安装方法：
http://brew.sh/，先装包管理工具Homebrew，再用brew install git
安装完，执行 git 命令，遇到如下错误：
dyld: Library not loaded: /usr/local/opt/gettext/lib/libintl.8.dylib
Referenced from: /usr/local/bin/git
Reason: image not found
Abort trap: 6
接下来执行 brew install gettext ：
Warning: git 2.19.1 is already installed and up-to-date
To reinstall 2.19.1, run `brew reinstall git`
Error: Git must be installed and in your PATH!
Warning: gettext 0.19.8.1 is already installed, it's just not linked
You can use `brew link gettext` to link this version.
接下来执行 brew link gettext：
Warning: gettext is keg-only and must be linked with --force
If you need to have this software first in your PATH instead consider running:
echo 'export PATH="/usr/local/opt/gettext/bin:$PATH"' >> ~/.bash_profile
接下来执行 brew link gettext --force：
Linking /usr/local/Cellar/gettext/0.19.8.1... 188 symlinks created
If you need to have this software first in your PATH instead consider running:
echo 'export PATH="/usr/local/opt/gettext/bin:$PATH"' >> ~/.bash_profile
再执行 echo 'export PATH="/usr/local/opt/gettext/bin:$PATH"' >> ~/.bash_profile
最后执行 git 检查一下是否安装成功，有如下输出即可说明安装成功：