Jackson Geller jaxgeller

The prep-script.sh will setup the latest Node and install the latest perf version on your Linux box.

When you want to generate the flame graph, run the following (folder locations taken from install script):

sudo sysctl kernel.kptr_restrict=0
# May also have to do the following:
# (additional reading http://unix.stackexchange.com/questions/14227/do-i-need-root-admin-permissions-to-run-userspace-perf-tool-perf-events-ar )
sudo sysctl kernel.perf_event_paranoid=0

This is the script we use at yerdle to print labels from our Rails backend to our Zebra ZP450 printer.

See this blog post for the whole story.

tl;dr

Don't run as root.
For sessions, set httpOnly (and secure to true if running over SSL) when setting cookies.
Use the Helmet for secure headers: https://github.com/evilpacket/helmet
Enable csrf for preventing Cross-Site Request Forgery: http://expressjs.com/api.html#csrf
Don't use the deprecated bodyParser() and only use multipart explicitly. To avoid multiparts vulnerability to 'temp file' bloat, use the defer property and pipe() the multipart upload stream to the intended destination.

tmux shortcuts & cheatsheet

start new:

tmux

start new with session name:

tmux new -s myname

Friendly URLs

By default, Rails applications build URLs based on the primary key -- the id column from the database. Imagine we have a Person model and associated controller. We have a person record for Bob Martin that has id number 6. The URL for his show page would be:

/people/6

But, for aesthetic or SEO purposes, we want Bob's name in the URL. The last segment, the 6 here, is called the "slug". Let's look at a few ways to implement better slugs.

	#!/usr/bin/env python

	#ZPL docs can be found at https://support.zebra.com/cpws/docs/zpl/zpl_manual.pdf
	#This works with Python 3, change the bytes to str if you are using Python 2

	import socket

	#One easy way to find the IP address is with this nmap command
	# nmap 192.168.0.* -p T:9100 --open

	#!/bin/bash

	# @link https://gist.github.com/mattscilipoti/8424018
	#
	# Called by "git push" after it has checked the remote status,
	# but before anything has been pushed.
	#
	# If this script exits with a non-zero status nothing will be pushed.
	#
	# Steps to install, from the root directory of your repo...


	var express = require('express');
	var app = express();
	var port = process.env.PORT \|\| 5000;

	var request = require('request');
	var zlib = require('zlib');

	@mixin circle($width, $color) {
	width: $width;
	height: $width;
	background: $color;
	-webkit-border-radius: $width/2;
	-moz-border-radius: $width/2;
	border-radius: $width/2;
	}

	.circle {

	-- show running queries (pre 9.2)
	SELECT procpid, age(clock_timestamp(), query_start), usename, current_query
	FROM pg_stat_activity
	WHERE current_query != '<IDLE>' AND current_query NOT ILIKE '%pg_stat_activity%'
	ORDER BY query_start desc;

	-- show running queries (9.2)
	SELECT pid, age(clock_timestamp(), query_start), usename, query
	FROM pg_stat_activity
	WHERE query != '<IDLE>' AND query NOT ILIKE '%pg_stat_activity%'