-console composer-1.8.0-1.el7.noarch 
-->  php-symfony-filesystem composer-1.8.0-1.el7.noarch 
-->  php-symfony-finder composer-1.8.0-1.el7.noarch 
-->  php-symfony-process composer-1.8.0-1.el7.noarch 
--> 
--->  php-PsrLog.noarch.0.1.1.0-1.el7  
--->  php-composer-ca-bundle.noarch.0.1.0.2-1.el7  
-->  php-composer(symfony/class-loader) php-composer-ca-bundle-1.0.2-1.el7.noarch 
--->  php-composer-semver.noarch.0.1.4.2-1.el7  
--->  php-composer-spdx-licenses.noarch.0.1.5.0-1.el7  
--->  php-composer-xdebug-handler.noarch.0.1.3.1-1.el7  
--->  php-fedora-autoloader.noarch.0.1.0.0-1.el7  
--->  php-jsonlint.noarch.0.1.6.1-1.el7  
--->  php-justinrainbow-json-schema5.noarch.0.5.2.7-1.el7  
--->  php-seld-phar-utils.noarch.0.1.0.1-1.el7  
--->  php-symfony-console.noarch.0.2.8.12-2.el7  
-->  php-composer(symfony/event-dispatcher) = 2.8.12 php-symfony-console-2.8.12-2.el7.noarch 
--->  php-symfony-filesystem.noarch.0.2.8.12-2.el7  
-->  php-symfony-common = 2.8.12-2.el7 php-symfony-filesystem-2.8.12-2.el7.noarch 
--->  php-symfony-finder.noarch.0.2.8.12-2.el7  
--->  php-symfony-process.noarch.0.2.8.12-2.el7  
--->  php72w-intl.x86_64.0.7.2.14-1.w7  
-->  php72w-common(x86-64) = 7.2.14-1.w7 php72w-intl-7.2.14-1.w7.x86_64 
-->  libicuuc.so.50()(64bit) php72w-intl-7.2.14-1.w7.x86_64 
-->  libicuio.so.50()(64bit) php72w-intl-7.2.14-1.w7.x86_64 
-->  libicui18n.so.50()(64bit) php72w-intl-7.2.14-1.w7.x86_64 
-->  libicudata.so.50()(64bit) php72w-intl-7.2.14-1.w7.x86_64 
--> 
--->  libicu.x86_64.0.50.1.2-17.el7  
--->  php-symfony-class-loader.noarch.0.2.8.12-2.el7  
--->  php-symfony-common.noarch.0.2.8.12-2.el7  
--->  php-symfony-event-dispatcher.noarch.0.2.8.12-2.el7  
-->  php-composer(symfony/dependency-injection) = 2.8.12 php-symfony-event-dispatcher-2.8.12-2.el7.noarch 
-->  php-composer(symfony/http-kernel) = 2.8.12 php-symfony-event-dispatcher-2.8.12-2.el7.noarch 
--->  php72w-common.x86_64.0.7.2.14-1.w7  
--> 
--->  php-symfony-dependency-injection.noarch.0.2.8.12-2.el7  
-->  php-composer(symfony/config) = 2.8.12 php-symfony-dependency-injection-2.8.12-2.el7.noarch 
-->  php-composer(symfony/expression-language) = 2.8.12 php-symfony-dependency-injection-2.8.12-2.el7.noarch 
-->  php-composer(symfony/yaml) = 2.8.12 php-symfony-dependency-injection-2.8.12-2.el7.noarch 
--->  php-symfony-http-kernel.noarch.0.2.8.12-2.el7  
-->  php-composer(symfony/browser-kit) = 2.8.12 php-symfony-http-kernel-2.8.12-2.el7.noarch 
-->  php-composer(symfony/debug) = 2.8.12 php-symfony-http-kernel-2.8.12-2.el7.noarch 
-->  php-composer(symfony/http-foundation) = 2.8.12 php-symfony-http-kernel-2.8.12-2.el7.noarch 
-->  php-composer(symfony/var-dumper) = 2.8.12 php-symfony-http-kernel-2.8.12-2.el7.noarch 
--> 
--->  php-symfony-browser-kit.noarch.0.2.8.12-2.el7  
-->  php-composer(symfony/dom-crawler) = 2.8.12 php-symfony-browser-kit-2.8.12-2.el7.noarch 
--->  php-symfony-config.noarch.0.2.8.12-2.el7  
--->  php-symfony-debug.noarch.0.2.8.12-2.el7  
--->  php-symfony-expression-language.noarch.0.2.8.12-2.el7  
--->  php-symfony-http-foundation.noarch.0.2.8.12-2.el7  
