ros error [sudo rosdep init]

ros安装，执行下面命令时：

sudo rosdep init

报下面错误：

ERROR: cannot download default sources list from:
https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/sources.list.d/20-default.list
Website may be down.

解决办法：
打开文件:

sudo vim /etc/hosts

并在最后一行添加：

151.101.84.133 raw.githubusercontent.com

保存退出即可