我已经在我的 Ubuntu 18.04 上使用 安装了 .NET Core sudo snap install dotnet-sdk --classic，但是在安装过程完成后，该dotnet命令仍然无法正常工作。这是我的控制台日志：
long@long-ub1804:~$ sudo snap install dotnet-sdk
[sudo] password for long:
error: This revision of snap "dotnet-sdk" was published using classic
confinement and thus may perform arbitrary system changes outside of the
security sandbox that snaps are usually confined to, which may put your
system at risk.
If you understand and want to proceed repeat the command including
--classic.
long@long-ub1804:~$ sudo snap install dotnet-sdk --classic
dotnet-sdk 2.2.202 …