Command line to install/upgrade .NET Core
There is no dotnet
command to update .Net Core. Instead, you should use the same approach you used to install it in the first place, which depends on your OS.
Not promoted officially but it looks like there are approved packages on Chocolatey for .NET Core SDK.
https://chocolatey.org/packages/dotnetcore-sdk
Example:
> choco install dotnetcore-sdk
Or:
> choco upgrade dotnetcore-sdk
Update (December 2020): For .NET 5 the chocolatey package has changed since it's not technically branded as .NET Core any longer.
https://chocolatey.org/packages/dotnet-sdk/
Example:
> choco install dotnet-sdk
Or:
> choco upgrade dotnet-sdk