sudo rosdep init
rosdep update如果你直接成功了，可直接跳过当我没说（不过90%的几率你都会失败的啦）
由于http://raw.githubusercontent.com这个网址墙的很厉害，大概率你是成功不了的，这里推荐一种本地化安装的方法
1. 下载rosdistro
git clone https://github.com/ros/rosdistro.git
（如果git都失败了...，可以百度github镜像网站，镜像站下载很方便）
将rosdistro存放在/home/yourname/rosdistro
2. 配置20-default.list文件
运行
sudo rosdep init重新生成/etc/ros/rosdep/sources.list.d/20-default.list. 没有则手动创建/etc/ros/rosdep/sources.list.d/20-default.list.
如果sudo rosdep init成功，直接跳过以下创建文件步骤
进入到/etc/ros/目录下
cd /etc/ros创建rosdep文件
sudo mkdir rosdep && cd rosdep创建sources.list.d文件
sudo mkdir sources.list.d && cd sources.list.d创建20-default.list文档
sudo gedit 20-default.list将20-default.list里面内容修改为下面的代码,注意内容/home/zjl修改为自己的记录路径
# os-specific listings first
yaml file:///home/zjl/rosdistro/rosdep/osx-homebrew.yaml osx
# generic
yaml file:///home/zjl/rosdistro/rosdep/base.yaml
yaml file:///home/zjl/rosdistro/rosdep/python.yaml
yaml file:///home/zjl/rosdistro/rosdep/ruby.yaml
gbpdistro file:///home/zjl/rosdistro/releases/fuerte.yaml fuerte
# newer distributions (Groovy, Hydro, ...) must not be listed anymore, they are being fetched from the rosdistro index.yaml instead3. 编辑以下文件
/etc/ros/rosdep/sources.list.d/20-default.list
/usr/lib/python2.7/dist-packages/rosdep2/gbpdistro_support.py
/usr/lib/python2.7/dist-packages/rosdep2/rep3.py
/usr/lib/python2.7/dist-packages/rosdistro/__init__.py搜索文件中的 https://raw.githubusercontent.com/ros/rosdistro/master字段，将其替换为file:///home/yourname/rosdistro(后面的部分保持不变，最好备份一下)
例如：
//进行如下修改
#DEFAULT_INDEX_URL = 'https://raw.githubusercontent.com/ros/rosdistro/master/index-v4.yaml'
DEFAULT_INDEX_URL = 'file:///home/zjl/rosdistro/index-v4.yaml
注：最好每个文件都确定一下是否只有一个
例如：我的电脑查找
最后发现不止一个 init.py ,这时最好两个都要修改
4. rosdep update
接下来就可以愉快的rosdep update啦
由于是本地安装就不会失败啦
附上成功截图
五 . 添加环境变量
echo "source /opt/ros/melodic/setup.bash" >> ~/.bashrc
source ~/.bashrc最后安装个实用插件
sudo apt install python-rosinstall python-rosinstall-generator python-wstool build-essential六 . 测试
运行
roscore若出现下图，并无报错，就安装好啦
//
/
这个解决方法是我在群里看到的，近期装了很多次ros都能完美解决，特地转载出来分享给大家，也给自己mark一下。
在安装ROS的过程中，很多同学在执行上述指令时会提示以下错误：
ERROR: cannot download default sources list from:https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/sources.list.d/20-default.listWebsite may be down.
通常的解决办法是用手机热点
或者查询
https://raw.githubusercontent.com的实际IP地址，但是也有可能会失效。
偶然的机会看到一教程的解决方案。
博主的思路是新思路:将相关资源备份到 gitee,修改 rosdep 源码,重新定位资源。成功率是百分百。
整理修改后提供解决ROS rosdep init/update报错的方法（终极版）。
步骤1
进入到 sources.list.d 文件夹（如果没有，则用mkdir指令新建）
修改 gedit 20-default.list
cd /etc/ros/rosdep/sources.list.dsudo gedit 20-default.list
将里面所有的
raw.githubusercontent.com/ros/rosdistro/master
替换成
gitee.com/wybros/rosdistro/raw/master
修改前：
# os-specific listings firstyaml https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/osx-homebrew.yaml osx# genericyaml https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/base.yamlyaml https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/python.yamlyaml https://raw.githubusercontent.com/ros/rosdistro/master/rosdep/ruby.yamlgbpdistro 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
修改后：
# os-specific listings first rosdep updateyaml https://gitee.com/wybros/rosdistro/raw/master/rosdep/osx-homebrew.yaml osx# genericyaml https://gitee.com/wybros/rosdistro/raw/master/rosdep/base.yamlyaml https://gitee.com/wybros/rosdistro/raw/master/rosdep/python.yamlyaml https://gitee.com/wybros/rosdistro/raw/master/rosdep/ruby.yamlgbpdistro https://gitee.com/wybros/rosdistro/raw/master/releases/fuerte.yaml fuerte# newer distributions (Groovy, Hydro, ...) must not be listed anymore, they are being fetched from the rosdistro index.yaml instead
步骤2
进入到 rosdep2 文件夹，
修改 gbpdistro_support.py
cd /usr/lib/python2.7/dist-packages/rosdep2/sudo gedit gbpdistro_support.py
将里面所有的
raw.githubusercontent.com/ros/rosdistro/master
替换成
gitee.com/wybros/rosdistro/raw/master
修改后如下
FUERTE_GBPDISTRO_URL = 'https://gitee.com/wybros/rosdistro/raw/' \'master/releases/fuerte.yaml'
步骤3
进入到 rosdep2 文件夹，
修改 rep3.py
cd /usr/lib/python2.7/dist-packages/rosdep2/sudo gedit rep3.py
将里面所有的
raw.githubusercontent.com/ros/rosdistro/master
替换成
gitee.com/wybros/rosdistro/raw/master
修改后如下
REP3_TARGETS_URL = 'https://gitee.com/wybros/rosdistro/raw/master/releases/targets.yaml'步骤4
进入到 rosdep2 文件夹，
修改 sources_list.py
cd /usr/lib/python2.7/dist-packages/rosdep2/sudo gedit sources_list.py
将里面所有的
raw.githubusercontent.com/ros/rosdistro/master
替换成
gitee.com/wybros/rosdistro/raw/master
修改后如下
DEFAULT_SOURCES_LIST_URL = 'https://gitee.com/wybros/rosdistro/raw/master/rosdep/sources.list.d/20-default.list'步骤5
进入到 rosdistro 文件夹
修改 __init__.py
cd /usr/lib/python2.7/dist-packages/rosdistro/sudo gedit __init__.py
将里面所有的
raw.githubusercontent.com/ros/rosdistro/master
替换成
gitee.com/wybros/rosdistro/raw/master
修改后如下
DEFAULT_INDEX_URL = 'https://gitee.com/wybros/rosdistro/raw/master/index-v4.yaml'最后
打开新终端执行
rosdep update如果出现如下提示则表示成功！
