Python 2无法正常工作，PYTHONPATH问题？

Question

I use python3 normally but also some python2 with ROS. After a longer time i tried to built my ros workspace and the error I get is

ImportError: "from catkin_pkg.package import parse_package" failed: No module named 'catkin_pkg'
Make sure that you have installed "catkin_pkg", it is up to date and on the PYTHONPATH.
CMake Error at /opt/ros/kinetic/share/catkin/cmake/safe_execute_process.cmake:11 (message):
execute_process(/home/work/py_venv/bin/python
"/opt/ros/kinetic/share/catkin/cmake/parse_package_xml.py"
"/opt/ros/kinetic/share/catkin/cmake/../package.xml"
"/home/work/catkin_ws/build/catkin_tools_prebuild/catkin/catkin_generated/version/package.cmake")

The first directory /home/work/py_venv/bin/python is a virtual environment for python3. I am not sure why it is looking there. I dont have any virtual environment activate (well on purpose at least). What I am totally missing though is the path to the standard python2 installation. Shouldnt it be there?

If I enter echo $PYTHONPATH in the terminal, I just get /opt/ros/kinetic/lib/python2.7/dist-packages I guess there is something missing? How can I set this variable correctly. Which value does it have at installation? I recently installed venv in python3 apart from that I am not aware of any changes I did to python since it stoped working.

Now that is a lot of questions. If you can answer any of them, it would be appreciated.

Edit: I know found the main problem is the prepending of the venv on the path , so that it look for the package in the python3 installation which does not contain the catkin package. How can I remove this from the path?

Answer 1

If you want to remove venv python path, you can do that as follow,

echo $PATH
export PATH=<remove unwanted path>

In this way, you can remove your venv python path.

Also, check this python --version which might be set to python3, if so change that as well.

Finally, check PYTHONPATH if it's not directed proper location change and try.