Create sub-directories and organize files by date

On Linux and Cygwin, you can use date -r to read out the modification date of a file.

for x in *.JPG; do
  d=$(date -r "$x" +%Y-%m-%d)
  mkdir -p "$d"
  mv -- "$x" "$d/"
done

(I use the unambiguous, standard and easily-sorted YYYY-MM-DD format for dates.)