procedure TForm1.Button1Click(Sender: TObject);
begin
  Panel1.EnumControls(
    function (Control: TControl): TEnumControlsResult
    begin
      if not Control.Visible then
        Result := TEnumControlsResult.Discard
      else
      begin
        ShowMessage(Control.Name + ' [' + Control.ClassName + ']');
        Result := TEnumControlsResult.Continue;
      end;
    end);
end;

uses
  {...,} Posix.Base, Posix.Fcntl;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Memo1: TMemo;
    procedure Button1Click(Sender: TObject);
  private
  public
  end;

  TStreamHandle = Pointer;

var
  Form1: TForm1;

function popen(const command: MarshaledAString; const _type: MarshaledAString): TStreamHandle; cdecl; external libc name _PU + 'popen';
function pclose(filehandle: TStreamHandle): int32; cdecl; external libc name _PU + 'pclose';
function fgets(buffer: Pointer; size: Int32; Stream: TStreamHandle): Pointer; cdecl; external libc name _PU + 'fgets'

implementation

{$R *.fmx}

var
  Thread: TThread = nil;

procedure TForm1.Button1Click(Sender: TObject);
begin
  Thread := TThread.CreateAnonymousThread(
    procedure
    var
      Handle: TStreamHandle;
      Data: array[0..511] of UInt8;
      str: string;
    begin
      Handle := popen(MarshaledAString(UTF8STring('ping ya.ru')), 'r');

      try
        while fgets(@Data[0], SizeOf(Data), Handle) <> nil do
        begin
          str := TrimRight(UTF8ToString(@Data[0]));

          TThread.Synchronize(TThread.Current,
            procedure
            begin
              Memo1.Lines.Add(str);
            end
            );

            if TThread.Current.CheckTerminated then
              Break;
        end;
      finally
        pclose(Handle);
      end;

      FreeAndNil(Thread);
    end
  );
  Thread.FreeOnTerminate := True;
  Thread.Start;
end;

procedure TForm1.Button2Click(Sender: TObject);
begin
  if Assigned(Thread) then
    if Thread.Started then
    begin
      Thread.Terminate;
      Thread := nil;
    end;
end;