ubuntu 20.04上用清华镜像源安装ROS-foxy

添加ros2清华镜像源地址
sudo sh -c 'echo "deb [arch=amd64] https://mirrors.tuna.tsinghua.edu.cn/ros2/ubuntu/ `lsb_release -cs` main" > /etc/apt/sources.list.d/ros2-latest.list'
获取ROS2公钥
curl http://repo.ros2.org/repos.key | sudo apt-key add -
更新系统
sudo apt-get update
安装ros-foxy
sudo apt install ros-foxy-desktop
验证安装的ROS2
ros2 run demo_nodes_cpp talker
ros2 run demo_nodes_py listener