Ubuntuバージョン	Ubuntuコードネーム	ROS1バージョン
Ubuntu 20.10	Groovy Gorilla ※	インストールできない
Ubuntu 20.04	Focal Fossa	ROS Noetic Ninjemys
Ubuntu 18.04	Bionic Beaver	ROS Melodic Morenia
Ubuntu 17.04	Zesty Zapus	ROS Lunar Loggerhead
Ubuntu 16.04	Xenial Xerus	ROS Kinetic Kame
※ROSの古いバージョンでGroovyという同じ名前があるので要注意。

Ubuntu20.10へROS Noeticをインストールしてみる

20.10 Groovy Gorilla

E: The repository 'http://packages.ros.org/ros/ubuntu groovy Release' does not have a Release file.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.

普通にインストールしようとするとエラー。

http://packages.ros.org/ros/ubuntu/dists/focal/
ここを見てみると、Focalしかない。
下記でgroovyから、focalに書き換えてしまう。

$ sudo sh -c 'echo "deb http://packages.ros.org/ros/ubuntu focal main" > /etc/apt/sources.list.d/ros-latest.list'

apt updateはできるようになったが、

$ sudo apt install ros-noetic-desktop-full
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 gazebo11 : Depends: libboost-regex1.71.0-icu66 but it is not installable
            Depends: libignition-msgs5 (>= 5.3.0) but it is not going to be installed
            Depends: libignition-transport8 (>= 8.0.0) but it is not going to be installed
            Depends: libprotobuf17 but it is not installable
 gazebo11-common : Depends: ttf-dejavu-core but it is not installable
 gazebo11-plugin-base : Depends: libignition-msgs5 (>= 5.3.0) but it is not going to be installed
                        Depends: libignition-transport8 (>= 8.0.0) but it is not going to be installed
                        Depends: libprotobuf17 but it is not installable
 libgazebo11 : Depends: libboost-regex1.71.0-icu66 but it is not installable
               Depends: libgdal26 (>= 3.0.0) but it is not installable
               Depends: libignition-fuel-tools4 (>= 4.1.0) but it is not going to be installed
               Depends: libignition-msgs5 (>= 5.3.0) but it is not going to be installed
               Depends: libignition-transport8 (>= 8.0.0) but it is not going to be installed
               Depends: libprotobuf17 but it is not installable
               Depends: libtinyxml2-6a (>= 6.0.0) but it is not installable
 libignition-common3-av-dev : Depends: libignition-cmake2-dev but it is not installable
 libignition-common3-core-dev : Depends: libignition-cmake2-dev but it is not installable
 libignition-common3-events-dev : Depends: libignition-cmake2-dev but it is not installable
 libignition-common3-graphics-dev : Depends: libignition-cmake2-dev but it is not installable
                                    Depends: libignition-common3-graphics (= 3.6.0-1~focal) but it is not going to be installed
 libignition-common3-profiler-dev : Depends: libignition-cmake2-dev but it is not installable
 libignition-fuel-tools4-dev : Depends: libignition-cmake2-dev but it is not installable
                               Depends: libignition-fuel-tools4 (= 4.2.1-2~focal) but it is not going to be installed
 libignition-math6-dev : Depends: libignition-cmake2-dev but it is not installable
 libignition-msgs5-dev : Depends: libignition-cmake2-dev but it is not installable
                         Depends: libignition-msgs5 (= 5.3.0-1~focal) but it is not going to be installed
 libignition-transport8-core-dev : Depends: libignition-transport8 (= 8.1.0-1~focal) but it is not going to be installed
                                   Depends: libignition-cmake2-dev but it is not installable
 libignition-transport8-log-dev : Depends: libignition-cmake2-dev but it is not installable
                                  Depends: libignition-transport8-log (= 8.1.0-1~focal) but it is not going to be installed
 ros-noetic-class-loader : Depends: libpocofoundation62 (>= 1.9.2) but it is not installable
 ros-noetic-controller-manager : Depends: libtinyxml2-6a (>= 5.0.0) but it is not installable
 ros-noetic-cv-bridge : Depends: libboost-regex1.71.0-icu66 but it is not installable
 ros-noetic-diagnostic-aggregator : Depends: libboost-regex1.71.0-icu66 but it is not installable
                                    Depends: libtinyxml2-6a (>= 5.0.0) but it is not installable
 ros-noetic-gazebo-plugins : Depends: libprotobuf17 but it is not installable
 ros-noetic-gazebo-ros : Depends: libprotobuf17 but it is not installable
 ros-noetic-gazebo-ros-control : Depends: libtinyxml2-6a (>= 5.0.0) but it is not installable
                                 Depends: ros-noetic-transmission-interface but it is not going to be installed
 ros-noetic-image-transport : Depends: libtinyxml2-6a (>= 5.0.0) but it is not installable
 ros-noetic-kdl-parser : Depends: libtinyxml2-6a (>= 5.0.0) but it is not installable
 ros-noetic-laser-assembler : Depends: libtinyxml2-6a (>= 5.0.0) but it is not installable
 ros-noetic-laser-filters : Depends: libtinyxml2-6a (>= 5.0.0) but it is not installable
 ros-noetic-nodelet : Depends: libtinyxml2-6a (>= 5.0.0) but it is not installable
 ros-noetic-pcl-ros : Depends: libpcl-common1.10 (>= 1.10.0+dfsg) but it is not installable
                      Depends: libpcl-features1.10 (>= 1.10.0+dfsg) but it is not installable
                      Depends: libpcl-filters1.10 (>= 1.10.0+dfsg) but it is not installable
                      Depends: libpcl-io1.10 (>= 1.10.0+dfsg) but it is not installable
                      Depends: libpcl-search1.10 (>= 1.10.0+dfsg) but it is not installable
                      Depends: libpcl-segmentation1.10 (>= 1.10.0+dfsg) but it is not installable
                      Depends: libpcl-surface1.10 (>= 1.10.0+dfsg) but it is not installable
 ros-noetic-pluginlib-tutorials : Depends: libtinyxml2-6a (>= 5.0.0) but it is not installable
 ros-noetic-rosbag : Depends: libboost-regex1.71.0-icu66 but it is not installable
                     Depends: ros-noetic-rosbag-storage but it is not going to be installed
 ros-noetic-rosconsole : Depends: libboost-regex1.71.0-icu66 but it is not installable
 ros-noetic-rospack : Depends: libtinyxml2-6a (>= 5.0.0) but it is not installable
 ros-noetic-rqt-gui-cpp : Depends: libtinyxml2-6a (>= 5.0.0) but it is not installable
                          Depends: ros-noetic-qt-gui-cpp (>= 0.3.0) but it is not going to be installed
 ros-noetic-rviz : Depends: libtinyxml2-6a (>= 5.0.0) but it is not installable
 ros-noetic-urdf : Depends: libtinyxml2-6a (>= 5.0.0) but it is not installable
E: Unable to correct problems, you have held broken packages.

エラーが出て、やっぱり難しそう。。