I was about to report "cpp dies if stdin is a terminal" when I remembered
   that, last time I reported it, my /usr/bin/cpp was a 44 character
   shell script that just ran cat.  Sure enough.
   
   It looks very much like the shell script "cppstdin" distributed with perl.
   
   Does anyone know that perl is installing a cpp over /usr/bin/cpp under
   any likely circumstances?  I last saw this right after installing perl,
   and I see it now just after installing a new perl.

perl installs the cppstdin in $prefix/bin, but i'm certain it
doesn't put anything in /usr/bin/cpp.  i've run perl's install
so many times i would have noticed it...

.mrg.