rostopic pub and YAML

If you having trouble figuring out how to encode arguments in YAML for rostopic pub, please see YAML command line for a detailed description and examples.

ERROR: Unable to communicate with master!

Example:

• rostopic type foo
  ERROR: Unable to communicate with master!

Solution:

• Is your Master running? If no, please run roscore

• Is your ROS_MASTER_URI set correctly? If no, please set the ROS_MASTER_URI tothe location of your Master.

• Can you contact the address specified in the ROS_MASTER_URI?

  $ echo $ROS_MASTER_URI
  http://foo:11311
  $ ping foo
  ping: unknown host foo

  If you get the "unknown host" error, please check your network settings or change the ROS_MASTER_URI to a resolvable address.