How to send keys instead of characters to a process?

Question

System.Diagnostics.Process exposes a StreamWriter named StandardInput, which accepts only characters as far as I know.

But I need to send keystrokes as well, and some keystrokes don't map well to characters.

What should I do?

Answer 1

You are mixing input streams with control signals. A console process has a default input stream which you can control with the StandardInput, as you already know. But Ctrl-C and Ctrl-Break are not characters sent to the process through this stream, but instead they are instead control signals that the process receives using the registered signal handlers, see CTRL+C and CTRL+BREAK Signals:

By default, when a console window has the keyboard focus, CTRL+C or CTRL+BREAK is treated as a signal (SIGINT or SIGBREAK) and not as keyboard input.

To send fake signals to a process you can use GenerateConsoleCtrlEvent and send either CTRL_C_EVENT or CTRL_BREAK_EVENT. This API has no .Net equivalent, so you have to PInvoke it.

To use it from .NET you simply need to include the function definition:

const int CTRL_C_EVENT = 0;
const int CTRL_BREAK_EVENT = 1;

[DllImport("kernel32.dll")]
static extern bool GenerateConsoleCtrlEvent(
    uint dwCtrlEvent,
    uint dwProcessGroupId);