James j-dexx

Generating Authy passwords on other authenticators

There is an increasing count of applications which use Authy for two-factor authentication. However many users who aren't using Authy, have their own authenticator setup up already and do not wish to use two applications for generating passwords.

Since I use 1Password for all of my password storing/generating needs, I was looking for a solution to use Authy passwords on that. I couldn't find any completely working solutions, however I stumbled upon a gist by Brian Hartvigsen. His post had a neat code with it to generate QR codes (beware, through Google) for you to use on your favorite authenticator.

His method is to extract the secret keys using Authy's Google Chrome app via Developer Tools. If this was not possible, I guess people would be reverse engineering the Android app or something like that. But when I tried that code, nothing appeared on the screen. My gues

Elixir installation guide

Version numbers should be the ones you want. Here I do it with the last ones available at the moment of writing.

The simplest way to install elixir is using your package manager. Sadly, at the time of writing only Fedora shows the intention to keep its packages up to date. There you can simply sudo dnf install erlang elixir and you are good to go.

Anyway, if you intend to work with several versions of erlang or elixir at the same time, or you are tied to a specific version, you will need to compile it yourself. Then asdf is your best friend.

Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns             
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns  =  20 µs
SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs

Transactions

As your business logic gets complex you may need to implement transactions. The classic example is a bank funds transfer from account A to account B. If the withdrawal from account A fails then the deposit to account B should either never take place or be rolled back.

Basics

All the complexity is handled by ActiveRecord::Transactions. Any model class or instance has a method named .transaction. When called and passed a block, that block will be executed inside a database transaction. If there's an exception raised, the transaction will automatically be rolled back.

Example

IE 7/8/9/10/11 Virtual machines from Microsoft

Linux installation notes (tested under Ubuntu 14.04LTS/12.04LTS), assuming VirtualBox is already installed on host.

Available images

	# This simplest thing is to clone Jim's repo (https://github.com/jimweirich/gilded_rose_kata) and then
	# put this file in the root directory.

	gem 'minitest', '~> 4.7'

	require "minitest/autorun"
	require "minitest/reporters"
	MiniTest::Reporters.use! MiniTest::Reporters::SpecReporter.new

	require_relative './gilded_rose'

	#!/bin/sh
	#
	# puma - this script starts and stops the puma daemon
	#
	# chkconfig: - 85 15
	# description: Description \
	# goes here...
	# processname: puma
	# config: /etc/puma.conf
	# pidfile: /home/stanislaw/apps/micro-apps/puma/puma.pid

	Lesson 1 SUMMARY


	1. The cursor is moved using either the arrow keys or the hjkl keys.
	h (left) j (down) k (up) l (right)

	2. To start Vim from the shell prompt type: vim FILENAME <ENTER>

	3. To exit Vim type: <ESC> :q! <ENTER> to trash all changes.
	OR type: <ESC> :wq <ENTER> to save the changes.

	# encoding: utf-8

	class AvatarUploader < CarrierWave::Uploader::Base

	include CarrierWave::MiniMagick

	# Choose what kind of storage to use for this uploader:
	storage :file

	# Override the directory where uploaded files will be stored.