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rostopic echo complains messages not built, but rosmsg says fine?

asked 2023-08-07 15:12:51 -0500

pbrownrobot gravatar image

Background: I have a fresh container of ros-noetic-base, that I want to have full readability of a ros master elsewhere.

  • rostopic list works fine, so connection to master is fine

  • rosmsg info specific/message/type works fine. it gives me full details on the message type

  • rostopic echo /some/topic FAILS, complaining: ERROR: Cannot load message class for [specific/message/type]. Are your messages built?

How can rosmsg be working fine, but rostopic echo fails like this?

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answered 2023-08-08 10:01:46 -0500

pbrownrobot gravatar image

Guess I'll answer my own question, in part.

Seems like rostopic requires loading python modules, and so makes use of the things in PYTHONPATH. Whereas rosmsg somehow uses the SOURCE CODE, and so makes use of things in ROS_PACKAGE_PATH

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Asked: 2023-08-07 15:12:51 -0500

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Last updated: Aug 08 '23