ROS安装时的rosdep问题

1. 把需要下载的文件手动下载到本地
2. 将下载地址修改为本地

参考：https://zhuanlan.zhihu.com/p/397624291

file:///home/ubuntu/ros/ros_github/base.yaml

file:///home/ubuntu/ros/ros_github/python.yaml

file:///home/ubuntu/ros/ros_github/ruby.yaml

file:///home/ubuntu/ros/ros_github/fuerte.yaml fuerte

=sudo vim /usr/lib/python2.7/dist-packages/rosdistro/init.py=========
file:///home/ubuntu/ros/ros_github/index-v4.yaml

关于melodic中python版本的问题，将python2.7转到python3

1. sudo apt-get install python3-catkin-pkg-modules
   sudo apt-get install python3-rospkg-modules
   sudo apt-get install python3-rosdep python3-rosinstall-generator python3-wstool python3-rosinstall build-essential
   sudo pip3 install catkin_pkg

2. catkin_make -DPYTHON_EXECUTABLE=/usr/bin/python3

3. pip3 install empy
   报错 pip3 no moudule ensurepip
   python3 -m ensurepip
   报错no module named ‘setuptools’
   sudo apt-get install python3-setuptools
   报错 AttributeError: module ‘setuptools.dist’ has no attribute ‘check_specifier’
   pip3 install --upgrade pip

4. pip3 install opencv-python-headless （如果出错就5）

5. pip3 install --upgrade pip