Ruby

command line apps

http://blog.honeybadger.io/writing-command-line-apps-in-ruby/ - tutorial on command line apps in ruby

http://culttt.com/2015/07/01/creating-and-using-modules-in-ruby/ - using ruby modules

http://www.stuartellis.name/articles/rake/#using-other-ruby-libraries-in-rake-tasks - rake tasks

GSUB

https://stackoverflow.com/questions/16579223/using-named-capture-groups-inside-ruby-gsub-blocks-regex - capture groups in gsub