安装brew时
```shell
/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"
```
如果报错
```shell
HEAD is now at 8175e404e Merge pull request #7942 from sjackman/bottle_tag
error: Not a valid ref: refs/remotes/origin/master
fatal: ambiguous argument 'refs/remotes/origin/master': unknown revision or path not in the working tree.
```
这次由于多次安装导致的，最简单的方式是直接卸载brew，然后再安装。

+ 将[https://raw.githubusercontent.com/Homebrew/install/master/uninstall](https://raw.githubusercontent.com/Homebrew/install/master/uninstall)保存为**uninstall.rb**
+ 执行**ruby uninstall.rb**

安装brew时
shell
/bin/bash -c "$(curl -fsSL https:raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

如果报错
shell
HEAD is now at 8175e404e Merge pull request 7942 from sjackman/bottl

brew 报错 error: Not a valid ref: refs/remotes/origin/master 的解决方法

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