ubuntu20.04使用指令报错

• 现象

  • rosrun diagnostic_analysis export_csv.py my.bag -d ~/Desktop
  • 报错
    • Traceback (most recent call last): File "/opt/ros/noetic/lib/diagnostic_analysis/export_csv.py", line 40, in <module> import roslib; roslib.load_manifest(PKG) File "/opt/ros/noetic/lib/python3/dist-packages/roslib/__init__.py", line 50, in <module> from roslib.launcher import load_manifest # noqa: F401 File "/opt/ros/noetic/lib/python3/dist-packages/roslib/launcher.py", line 42, in <module> import rospkg ImportError: No module named rospkg
  • pip install rospkg尝试安装，发现装完了
    • Looking in indexes: http://pypi.doubanio.com/simple Requirement already satisfied: rospkg in /usr/lib/python3/dist-packages (1.4.0)

• 原因

  • Ubuntu20.04源仓库没有pip2 ， python2已经不再维护了

• 解决办法1

  • wget https://bootstrap.pypa.io/pip/2.7/get-pip.py
  • sudo python2 get-pip.py
  • sudo rm get-pip.py
  • pip2 install rospkg

• 解决办法2（推荐）

  • sudo update-alternatives --install /usr/bin/python python /usr/bin/python2 100
  • sudo update-alternatives --install /usr/bin/python python /usr/bin/python3 200
  • 默认使用python3