WEBVTT 00:00.080 --> 00:03.200 Now you can create your own Python and Cplusplus nodes. 00:03.200 --> 00:05.150 You've also learned how to launch them. 00:05.150 --> 00:12.050 So for both Python and Cplusplus, after you install the node, you get an executable inside the install 00:12.050 --> 00:13.970 folder of your roster workspace. 00:13.970 --> 00:20.240 And finally, you've also seen that you can use a command line tool named Ros to run to start the node. 00:20.240 --> 00:25.400 As you will see in this lesson, it will give you more control over the nodes that you are starting. 00:25.400 --> 00:27.170 So let's experiment a bit. 00:27.200 --> 00:32.660 We're gonna review some stuff you already know with the Ros2 command line and then learn new stuff. 00:32.660 --> 00:35.060 So you open first a terminal. 00:35.060 --> 00:40.640 And just as a quick recap, make sure that you have correctly sourced the environment. 00:40.670 --> 00:50.060 Okay, so if I show you the bash SC so cat bash RC here, you see at the end I have my line to source 00:50.060 --> 00:56.420 the global Ros2 installation and then the line to source the workspace. 00:56.690 --> 01:02.350 And here well make sure you just replace that with whatever distribution you are using. 01:02.350 --> 01:03.520 And that's very important. 01:03.520 --> 01:05.110 So you can run ros2 stuff. 01:05.110 --> 01:09.040 And so you can also run the stuff you've installed in your workspace. 01:09.040 --> 01:10.570 So let's clear that. 01:10.570 --> 01:15.490 And as we just opened a terminal the bashrc is automatically executed. 01:15.490 --> 01:16.720 So here nothing to do. 01:16.750 --> 01:19.810 So let's come back to this ros2 command line. 01:19.810 --> 01:24.040 If I just put Ros2 space and then I do tab twice. 01:25.390 --> 01:27.520 You see I have all the different functionalities. 01:27.520 --> 01:29.740 So those are quite a lot. 01:29.770 --> 01:33.100 We're going to see some of the most important ones in this course. 01:33.100 --> 01:36.700 And the one we've already used is Ros2 run. 01:36.700 --> 01:39.370 So with Ros to run you can start a node. 01:39.400 --> 01:44.680 To start a node you need to provide the package name and then the executable name okay. 01:44.710 --> 01:53.860 So for example we have started in the installation section demo nodes CP that's the package name. 01:53.860 --> 01:58.210 And you should be able to use the Autocompletion with tab okay. 01:58.260 --> 02:00.480 So nodes and then see tab. 02:00.480 --> 02:03.570 We have demo nodes cp and then space. 02:03.570 --> 02:06.780 And then you're going to provide the name of the executable. 02:06.780 --> 02:10.350 So here we had so you can press tab twice for example. 02:10.770 --> 02:13.530 You see we have a lot of executables here. 02:13.530 --> 02:17.550 And we have run previously the Docker executable okay. 02:17.580 --> 02:23.610 So Ros to run and then the package and then the executable I press enter. 02:23.610 --> 02:26.220 And you see that we are starting a node okay. 02:26.250 --> 02:28.410 And I press Ctrl C to stop. 02:28.410 --> 02:34.980 So that's a node that's already installed for you in the global Ros2 installation. 02:35.520 --> 02:36.750 Now let's do clear. 02:36.750 --> 02:41.520 And we can start the nodes that we have just created in our workspace. 02:41.520 --> 02:43.290 So I can do Ros to run. 02:43.320 --> 02:50.670 Then my for example Pi PG with you see I use the Autocompletion again and then the node. 02:50.670 --> 02:55.590 Well if you don't remember the name of the executable for that node, you just press tab twice. 02:55.590 --> 03:01.190 And you see here we have the auto autocompletion that puts automatically by node because we only have 03:01.190 --> 03:03.380 one executable for now. 03:03.620 --> 03:04.250 All right. 03:04.250 --> 03:06.980 So package executable. 03:07.010 --> 03:08.300 I run that. 03:08.480 --> 03:08.990 Okay. 03:08.990 --> 03:13.610 And then I do control C and I can do the same with the other package. 03:13.760 --> 03:19.160 So I put CP package and then I press tab twice if I don't remember. 03:19.190 --> 03:19.520 Okay. 03:19.550 --> 03:20.540 CP node. 03:20.540 --> 03:25.850 And we start the C plus plus node that we have created. 03:25.880 --> 03:30.470 I'm just going to show you what happens if you haven't sourced the workspace. 03:30.470 --> 03:35.990 So let's open I'm going to open it with Git Bash RC. 03:36.860 --> 03:41.540 I am just going to comment that line here and save the file. 03:41.990 --> 03:42.260 Okay. 03:42.290 --> 03:45.680 So when I open a new terminal I'm going to do a new window here. 03:45.860 --> 03:51.710 That terminal is going to be sourced for the global Ros2 installation but not for the workspace. 