$ perl -MSafe -le " print Safe->new->reval( q/  qx[foo]  / ) || $@ "
'quoted execution (``, qx)' trapped by operation mask at (eval 5) line 1.


$ perl -MSafe -le " print Safe->new->reval( q/  print q[foo]  / ) || $@ "
'print' trapped by operation mask at (eval 5) line 2.


$ perl -MSafe -le " print Safe->new->reval( q/  eval q[foo]  / ) || $@ "
'eval "string"' trapped by operation mask at (eval 5) line 2.