可以嘗試利用composer下載Yii框架，編輯composer.json文件：

{
    "require":{
        "yiisoft/yii2":"~2.0.0"
    }
}

　　然後在這個包含composer.json文件的目錄下執行命令：

composer install

　　然後就等待下載完成

問題零：Your requirements could not be resolved to an installable set of packages.

　　如果出現下面這種情況：

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

　　需要安裝一個插件（plug），運行命令安裝即可：

composer global require "fxp/composer-asset-plugin:^1.4.1"

問題一：proc_get_status() has been disabled for security reasons

　　如果出現下面這種情況：

[ErrorException]
proc_get_status() has been disabled for security reasons
PHP Fatal error: Uncaught exception ‘ErrorException‘ with message ‘proc_get_status() has been disabled for security reasons‘
in phar:///usr/local/bin/composer/vendor/symfony/process/Process.php:1279

　　這是因為安全原因，將proc_get_status函數禁用了，可以通過編輯php的配置文件php.ini，搜索proc_get_status，將他從disable_functions中刪除即可。

問題二：需要輸入token

　　如果是第一次使用composer，那麽在下載文件yii框架的過程中，有幾項需要輸入token，如下圖：

[root@localhost tmp]# composer install
Loading composer repositories with package information
Updating dependencies (including require-dev)

Could not fetch https://api.github.com/repos/jquery/jquery-dist, please create a GitHub OAuth token to go over the API rate limit
Head to https://github.com/settings/tokens/new?scopes=repo&description=Composer+on+localhost.localdomain+2018-02-22+1945
to retrieve a token. It will be stored in "/root/.composer/auth.json" for future use by Composer.
Token (hidden):

　　只要粘貼上面的URL到瀏覽器中打開，然後生成一個token，然後復制這個新的token，在命令行中需要token的地方輸入該token即可，該token會存儲在用戶家目錄/.composer/auth.json中：

{
    "bitbucket-oauth": {},
    "github-oauth": {
        "github.com": "6ad4ef7375b1fb9........"},
    "gitlab-oauth": {},
    "gitlab-token": {},
    "http-basic": {}
}

　　此後可以不用再輸入token了，composer會自動去auth.json中找。

使用composer遇到的問題及解決方法