macOS 安装 wget

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.