sub same_file_p {
  my @stat1 = stat shift;
  my @stat2 = stat shift;
  return "@stat1[0,1]" eq "@stat2[0,1]";
}

##</code><code>##

sub all_same_file { # true if all arguments represent the same file
  my %counts;
  $counts{join " ", (stat)[0,1]}++ for @_; 
  1 == keys %counts;
}