the rosdep view is empty: call 'sudo rosdep init' and 'rosdep update'

修复ros录制包的时候，执行某个命令，报这个错误，报错的原因还不明白，暂时找到解决办法，参考：https://blog.csdn.net/u010918541/article/details/50445415

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

２、sudo rosdep init

３、rosdep update 此处不可以加sudo

因为总会报错，第三步重点是不加sudo可以解决

ERROR: unable to process source [https://raw.githubusercontent.com/ros/rosdistro/master/releases/fuerte.yaml]:

不一样的地方是增加distro了，可以看出是更新了。

Skip end-of-life distro "ardent"
Skip end-of-life distro "bouncy"
Skip end-of-life distro "crystal"
Add distro "dashing"
Add distro "eloquent"
Add distro "foxy"
Skip end-of-life distro "groovy"
Skip end-of-life distro "hydro"
Skip end-of-life distro "indigo"
Skip end-of-life distro "jade"
Add distro "kinetic"
Skip end-of-life distro "lunar"
Add distro "melodic"
Add distro "noetic"
updated cache in /home/ht/.ros/rosdep/sources.cache
ERROR: Not all sources were able to be updated.