[原文链接]（https://answers.ros.org/question/345764/e-unable-to-locate-package-ros-melodic-desktop-full-or-ros-melodic-desktop/）

步骤：

1. Setup your sources list：sudo sh -c 'echo "deb http://packages.ros.org/ros/ubuntu $(lsb_release -sc) main" > /etc/apt/sources.list.d/ros-latest.list'
2. Set up your keys sudo apt-key adv --keyserver 'hkp://keyserver.ubuntu.com:80' --recv-key C1CF6E31E6BADE8868B172B4F42ED6FBAB17C654
3. Run sudo apt update
4. Install your ros version sudo apt install ros-melodic-desktop-full