About linux : ROS-Noetic-setup-etcrosnoeticsetupbash-not-created

I am attempting to set up ROS noetic for Linux Mint 20. However, “sudo apt search ros-noetic” does not return anything. I ran the most similar package I could find, “ros-desktop-full,” and followed the rest of the wiki’s installation instructions from there, but can’t figure out how to finish environment setup, since /etc/ros/noetic/setup.bash was not created.

sudo find / -name ros:

/opt/ros
/etc/ros
/usr/include/ros
/home/thomas/Documents/school_stuff/internship/dependencies/DynamixelSDK/ros

ls /usr/include/ros:

advertise_options.h             publisher_link.h
advertise_service_options.h     rate.h
assert.h                        roscpp_serialization_macros.h
builtin_message_traits.h        ...etc

ls /etc/ros:

genmsg  rosdep

ls ~/Documents/school_stuff/internship/dependencies/DynamixelSDK/ros:

dynamixel_sdk  dynamixel_sdk_examples

/opt/ros is empty (this directory was not created automatically; I created it manually)

sudo find / -name setup.bash:

/home/thomas/catkin_ws/build/catkin_generated/installspace/setup.bash
/home/thomas/catkin_ws/build/atomic_configure/setup.bash
/home/thomas/catkin_ws/devel/setup.bash

ros-desktop-full isn’t what you want. Instead you want the noetic specific version; which is why the noetic setup file is missing. When installing on Mint your apt sources will be trying to use the Mint name(Ulyana) and not the Ubuntu name ROS uses(Focal). To fix this you can simply edit your ros apt listing in /etc/apt/sources.list.d/ros-latest.list. If you don’t want to append manually you can run

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

Then after an apt update you should be able to successfully install via sudo apt install ros-noetic-desktop-full