ROS 2 Launch Environment Variables: Case-Sensitivity Across Platforms

Answer to the question

1. Does the launch package enforce case‑sensitivity on Windows?

No. The ROS 2 launch system passes environment variable names directly to the underlying operating system. On POSIX systems the names are case‑sensitive, while on Windows they are case‑insensitive. The launch package has no flag or option to change this behaviour.

2. Recommended pattern for cross‑platform variable definition

• Use a single, consistent spelling for every variable. Avoid names that differ only by case. • Prefer all‑uppercase names (e.g., MY_VAR) to match the common convention on both platforms. • Add a unique prefix for your package or project (e.g., MYPROJECT_FOO) to prevent accidental collisions with other software. • When reading a variable with EnvironmentVariable or LaunchConfiguration, use the same spelling that was set. • If you need to support legacy names, set a single canonical name and expose an alias only in the documentation, not in the launch file itself.

Minimal test to confirm behaviour

On each target OS run the following Python script after a launch file has set two variables that differ only by case. The script prints the environment dictionary.

import os
print('FOO:', os.environ.get('FOO'))
print('foo:', os.environ.get('foo'))

Example launch snippet (Python launch file):

from launch import LaunchDescription
from launch.actions import SetEnvironmentVariable

ld = LaunchDescription([
    SetEnvironmentVariable(name='FOO', value='value1'),
    SetEnvironmentVariable(name='foo', value='value2'),
    # launch a simple process that prints the environment
    # e.g., a Python node that imports os and prints the two keys
])

return ld

On Linux you should see two distinct values. On Windows you will see that FOO and foo refer to the same entry, with the value from the last assignment.

Practical verification checklist

• Run the above test on the ROS 2 distribution you ship (e.g., Humble, Iron).
• Confirm that the launch package version is the one you expect; newer point releases may change the environment‑block serialization on Windows.
• After any ROS 2 update, repeat the test to ensure no regression.

By following the single‑spelling, uppercase, prefixed convention, you guarantee that the same name resolves to the same value regardless of the host operating system.