\begin{Schunk}
\begin{Sinput}
 (ls.new <- ls())
\end{Sinput}
\begin{Soutput}
[1] "dat"       "ls.old"    "opts.orig" "par.orig"  "pjmar"     "tdir"     
\end{Soutput}
\begin{Sinput}
 setdiff(ls.new, ls.old)
\end{Sinput}
\begin{Soutput}
[1] "dat"    "ls.old"
\end{Soutput}
\end{Schunk}
