A bash function to resize a collection of icons (e.g. png images) and organize them using android studio's drawable directory format.

resize_drawables.sh

#!/bin/bash

# Given a collection of .png files, this function will resize the images
# and organize them in a way that android studio expects.
#
# Usage:  resize_drawables *.png
#
# Given a file, my_icon.png, the command:
#
#   rezie_drawables my_icon.png
#
# will output:
#
#    drawable-mdpi/my_icon.png
#    drawable-hdpi/my_icon.png
#    drawable-xhdpi/my_icon.png
#    drawable-xxhdpi/my_icon.png
#    drawable-xxxhdpi/my_icon.png

function resize_drawables()
{
    for file in "$@"; do
        sizes=(24, 36, 48, 72, 96)
        locations=(mdpi hdpi xhdpi xxhdpi xxxhdpi)

        for i in ${!sizes[@]}; do
            mkdir -p drawable-${locations[$i]}
            sips -Z ${sizes[$i]} $file --out drawable-${locations[$i]}
        done
    done
}