Script which finds the newest screenshot image and adds a shadow to it

drop_shadow.sh

#!/usr/bin/env bash

if [ $# -eq 0 ]; then
  echo "Needs the filename as the first argument"
  exit -1
fi

type /usr/local/bin/convert >/dev/null 2>&1 || { echo >&2 "The convert command must be available."; exit 1; }

input_filename="${1}"
output_dir="./"
if [ "${input_filename}" == "--last-screenshot" ]; then
  ss_dir="/Users/claudioc/Screenshots/"
  input_filename="$(ls -1rt ${ss_dir}Screenshot* | tail -1)"
  if [[ "${input_filename}" =~ "_shadow" ]]; then
    echo "Nothing to be done"
    exit 0
  fi
  output_dir="${ss_dir}"
fi

# https://stackoverflow.com/questions/965053/extract-filename-and-extension-in-bash#965072
filename=$(basename -- "${input_filename}")
extension="${filename##*.}"
filename="${filename%.*}"

/usr/local/bin/convert "${input_filename}" \( +clone -background black -shadow 30x8+0+0 \) +swap -background none -layers merge +repage "${output_dir}${filename}_shadow.${extension}"