How to get nodes and topics without ros running

Question

So I tried to get my head arround how to best solve this problem but I'm probably missing a simple solution. i have a ros workspace. In this workspace I have multiple packages. And in each package I have probably multiple ros nodes.

Now what I want to do is I want to write a script that can get my all the nodes and possibly also all the publishers subscribers. Also if possible the parameters and services .

One idea of me was getting all the packages via the rospack list | workspace_name and that also works great to get the packages in the workspace.

But now the problem is how to I get all the publishers /subscribers. I know that I could get them online if the node is running via the rosnode command but how should I do this offline.

I hope I just overlooked something, I hope someone could help me what the offline methode for this is.

For additional information I'm working on ros Kinetic on Ubuntu 16.04.

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Originally posted by Lycea on ROS Answers with karma: 15 on 2018-07-04

Post score: 1

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Original comments

Comment by Delb on 2018-07-04:
Why do you want to do that ? Being "offline" means that you don't initialize your nodes and publishers/subscribers and everything else so you won't be able to find anything.

Comment by gvdhoorn on 2018-07-05:
I second the comment by @Delb: it would be good if you can provide some more context. Perhaps easier alternatives or more suitable approaches exist for what your ultimate goal is.

Answer 1

I think grep is your best option. Navigate to the src directory of your Catkin workspace to issue these commands.

List Python and C++ nodes:

grep -Er "rospy.init_node|ros::init"

List Python and C++ subscribers:

grep -Er "rospy.Subscriber|.subscribe\("

List Python and C++ publishers:

grep -Er "rospy.Publisher|.advertise<"

List Python and C++ services:

grep -Er "rospy.Service\(|.advertiseService\("

Note that this assumes in Python you always call things relative to rospy. For C++ you could also grep on ros::Subscriber, ros::Publisher, and ros::ServiceServicer, but I did it the way I did so you can account for when you have separate header and source files - the commands I provide pick up on where the actual definition is provided.

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Originally posted by adamconkey with karma: 642 on 2018-07-04

This answer was ACCEPTED on the original site

Post score: 1

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Original comments

Comment by Lycea on 2018-08-07:
Thank you for that answer that was what I was searching for . I did it now in a kind of similar way to as you wrote. :)