As you mentioned, you have dotnet CLI.

So the answer is – each C# code needs a project, that specifies some stuff (what framework it uses, some build settings, etc.). That info is put into *.csproj file. And then inside of it you can add references to C# code files .cs. Or you can just put .cs files in the same directory and they will be picked up automatically.

So what you need to do is:

1. Create project with dotnet new console – it will create simple console app with one C# file Program.cs, which will have Console.WriteLine in it
2. To build it, simply run dotnet build, it will automatically look for csproj file
3. To run it, execute dotnet run – it will automatically pick csproj file.

To add new C# file, just do

'public static class Test { public static void Method() { Console.WriteLine("my first c sharp code"); } }' >> Test.cs
'Test.Method();' >> Program.cs

This will create Test class in Test.cs file and add its method invocation to Program.cs

It’s not possible to directly compile and run a .cs file, you need to create a project first and add that file to your project.

There’s an issue and ongoing conversation to add this feature in dotnet cli.

Not an exact answer to the question but an elaborated comment on the assertion:

It’s not possible to directly compile and run

there are some REPL (Read Eval Print Loop) that allow you to run a csharp file.

csi.exe, shipped with visual studio, used to be a good one.

I encourage you ro read from https://www.nuget.org/packages/CSharpRepl/0.3.5.

Whatever, dotnet run with a csproj is a good way to run cs files (with better perfs once the exe exists).