ROS学习篇第（一）篇：安装ros我踩过的坑

系统：ubuntu 18.04 + ROS melodic

基本步骤可以参照http://wiki.ros.org/melodic/Installation/Ubuntu

问题1:更换软件源问题（可以解决大部分问题）

感谢 寥廓长空 https://blog.csdn.net/baidu_36602427/article/details/86551862
我的源：

zyf@zyf-TM1707:~$ lsb_release -a
No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 18.04.3 LTS
Release:	18.04
Codename:	bionic
---------------------------------------------------------------------------------------------
#ala
deb http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-security main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-updates main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-backports main restricted universe multiverse
deb http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse
deb-src http://mirrors.aliyun.com/ubuntu/ bionic-proposed main restricted universe multiverse

问题2

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

解决

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

问题3

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.

感谢 风起了 https://blog.csdn.net/u013468614/article/details/102917569

rosdep init 经常出现error，网络问题可尝试修改DNS

感谢datuzijean https://blog.csdn.net/datuzijean/article/details/92620945
也可改成：
nameserver：114.114.114.114
nameserver: 8.8.8.8