New ros2 bag echo verb to dump a single topic to stdout?

[moooeeeep]

Description

I was looking to dump a single topic's content to stdout in csv format, like rostopic echo -b <bagfile> -p <topic> used to do.

Related question: https://robotics.stackexchange.com/questions/114194/exporting-single-topic-data-to-csv-with-rosbag2-bag-files

I had the impression that this feature doesn't exist, so I wrote a small script using the Python API. I wondered if it would be useful to add this as a new verb to the cli (the actual name would be open for debate)?

Related Issues

None

Completion Criteria

• CLI verb to dump topic from bagfile to stdout (yaml and/or csv format)
• Required customization options, e.g., to specify storage id and output format

Implementation Notes / Suggestions

Similar to the test code of the SequentialReader, but with formatted output.

Testing Notes / Suggestions

Process known bagfiles for different sets of options and verify the captured output.

[MichaelOrlov]

Hi @moooeeeep I would imagine that this functionality would be an extension/addition to the ros2 bag convert CLI command.
Please refer to the https://github.com/ros2/rosbag2/blob/rolling/README.md#converting-bags for details about convert verb usage and possible options.