use File::Spec::Unix ();

sub remove_dot_dot {
   local $_ = $_[0];
   $_ = File::Spec::Unix->canonpath($_);
   1 while s#[^/]+/\.\./##g;
   s#/[^/]+/\.\.$#/#g;
   s#^[^/]+/\.\.$#.#g;
   return $_;
}