Óscar de Arriba odarriba

Ruby, RVM and Mountain Lion

Key problems

Mountain Lion (10.8) has three main difference compared to Lion (10.7):

XCode 4.4 does not install Command Line Tools by default
X11 isn't available anymore
The installed version of OpenSSL has some bugs

How to work around

This is my best try at transcribing of the lightning talk I gave at RUG::B on April 2016. Due to poor time management (LOL) the delivery was rushed and some examples were skipped, I hope having them posted here makes them more useful.

xargs

xargs is a small but very useful program that is installed in most if not all of your computers¹. Many of you probably know it. Those who don't will learn something really useful, but those who do will learn a couple of cool tricks, too.

Why xargs

You might have heard about the Unix philosophy:

	#!/usr/bin/env ruby

	# Put this file in the root of your Rails project,
	# then run it to output the SQL needed to change all
	# your tables and columns to the same character set
	# and collation.
	#
	# > ruby character_set_and_collation.rb

	DATABASE = ''

	authors:
	hanzou:
	name: Hanzou Hattori
	display_name: Hanzou
	gravatar: c66919cb194f96c696c1da0c47354a6a
	email: [email protected]
	web: http://company.com
	twitter: company
	github: hhattori
	jorgen:

	var MoonInfo = function(day, month, year) {

	var n0 = parseInt( "0" );
	var f0 = parseFloat( "0.0" );
	var AG = f0; // Moon's age
	var DI = f0; // Moon's distance in earth radii
	var LA = f0; // Moon's ecliptic latitude
	var LO = f0; // Moon's ecliptic longitude
	var Phase = " ";
	var Zodiac = " ";

	# First, make sure that you have the most recent rvm. Several bugs with 2.0.0-preview1
	# have recently been fixed.
	#
	# Second, the openssl that comes with MacOS is too old for Ruby 2.0. You need to install
	# a newer one with homebrew or the rvm pkg command.

	# Option 1, with homebrew openssl:

	brew update
	brew install openssl

	# Use Homebrew and be happy.
	brew update
	brew install opencv

	# Give the correct pathnames. Of course, `2.4.3` is the current version at this time, change it accordingly.
	gem install ruby-opencv -- --with-opencv-lib=/usr/local/Cellar/opencv/2.4.3/lib \
	--with-opencv-include=/usr/local/Cellar/opencv/2.4.3/include/opencv \
	--with-opencv-include=/usr/local/Cellar/opencv/2.4.3/include/opencv2

	def confirmation(credentials)
	return false if params['ds_signature'].blank?
	# The DES3-CBC key generation it's the same that in the creation gist
	# You can take a look at the explanation
	secret_key = credentials[:secret_key]
	secret_key_base64 = Base64.strict_decode64(secret_key)

	des3 = OpenSSL::Cipher::Cipher.new('des-ede3-cbc')
	block_length = 8
	des3.padding = 0

	require 'net/http'
	require 'uri'
	require 'json'

	def open(url)
	Net::HTTP.get(URI.parse(url))
	end

	page_content = open('http://www.loteriasyapuestas.es/servicios/premioDecimoProvisionalWeb')
	res_json = JSON.parse(page_content)