Batch rename Google Camera App portraits for organisation in a single directory; see https://www.how-hard-can-it.be/batch-rename-google-camera-portraits/ for details

rename_google_camera_app_portraits.sh

#!/bin/bash

# Stop on all errros
set -e

# Enable extended globbing
shopt -s extglob 

for dir in IMG_*/
do
  if [[ $(ls "${dir}"/*.jpg | wc -l) -ne 2 ]]
  then
    echo "Directory '${dir}' does not have exactly two files. Best to do nothing in that case."
  else
    echo "Directory '${dir}' has exactly two files. All good..."
    pushd "${dir}"
      dir_name=${dir%*/}
      mv !(*_COVER.jpg) "${dir_name}.jpg"
      mv *_COVER.jpg "${dir_name}_PORTRAIT.jpg"
      mv * ../
    popd
    rmdir "${dir}"
    echo "...done processing directory '${dir}'!"
  fi
done