imagemagick bash script

responsive.sh

#!/bin/bash

SIZES=(640 1280 1920 2560 3200)

if [ $# -eq 0 ]; then
  echo "画像ファイルを指定してください！"
  echo "Usage1: "$0" image.jpg"
  echo "Usage2: "$0" *.jpg"
  exit 1
fi

main () {
  for file in "$@"
  do
    echo "convert start: $file"
    resize "$file"
    echo "convert done: $file"
  done
  echo "all done!"
}

resize () {
  target="$1"
  extension="${target##*.}"
  filename="${target%.*}"

  if [ ! -f $target ]; then
    echo "File $target not found"
    exit 1
  fi

  width=$(identify -format "%[fx:w]" $target)
  cp "${target}" "${filename}_${width}.${extension}"
  echo "clone file ${target} to ${filename}_${width}.${extension}"

  for w in ${SIZES[@]}; do
    if [ "$w" -gt "$width" ]; then
      echo "end"
      break
    fi
    convert "${target}" -resize "${w}x" -set filename:mysize '%w' "${filename}_%[filename:mysize].${extension}"
    echo "converted to ${w}px"
  done
}

main "$@"