有个问题记录一下：
- ROS程序和普通程序有什么区别？
- 什么是ROS应用？什么是ROS接口？
第一个问题，本质上没有区别的。
使用上有一些区别罢了。
第二个问题，pub或sub都支持很多模式，自己写个聊天工具都不难的。
命令行接口查看
图形化接口查看
当然直接写个sub也行的。
这里直接在云课中使用古月居21讲内容。
推荐学生阅读（2019年左右一篇文章）：
互联网下半场：从超级入口到超级接口，从超级APP到超级API
shiyanlou:~/ $ history [16:03:39]
1 git clone https://github.com/rapiz1/DungeonRush.git
2 apt install libsdl2-dev libsdl2-image-dev libsdl2-mixer-dev libsdl2-net-dev libsdl2-ttf-dev
3 sudo apt install libsdl2-dev libsdl2-image-dev libsdl2-mixer-dev libsdl2-net-dev libsdl2-ttf-dev
4 w
5 sudo apt update
6 sudo apt install libsdl2-dev libsdl2-image-dev libsdl2-mixer-dev libsdl2-net-dev libsdl2-ttf-dev
7 ls
8 cd DungeonRush
9 ls
10 cmake -B build && cmake --build build
11 mkdir build
12 cmake -B build && cmake --build build
13 cd build
14 cmake ..
15 make
16 cd bin
17 ls
18 ./dungeon_rush
19 cd ..
20 make
21 cd bin
22 ./dungeon_rush
23 cd ..
24 make
25 cd bin
26 ./dungeon_rush
27 git clone https://gitcode.net/ZhangRelay/ros_book.git
28 unzip ros_21_tutorials-master.zip
29 cd ros_ws
30 catkin_make
31 cal
32 w
33 source devel/setup.zsh
34 rosrun learning_topic person_publisher
35 roscore
36 rostopic list
37 rosnode list
38 rostopic
39 rostopic info /person_info
40 source devel/setup.bash
41 source devel/setup.zsh
42 rosrun learning_topic person_subscriber
43 rostopic info /person_info
44 ./person_publisher
45 rosrun learning_topic person_publisher
46 ./person_subscriber
47 rosrun learning_topic person_publisher
48 ./person_subscriber
49 ./person_publisher
50 rostopic echo /person_info
51 rqt
52 ./person_subscriber
53 rostopic list
54 rostopic pub /person_info learning_topic/Person "name: 'csgl'nage: 62nsex: 0"
55 rqt
shiyanlou:~/ $ [16:03:44]
