Source and Inspect the ROS Environment

ROS 2 relies on shell environment setup files.

The Jazzy beginner documentation is explicit: without sourcing the setup files, the shell may not be able to access ROS 2 commands or find ROS packages.

Source Jazzy

In a Bash terminal, run:

source /opt/ros/jazzy/setup.bash

Now test:

ros2 --help

Inspect the environment

Run:

printenv | grep -i ROS

The beginner documentation tells you to look for variables including:

ROS_VERSION=2
ROS_PYTHON_VERSION=3
ROS_DISTRO=jazzy

Your output may include additional ROS variables.

New terminal experiment

Open another terminal.

Do not source Jazzy manually yet.

Run:

printenv | grep -i ROS
which ros2

Then source Jazzy and repeat the commands.

What changed?

That change is the shell environment becoming aware of the ROS installation.

Optional startup convenience

The official beginner documentation shows adding the setup command to Bash startup configuration:

echo "source /opt/ros/jazzy/setup.bash" >> ~/.bashrc

Do this only if the course/instructor environment expects persistent sourcing. On a shared or multi-distro machine, manually sourcing may be clearer because you can deliberately choose a distribution.

Evidence checkpoint

Capture a before/after comparison:

BEFORE SOURCE
which ros2:
ROS_DISTRO:

AFTER SOURCE
which ros2:
ROS_DISTRO:

Then answer:

Did sourcing install ROS 2?

Correct answer: no. It configured the current shell to use an installation that already existed.