rosdep init or rosdep update ERROR

ERROR: unable to process source https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/...

Solution: 修改hosts文件，添加这个网站的ip地址:

#打开hosts文件
sudo gedit /etc/hosts
#在文件末尾添加
151.101.84.133  raw.githubusercontent.com
#保存后退出 

rosdep init

ERROR: default sources list file already exists: /etc/ros/rosdep/sources.list.d/20-default.list Please delete if you wish to re-initialize

cd /etc/ros/rosdep/sources.list.d/
sudo rm 20-default.list
cd
rosdep update
sudo rosdep init
rosdep update