Simple png/jpg -> optimised jpg script

imgcmprs.sh

#!/usr/bin/env bash

function cleanup() {
  rm -rf "$temp_dir" > /dev/null 2>&1
}

trap cleanup EXIT

function setup() {
  temp_dir='/tmp/imgcmprs'
  mkdir -p "$temp_dir"
}

if [[ -z "$1" ]]; then

  echo 'usage: imgcmprs path [...]' >&2
  exit 1

fi

setup

current=0
total=$#
for file in "$@"; do

  current=$(( $current + 1 ))

  if [[ ! -f "$file" ]]; then
    echo 'input file "$file" is not a regular file' >&2
    exit 2
  fi

  file_dir=$(dirname "$file")
  file_name=$(basename "$file")
  file_base="${file_name%.*}"
  file_ext="${file_name##*.}"

  temp_file=$(mktemp "$temp_dir/XXXXXXXX")
  mv "$temp_file" "$temp_file.jpg"
  temp_file="$temp_file.jpg"

  echo -en "Processing $current of $total\r"

  if [[ "$file_ext" != "jpg" ]]; then
    convert "$file" -quality 100 "$temp_file"
  else
    cp "$file" "$temp_file"
  fi

  jpegoptim -v --max=82 --strip-all --strip-icc "$temp_file" > /dev/null 2>&1

  if [[ $? != 0 ]]; then
    echo 'Processing of file "$file" did not work.'
    exit 3
  fi
  mv "$temp_file" "$file_dir/$file_base.jpg"

done