[MAC] convert png to icns with terminal

Use sips to convert png to icns

$ sips
sips 10.4.4 - scriptable image processing system.

This tool is used to query or modify raster image files and ColorSync ICC profiles.
Its functionality can also be used through the "Image Events" AppleScript suite.
Try 'sips --help' or 'sips --helpProperties' for help using this tool

Command

$ sips -s format icns input.png --out output.icns