在今天的指南中，很好地讨论如何在CentOS 8/RHEL 8 Linux机器上安装PHP Composer。 Composer是一个PHP应用程序包管理器，旨在提供一种标准格式来管理PHP软件和所需库的依赖性。当开发人员想要管理外部软件包并将其集成到他们的PHP项目中时，此工具很有用。

在CentOS 8/RHEL 8上安装PHP Composer

现在我们已经介绍了基础知识，我们可以在CentOS 8/RHEL 8 Linux盒子中开始实际安装Composer了。

安装PHP

首先，确保PHP已安装在本地系统中。

$sudo dnf install @php

确认安装PHP。

$php -version
PHP 7.2.11 (cli) (built: Oct  9 2016 15:09:36) ( NTS )
Copyright (c) 1997-2016 The PHP Group
Zend Engine v3.2.0, Copyright (c) 1998-2016 Zend Technologies

我们有关于在CentOS 8上安装PHP的完整指南。

下载Composer安装程序

接下来是在本地下载Composer安装程序。

sudo dnf -y install wget
wget https://getcomposer.org/installer -O composer-installer.php

在CentOS 8/RHEL 8上安装PHP Composer

下载安装程序后，我们可以使用以下命令在计算机上安装composer。

sudo php composer-installer.php --filename=composer --install-dir=/usr/local/bin

安装将为我们提供类似于以下的输出。

All settings correct for using Composer
Downloading...

Composer (version 1.9.1) successfully installed to: /usr/local/bin/composer
Use it: php /usr/local/bin/composer

验证我们在CentOS 8/RHEL 8上安装了Composer。

$composer --version
Composer version 1.9.1 2019-11-01 17:20:17

要查看使用情况页面，请使用：

$composer
   ______
 /____/___  ____ ___  ____  ____  ________  _____
// /__ \/__ `__ \/__ \/__ \/___/_ \/___/
//___//_////////_///_/(__  )  __//
____/____/_//_//_/.___/____/____/___/_/
                    /_/
Composer version 1.9.1 2019-11-01 17:20:17

Usage:
  command [options] [arguments]

Options:
  -h, --help                     Display this help message
  -q, --quiet                    Do not output any message
  -V, --version                  Display this application version
      --ansi                     Force ANSI output
      --no-ansi                  Disable ANSI output
  -n, --no-interaction           Do not ask any interactive question
      --profile                  Display timing and memory usage information
      --no-plugins               Whether to disable plugins.
  -d, --working-dir=WORKING-DIR  If specified, use the given directory as working directory.
      --no-cache                 Prevent use of the cache
  -v|vv|vvv, --verbose           Increase the verbosity of messages: 1 for normal output, 2 for more verbose output and 3 for debug

Available commands:
  about                Shows the short information about Composer.
  archive              Creates an archive of this composer package.
  browse               Opens the package's repository URL or homepage in your browser.
  check-platform-reqs  Check that platform requirements are satisfied.
  clear-cache          Clears composer's internal package cache.
  clearcache           Clears composer's internal package cache.
  config               Sets config options.
  create-project       Creates new project from a package into given directory.
  depends              Shows which packages cause the given package to be installed.
  diagnose             Diagnoses the system to identify common errors.
  dump-autoload        Dumps the autoloader.
  dumpautoload         Dumps the autoloader.
  exec                 Executes a vendored binary/script.
  global               Allows running commands in the global composer dir ($COMPOSER_HOME).
  help                 Displays help for a command
  home                 Opens the package's repository URL or homepage in your browser.
  i                    Installs the project dependencies from the composer.lock file if present, or falls back on the composer.json.
  info                 Shows information about packages.
  init                 Creates a basic composer.json file in current directory.
  install              Installs the project dependencies from the composer.lock file if present, or falls back on the composer.json.
  licenses             Shows information about licenses of dependencies.
  list                 Lists commands
  outdated             Shows a list of installed packages that have updates available, including their latest version.
  prohibits            Shows which packages prevent the given package from being installed.
  remove               Removes a package from the require or require-dev.
  require              Adds required packages to your composer.json and installs them.
  run                  Runs the scripts defined in composer.json.
  run-script           Runs the scripts defined in composer.json.
  search               Searches for packages.
  self-update          Updates composer.phar to the latest version.
  selfupdate           Updates composer.phar to the latest version.
  show                 Shows information about packages.
  status               Shows a list of locally modified packages, for packages installed from source.
  suggests             Shows package suggestions.
  u                    Upgrades your dependencies to the latest version according to composer.json, and updates the composer.lock file.
  update               Upgrades your dependencies to the latest version according to composer.json, and updates the composer.lock file.
  upgrade              Upgrades your dependencies to the latest version according to composer.json, and updates the composer.lock file.
  validate             Validates a composer.json and composer.lock.
  why                  Shows which packages cause the given package to be installed.
  why-not              Shows which packages prevent the given package from being installed.