mkdir -p ros_ws/src
cd ros_ws/src/
catkin_init_workspace
######################################显示以下
#Creating symlink "/home/wfq/ros_ws/src/CMakeLists.txt" pointing to "/opt/ros/melodic/share/catkin/cmake/toplevel.cmake"
######################################
cd ~/ros_ws
catkin_make
######################################显示以下
#base path: /home/wfq/ros_ws
#Source space: /home/wfq/ros_ws/src
#Build space: /home/wfq/ros_ws/build
#Devel space: /home/wfq/ros_ws/devel
#Install space: /home/wfq/ros_ws/install
######################################
source devel/setup.bash
#或者把source ~/ros_ws/devel/setup.bash添加到~/.bashrc里
echo ${ROS_PACKAGE_PATH} #检查一下~/ros_ws/src有没有自动添加成功
2、构建ROS功能包(PACKAGE)
cd ~/ros_ws/src # catkin_create_pkg[depend1] [depend2] #如 catkin_create_pkg ros_robotics #此时rospack list已经可以检测到了 cd ~/ros_ws catkin_make
经过以上操作，通过env | grep PATH查看LD_LIBRARY_PATH, CMAKE_PREFIX_PATH, ROS_PACKAGE_PATH,里面都有ros_ws目录了
