Get the handle and write to the console that launched our process

Question

How could I write to the standard output of some already open console? I find the console I need with this piece of code:

    IntPtr ptr = GetForegroundWindow();         


        

Answer 1

If you just want to write to the console that's used by some other app, then you can use the following - you'll need to use P/Invoke to do the first step:

• AttachConsole(pid) to attach to that console - if your process is already associated with a console, you'll have to FreeConsole first, since a process can be associated with only one console at a time.
• Now that you're attached, get the console output handle using CreateFile("CONOUT$", GENERIC_WRITE, FILE_SHARE_WRITE, ... ) - might be able to do this part in managed code.
• Now that you've got the HANDLE, wrap it up in managed code - this part you already know.

Having said that, even though you can do this, it's not necessarily a good idea to do so. There's nothing to stop the original process from writing to the console while you are doing likewise, and the output from both getting mixed-up, depending on how the processes are doing buffering. If you want to do something like notify the user of something regardless of which window is active, there may be a better way of doing that.