Автор: http://www.swissdelphicenter.ch

uses
  libc;

procedure TForm1.Button1Click(Sender: TObject);
var
  iPrg: Integer;
begin
  //Execute kcalc - A calculator for KDE
  iPrg := libc.system('kcalc');
  if iPrg = -1 then
    ShowMessage('Error executing your program');
end;