WEBVTT

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After all this installation process.

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Let's launch a first Ros2 program.

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For that.

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We won't write any code here.

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We will just use existing examples that were downloaded during the installation.

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So for now, just type what I write.

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You don't need to really understand.

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I will explain everything in the next few sections.

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Okay?

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The goal is just to have something that works quickly so we can validate that Ros2 is working.

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So you can open two terminals however you want.

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And in the first terminal we are going to do Ros two and then space run.

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And then we will need to provide a package name.

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So again I'm going to come back to this later.

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So demo nodes CP you can press Tab for auto completion okay.

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It should work.

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And then space we're going to run talker okay.

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So it's called talker Ros to run demo node CP with underscores.

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And then talker.

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We are going to run that and you should see this.

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So some logs saying hello world 123 etc..

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If you have an error here already it means that probably you haven't sourced correctly your environment

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and you need to go back to the previous lesson.

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Okay, so we have this one here.

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You can see we have a program printing Hello World with a number.

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Now on that terminal let's do Ros2 run demo nodes cpp this time with listener.

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And you see we have I heard Hello world and that corresponds actually to what was seemed to be published

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here on that terminal.

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You see hello world 40 and hello world 40.

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Okay.

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So you see that this terminal is talking to that terminal.

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All right.

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To stop a program you can press Ctrl C.

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So let's press Ctrl C here.

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And you can see that program has been finished and this one is still running.

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But as you see as this one is not running, as the talker is not running, then the listener is not

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receiving anything.

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And I can do ctrl C here as well.

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All right.

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So if you can successfully start and stop those two programs, it means that everything went well.

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And you can continue with the next section.

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If it doesn't work, something is wrong with the installation or the environment.

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In this case.

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Come back to the previous lessons and make sure you have followed every step.