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[ROS2] What is the "rqt --force-discover" option meaning?

asked 2019-11-21 19:52:30 -0500

harderthan gravatar image

Hello, experts. My environment is Ubuntu 18, ROS2 Crystal.

I installed the rqt-graph plugin to debugging. But, I can't find out the plugin on rqt-gui. In normal case, It should to be on "Plugins->introspection->Node Graph".

After $ rqt ---force-discover, it is working now. Further, other plugins come out on "Plugins" tap.

What is the "rqt --force-discover" option meaning?

The description, written on the rqt usage guide, said below.

"--force-discover force a rediscover of plugins"

Do you explain "rediscover" progress meaning?

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stevemacenski gravatar image stevemacenski  ( 2019-11-21 20:53:52 -0500 )edit

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answered 2019-11-22 11:14:29 -0500

Dirk Thomas gravatar image

The list of available plugins is cached for one day ( to speed up repeated invocation of rqt. If plugins are added within that period they don't show up automatically since the cached information is used.

Passing --force-discover will invalidate the existing cache and ensures that the list of available is queried again (which takes a little bit of time, depending on the size of the ROS installation up to a few seconds).

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Asked: 2019-11-21 19:52:30 -0500

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Last updated: Nov 22 '19