1、先安装brew，安装过的可以忽略

/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"

2、安装bash-completion

brew install bash-completion

3、系统配置

下载此文件
https://github.com/git/git/blob/master/contrib/completion/git-completion.bash
然后复制到家目录
cp xxx/git-completion.bash ~/.git-completion.bash
vim ~/.bash_profile 加入以下代码

if [ -f ~/.git-completion.bash ]; then
   . ~/.git-completion.bash
fi

读取文件
source ~/.git-completion.bash