Shortcut for ImageOptim.app tool, lossless image optimizer for MacOS.

imageoptim.sh

#!/usr/bin/env bash

##
# Shortcut for ImageOptim.app tool, Lossless image optimizer for MacOS.
# Only files and directories are allowed as arguments.
#
# Example:
#   imageoptim /path/to/image.png
#   imageoptim /path/to/images
#
# See: https://imageoptim.com/command-line.html
#
# Installation:
# 1. Download and install ImageOptim.app from https://imageoptim.com/mac
# 2. Download this script using curl and make it executable:
#    curl -fsSL https://jonlabelle.com/snippets/raw/3529/imageoptim.sh -o imageoptim
#    chmod +x imageoptim
# 3. Move it to a directory in your PATH, e.g.:
#    mv imageoptim ~/bin/
#
# Author: Jon LaBelle
# License: MIT
# Date: 2026-02-23
#
# Snippet: https://jonlabelle.com/snippets/view/shell/imageoptimapp-cli-shortcut
# Gist: https://gist.github.com/jonlabelle/68c37f59bf7f9fd4d1834b7fbf60618f
##

# Check if ImageOptim.app is installed
if ! [[ -d "/Applications/ImageOptim.app" ]]; then
  echo "ImageOptim.app is not installed."
  echo "Download it from: https://imageoptim.com/mac"
  echo "After installation, run this command again."
  exit 1
fi

# Show help if no arguments are provided or if --help/-h is passed
if [[ "$#" -eq 0 ]] || [[ "$1" == "--help" ]] || [[ "$1" == "-h" ]]; then
  cat <<'EOF'
ImageOptim - Lossless image optimizer for macOS

Usage:
  imageoptim [options] <file|directory> [<file|directory> ...]

Arguments:
  file|directory                     Image file or directory containing images to optimize

Options:
  -p, --preserve-timestamps          Preserve file modification timestamps
  -h, --help                         Show this help message

Examples:
  imageoptim photo.jpg
  imageoptim --preserve-timestamps photo.jpg
  imageoptim ~/Pictures
  imageoptim image1.png image2.jpg ~/Desktop/images

Dependencies:
  ImageOptim.app                     https://imageoptim.com/mac
EOF
  exit 0
fi

preserve_timestamps=false
case "$1" in
-p | --preserve-timestamps)
  preserve_timestamps=true
  shift
  ;;
*)
  ;;
esac

if [[ "$#" -eq 0 ]]; then
  echo "Error: no files or directories provided"
  exit 1
fi

# Validate that all provided files and directories exist
for arg in "$@"; do
  if ! [[ -e "${arg}" ]]; then
    echo "Error: '${arg}' does not exist"
    exit 1
  fi
done

timestamp_files=()
timestamp_references=()
timestamp_dir=""

restore_timestamps() {
  local index
  local restore_failed=0

  for ((index = 0; index < ${#timestamp_files[@]}; index++)); do
    if ! [[ -e "${timestamp_files[index]}" ]] ||
      ! touch -r "${timestamp_references[index]}" "${timestamp_files[index]}"; then
      echo "Error: failed to restore timestamp for '${timestamp_files[index]}'"
      restore_failed=1
    fi
  done
  timestamp_files=()
  timestamp_references=()

  if [[ -n "${timestamp_dir}" ]]; then
    if rm -rf "${timestamp_dir}"; then
      timestamp_dir=""
    else
      echo "Error: failed to remove temporary directory '${timestamp_dir}'"
      restore_failed=1
    fi
  fi

  return "${restore_failed}"
}

save_timestamp() {
  local file="$1"
  local index="${#timestamp_files[@]}"
  local reference="${timestamp_dir}/${index}"

  : >"${reference}"
  if ! touch -r "${file}" "${reference}"; then
    echo "Error: failed to save timestamp for '${file}'"
    exit 1
  fi

  timestamp_files[index]="${file}"
  timestamp_references[index]="${reference}"
}

if [[ "${preserve_timestamps}" == true ]]; then
  trap restore_timestamps EXIT
  trap 'exit 129' HUP
  trap 'exit 130' INT
  trap 'exit 131' QUIT
  trap 'exit 143' TERM

  timestamp_dir="$(mktemp -d "${TMPDIR:-/tmp}/imageoptim.XXXXXX")" || exit 1

  for arg in "$@"; do
    if [[ -f "${arg}" ]]; then
      save_timestamp "${arg}"
    elif [[ -d "${arg}" ]]; then
      if ! find "${arg}" -path "${timestamp_dir}" -prune -o -type f -print0 >"${timestamp_dir}/files"; then
        echo "Error: failed to enumerate files in '${arg}'"
        exit 1
      fi

      while IFS= read -r -d '' file; do
        save_timestamp "${file}"
      done <"${timestamp_dir}/files"
    fi
  done
fi

# Run ImageOptim with error handling
imageoptim_exit=0
/Applications/ImageOptim.app/Contents/MacOS/ImageOptim "$@" || imageoptim_exit=$?

restore_exit=0
if [[ "${preserve_timestamps}" == true ]]; then
  restore_timestamps || restore_exit=$?
  if [[ -z "${timestamp_dir}" ]]; then
    trap - EXIT HUP INT QUIT TERM
  fi
fi

if ((imageoptim_exit != 0)); then
  echo "ImageOptim failed. Check that your files are valid images."
  exit 1
fi

exit "${restore_exit}"