An error occurred while installing nokogiri (1.8.4) 安装 nokogiri 1.8.4 报错的解决方案

我是Mac系统，在搭建GitHubPages + Jekyll的时候，在输入命令 bundle install后， Fetching nokogiri 1.8.4 报错，各种百度、Google无效，下面展示我的解决方案：

1. brew unlink xz
2. gem install nokogiri -v '1.8.4'，
然后报错：
ERROR:  While executing gem ... (Gem::FilePermissionError)
    You don't have write permissions for the /Library/Ruby/Gems/2.3.0 directory.
Loving:vno-jekyll Love$ sudo gem install nokogiri -v '1.8.4'
Building native extensions. This could take a while...
ERROR:  While executing gem ... (Gem::FilePermissionError)
    You don't have write permissions for the /usr/bin directory.
3. sudo gem install nokogiri -v '1.8.4' -n /usr/local/bin/ （这行命令输入完以后，在**bundle install**再进行安装的时候就解决了！）