在Ubuntu 18.04中安装ROS melodic笔记

https://blog.youkuaiyun.com/qq_41450811/article/details/99079041?depth_1-utm_source=distribute.pc_relevant.none-task&utm_source=distribute.pc_relevant.none-task

以上博客提到ros安装最新密匙

按照上面的链接安装时遇到
sudo rosdep init找不到命令，通过以下链接解决
https://blog.youkuaiyun.com/weixin_40772628/article/details/103377637

rosdep update 一直失败问题
sudo rm /etc/ros/rosdep/sources.list.d/20-default.list
sudo rosdep init
rosdep update
重新再一次，更换源，重复上述操作，参见
https://www.cnblogs.com/qiangzi0221/p/7707128.html
更改下载超时时间设置
sudo nano /usr/lib/python2.7/dist-packages/rosdep2/gbpdistro_support.py
DOWNLOAD_TIMEOUT = 15.0
默认15.0改成120.0
再不行就使用手机热点

运行至
roscore
命令时，发生错误
Command ‘roscore’ not found，but can be installed with:
sudo apt install python-roslaunch

安装ros-melodic-desktop解决
sudo apt-get install ros-melodic-desktop

参见
https://blog.youkuaiyun.com/shuipengpeng/article/details/80026183

运行
source ~/.bashrc
roscore
成功！