The
topic commands use iceoryx2 service discovery, so they work from any
directory, no workspace required. Run them in a second terminal while a graph
is running.List and inspect live topics
cerulion topic list prints this machine’s shared-memory topics first, then the robots and topics it discovers on the LAN.
No active local topics.
cerulion topic info <topic> prints one topic’s schema and its last sequence number and timestamp:
Watch messages with echo
cerulion topic echo <topic> subscribes and prints each message until you press Ctrl+C.
--truncate-length N changes that.
Measure publish rate
cerulion topic hz <topic> measures how often a topic publishes, until Ctrl+C.
For the periodic camera created with
--policy period_ms=33, topic hz
should report roughly 30 Hz.Open the interactive dashboard
cerulion tui launches an interactive terminal dashboard. Logging is suppressed while the TUI is open.
Keep a record instead of watching
echo and hz answer questions about now. To keep the data, record the run to an MCAP bag and inspect it afterwards — see Record and replay a run. To watch the data rather than read it, Cerulion Studio renders live topics as you check them.
Clean up stale services
iceoryx2 keeps on-disk bookkeeping for each node. When a graph’s topology changes between runs, stale entries from dead nodes can cause discovery errors.cerulion clean removes bookkeeping for dead nodes only; live sibling processes are left untouched. It prints cleanup counts and per-cause remediation, and names every node it could not reclaim together with the reason. A node whose only obstacle is a non-empty directory gets its orphan port tags reclaimed, after which the command runs a second sweep and reports that separately. A graph that stops normally already runs a short cleanup pass of its own as it exits, so reach for this command mainly after a run that was killed, or when you want everything cleared at once.
Next steps
Wire and run a graph
Produce the topics you inspect here.
Messages and schemas
Understand the message shapes that echo prints.
Visualize a running graph
Render these topics on the Studio stage instead of reading them.
Reach remote robots
Discovery, pairing, and pulling a robot’s topics to your desk.