ROS- 解决 rosdep update 出现的错误

安装ROS时，反复出现下面的错误，

1.执行sudo rosdep init 出现错误

sudo rosdep init

错误如下：

ERROR: cannot download default sources list from:
https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/sources.list.d/20-default.list
Website may be down.

解决：
sudo rm /etc/ros/rosdep/sources.list.d/20-default.list
sudo apt-get update
sudo rosdep init
rosdep update

错误如下：
然后出现的错误

解决方法：

sudo rm /etc/ros/rosdep/sources.list.d/20-default.list
sudo apt-get update
sudo rosdep init
rosdep update

2. rosdep update 时出现错误

执行 rosdep update后 错误如下，

reading in sources list data from /etc/ros/rosdep/sources.list.d
Hit https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/osx-homebrew.yaml
ERROR: unable to process source [https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/base.yaml]:
    <urlopen error [Errno 104] Connection reset by peer> (https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/base.yaml)
ERROR: unable to process source [https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/python.yaml]:
    <urlopen error [Errno 104] Connection reset by peer> (https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/python.yaml)
ERROR: unable to process source [https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/ruby.yaml]:
    <urlopen error [Errno 104] Connection reset by peer> (https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/ruby.yaml)
ERROR: unable to process source [https://raw.githubusercontent.com/ros/rosdistro/master/releases/fuerte.yaml]:
    Failed to download target platform data for gbpdistro:
    <urlopen error [Errno 104] Connection reset by peer>
Query rosdistro index https://raw.githubusercontent.com/ros/rosdistro/master/index-v4.yaml
Skip end-of-life distro "ardent"
Skip end-of-life distro "bouncy"
Add distro "crystal"
ERROR: error loading sources list:
    <urlopen error <urlopen error [Errno 104

解决方法：

sudo apt-get update && sudo apt-get install python-rosdep
sudo rosdep init
rosdep update

如果还有错误，，嗯，继续执行 ，直至成功！！

rosdep update

在ros wiki answer也看到有人说是网络问题，于是我连接了手机热点，但是，眼看就要成功了，还是最终失败了，
几次中断的地方还不一样，
没办法，多试几次吧，总会好的。

中断，，

Finally, 大功告成！！！