linux 设置pip 镜像 Pip Warning：–trusted-host 问题解决方案

pip升级到7.0以后，在使用http镜像进行包安装及升级的时候往往会有如下提示：

Collecting beautifulsoup4
The repository located at mirrors.aliyun.com is not a trusted or secure host and is being ignored. If this repository is available via HTTPS it is recommended to use HTTPS instead, otherwise you may silence this warning and allow it anyways with ‘–trusted-host mirrors.aliyun.com’.
Could not find a version that satisfies the requirement beautifulsoup4 (from versions: )
No matching distribution found for beautifulsoup4

解决办法如下：

1.安装时加入–trusted-host mirrors.aliyun.com参数：

2.在pip.conf中加入trusted-host选项，该方法是一劳永逸