ROS安装sudo rosdep init失败解决方法（离线安装）

现象：

执行sudo rosdep init 报错

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.

原因：

raw.githubusercontent.com被墙了

解决方案：

1. 修改主机host，增加域名解析记录（不一定成功）
2. 翻墙
3. 离线安装

本文使用解决方案3，离线安装步骤：

1. 下载文件https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/sources.list.d/20-default.list，
   百度网盘下载链接
   20-default.list文件放到/etc/ros/rosdep/sources.list.d/目录下。
2. 下载rosdistro
   git clone https://github.com/ros/rosdistro.git
   百度网盘下载链接
   下载后放到/etc/ros目录下
3. 修改20-default.list文件，将https://raw.githubusercontent.com替换为本地目录地址

   # os-specific listings first
   #yaml https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/osx-homebrew.yaml osx
   yaml file:///etc/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
   
   yaml file:///etc/ros/rosdistro/master/rosdep/base.yaml
   yaml file:///etc/ros/rosdistro/master/rosdep/python.yaml
   yaml file:///etc/ros/rosdistro/master/rosdep/ruby.yaml
   gbpdistro file:///etc/ros/rosdistro/master/releases/fuerte.yaml fuerte

4. 修改以下三个文件，将https://raw.githubusercontent.com替换为本地目录地址

   1. /usr/lib/python2.7/dist-packages/rosdep2/gbpdistro_support.py
   2. /usr/lib/python2.7/dist-packages/rosdep2/rep3.py
   3. /usr/lib/python2.7/dist-packages/rosdistro/__init__.py

   gbpdistro_support.py

   #FUERTE_GBPDISTRO_URL = 'https://raw.githubusercontent.com/ros/rosdistro/' \
   # 'master/releases/fuerte.yaml'
   FUERTE_GBPDISTRO_URL = 'file:///etc/ros/rosdistro/' \
   'master/releases/fuerte.yaml'

   rep3.py

   #REP3_TARGETS_URL = 'https://raw.githubusercontent.com/ros/rosdistro/master/releases/targets.yaml'
   REP3_TARGETS_URL = 'file:///etc/ros/rosdistro/master/releases/targets.yaml'

   __init__.py

   #DEFAULT_INDEX_URL = 'https://raw.githubusercontent.com/ros/rosdistro/master/index-v4.yaml'
   DEFAULT_INDEX_URL = 'file:///etc/ros/rosdistro/master/index-v4.yaml'