Can we start a ROS node without a Master URI or a Dummy URI and later provide the Master URi so that the node registers to it?

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I was trying for a car application, the master is running on the car ,so when the car comes in the vicinity of the edge server ,the node running on the server should register to it . Other way is start the node once the master in car is available(car come close to this server) ,but it delays start

the problem is there is no way to inform the edge server the master URI of the car ,until the car comes close enough and is connected to edge server

So the question was if there is anyway to change the ROS_MASTER_URI of a rosnode in runtime ?

Well, for regular ROS, the above answer holds. So this is a No!

However, for this use case, it could help to investigate multimaster approaches like e.g. multimaster_fkie and treat it like a multi-robot system.

okay thanks for the feedback , since its not possible to change the master URI ,Is there a way to unregister the node from a master and reregister to another master using the Master API ? ( http://wiki.ros.org/ROS/Master_API ) .