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+1.如果是安装本地的rpm包
+(1)dnf install 会自动处理依赖
+(2)rpm -ivh xx.rpm直接安装。
+2.如果想强制安装旧版本的rpm
+rpm -Uvh --oldpackage [filename]
+--oldpackage allows you to install older package
+-U means upgrade, but in this case it will just replace the other version.
+if you use -i instead of -U you will end up with both versions installed.