sudo apt-get install libignition-math6-dev
出现错误！
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:
The following packages have unmet dependencies:
libignition-math6-dev : Depends: libignition-math6 (= 6.7.0-1~focal) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.建议全部卸载ros，gazebo所有组件，千万不要动libgc6等库，否则linux会崩溃，数据丢失
一定要定时将文件git备份！！！linux下数据全部丢失！