Teddy Caddy tcaddy

This page collects a set of bash scripting idioms and tools for easy reference.

Improved Error Detection: `set -e` and `set -u`

With -e (errexit), bash exits immediately if an unchecked command exits with a nonzero value. A checked command is part of a while, until, if, elif, or an expression with && or ||. Everything else is unchecked. For a pipeline, only the last command is considered. Adding "or no-op", || :, ensures a command is safe, e.g., do-something | grep 'may_not_match' || :. NB. Calling a bash function in a checked context effectively disables -e for all commands in the function. Use the optional shellcheck, check-set-e-suppressed, to alert on this.

set -e, -u, -o, -x pipefail

The set lines

These lines deliberately cause your script to fail. Wait, what? Believe me, this is a good thing.
With these settings, certain common errors will cause the script to immediately fail, explicitly and loudly. Otherwise, you can get hidden bugs that are discovered only when they blow up in production.

set -euxo pipefail is short for:

set -e
set -u

The setup of a bluetooth speaker on a Pi Zero W is pretty touchy.

Please get in touch via Twitter @actuino or http://www.actuino.fr/ if you've got comments or improvements to this quick draft.

First checks

Use a solid power source
check the speaker works on another hardware (android phone f.i.)
make sure you've updated your Raspbian, install and run rpi-update just in case.

An Ansible summary

Jon Warbrick, July 2014, V3.2 (for Ansible 1.7)

Configuration file

intro_configuration.html

First one found from of

Falsehoods Programmers Believe About "Women In Tech"

We have absolutely no idea what we're doing in tech. Please explain the utmost basic things to us.
We only do web design. Our whole reason of being in tech is to make things pretty. Consider us the doilies of the industry.
We're not laughing about your joke, so we clearly need you explain it to us. In great detail.
We're only in tech to find a husband, boyfriend or generally to get laid.

	apiVersion: v1
	kind: ConfigMap
	metadata:
	name: example
	namespace: default
	data:
	APPLICATION_HOST: example.com
	LANG: en_US.UTF-8
	PIDFILE: /tmp/server.pid
	PORT: "3000"

	Add-Type -AssemblyName System.Windows.Forms

	while ($true)
	{
	$Pos = [System.Windows.Forms.Cursor]::Position
	$x = ($pos.X % 500) + 1
	$y = ($pos.Y % 500) + 1
	[System.Windows.Forms.Cursor]::Position = New-Object System.Drawing.Point($x, $y)
	Start-Sleep -Seconds 10
	}

	require 'rails_helper'

	RSpec.describe TodosController, :type => :controller do

	describe "GET #index" do
	#describe "POST #create" do
	#describe "GET #show" do
	#describe "PATCH #update" do (or PUT #update)
	#describe "DELETE #destroy" do
	#describe "GET #new" do

	# This is a skeleton for testing models including examples of validations, callbacks,
	# scopes, instance & class methods, associations, and more.
	# Pick and choose what you want, as all models don't NEED to be tested at this depth.
	#
	# I'm always eager to hear new tips & suggestions as I'm still new to testing,
	# so if you have any, please share!
	#
	# @kyletcarlson
	#
	# This skeleton also assumes you're using the following gems:

	Rails.application.eager_load!
	ActiveRecord::Base.descendants # It returns all models and its attributes.
	ApplicationRecord.descendants.collect(&:name) # It returns only the model names