Ubuntu-.NET Core手动更换版本（卸载再安装）

原环境：

.NET Core SDK（反映任何 global.json）:
 Version:   2.2.110
 Commit:    4797dabd3c

运行时环境:
 OS Name:     Windows
 OS Version:  6.1.7601
 OS Platform: Windows
 RID:         win7-x64
 Base Path:   C:\Program Files\dotnet\sdk\2.2.110\

Host (useful for support):
  Version: 2.2.8
  Commit:  b9aa1abc51

.NET Core SDKs installed:
  2.1.522 [C:\Program Files\dotnet\sdk]
  2.2.110 [C:\Program Files\dotnet\sdk]

.NET Core runtimes installed:
  Microsoft.AspNetCore.All 2.1.26 [C:\Program Files\dotnet\shared\Microsoft.AspN
etCore.All]
  Microsoft.AspNetCore.All 2.2.8 [C:\Program Files\dotnet\shared\Microsoft.AspNe
tCore.All]
  Microsoft.AspNetCore.App 2.1.26 [C:\Program Files\dotnet\shared\Microsoft.AspN
etCore.App]
  Microsoft.AspNetCore.App 2.2.8 [C:\Program Files\dotnet\shared\Microsoft.AspNe
tCore.App]
  Microsoft.NETCore.App 2.1.26 [C:\Program Files\dotnet\shared\Microsoft.NETCore
.App]
  Microsoft.NETCore.App 2.2.8 [C:\Program Files\dotnet\shared\Microsoft.NETCore.
App]

To install additional .NET Core runtimes or SDKs:
  https://aka.ms/dotnet-download

现环境：

root@servercore:~# dotnet --info
.NET Core SDK (reflecting any global.json):
 Version:   2.2.402
 Commit:    c7f2f96116

Runtime Environment:
 OS Name:     ubuntu
 OS Version:  18.04
 OS Platform: Linux
 RID:         ubuntu.18.04-x64
 Base Path:   /usr/share/dotnet/sdk/2.2.402/

Host (useful for support):
  Version: 2.2.8
  Commit:  b9aa1abc51

.NET Core SDKs installed:
  2.2.402 [/usr/share/dotnet/sdk]

.NET Core runtimes installed:
  Microsoft.AspNetCore.All 2.2.8 [/usr/share/dotnet/shared/Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.App 2.2.8 [/usr/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 2.2.8 [/usr/share/dotnet/shared/Microsoft.NETCore.App]

To install additional .NET Core runtimes or SDKs:
  https://aka.ms/dotnet-download

当然sdk使用2.2.108比2.2.110可能要稳一点，微软官方开发环境的最佳sdk版本图：

OS	Development Environment	.NET Core SDK
Any supported	Command line and/or Visual Studio Code	2.2.401
Windows	Visual Studio 2019 version 16.2	2.2.401
Windows	Visual Studio 2019 version 16.1	2.2.301
Windows	Visual Studio 2019 version 16.0	2.2.205
Windows	Visual Studio 2017	2.2.108

二，验证过程

1.卸载（参照：微软文档）：

dpkg --list  #查看安装的包

#apt-get remove 要删除的包

apt-get remove dotnet-host

apt-get remove dotnet-hostfxr

apt-get remove dotnet-runtime

apt-get remove dotnet-sdk-2.2

2.安装：

wget -q https://packages.microsoft.com/config/ubuntu/18.04/packages-microsoft-prod.deb -O packages-microsoft-prod.deb
sudo dpkg -i packages-microsoft-prod.deb

sudo apt-get install apt-transport-https
sudo apt-get update

sudo apt-get install dotnet-sdk-2.2=2.2.110-1

#sudo apt-get install dotnet-sdk-2.2=2.2.108-1

3.查看修改完的环境：

.NET Core SDK (reflecting any global.json):
 Version:   2.2.110
 Commit:    4797dabd3c

Runtime Environment:
 OS Name:     ubuntu
 OS Version:  18.04
 OS Platform: Linux
 RID:         ubuntu.18.04-x64
 Base Path:   /usr/share/dotnet/sdk/2.2.110/

Host (useful for support):
  Version: 2.2.8
  Commit:  b9aa1abc51

.NET Core SDKs installed:
  2.2.110 [/usr/share/dotnet/sdk]

.NET Core runtimes installed:
  Microsoft.AspNetCore.All 2.2.8 [/usr/share/dotnet/shared/Microsoft.AspNetCore.All]
  Microsoft.AspNetCore.App 2.2.8 [/usr/share/dotnet/shared/Microsoft.AspNetCore.App]
  Microsoft.NETCore.App 2.2.8 [/usr/share/dotnet/shared/Microsoft.NETCore.App]

To install additional .NET Core runtimes or SDKs:
  https://aka.ms/dotnet-download

　　OK,修改完毕。