假设yum知道包p-12000的repo A。rpm和repo B包p-12001.rpm;并且回购A的优先级比回购b高(优先级号低)
yum将如何决定安装哪个包?
较高的回购优先级(较低的优先级编号)优先于包的版本号。通过设置存储库优先级，您可以将yum配置为从特定存储库安装包，即使另一个存储库的版本号更高。
From man dnf.conf:
priority
The priority value of this repository, default is 99. If there is more
than one candidate package for a particular operation, the one from a
repo with the lowest priority value is picked, possibly despite being
less convenient otherwise (e.g. by being a lower version).