Earlier today I faced an unusual problem in that the app I’m currently working on involves generating a PDF from HTML (for which we’re using the WebKit HTML to PDF library) and I needed to include the designers’ PNGs without making a network request for them. The immediate answer to this is to use the Data URI scheme. This left me with a handful of PNGs which I needed to convert to Base64. There are online tools which will do this conversion but, to be honest, I just don’t trust them.

My colleague (a very capable Ruby developer) showed me a great way to achieve this using nothing but Ruby. The command line snippet below will probably be fairly self-explanatory and will result in the Base64 string being copied to the clipboard ready for pasting into an <img /> attribute.

ruby -e "require 'base64'; puts Base64.strict_encode64(File.open('./app/assets/images/exclamation.png').read)" | pbcopy

Update: to do the same thing in bash

opopenssl base64 -in image.png -out image.txt

An alternative to -out is to pipe it to pbcopy

openssl base64 -in image.png | pbcopy`