我采取了以下步骤，在运行El Capitan(10.11.4)的Mac上成功摆脱了rbenv.根据我的经验，Rbenv是Failed to build gem native extension errors的主要原因.

I took these steps to successfully get rid of rbenv on my mac running El Capitan (10.11.4). Rbenv is a major cause of Failed to build gem native extension errors from my experience.

• 使用brew移除:brew remove rbenv
• 删除.rbenv目录:rm -rf ~/.rbenv
• 打开.bash_profile文件并删除其中包含rbenv的所有行:vi ~/.bash_profile
• 打开.bashrc文件并删除其中包含rbenv的所有行:vi ~/.bashrc

• Remove using brew: brew remove rbenv
• Delete .rbenv directory: rm -rf ~/.rbenv
• Open .bash_profile file and delete any lines with rbenv in them: vi ~/.bash_profile
• Open .bashrc file and delete any lines with rbenv in them: vi ~/.bashrc

最后，重新加载.bash_profile和.bashrc:

. 〜/.bash_profile&& . 〜/.bashrc

. ~/.bash_profile && . ~/.bashrc