Ubuntu18.04-ROS安装大坑之一：sudo rosdep init报错，ERROR: cannot download default sources list from:...

Ubuntu18.04安装

根据官网安装，或者根据爱跑步的mango的博客都可以，同事这篇博客提出rosdep init出错的解决方案，但是我按照这个方式并没有解决：

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分割线内容，是爱跑步的mango的解决方案

cd /etc
sudo nano hosts

在文本最后添加以下内容，保存并退出

151.101.84.133 raw.githubusercontent.com

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依然出现：

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.

最后通过简书的博客解决这个问题：
感谢简书大佬：自信侠
感谢知乎大佬：liangxiao05

直接sudo建立相关目录和文件，使用vim/nano/gedit都可以，看个人喜好

sudo mkdir /etc/ros/rosdep/sources.list.d
cd /etc/ros/rosdep/sources.list.d
sudo nano gedit 20-default.list

然后copy以下内容，保存并退出

# os-specific listings first
yaml https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/osx-homebrew.yaml osx

# generic
yaml https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/base.yaml
yaml https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/python.yaml
yaml https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/ruby.yaml
gbpdistro https://raw.githubusercontent.com/ros/rosdistro/master/releases/fuerte.yaml fuerte

# newer distributions (Groovy, Hydro, ...) must not be listed anymore, they are being fetched from the rosdistro index.yaml instead

但是在rosdep init的时候，会出现小问题，不过没关系

sudo rosdep init

小插曲~~~

ERROR: default sources list file already exists:
/etc/ros/rosdep/sources.list.d/20-default.list
Please delete if you wish to re-initialize

直接删除就好

sudo rm /etc/ros/rosdep/sources.list.d/20-default.list

继续init，update就好了

sudo rosdep init
rosdep update

敬请享受吧~~~