lib/texinputs/pdfsetup.sty

adapted deriv;

%%
%% $Id$
%%
%% conditional url/hyperref setup
%%

\@ifundefined{pdfoutput}{\usepackage{url}}
{\usepackage[pdftex,a4paper,colorlinks=true]{hyperref}
  \IfFileExists{thumbpdf.sty}{\usepackage{thumbpdf}}{}}