CaptureConsoleOutput.pas

/**
 * @Author: Jordi Corbilla
 * (c) Copyright by Jordi Corbilla.
 **/
//Anonymous procedure approach by Lars Fosdal
type
    TArg<T> = reference to procedure(const Arg: T);

procedure TForm1.CaptureConsoleOutput(const ACommand, AParameters: String; CallBack: TArg<PAnsiChar>);
const
  CReadBuffer = 2400;
var
  saSecurity: TSecurityAttributes;
  hRead: THandle;
  hWrite: THandle;
  suiStartup: TStartupInfo;
  piProcess: TProcessInformation;
  pBuffer: array [0 .. CReadBuffer] of AnsiChar;
  dBuffer: array [0 .. CReadBuffer] of AnsiChar;
  dRead: DWORD;
  dRunning: DWORD;
  dAvailable: DWORD;
begin
  saSecurity.nLength := SizeOf(TSecurityAttributes);
  saSecurity.bInheritHandle := true;
  saSecurity.lpSecurityDescriptor := nil;
  if CreatePipe(hRead, hWrite, @saSecurity, 0) then
    try
      FillChar(suiStartup, SizeOf(TStartupInfo), #0);
      suiStartup.cb := SizeOf(TStartupInfo);
      suiStartup.hStdInput := hRead;
      suiStartup.hStdOutput := hWrite;
      suiStartup.hStdError := hWrite;
      suiStartup.dwFlags := STARTF_USESTDHANDLES or STARTF_USESHOWWINDOW;
      suiStartup.wShowWindow := SW_HIDE;
      if CreateProcess(nil, PChar(ACommand + ' ' + AParameters), @saSecurity, @saSecurity, true, NORMAL_PRIORITY_CLASS, nil, nil, suiStartup,
        piProcess) then
        try
          repeat
            dRunning := WaitForSingleObject(piProcess.hProcess, 100);
            PeekNamedPipe(hRead, nil, 0, nil, @dAvailable, nil);
            if (dAvailable > 0) then
              repeat
                dRead := 0;
                ReadFile(hRead, pBuffer[0], CReadBuffer, dRead, nil);
                pBuffer[dRead] := #0;
                OemToCharA(pBuffer, dBuffer);
                CallBack(dBuffer);
              until (dRead < CReadBuffer);
            Application.ProcessMessages;
          until (dRunning <> WAIT_TIMEOUT);
        finally
          CloseHandle(piProcess.hProcess);
          CloseHandle(piProcess.hThread);
        end;
    finally
      CloseHandle(hRead);
      CloseHandle(hWrite);
    end;
end;

Unfortunately, not unicode supported 😢
CaptureConsoleOutput('cmd /c echo hello `メガネの歯列矯正 ', '',
procedure(const Line: PAnsiChar)
begin
Memo1.Lines.Add(string(Line));
end);

Output: hello ????????

Use:

Memo1.Lines.Add(Line);