Delphi procedure to run an external command line program and capture and display the output.

RunProcessAndCaptureOutput.pas

procedure RunProcessAndCaptureOutput(const CmdLine: string; Memo: TMemo; HideLinesCount: Integer = 0);
var
  SecAttr: TSecurityAttributes;
  PipeR, PipeW: THandle;
  StartupInfo: TStartupInfo;
  ProcessInfo: TProcessInformation;
  Buffer: packed array[0..4096-1] of AnsiChar;
  Count: Cardinal;
  S, Leftover: AnsiString;
  i, P: Cardinal;
  C: AnsiChar;
begin
  SecAttr.nLength:=SizeOf(SecAttr);
  SecAttr.lpSecurityDescriptor:=nil;
  SecAttr.bInheritHandle:=True;
  if not CreatePipe(PipeR, PipeW, @SecAttr, 0) then
    raise Exception.Create('CreatePipe: '+SysErrorMessage(GetLastError));
  SetHandleInformation(PipeR, HANDLE_FLAG_INHERIT, 0);
  FillChar(StartupInfo, SizeOf(StartupInfo), 0);
  StartupInfo.cb:=SizeOf(StartupInfo);
  StartupInfo.dwFlags:=STARTF_USESTDHANDLES;
  StartupInfo.hStdOutput:=PipeW;
  StartupInfo.hStdError:=PipeW;
  FillChar(ProcessInfo, SizeOf(ProcessInfo), 0);
  if not CreateProcess(nil, PChar(CmdLine), nil, nil, True, CREATE_NO_WINDOW, nil, nil, StartupInfo, ProcessInfo) then
    raise Exception.Create('CreateProcess: '+SysErrorMessage(GetLastError));
  CloseHandle(ProcessInfo.hProcess);
  CloseHandle(ProcessInfo.hThread);
  CloseHandle(PipeW);
  Leftover:='';
  while ReadFile(PipeR, Buffer[0], SizeOf(Buffer)-1, Count, nil) and (Count > 0) do
  begin
    Buffer[Count]:=#0;
    i:=0;
    P:=0;
    while i < Count do
    begin
      C:=Buffer[i];
      if C in [#10, #13] then
      begin
        if HideLinesCount > 0 then
          Dec(HideLinesCount)
        else
        begin
          Buffer[i]:=#0;
          S:=Leftover+AnsiString(PAnsiChar(@Buffer[P]));
          OemToCharBuffA(@S[1], @S[1], Length(S));
          Memo.Lines.Add(string(S));
        end;
        Leftover:='';
        case C of
          #10: if Buffer[i+1] = #13 then Inc(i);
          #13: if Buffer[i+1] = #10 then Inc(i);
        end;
        P:=i+1;
      end;
      Inc(i);
    end;
    Leftover:=AnsiString(PAnsiChar(@Buffer[P]));
    Application.ProcessMessages;
  end;
  if (Leftover <> '') and (HideLinesCount <= 0) then
  begin
    OemToCharBuffA(@Leftover[1], @Leftover[1], Length(Leftover));
    Memo.Lines.Add(string(Leftover));
  end;
  CloseHandle(PipeR);
end;