2. Change api:
$ tinypng -k I_KC7xGPxXfZPrEbrc-kXWBetAQ323rz
hint: change the above api to your owns. Get api: https://tinypng.com/developers (free 500 images/month. )
Usage: tinypng [options] [image.png|*.png]
-k, --api-key Set default TinyPNG API key.
-r, --allow-rewrite Rewrite the original files with compressed data.
-n, --allow-nonpng Allow you to compress files without .png extention.
-p, --postfix Postfix for compressed files when rewriting disabled.
-h, --help This message.
-v, --version Show version.
Example: tinypng -r image/
this is the folk from https://github.com/ozio/tinypng, this folk just add the feature to support multi level directory.