新建工作空间，catkin_make出现如下错误：
Base path: /home/caohaojie/ros_ws
Source space: /home/caohaojie/ros_ws/src
Build space: /home/caohaojie/ros_ws/build
Devel space: /home/caohaojie/ros_ws/devel
Install space: /home/caohaojie/ros_ws/install
####
#### Running command: "cmake /home/caohaojie/ros_ws/src -DCATKIN_DEVEL_PREFIX=/home/caohaojie/ros_ws/devel -DCMAKE_INSTALL_PREFIX=/home/caohaojie/ros_ws/install -G Unix Makefiles" in "/home/caohaojie/ros_ws/build"
####
-- The C compiler identification is GNU 9.3.0
-- The CXX compiler identification is GNU 9.3.0
-- Check for working C compiler: /usr/bin/cc
-- Check for working C compiler: /usr/bin/cc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- Check for working CXX compiler: /usr/bin/c++
-- Check for working CXX compiler: /usr/bin/c++ -- works
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Detecting CXX compile features
-- Detecting CXX compile features - done
CMake Error at CMakeLists.txt:22 (message):
Search for 'catkin' in workspace failed (catkin_find_pkg catkin
/home/caohaojie/ros_ws/src): Traceback (most recent call last):
File "/home/caohaojie/.local/bin/catkin_find_pkg", line 5, in <module>
from pkg_resources import load_entry_point
File "build/bdist.linux-x86_64/egg/pkg_resources.py", line 2603, in <module>
File "build/bdist.linux-x86_64/egg/pkg_resources.py", line 666, in require
File "build/bdist.linux-x86_64/egg/pkg_resources.py", line 565, in resolve
pkg_resources.DistributionNotFound: pyparsing
-- Configuring incomplete, errors occurred!
See also "/home/caohaojie/ros_ws/build/CMakeFiles/CMakeOutput.log".
Invoking "cmake" failed
解决方法：
降低catkin-pkg的版本
$pip3 install catkin-pkg==0.4.16
