roscore失败

记住sudo gedit ~/.bashrc时，source /opt/ros/kinetic/setup.bash要放在最后3行以内才有效，最后source ~/.bashrc

roscore出现

Traceback (most recent call last):
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/roslaunch/__init__.py", line 257, in main
    write_pid_file(options.pid_fn, options.core, options.port)
  File "/opt/ros/kinetic/lib/python2.7/dist-packages/roslaunch/__init__.py", line 110, in write_pid_file
    with open(pid_fn, "w") as f:
IOError: [Errno 13] Permission denied: '/home/ycx/.ros/roscore-11311.pid'

一开始在看看ros包有没有少，https://blog.csdn.net/qq_45539458/article/details/106456408
sudo apt-get install ros-kinetic-desktop-full

不行在看一篇，https://blog.csdn.net/fantasysolo/article/details/80431801
sudo rosdep fix-permissionske
行了

还有种说法是python问题，但我没试完就找到了上面那篇…
https://blog.csdn.net/qq_39506862/article/details/87689824
sudo apt-get install defusedxml*
conda install -c conda-forge defusedxml
要装Anaconda，下载https://www.anaconda.com/products/individual#download
参考https://blog.csdn.net/ksws0292756/article/details/79143460