在Mac上安装了git之后，发现命令不能自动补全，本文介绍怎么让git命令能够自动补全。
确保bash能够自动
在终端（本文使用的是OS X的终端）执行如下命令：
ccli@ccli-mac:dal$ brew list
看看是否已经安装有bash-completion，比如我的机器(已经安装了)运行上面的命令会显示：
bash-completion glib libtiff perl sqlite
如果没有安装，运行如下命令安装bash-completion：
brew install bash-completion
等待安装完成之后，运行如下命令：
brew info bash-completion
运行上面的命令后会在终端显示下图：
bash-completion: stable 1.3 (bottled)
Programmable completion for Bash 3.2
https://salsa.debian.org/debian/bash-completion
Conflicts with:
bash-completion@2 (because Differing version of same formula)
/usr/local/Cellar/bash-completion/1.3_3 (190 files, 676.4KB) *
Poured from bottle on 2018-05-28 at 09:59:40
From: https://github.com/Homebrew/homebrew-core/blob/master/Formula/bash-completion.rb
==> Caveats
Add the following line to your ~/.bash_profile: [[ -r "/usr/local/etc/profile.d/bash_completion.sh" ]] && . "/usr/local/etc/profile.d/bash_completion.sh"
Bash completion has been installed to: /usr/local/etc/bash_completion.d
==> Analytics
install: 14,875 (30 days), 44,147 (90 days), 189,622 (365 days)install_on_request: 13,491 (30 days), 40,092 (90 days), 173,591 (365 days)build_error: 0 (30 days)
仔细阅读箭头所指的地方，依照提示将这行内容
[[ -r "/usr/local/etc/profile.d/bash_completion.sh" ]] && . "/usr/local/etc/profile.d/bash_completion.sh"
添加到 ~/.bash_profile文件(如果没有该文件，新建)，然后重启终端，bash-completion功能安装完成。
让git支持自动补全
从github上clone git的源码到本地：
git clone https://github.com/git/git.git
找到”contrib/completion/”目录下的git-completion.bash，将该文件拷贝到~/目录下下并重命名为.git-completion.bash:
cp git-completion.bash ~/.git-completion.bash
在~/.profile文件中追加如下内容：
source ~/.git-completion.bash
重启终端，现在git能够使用tab键自动补全命令了，enjoy it！
