Convert PNG file to ICNS file on Mac

png2icns.sh

#!/bin/bash

if [ $# -eq 0 ]
then
    echo 1024x1024 png file to icns converter
    echo
    echo Usage: $0 png-filename [output-folder]
    echo
    echo Ex : $0 app.png
    echo Ex : $0 app.png myapp
    exit
fi

if [ $# -eq 1 ]
then
    output="${1%.*}"
else
    output=$2
fi

mkdir $output.iconset

for s in 16 24 32 48 64 96 128 256 512 1024
do
    for mul in 1 2 3
    do
        if [ $mul -gt 1 ]
        then
            add="@${mul}x"
        else
            add=""
        fi
        if [ $(($s*$mul)) -le 1024 ]
        then
            echo sips -z $(($s*$mul)) $(($s*$mul)) $1 --out ${output}.iconset/icon_${s}x${s}${add}.png
            sips -z $(($s*$mul)) $(($s*$mul)) $1 --out ${output}.iconset/icon_${s}x${s}${add}.png
        fi
    done
done

iconutil -c icns ${output}.iconset