function InitializeSetup: Boolean;
var
  Params: string;
begin
  // prepare Params variable for reusing
  Params := '/SAVEINF=opt.txt';
  // allow this setup to run if the expected parameter is specified; or, if it is not, allow to run it
  // when ShellExecute fails; it works like this - first evaluates the CmdLineParamExists function and
  // if that returns True, the second part of the statement (ShellExecute) won't run (evaluate); when
  // the parameter is not found, the CmdLineParamExists returns False and statement evaluation goes on,
  // ShellExecute attempts to run the setup and to the Result returns True (allow this instance to run)
  // when the function fails for some reason (the returned value <= 32); in other words, you will allow
  // this setup instance to run if executing of the new setup instance fails
  Result := CmdLineParamExists(Params) or (ShellExecute(0, '', ExpandConstant('{srcexe}'), Params, '', SW_SHOW) <= 32);
end;