Nathan Searles nathansearles

Opening and closing an SSH tunnel in a shell script the smart way

I recently had the following problem:

From an unattended shell script (called by Jenkins), run a command-line tool that accesses the MySQL database on another host.
That tool doesn't know that the database is on another host, plus the MySQL port on that host is firewalled and not accessible from other machines.

We didn't want to open the MySQL port to the network, but it's possible to SSH from the Jenkins machine to the MySQL machine. So, basically you would do something like

ssh -L 3306:localhost:3306 remotehost

Note: these are pretty rough notes I made for my team on the fly as I was reading through some pages. Some could be mildly inaccurate but hopefully not terribly so. I might resort to convenient fiction & simplification sometimes.

My top contenders, mostly based on popularity / community etc:

Angular
Backbone
React
Ember

Mostly about MVC (or derivatives, MVP / MVVM).

Encoding Video

Installing

Install FFmpeg with homebrew. You'll need to install it with a couple flags for webm and the AAC audio codec.

brew install ffmpeg --with-libvpx --with-libvorbis --with-fdk-aac --with-opus

What forces layout / reflow

All of the below properties or methods, when requested/called in JavaScript, will trigger the browser to synchronously calculate the style and layout*. This is also called reflow or layout thrashing, and is common performance bottleneck.

Generally, all APIs that synchronously provide layout metrics will trigger forced reflow / layout. Read on for additional cases and details.

Element APIs

Getting box metrics

elem.offsetLeft, elem.offsetTop, elem.offsetWidth, elem.offsetHeight, elem.offsetParent

	<form action="/cart/add" method="post">
	{% if product.variants.size > 1 %}
	{% if product.options[0] %}
	{% assign used = '' %}
	<label for="select-one">{{ product.options[0] }}</label>
	<select id='select-one' onchange="letsDoThis()">
	{% for variant in product.variants %}
	{% unless used contains variant.option1 %}
	<option value="{{ variant.option1 }}">{{ variant.option1 }}</option>
	{% capture used %}{{ used }} {{ variant.option1 }}{% endcapture %}

	#!/bin/bash
	#####################################################
	# Name: Bash CheatSheet for Mac OSX
	#
	# A little overlook of the Bash basics
	#
	# Usage:
	#
	# Author: J. Le Coupanec
	# Date: 2014/11/04

	<VirtualHost *:80>

	ServerName forum.example.com
	Redirect permanent / https://forum.example.com

	</VirtualHost>

	<VirtualHost *:443>

	ServerName forum.example.com

	var uniqueArray = function(arrArg) {
	return arrArg.filter(function(elem, pos,arr) {
	return arr.indexOf(elem) == pos;
	});
	};

	var uniqEs6 = (arrArg) => {
	return arrArg.filter((elem, pos, arr) => {
	return arr.indexOf(elem) == pos;
	});

	#!/bin/bash
	set -e

	show_help() {
	cat << EOF
	Usage: ${0##*/} [-u USER] [-p PASS] [-P PORT] [-H HOST] [DATABASE]
	${0##*/} -h

	Open a standard connection in Sequel PRO.

	// one-liner version
	// retains latin-1 supplement chars as well as latin extended-a and latin extended-b

	Shopify.handleize = function (str) {
	return str.toLowerCase().replace(/[^\w\u00C0-\u024f]+/g, "-").replace(/^-+\|-+$/g, "");
	};