03:51.710 --> 03:56.750 So if I try to do Ros2 run my pi By PG. 03:56.780 --> 03:59.750 Here you will not have the autocompletion anyway. 04:00.410 --> 04:01.820 So mypy PG. 04:01.820 --> 04:03.470 And then that was py node. 04:03.500 --> 04:07.400 You see that I will have package not found. 04:07.400 --> 04:14.660 So if you have this error with a package that you have created yourself, that is very likely because 04:14.660 --> 04:18.200 you haven't correctly sourced the workspace. 04:18.200 --> 04:24.260 Or maybe you have the correct source line in the bashrc, but then you have created and built the package 04:24.260 --> 04:27.440 in one terminal and you haven't sourced the terminal again. 04:27.440 --> 04:31.070 So in this case source the bashrc or open a new terminal. 04:31.580 --> 04:31.910 Okay. 04:31.940 --> 04:37.670 So now I'm going to close that and just put back and save and close. 04:40.550 --> 04:41.840 All right now let's continue. 04:41.840 --> 04:45.230 And let's discover other functionalities of the Ross two command line. 04:45.230 --> 04:48.530 For this I'm going to open some terminals. 04:48.920 --> 04:52.670 I'm going to open for like that with Terminator. 04:52.670 --> 04:58.390 So if you don't know how I did this you can go back to the installation section and I explain everything. 04:58.390 --> 05:01.810 So we have the Ros2 run command line. 05:01.810 --> 05:07.060 Actually if you want to have more information with any thing you just type dash h for help. 05:07.060 --> 05:10.810 And you see you have an explanation with what you have to give here. 05:10.810 --> 05:12.910 For example package name executable. 05:12.910 --> 05:14.620 You can also give some arguments. 05:14.620 --> 05:15.700 We're going to see that later. 05:15.700 --> 05:20.830 And we're going to see another command which is ros2 node. 05:20.830 --> 05:26.470 And with Ros2 node you will be able to introspect the nodes that are currently running. 05:26.470 --> 05:28.510 So we have Ros2 node list. 05:28.510 --> 05:32.170 And you can see Ros2 node list is returning nothing. 05:32.170 --> 05:35.380 This is going to list all the nodes that are currently running. 05:35.380 --> 05:37.450 So now we have zero node. 05:37.960 --> 05:47.170 Let's do Ros to run my pi pkg with pi node okay it's running. 05:47.170 --> 05:49.300 Now let's run this again. 05:49.510 --> 05:53.140 And you can see I have pi tests okay. 05:53.170 --> 05:54.300 Let's do Ross. 05:54.330 --> 06:01.680 To run my cp pg with CP node. 06:01.920 --> 06:04.680 So we have two nodes running. 06:05.280 --> 06:05.790 I do. 06:05.820 --> 06:09.750 Ross two node list and we have you see CP test and pi test. 06:09.750 --> 06:12.900 So we can see all the nodes that are running. 06:12.960 --> 06:14.250 Now you can do something else. 06:14.250 --> 06:19.890 You can also do Ross two node info to get more information about a specific node. 06:19.890 --> 06:22.740 And for that you need to provide the name of the node. 06:22.740 --> 06:26.310 So it's quite useful to do node list first. 06:26.310 --> 06:30.480 And then you can just take a for example that one CP test. 06:30.480 --> 06:37.740 So starting with slash here you press enter and you have more information here. 06:39.870 --> 06:45.300 So you see that for this node we have all of those subscribers publishers. 06:45.300 --> 06:48.810 So that corresponds to topics which we're going to see later. 06:48.810 --> 06:53.480 And we have all of the service servers and service clients here that also we're going to see later. 06:53.480 --> 06:58.070 So with this you see what rose to communications this node is using. 06:58.070 --> 07:02.570 And by default there are a few ones for parameters for log etc.. 07:02.600 --> 07:02.990 All right. 07:02.990 --> 07:04.520 So it can be quite useful. 07:04.520 --> 07:09.620 And you can do also ros2 node and then dash h for the help. 07:10.370 --> 07:14.930 And you can see the different commands info list okay. 07:14.960 --> 07:16.460 And how you can use them. 07:16.850 --> 07:17.240 Great. 07:17.240 --> 07:19.520 So let's come back to the previous view. 07:19.520 --> 07:23.630 And well let's stop those. 07:23.630 --> 07:25.280 So that's about it for now. 07:25.280 --> 07:31.460 You have the Ros2 run command and you have the rose two node with list and info. 07:31.910 --> 07:34.760 With that you can start nodes and introspect nodes. 07:34.760 --> 07:40.610 Now there is one important thing to remember when you start nodes is that you cannot have two nodes 07:40.610 --> 07:42.170 with the same name. 07:42.200 --> 07:46.820 Okay, so when you have the rose two node list, you should not have two nodes with the same name. 07:46.820 --> 07:50.030 And how to make sure that you don't have two nodes with the same name. 07:50.030 --> 07:52.580 Well, let's go to the next video.