1. 安装go
手动方式
官网下载压缩包，然后配置GOROOT和PATH，笔者采用下边这种方式。
Homebrew方式
笔者在 macOS Catalina 版本0.15.1 (19B88) 下直接安装遇到点问题，如下：
// 考虑使用 install 直接搞定，结果各种超时
$ brew install go
Error: Net::OpenTimeout
// 参考 http://mirrors.ustc.edu.cn/help/homebrew-bottles.html 更换源，结果报错
$ brew install go
··· ···
Error: Xcode alone is not sufficient on Dunno.
Install the Command Line Tools:
xcode-select --install
// 安装xcode-select，反馈已经安装
$ xcode-select --install
xcode-select: error: command line tools are already installed, use "Software Update" to install updates
// 尝试升级xcode-select，发现无需升级
$ softwareupdate --list
Software Update Tool
Finding available software
No new software available.
$ softwareupdate -i Command Line Tools
Software Update Tool
Command: No such update
Line: No such update
Tools: No such update
No updates are available.
// 最后怀疑brew版本问题，发现确实版本过低
$ brew --version
Homebrew 1.7.1
Homebrew/homebrew-core (git revision b0f2e; last commit 2019-11-17)
// 重新安装新版本
$ /usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
$ brew --version
Homebrew 2.1.16
Homebrew/homebrew-core (git revision b0f2e; last commit 2019-11-17)
Homebrew/homebrew-cask (no git repository)
// 再次安装，终于ok了
$ brew install go
==> Downloading https://mirrors.ustc.edu.cn/homebrew-bottles/bottles/go-1.13.4.catalina.bottle.tar.gz
######################################################################## 100.0%
==> Pouring go-1.13.4.catalina.bottle.tar.gz
🍺 /usr/local/Cellar/go/1.13.4: 9,271 files, 414MB
$ go version
go version go1.13.4 darwin/amd64