-->  php-composer(symfony/polyfill-php54) < 2.0 php-symfony-http-foundation-2.8.12-2.el7.noarch 
-->  php-composer(symfony/polyfill-php55) < 2.0 php-symfony-http-foundation-2.8.12-2.el7.noarch 
-->  php-composer(symfony/polyfill-php54) >= 1.0 php-symfony-http-foundation-2.8.12-2.el7.noarch 
-->  php-composer(symfony/polyfill-php55) >= 1.0 php-symfony-http-foundation-2.8.12-2.el7.noarch 
--->  php-symfony-var-dumper.noarch.0.2.8.12-2.el7  
--->  php-symfony-yaml.noarch.0.2.8.12-2.el7  
--> 
--->  php-symfony-dom-crawler.noarch.0.2.8.12-2.el7  
-->  php-composer(symfony/css-selector) = 2.8.12 php-symfony-dom-crawler-2.8.12-2.el7.noarch 
--->  php-symfony-polyfill.noarch.0.1.5.0-1.el7  
-->  php-composer(ircmaxell/password-compat) < 2.0 php-symfony-polyfill-1.5.0-1.el7.noarch 
-->  php-composer(paragonie/random_compat) < 3.0 php-symfony-polyfill-1.5.0-1.el7.noarch 
-->  php-composer(ircmaxell/password-compat) >= 1.0 php-symfony-polyfill-1.5.0-1.el7.noarch 
-->  php-composer(paragonie/random_compat) >= 1.0 php-symfony-polyfill-1.5.0-1.el7.noarch 
--> 
--->  php-paragonie-random-compat.noarch.0.2.0.12-1.el7  
--->  php-password-compat.noarch.0.1.0.4-1.el7  
--->  php-symfony-css-selector.noarch.0.2.8.12-2.el7  
-->  php72w-common-7.2.14-1.w7.x86_64  php-common < 7.2 
--> 
--> 
--->  php71w-common.x86_64.0.7.1.25-1.w7  
-->  php71w-common(x86-64) = 7.1.25-1.w7 php71w-process-7.1.25-1.w7.x86_64 
-->  php71w-common(x86-64) = 7.1.25-1.w7 php71w-cli-7.1.25-1.w7.x86_64 
-->  php71w-common(x86-64) = 7.1.25-1.w7 php71w-xml-7.1.25-1.w7.x86_64 
-->  php71w-common(x86-64) = 7.1.25-1.w7 php71w-mbstring-7.1.25-1.w7.x86_64 
-->  php71w-common(x86-64) = 7.1.25-1.w7 php71w-fpm-7.1.25-1.w7.x86_64 
-->  php71w-common(x86-64) = 7.1.25-1.w7 php71w-pdo-7.1.25-1.w7.x86_64 
-->  php71w-common(x86-64) = 7.1.25-1.w7 php71w-mcrypt-7.1.25-1.w7.x86_64 
-->  php71w-common(x86-64) = 7.1.25-1.w7 php71w-gd-7.1.25-1.w7.x86_64 
-->  php71w-common(x86-64) = 7.1.25-1.w7 php71w-opcache-7.1.25-1.w7.x86_64 
--->  php71w-common.x86_64.0.7.1.26-1.w7  
--> 
--->  php71w-cli.x86_64.0.7.1.25-1.w7  
-->  php71w-cli(x86-64) = 7.1.25-1.w7 php71w-devel-7.1.25-1.w7.x86_64 
--->  php71w-cli.x86_64.0.7.1.26-1.w7  
--->  php71w-fpm.x86_64.0.7.1.25-1.w7  
--->  php71w-fpm.x86_64.0.7.1.26-1.w7  
--->  php71w-gd.x86_64.0.7.1.25-1.w7  
--->  php71w-gd.x86_64.0.7.1.26-1.w7  
--->  php71w-mbstring.x86_64.0.7.1.25-1.w7  
--->  php71w-mbstring.x86_64.0.7.1.26-1.w7  
--->  php71w-mcrypt.x86_64.0.7.1.25-1.w7  
--->  php71w-mcrypt.x86_64.0.7.1.26-1.w7  
--->  php71w-opcache.x86_64.0.7.1.25-1.w7  
--->  php71w-opcache.x86_64.0.7.1.26-1.w7  
--->  php71w-pdo.x86_64.0.7.1.25-1.w7  
--->  php71w-pdo.x86_64.0.7.1.26-1.w7  
--->  php71w-process.x86_64.0.7.1.25-1.w7  
--->  php71w-process.x86_64.0.7.1.26-1.w7  
--->  php71w-xml.x86_64.0.7.1.25-1.w7  
--->  php71w-xml.x86_64.0.7.1.26-1.w7  
--> 
--->  php71w-devel.x86_64.0.7.1.25-1.w7  
--->  php71w-devel.x86_64.0.7.1.26-1.w7  
-->  php72w-common-7.2.14-1.w7.x86_64  php-common < 7.2 
--> 
:php72w-common conflicts with php71w-common-7.1.26-1.w7.x86_64
  --skip-broken 
 :rpm -Va --nofiles --nodigest