Errors encountered during ROS installation
sudo rosdep init command error:
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.
Then enter sudo gedit /etc/hosts on the command line, add 151.101.192.133 raw.githubusercontent.com to the host file and save it.
sudo rm /etc/ros/rosdep/sources.list.d/20-default.list