Console.Write() doesn't show output until a newline

(from dotnet/corefx#8183 by @omajid)

On RHEL 7, Console.Write()'s output does not get displayed until a newline is used (or the program exits).

If you run the following application, you don’t see anything as the output until 10 seconds have passed. Then all of “HelloWorld!” appears at once.

 public static void Main(string[] args)
 {
     Console.Write("Hello World");
     Console.Out.Flush();
     Task.Delay(10000).Wait();
     Console.WriteLine("!");
 }

Console applications that do input/output may use a style like the following:

public static void Main(string[] args)
{
    Console.Write("Name: ");
    var name = Console.ReadLine();
    Console.WriteLine("Your name is '" + name + "'.");
}

This doesn’t work for me. You get no output at all at first. If you type in something (say “Foo”) and hit ENTER, then you see all of the output at once:

Name: Foo
Your name is 'Foo'.

If you don’t hit enter, then it seems like the application has hung. A Console.Out.Flush() doesn’t fix this, as in the following:

public static void Main(string[] args)
{
    Console.Write("Name: ");
    Console.Out.Flush();
    var name = Console.ReadLine();
    Console.WriteLine("Your name is '" + name + "'.");
}

I ran all the test cases while ssh’ed into the RHEL 7 VM.

$ dotnet --version
1.0.0-rc2-002538

[ellismg]

The customer experience is pretty bad, and it seems like most folks will hit this, so I’d consider it.

[analogrelay]

@brthor Nothing I know of in build needs to both capture and forward. When we launch csc we capture, but don’t forward. Everything else is forwarded.