之前好用的，ubutun自动更新之后就出现了dotnet 不可用

并且purge后重新安装也不性：

具体错误如下：

dotnet --version

-----------------------------------------------------------------------------------------

The command could not be loaded, possibly because:
* You intended to execute a .NET application:
The application '--version' does not exist.
* You intended to execute a .NET SDK command:
No .NET SDKs were found.

Download a .NET SDK:
https://aka.ms/dotnet-download

Learn about SDK resolution:
https://aka.ms/dotnet/sdk-not-found

-----------------------------------------------------------------------------------------

dotnet --info 

-----------------------------------------------------------------------------------------

global.json file:
Not found

Host:
Version: 6.0.8
Architecture: x64
Commit: 55fb7ef977

.NET SDKs installed:
No SDKs were found.

.NET runtimes installed:
Microsoft.AspNetCore.App 6.0.8 [/usr/lib/dotnet/dotnet6-6.0.108/shared/Microsoft.AspNetCore.App]
Microsoft.NETCore.App 6.0.8 [/usr/lib/dotnet/dotnet6-6.0.108/shared/Microsoft.NETCore.App]

Download .NET:
https://aka.ms/dotnet-download

Learn about .NET Runtimes and SDKs:
https://aka.ms/dotnet/runtimes-sdk-info

-----------------------------------------------------------------------------------------

 暂时还没找到问题所在和解决办法，有没有指导如何解决的？