Printing a QR code from the command line.

qrcode.sh

#!/usr/bin/env bash

##
# The dimensions for the physical QR code, in pixels.
# The Brother QL-570 Label Printer tape is 2.44" wide
# at 72ppi, and 72 * 2.44 = 175.68, so 175 is good.
size=175x175

##
# Usage: qrcode [url]
# Summary: Prints a QR code to the [url] on the default printer.
curl https://chart.googleapis.com/chart \
  --data-urlencode chs=$size \
  --data-urlencode cht=qr \
  --data-urlencode chl=$1 \
  --data-urlencode choe=UTF-8 | lp -o media=Custom.$size