问题：在 ubuntu22.04 一通骚操作后，dotnet 命令行居然不能用了，连最基本的 dotnet --info 都报错。

具体错误信息：

$ dotnet --info 
A fatal error occurred. The folder [/usr/share/dotnet/host/fxr] does not exist

感觉莫名其妙啊，手动创建文件夹后，继续报错：

$ dotnet --info
A fatal error occurred, the folder [/usr/share/dotnet/host/fxr] does not contain any version-numbered child folders

解决1：卸载重装

卸载

sudo apt-get remove dotnet* -y

重装

sudo apt-get install dotnet6 -y

问题依旧

解决2：手动安装

卸载

sudo apt-get remove dotnet* -y
sudo apt-get remove aspnet* -y

清理

$ whereis dotnet
dotnet: /usr/bin/dotnet /usr/lib/dotnet /usr/share/dotnet /usr/share/man/man1/dotnet.1.gz

$ sudo rm -rf /usr/bin/dotnet /usr/lib/dotnet /usr/share/dotnet /usr/share/man/man1/dotnet.1.gz

下载

wget 
https://download.visualstudio.microsoft.com/download/pr/8159607a-e686-4ead-ac99-b4c97290a5fd/ec6070b1b2cc0651ebe57cf1bd411315/dotnet-sdk-6.0.401-linux-x64.tar.gz

速度还可以

dotnet-sdk-6.0.401-linux-x64.tar.gz                 45%[=================================================>                                                              ]  79.97M  2.79MB/s    eta 36s    

解压

tar -zxvf dotnet-sdk-6.0.401-linux-x64.tar.gz   -C /path/to/dotnet

设置环境变量

export DOTNET_ROOT=$(pwd)/.dotnet
export PATH=$PATH:$DOTNET_ROOT:$DOTNET_ROOT/tools

验证

$ dotnet --info
.NET SDK (reflecting any global.json):
 Version:   6.0.401
 Commit:    0906eae6f8

Runtime Environment:
 OS Name:     ubuntu
 OS Version:  22.04
 OS Platform: Linux
 RID:         ubuntu.22.04-x64
 Base Path:   /opt/sdk/dotnet/sdk/6.0.401/

global.json file:
  Not found

Host:
  Version:      6.0.9
  Architecture: x64
  Commit:       163a63591c

.NET SDKs installed:
  6.0.401 [/opt/sdk/dotnet/sdk]

.NET runtimes installed:
  Microsoft.AspNetCore.App 6.0.9 [/opt/sdk/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 6.0.9 [/opt/sdk/dotnet/shared/Microsoft.NETCore.App]

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

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

完美解决！！！