Photo unrotate

#!/bin/sh

if [ $# -eq 0 ]; then
  echo "This script will rewrite Orientation EXIF tag from photo"
  echo "to top-left (normal) but ONLY if the photo is rotated."
  echo "Warning: This script will overwrite source files!"
  echo ""
  echo "Usage: $0 <one_photo_to_process>"
  exit 1
else
  I="$*"
  # existing file?
  if [ -f "${I}" ]; then
    EXIF=`exif -m --ifd=0 -t Orientation "${I}" 2> /dev/null`
    # is there EXIF tag?
    if [ $? -eq 0 ]; then
      # rotated?
      if [ "${EXIF}" != "Top-left" ] && [ "${EXIF}" != "Unknown value 0" ]; then
        echo "UNROTATING: $I ($EXIF)"
        #exif -t Orientation --remove -o "${I}" "${I}" > /dev/null
        exif --ifd=0 -t Orientation --set-value=1 -o "${I}" "${I}" > /dev/null
      fi
    else
      echo "EXIF Orientation TAG missing: ${I}"
    fi
  else
    echo "Missing file: ${I}"
  fi
fi