尝试在yum及更高版本上安装Ubuntu 20.04是错误消息。
sudo apt-get install yum
输出
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package yum is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
E: Package 'yum' has no installation candidate