[ROS] (01) Create ROS workspace

  Articles are only study notes during personal study,主要参考ROS教程¹.

---

1. 创建catkin工作空间

  CatkinA workspace is a folder,可以在其中修改、构建和安装 catkin 包.

mkdir -p ~/catkin_ws/src
cd ~/catkin_ws/
catkin_make

  在运行上述命令后,在catkin_wsunder the workspacebuild、devel、srcThe three directory folders（这3个catkinBuild system default）.

• build（Build Space）：catkin(CMake)cache information and other middleware
• devel（Development Space）：生成目标文件（包括头文件、动态链接库、静态链接库、可执行文件等）、环境变量
• src（Source Space）：ROS的catkin软件包（源码）
  

Tips：Some of the earlier tutorials remaincatkin_init_workspaceThis initialization command,它的作用就是在catkin_ws工作空间的src目录下创建CMakeLists.txt 文件.但实际上catkin_make命令包含了catkin_init_workspace,No need to call again（当然你也可以使用,没有任何影响）.

  接下来设置环境变量,首先source一下新生成的setup.*sh文件（在develYou can see a few in the directorysetup.*sh）：

source devel/setup.bash

  But the above command only works on the current terminal,This results in the need to open a new terminal every timesource命令一下,Refresh environment variables,才能使用ROS相关命令.解决办法是,在终端中输入如下命令,So every time you open the terminal,.bashrc会自动运行：

 echo "source ~/catkin_ws/devel/setup.bash" >> ~/.bashrc
 source ~/.bashrc

   我们用 vi 编辑器打开 ~/.bashrc 文件,在文件的末尾（红色框内）This line is what we addedROS系统的环境变量,The previous line is what we createdcatkin_ws工作空间的环境变量.在终端中输入如下命令：

vi ~/.bashrc

  Want to see environment variables,在终端中输入如下命令：

 echo $ROS_PACKAGE_PATH

  After passing the above command,The display contains those saved withROS软件包的路径,And use colons between each path（:）分隔开来.

路径PATH格式：/home/<username>/catkin_ws/src:/opt/ros/<distro>/share

2. catkin工作空间结构

要查看catkin工作空间的结构,可以使用tree命令,显示文件结构,在终端中输入如下命令：

cd ~/catkin_ws
sudo apt install tree
tree

The displayed structure is shown below：

.
├── build
│   ├── atomic_configure
│   │   ├── env.sh
│   │   ├── local_setup.bash
│   │   ├── local_setup.sh
│   │   ├── local_setup.zsh
│   │   ├── setup.bash
│   │   ├── setup.sh
│   │   ├── _setup_util.py
│   │   └── setup.zsh
│   ├── catkin
│   │   └── catkin_generated
│   │       └── version
│   │           └── package.cmake
│   ├── catkin_generated
│   │   ├── 
......
├── devel
│   ├── cmake.lock
│   ├── env.sh
│   ├── lib
│   ├── local_setup.bash
│   ├── local_setup.sh
│   ├── local_setup.zsh
│   ├── setup.bash
│   ├── setup.sh
│   ├── _setup_util.py
│   └── setup.zsh
└── src
    └── CMakeLists.txt -> /opt/ros/melodic/share/catkin/cmake/toplevel.cmake

---

1. ROS.otg. ROS教程[EB/OL]. 2020-12-22[2022-7-5]. http://wiki.ros.org/cn/ROS/Tutorials. ︎