In this exercise, we will setup ROS to be used from the terminal.
In order to start programming in ROS, you should know how to install ROS on a new machine as well and check that the installation worked properly. This module will walk you through a few simple checks of your installed ROS system. Assuming you are working from the VM, you can skip any installation instructions as ROS is already installed.
Scan-N-Plan Application: Problem Statement¶
We believe we have a good installation of ROS but let’s test it to make sure.
Scan-N-Plan Application: Guidance¶
If you are ever having problems finding or using your ROS packages make sure that you have your environment properly setup. A good way to check is to ensure that environment variables that ROS sets are present:
env | grep ROS env | grep AMENT
If they are not then you might need to ‘source’ some setup.*sh files.
Now repeat the check from above and verify that the environment variables are now present.
This process allows you to install several ROS distributions (even ROS1 and ROS2) side-by-side on the same computer and switch between them by sourcing the distribution-specific
setup.bashfile. Your training PC also has a ROS1 “noetic” distribution installed. Try activating that distribution in the same terminal window you used above and observe how the environment variables change.
source /opt/ros/noetic/setup.bash env | grep ROS
If you switch back to the “foxy” ROS2 distribution, you’ll notice that your environment is stil polluted with some variables from the ROS1 “noetic” distribution. To prevent confusion, it can be helpful to always start with a fresh terminal window rather than switching between distributions in the same terminal window.
In a “bare” ROS install, you will need to run the “source” command on every new shell you open to have access to the ROS commands. If your project only uses a single distribution, it can be helpful to configure our
~/.bashrc file to automatically source this setup file for each new terminal window. See here for details. If you will be using multiple ROS distributions on one machine, then you do NOT want this auto-sourcing behavior. The auto-sourcing will always source the same distribution, and sourcing another distribution after this can cause issues. This class uses multiple ROS distros (noetic for ROS1 and foxy for ROS2), so we have not configured this auto-sourcing behavior for your training PC.
- Open a new terminal window and source the ROS2 “foxy” distribution. Experiment with terminal windows, sourcing, and checking your environment until you are comfortable with this concept.
Remember to source the appropriate
setup script in every new terminal window you open. Forgetting this step is a common error among new ROS users.