Eu tento redirecionar no Windows o cmd.exe stdout & stdin (com CreateProcess ()). Funciona bem desde que eu execute comandos simples ou abra aplicativos da interface gráfica do usuário, mas se eu tentar executar um software como python, ele não me fornecerá mais sua saída (nem obterá a entrada através do stdin).

Exemplo de código:

#include <windows.h> 
#include <iostream>
#include <string>
#include <thread>

using namespace std;

HANDLE child_input_read;
HANDLE child_input_write;
HANDLE child_output_read;
HANDLE child_output_write;

void writeToPipe()
{
	while (true)
	{
		DWORD bytes_written;
		string msg;
		getline(cin, msg);
		msg += '\n';
		BOOL success = WriteFile(child_input_write, msg.c_str(), msg.size(), &bytes_written, NULL);
		if (!success)
		{
			break;
		}
	}
}
void readFromPipe()
{
	while (true)
	{
		DWORD bytes_read;
		char buffer[512];
		BOOL success = ReadFile(child_output_read, buffer, sizeof(buffer)-1, &bytes_read, NULL);
		buffer[bytes_read] = 0;
		if (!success)
		{
			break;
		}
		cout << buffer;
	}
}
void createCmdProcess()
{
	PROCESS_INFORMATION process_info;
	STARTUPINFO startup_info;
	SECURITY_ATTRIBUTES security_attributes;

	// Set the security attributes for the pipe handles created 
	security_attributes.nLength = sizeof(SECURITY_ATTRIBUTES);
	security_attributes.bInheritHandle = TRUE;
	security_attributes.lpSecurityDescriptor = NULL;
	CreatePipe(&child_output_read, &child_output_write, &security_attributes, 0);
	CreatePipe(&child_input_read, &child_input_write, &security_attributes, 0);

	// Create the child process
	ZeroMemory(&process_info, sizeof(PROCESS_INFORMATION));
	ZeroMemory(&startup_info, sizeof(STARTUPINFO));
	startup_info.cb = sizeof(STARTUPINFO);
	startup_info.hStdInput = child_input_read;
	startup_info.hStdOutput = child_output_write;
	startup_info.hStdError = child_output_write;
	startup_info.dwFlags |= STARTF_USESTDHANDLES;
	CreateProcess(NULL, "cmd.exe", NULL, NULL, TRUE, 0, NULL, NULL, &startup_info, &process_info);
}

int main()
{
	createCmdProcess();
	thread t(writeToPipe);
	thread t2(readFromPipe);
	t.join();
	t2.join();
	system("pause");
}