Create a folder called on your Desktop called 'assets'. Use an 'img' & 'ic' suffix in your Sketch export panel. After exporting run this shell script to place those images in their appropriate folders.

asset-place.sh

cd Desktop/assets/
  mkdir images; mkdir icons
done
for file in $(find . -type f -iname '*-img*'); do
  mv "$file" "images/${file/-images/}"
done
for file in $(find . -type f -iname '*-ic*'); do
  mv "$file" "icons/${file/-icons/}"
done