适用于macOS Sierra
Apple Store下载安装Xcode
安装Homebrew包管理，类似于Ubuntu下的apt-get: 终端下输入 ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
终端下输入：brew install wget
安装完毕！
==> Pouring wget-1.18.sierra.bottle.tar.gz
$ wget
wget: missing URL
Usage: wget [OPTION]... [URL]...
Try `wget --help' for more options.