遇到ros_build中的断言错误，如下：
Assertion failed: check for file existence, but filename
(RT_LIBRARY-NOTFOUND) unset. Message: RT Library
Call Stack (most recent call first):
/opt/ros/melodic/share/catkin/cmake/tools/rt.cmake:44 (assert_file_exists)
/opt/ros/melodic/share/catkin/cmake/all.cmake:164 (include)
/opt/ros/melodic/share/catkin/cmake/catkinConfig.cmake:20 (include)
CMakeLists.txt:4 (find_package)
可使用以下链接（我确实解决了，但是正如此博主所说，他也不知道这个方法对不对....）
What for catkin needs to link to librt (realtime extension)? - ROS Answers: Open Source Q&A Forum