anchor.diff:        # Tar up the layer and throw it into 'layer.tar'.
         echo "Packing layer..."
         mkdir $out
  -      tar -C layer --hard-dereference --mtime="@$SOURCE_DATE_EPOCH" --owner=${toString uid} --group=${toString gid} -cf $out/layer.tar .
  +      tar -C layer --hard-dereference --sort=name --mtime="@$SOURCE_DATE_EPOCH" --owner=${toString uid} --group=${toString gid} -cf $out/layer.tar .
   
         # Compute a checksum of the tarball.
         echo "Computing layer checksum..."
  
positive.code:         comm <(sort -n baseFiles|uniq) \
               <(sort -n layerFiles|uniq|grep -v ${layer}) -1 -3 > newFiles
          # Append the new files to the layer.
          tar -rpf temp/layer.tar --hard-dereference --mtime="@$SOURCE_DATE_EPOCH" \
            --owner=0 --group=0 --no-recursion --files-from newFiles
  
          echo "Adding meta..."
  
negative.code:         chmod -R a-w image
  
          echo "Cooking the image..."
          tar -C image --hard-dereference --sort=name --mtime="@$SOURCE_DATE_EPOCH" --owner=0 --group=0 --xform s:'./':: -c . | pigz -nT > $out
  
          echo "Finished."
        '';
  